Theses and dissertations (Applied Sciences)

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Adressing food and nutrition insecurity through the development and implementation of an agricultural and nutrition education programme on legumes for older farmers living in Mariannhill, KwaZulu-Natal, South Africa
(2020) Mkhize, Nkumbulo Xolile; Napier, Carin E.; Oldewage-Theron, Wilna; Duffy, Kevin Jan
Introduction Food and nutrition security can be influenced by various external and internal factors that contribute to a compromised wellbeing status amongst older farmers who are considered as a vulnerable group. This group faces diverse socio-economic and health challenges within an evolving food system. The complexity of this challenge persistently requires multisectoral intervention programmes, as reflected in the nature of this study. Aim and Objectives The aim of the study was to determine the levels of and address the food intake and nutrition insecurity status of elderly farmers. The main objective was to address the challenges that compromised the health of selected previously non-legume producing farmers by encouraging legume production and consumption amongst them. The findings of the study informed the proposal of appropriate strategies to develop an intervention programme intended to educate the identified elderly farmers and to promote their dietary diversification by means of legume production and consumption. Methodology The study employed a cross-sectional design. A baseline study was conducted that aimed at examining variable relationships using a mixed methods approach involving both qualitative and quantitative data collection techniques. A sample of 112 elderly farmers participated in the baseline study, followed by a case-controlled intervention programme that included preand post-intervention surveys. The measuring instruments included socio-demographic as well as health and medical surveys to elicit data such as blood pressure, blood indices for glucose and cholesterol due to dietary intake, household food security, legume knowledge, legume acceptability and agricultural practices. The data informed the findings of both the baseline and the intervention phases of the study. The baseline study involved a sample of 112 elderly farmers, whereas the intervention study involved two case controls (n=103) that comprised an experimental group (EG: n=53) and a control group (CG: n=50). Data were obtained for both groups by analysing blood indices, dietary intake, yields of legume production (EG only) and legume acceptability levels using statistical analyses of variance, significance and trends of pre- and post-intervention surveys over two years. A follow-up survey (FU) was conducted six months after the conclusion of the intervention phase and involved only the EG (n=32), to assess the impact of the intervention programme on their dietary intake and farming practices. The follow-up study thus compared the intervention data of the farmers’ consumption and production patterns with data obtained postintervention. During this latter study, only dietary intake and production levels were measured. All the data were analysed using IBM Statistical Package for Social Sciences (SPSS), Food Finder software, the Mann-Whitney U test, Analysis of Variance (ANOVA) and T-tests for statistical frequencies, variances and correlations. Results In the baseline study, 79.5% of the participants were women. The mean age of the participants was 63.3 ± 8.2 years. A diverse legume consumption was not observed as indicated by a low legume food group diversity score (FGDS) for 0-9 varieties with a mean of 3.5 (SD ± 1.70). Legumes were the least (19.0%) preferred crop planted by the farmers prior to the study. In the intervention study, the majority of participants were also women (73.6% in the EG and 66.0% in the CG). Of the six varieties of legumes under study, red kidney beans was the most preferred (141.60 kg/ha-1 SD ± 162.11). There was a high significance (p=0.001) amongst the six legume varieties produced, which implies that some legumes had a higher yield than others. A comparison between the genders indicated that the women produced 81.70 kg/ha-1 (SD ± 77.95), while the men produced 33.63 kg/ha-1 (SD ± 166.40). The higher yields produced by the women were significant (p=0.011). Legume consumption improved for the EG because the intervention programme resulted in a significantly (p=0.000) increased dietary diversity score (DDS) of legume intake with a mean (±SD) FGDS from 2.4 (SD ± 1.35) to 5.7 (SD ± 2.56) and a mean (±SD) Dietary Diversity Score (DDS) from 8.59 ± 0.74 to 8.23 ± 1.11, while that of the CG was 3.0 (SD ± 1.82). According to the post-intervention survey, the blood results of the EG indicated nutrient improvement at the 5.0% significance level for blood glucose (p=0.038) and cholesterol (p=0.008). The blood glucose levels of the EG were statistically significant (p=0.037) when this group was compared with the CG in both the pre-intervention and post-intervention surveys. Trend analyses were conducted and compared between those men and women who participated throughout the study (i.e. participation from the baseline to the post-intervention surveys). It was found that cholesterol (p=0.033) and Systolic Blood Pressure (SBP) (p=0.013) were statistically significant when the genders were compared across all phases of the study. Data obtained for the EG in the Follow Up (FU) study six months after the intervention study indicated that the production of legumes had declined (71.8%). This was because the legume intake with a mean (±SD) FGDS of 3.0 ± 2.2 indicated a significant (p=0.000) drop from 5.7 (SD ± 2.56) with DDS from 8.23 (± 1.11) to 8.81 (± 0.47) at p=0.005 significance as determined by the FU survey. It was also found that limited marketing of legumes had occurred, which suggests that the sustainability of legume production and consumption post-intervention by the elderly farmers was a challenge. However, 100.0% of the farmers indicated that they intended to continue their production and consumption of legumes, provided that the constant supply of legumes did not cease. Conclusions Evidence was obtained that the intervention project positively impacted the production and consumption of legumes and that the elderly farmers thus diversified their dietary intake for the better during this phase of the study. However, further investigations need to be conducted to explain the decline in consumption and production in the post-intervention period if support for a healthier lifestyle amongst elderly farmers is to be sustained. The technology to produce legumes with high yields to address food insecurity through more appropriate consumption patterns also needs to be explored in greater depth. Because the two streams of knowledge transfer that involved hands-on training of elderly farmers improved legume production and consumption patterns, this study established a sound foundation on which future studies and intervention strategies for food security amongst vulnerable groups may be built.
Analysis of nanoscale ingredients in commercial food and cosmetic products by field-flow fractionation and single particle ICP-MS
(2020-09) Naidoo, Lyndon; Bisetty, Krishna; Kanchi, Suvardhan; Sabela, Myalowenkosi Innocent
There is a growing need to disclose the possible presence of nanostructures on the labels of commercial food and cosmetic products in South Africa. Synthetic amorphous silica (SiO2) and titanium dioxide (TiO2) are the two widely used nanoparticles (NPs) selected for this study. This work was undertaken in two stages. The first part deals with an analytical method developed for the separation and characterization of TiO2 NPs capped with poly(ethylene glycol) (PEG) as a potential reference material for sunscreen analysis. The second aspect of this work focuses on SiO2, a highly attractive biomaterial widely used as a food additive (E551) to improve the flow properties of powdered food ingredients. Also, modern computational methods were implemented in both case studies, to better understand the nanoparticulate interactions with the organic substrates at an atomistic and molecular level. For the cosmetics study, asymmetric flow field-flow fractionation (AF4) coupled online to multi-angle light scattering (MALS) and dynamic light scattering (DLS) detectors were employed to assess the geometry and size of the PEGylated TiO2 NPs in terms of the evaluated radius of gyration (rg) and hydrodynamic radius (rh). Single particle inductively coupled plasma mass spectrometry (spICP-MS) and transmission electron microscopy (TEM) were implemented to provide information on the core diameter (d) of the TiO2 particle. To overcome agglomeration, Monte Carlo simulations were employed in this study to assess the effectiveness of PEG capped onto spherically constructed TiO2 anatase nanoclusters by systematically performing a series of adsorption studies. For PEG-TiO2 NPs, AF4-MALS-DLS reported rg and rh values of 28.7 nm and 40.3 nm respectively, with the shape factor (rg/rh) values generally reported in the range of 0.7 to 0.8, indicative of spherical particle geometry. SpICP-MS and TEM obtained complementary measurements of d = 32.0 nm and d = 38.4 nm, respectively. The computational modelling results demonstrated the strong binding affinity of PEG as a capping agent to TiO2, exhibiting stabilisation of TiO2 NPs in aqueous medium. Finally, the developed AF4-MALS-DLS method was applied to two commercial SPF 50 sunscreens, exhibiting promising separation and detection efficiency. These findings can contribute to regulatory measures in line with the South African National Nanotechnology Strategy for the cosmetics industry. With regards to the food application study, a multivariate method was developed for the detection and characterization of SiO2 particles also based on AF4-MALS-DLS. This analytical approach attempts to address the fate and the presence of nanoparticulate SiO2 additives (E551) in food products. The experimental design using SiO2 NP standards resulted in the following optimum conditions of the system: crossflow, 0.8 ml/min; injection time, 5 min and sonication time, 60 min. It was observed that the average geometric diameters (Dgeo) for SiO2 NPs in three selected commercial coffee creamers (A, B and C) detected by AF4-MALS were 286.7 nm, 129.8 nm and 190.7 nm respectively. Similar trends for the coffee creamers were observed for the hydrodynamic diameter (Dh) measurements using AF4-DLS i.e. 301.5 nm, 141.3 nm and 197.8 nm respectively. The rg/rh values were reported ranging from 0.7 to 0.8, indicative of spherical particle geometry. Also, the electrostatic interactions between SiO2 NPs and glucose/water mixtures, as evaluated by Monte Carlo simulations, revealed O-interactions dominating over the flat amorphous SiO2 surface. The strongest interaction observed (around - 239 kcal/mol) for the SiO2-water/glucose mixture demonstrates the hydrophilic nature of SiO2 NPs. The findings in both case studies provide fundamental information to improve the understanding of nanoparticulate interactions with additives and paves the way for the labelling of cosmetic and food products that potentially exhibit nanomaterials in complex matrices.
Analysis of the nutritional status and dietary intake data of a group of elderly at a day and frail care centre in Verulam
(2011) Govender, Theloshni; Oldewage-Theron, Wilna; Napier, Carin E.
Background: South Africa, a richly diverse developing country has been faced by the consequences of transition attributed to urbanisation and acculturation. A Westernised lifestyle has, therefore, resulted in increasing disease patterns that are characterized by a combination of poverty-related diseases together with the emerging chronic diseases. The shift to a Westernised lifestyle has resulted to a shift in the composition of dietary staples leading to dietary factors related to an increase in lifestyle diseases. These include a high fat, low fibre diet, as well as an inadequate intake of fruits and vegetables. However, this in turn has led to higher energy intakes with insufficient and imbalanced micronutrient intake. Research conducted amongst the elderly in South Africa has clearly indicated that the elderly live within a limited financial budget leading to extreme levels of food insecurity and the social burden of being the head of the household, in addition to being the caregiver to grandchildren and sick children. Due to the current living status the elderly encounter reduced food intake in addition to a reduced variety in their diet, therefore, micronutrient deficiencies are common amongst this age group. Therefore, a consumption of energy-dense foods, particularly staple foods, to stretch the food budget which are more affordable and thus allow for an increased consumption is evident. Aim: To determine the socio-demographic profile, health and nutritional status in relation to the dietary intake patterns to reflect malnutrition among free living elderly (60yrs+) in Verulam. Methodology: Fifty nine randomly selected men and 191 women aged 60+ participated on a voluntary basis in this study. A descriptive survey method was used for this cross sectional study. Trained fieldworkers assisted with the administration of all questionnaires and a registered nurse measured blood pressure. Socio-demographic questionnaires were administered to determine the socio-economic characteristics of the elderly within this community. Anthropometric measurements determined the Body Mass Index according to the World Health Organisation and Asian cut-off points to indentify the risk factors. The Health questionnaire identified the health status correlated to the respondent’s profundity of disease and deficiencies associated to dietary patterns. Blood pressure measurements were taken to determine the hypertension prevalence related to the dietary intake. Two 24-Hour Recall questionnaires were completed by the 250 respondents to identify actual vii food intake and measured against the Dietary Recommended Intake (DRIs). A food frequency questionnaire (FFQ) determined the respondent’s food variety score over a period of one week. The socio-demographic questionnaire, health questionnaire, food frequency questionnaire and anthropometric measurements were captured on an Excel® spread sheet by the researcher and analyzed for descriptive statistics using the Statistical Package for the Social Sciences (SPSS) version 17.0 with the assistance of a statistician. The 24-Hour Recall data were captured and analyzed by a nutrition professional using the MRC Food Finder® version 3.0 software, based on the South African Food Composition tables. Results: The majority of the respondent’s role in the family was mothers (70.8%) and lived in an urban area (68.8%). In addition, 73.2 percent (n=183) of the respondents shared the house with one to five people, and lived in a brick house (74.4%, n=186) with more than 3 rooms (74.0%, n=185). The elderly in this sample were pensioners and, therefore, 76.0 percent (n=190) received state grants of which the total household income ranged between R1001-R1500 (35.2%, n=88). Food insecurity is prevalent as reported by 28.4 percent. Primary school was the highest level of education completed by 52.4 percent (n=131) and English is the most spoken language amongst this group (74.0%, n=185). Women had higher BMI values particularly in the overweight (18.32%, n=35) and obese I and II (58.6%, n=112) categories when compared with men. Blood pressure measurements indicated that 60.0 percent (n=150) of the respondents suffered from hypertension. The use of chronic medication was reported by 84.4 percent (n=212). The total range of individual food items consumed by an individual during the seven-day data collection period measured by the (FFQ) was between 4-66 foods. However, the highest consumption was four food items by 23.2 percent (n=58) of the respondents. The summary of the food variety within food groups indicated a high dietary diversity, of which the other vegetable group reported the highest individual mean FVS (±SD) of 10.86 (±5.82), followed by other fruit, cereal, flesh and Vitamin A rich groups with 5.73 (±4.41), 5.03 (±1.85), 4.08 (±2.23) and 2.43 (±1.09) respectively. The nutrient analysis indicated a deficient intake by both men and women of all the nutrients, except for the mean (±SD) total protein in the women 45.10 (±12.55) and carbohydrate 212.83 (±36.97) in the men. The energy contribution indicated 98.3 percent (n=58) men and 85.72 percent (n=158) women consumed <100 percent of the EER for viii energy. However, the findings from the Top 20 food items measured by the 24-Hour Recall indicated that this community’s diet is largely carbohydrate-based, containing primarily starchy staple foods, sufficient intake of animal products, and insufficient intakes of dairy foods, fruit and vegetables, possibly resulting in the micronutrient deficiencies. The energy distribution of the macronutrients from the average of both 24-Hour Recalls indicates that both men and women are in range of 15-30 percent total fat intake, 10-15 percent protein and 55-75 percent carbohydrate. Conclusion: The results of the study reflect that the elderly in this community are faced with poverty, food insecurity as well as social factors thus contributing to a compromised nutritional status. The progression of malnutrition in particular overnutrition is experienced by the majority of the respondents in this study, however, an increased BMI and the prevalence of hypertension is a risk marker for noncommunicable diseases. However, the high prevalence of inadequate food and nutrient intake amongst elderly discloses the need for nutrition interventions and should be aimed at modifying the elderly food choices when purchasing food, healthier food preparation methods, increasing fruit and vegetable portions and improving daily physical activity to attain a better quality of life.
Anthropometric profile and food consumption patterns of an emerging middle income community in Umlazi
(2017) Memela, Sinenhlanhla Ntokozo; Napier, Carin E.
Introduction: The nutrition transition is a global phenomenon affected by developing economic prosperity. ‘Nutrition transition’ may be defined as changes in dietary patterns and nutrient intakes occurring in individuals, families, groups of people or whole populations when the food environment and other circumstances change. Post-1994 democratic elections in South Africa, economic laws called for the de-racialization of the economy. As a result of the annulment of the apartheid laws in the 1990s entrepreneurial opportunities became available for black people. Based on the 2011 Census, the middle class constituted 8.3 million (17%) out of the 51 million population in South Africa. Blacks made up 51%, whites 34%, coloureds 9% and Indians 6%. This is a vast difference from two decades prior to this when blacks made up only 3.3% of the population, with coloureds making up 9.1% and Indians 18.5%. In a number of Sub-Saharan African studies obesity has been shown to have a significant link to socio-economic status determined by access to water and electricity, smaller numbers of members residing in one household and increased amounts of money spent on food among other factors, which all promote a tendency to leading a more Westernised lifestyle. The main objective of the study was to determine the anthropometric status and analyse the food consumption of a community of emerging middle income status in Umlazi Township (Ward 84) outside Durban in the province of KwaZulu-Natal. Methods: This study had a sample size of n=250 adult men (n=56) and women (n=194) who were heads of households or primary caregivers above the age of 19 years old with households receiving a total household income of more than R100 000.00 per annum/ more than R8000.00 per month. The study was quantitative and descriptive in nature with different tools used to measure the sample population. These included waist circumference and height and weight measurement to determine BMI and WHtR. A socio-demographic questionnaire was completed where the multi-dimensional poverty index (MPI) was established; a food frequency questionnaire (FFQ) and three 24-hour food recall were also administered to all participants; one weekend day recall and two weekday recalls. Data were analysed on SPSS and nutrient analysis done through Food Finder Version 3 Software and compared to the World Health Organisation standards recommendations for optimal health. Results: The mean age of the group was 52 years old. Slightly more than half (51.6%; n=129) of the population was unemployed. Retired participants made up 27.2% (n=68) of the population. The majority (80%) of the households indicated that between one to three members contributed to the total household income. The MPI of the Ward 84 community amounted to 9.09. The prevalence of obesity was 37.59% (n=21) among men and 76.80% (n=149) for women. Women had a higher prevalence of risk factors linked to non-communicable diseases than men. Mineral and fat soluble vitamin intake was deficient; however protein and carbohydrates were consumed in excess with means of 187.70% and 111.43% respectively. Top 20 foods consumed lists indicated that little fruit or vegetables were consumed. The average food variety score was medium indicating the consumption of between >30 but <60 different foods across the total population. A positive relationship of statistical significance was found between food variety score and income (p=0.007). Conclusion: The Ward 84 community consisted of an ageing population with households mostly supported by another member’s income from within or outside the household. The adults had sufficient education to have secured promotions in the employment arena and could afford a lifestyle similar to that of those who had always been more privileged. Although the Umlazi residents benefited from good housing and infrastructure and appeared to have averted poverty, the prevalence of overnutrition malnutrition was high and linked with an excessive intake of macronutrients. Majority (70%) of the community of Ward 84 is ‘food secure’ as indicated by the number of participants’ households indicating never having a shortage of money to buy food. This correlates negatively with the high prevalence of overweight and obesity (BMI) (p=-0.029). According to literature a persistent issue in black communities is the acceptance of an overweight body image being perceived as ‘healthy’ and an indicator of affluence. This community appears to be in the 4th stage/ pattern of the nutrition transition. It appears that a ‘westernised diet’ and lifestyle is more accessible and is embraced by this urban community as described in various literature and seen in the top 20 foods lists compiled from the 24 hour recalls. There is some oversight regarding the nutrient quality of a varied diet and achieving energy balance with macronutrient intake linked to informed nutritional choices. Suggested interventions could include the dissemination of information regarding nutrition and practical suggestions to achieve energy balance. In addition, future research could investigate the prospects of introducing participation in urban agriculture, investigate the issue of physical activity, and foster an environment for more physical activity and increase availability and access to micronutrient dense foods and investigate the development of a body mass index specifically for the black African population.
Application of thermostable a-Amylase from Thermomyces lanuginosus ATCC 58157 to nutritionally enhance starch based food
(2006) Padayachee, Thiriloshani
In Sub-Saharan Africa there is an urgent need to sustain and improve the quality of its food resources. Poverty eradication features high on the agenda of a number of world health organisations, while the number of underweight children in Africa continues to increase (Pellet, 1996). Providing nutritionally enhanced foods to the poor will help towards achieving this objective. Protein-energy malnutrition has been identified as one of the most important problems facing Africa, with maize as the staple diet (Nkama et al., 1995). However, a combination of several factors limits availability and the nutritional quality of maize. During starvation, energy and protein intakes decrease by 20-30%, with most of the children in Africa having an average protein intake of only 20 g per day (Igbedioh, 1996). Energy availability also affects protein utilization because of interrelationships of protein and energy metabolism (Elwyn, 1993). The diets of inhabitants in developing regions depend mainly on cereals (maize) for both protein and dietary energy which lacks indispensable amino acids, minerals, vitamins and carbohydrates. In light of these growing concerns an attempt was made to devise a scientific strategy to combat the nutritional shortfalls of maize meal. A multidisciplinary and concerted approach was followed within this project aimed at designing an improved thermostable amylase and applying the enzyme to nutritionally enhance maize meal. It was envisaged that the manipulation of maize meal, by the application of enzyme technology will improve the nutritional status of this staple food. The consequences is that an alternate solution for the eradication of an ailing, poverty stricken and malnourished African population is achievable. It is possible that the boundaries defining the limits of life will extend to even greater extremes through the application of novel technologies.
Biodiversity of anaerobic cellulolytic bacteria in landfill sites
(2001) Goldstone, Loren; Tivchev, G. N.
Landfills play an important role in the removal of waste from the surroundings. There is a limit to the types of waste that can be recycled and the landfill becomes the final method of waste disposal. Because waste constitutes a wide variety of materials, the microbial consortia that develop within a landfill will be equally varied, depending on the type of waste deposited, the temperature of the landfill and moisture content of the waste. The metabolism of these microbial consortia can result in products that are either harmful or beneficial. In order to increase the pool of knowledge on landfill microbiology, it is important to study the various consortia that inhabit the landfill to determine the various microbial interactions that occur and subsequently to manipulate these interactions to enhance the benefits of a landfill site and reduce the harmful effects. In this research, an attempt was made to isolate anaerobic cellulolytic bacteria from a landfill site. Six waste samples, varying in age were obtained over a period of two years. Samples were excavated from a maximum depth of 4m. Samples are processed in anaerobic, phosphate buffer and cultivated in various pre-reduced anaerobic media and incubated under anaerobic conditions. Samples were also collected from other potential anaerobic sites namely, anaerobic sludge, decomposing bagasse, compost, manure, rumen and pond sediment. Results of degradation of the cellulose source (Whatman No. 1 filter paper) indicated that it was possible to cultivate cellulose-degrading microorganisms from the landfill. Zones of clearing around colonies, which would be indicative of cellulose degradation on solid media, were not obtained. Samples from the anaerobic sludge, compost and rumen showed degradation of cellulose in liquid media but not on solid media. It is concluded that the solid media used was unsuitable for the cultivation of anaerobic, cellulolytic bacteria or that the anaerobic conditions employed were not adequate to initiate the growth of the anaerobic cellulolytic bacteria.
Characterisation and application of bambara protein-polysaccharide complex coacervates in encapsulation of bioactive compounds
(2019) Busu, Nyasha M.; Amonsou, Eric Oscar
Bambara groundnut (Vigna subterranea) is a leguminous crop that is indigenous to Africa. In South Africa, the legume is cultivated in KZN, Limpopo and Mpumalanga where it is considered a traditional food. Bambara groundnut is a good source of protein (15 – 28 %) and contains substantial amounts of starch. The legume thrives well in areas of low agricultural input. Despite its good protein content, bambara groundnut is mostly cultivated in rural areas for by subsistence farmers. In recent years, there has been increased interest in bambara groundnut protein as an alternative protein source. The purpose of this study is to investigate the complexation behavior of bambara protein with gum Arabic and test the application of the formed complexes in encapsulation and delivery of bioactive compounds. In the first part of this study, four protein fractions extracted at different pH including the salt-solubilisation method were complexed with gum Arabic. The protein content as well as physicochemical properties (SDS-PAGE, FTIR, Zeta potential, SEM) of the protein fractions and resulting bambara protein-gum Arabic (BPI-GA) complexes were then investigated. In subsequent parts of the study, bambara protein extracted by the salt-solubilisation method was complexed with gum Arabic. The influence of ionic strength and biopolymer mixing ratio on complex formation was investigated. Subsequently, the emulsification properties, foaming properties, encapsulation efficiency and release properties of the formed complexes were also investigated under simulated gastric and intestinal pH conditions. The salt-soluble fraction showed the highest protein content (82%) whilst the lowest protein content (76%) was recorded at pH 2. The FTIR analyses revealed an increase in β-sheet content with decrease in pH of extraction. Complexation of the protein fractions with GA resulted in the optimal pHs of interaction shifting towards acidic regions (pHopt: 4.8 to 2.9) as pH of protein extraction became more acidic. Upon complexation, protein fractions produced coacervate yields ranging between 41 - 68%, with the pH 2 fraction recording the lowest (41%) yield. Further, addition of gum arabic seemed to broaden the turbidity profiles. When assessed by SEM, the particles appeared as spherical and aggregated structures between 100-200 nm.
Characterisation of biodiesel from Litsea glutinosa
(2014-08-08) Perumal, Alicia Ann; Odhav, Bharti
Global warming is a major concern to the world’s population. It is caused by greenhouse gases that result from the burning of fossil fuel. The fossil fuel reserves are rapidly depleting as the needs and wants of man in the world increases. Biodiesel is one of the solutions proposed to remedy this environmental crisis facing the world today. The aim of this study was to characterise the biodiesel that can be produced from the oil of Litsea glutinosa by transesterification. Biodiesel can be used in a diesel engine without modification and be produced from many different natural renewable oil sources such as algae, plants and kitchen waste material. Jatropha curcas has been identified as a potential producer of oil for biodiesel. The biodiesel properties of Jatropha curcas meet the required American Society for Testing and Materials (ASTM) standards. The fruit of Jatropha curcas contains 40.0% lipids. The oil has a saponification number of 202.6 and an iodine value of 93.0. However Jatropha curcas cannot be grown in South Africa because it is a highly invasive plant. Cetane number is the most important parameter of biodiesel. The higher the cetane value, the better the quality of the biodiesel. Oil from Jatropha curcas has a cetane number of 57.1. An alternative is the oil from Litsea glutinosa, which is found as a naturalised free forest along the South African coastline, and is also found in many Asian countries. It has many medicinal properties, however, it is not edible and hence its use for biodiesel does not add to the debate of fuel versus food production. The cetane number of oil from Litsea glutinosa is 64.79, which is ideal for ignition, and the fruit with 61.29% lipids can yield valuable quantities of biodiesel. Thus, the aim of the research was to determine the potential of Litsea glutinosa as a source of biodiesel. Furthermore, to maintain a sustainable source, Litsea glutinosa was micropropagated, and transformation of Litsea glutinosa was attempted for hairy root cultures. The Clevenger apparatus was used to extract fatty acids from dried crushed fruit of Litsea glutinosa. Fatty acids were converted to fatty acid methyl esters by transesterification. Transesterification was conducted in the presence of nitrogen and the reaction was catalysed with a mixture of methanol and sodium hydroxide (NaOH). The ratio 1 : 3 of oil to catalyst mixture was used for optimum transesterification to ensure a forward reaction and it was transferred to a separating funnel to allow the glycerol and fatty acid methyl esters to separate. GC-MS was used to determine the fatty acids. The iodine number, saponification number, acid value, viscosity, kinematic viscosity, density, specific gravity, thermostability, distillation point and sulphur content were determined. The seeds of Litsea glutinosa were germinated and tissue culture callus was produced from the seeds and leaves. The leaves and stems were used to produce hairy root cultures by inoculating them with Agrobacterium rhizogenes. Litsea glutinosa yielded 61% oil, which included 47 fatty acids in the fruit and 24 fatty acids in the seeds. The fatty acid profile of the oils indicated that the predominant fatty acids present were those that are essential for good quality biodiesel. The dominant fatty acids found in the fruit were 65.4% 9-octadecenoic acid and 13.6% hexadecanoic acid. The dominating fatty acids found in the seeds contained 36.3% 9-octadecenoic acid, 13.9%, hexadecanoic acid and 39.1%, dodecanoic acid. The iodine value was 6.3. The saponification value was 274. The acid value was 0.45 mg KOH. g-1. The viscosity was 22.48 mm2. s-1 and the kinematic viscosity was 23.84 mm2. s-1. The density was 942.69 kg. m-3 and the specific gravity was found to be 0.9 g. cm-3. The distillation temperature ranged between 52.2°C to 610.2°C. The sulphur content was found to be 383 µg. ml-1. These characteristics indicate that Litsea glutinosa can be used as a source of biodiesel, because the properties meet the required ASTM standards. However, the production of biodiesel from Litsea glutinosa has not been commercialised because the production of fuel is dependent on the fruit of the plant, which is seasonal. To overcome this, a part of this study investigated micropragation of Litsea glutinosa and transformation of Litsea glutinosa by Agrobacterium rhizogenes into hairy roots and attempts where made to determine whether fatty acid could be produced by these techniques. Callus cultures were grown on MS media and McCowns woody plant media supplemented with 1 ml BAP and 1 ml 2,4-D per 1 L of media. Callus cultures were obtained in the light. However, Litsea glutinosa resisted transformation by Agrobacterium rhizogenes.
Characterization and application of amadumbe starch nanocrystals in biocomposite films
(2017) Mukurumbira, Agnes R.; Amonsou, Eric Oscar; Mellem, John Jason
Amadumbe (Colocasia Esculenta) commonly known as Taro is an underutilized tuber crop that produces underground corms. It is a promising tropical tuber grown in various parts of the world including South Africa, where it is regarded as a traditional food. It is a significant subsistence crop, mostly cultivated in rural areas and by small scale farmers. Amadumbe is adapted to growing in warm and moist conditions. The tubers are characterised by a high moisture content and consequently high post-harvest losses. The losses can be minimized through the utilization of various preservation techniques such as flour and starch production. Amadumbe corms may contain up to 70-80% starch. The starch granules are characterised by a small size and relatively low amylose content. The combination of high starch content, low amylose and small starch granules thus make amadumbe a potentially good candidate for nanocrystal production. In this study two amadumbe varieties were utilized to extract starch. Amadumbe starch nanocrystals (SNC) were produced using an optimized hydrolysis method. The physicochemical properties (morphology, crystallinity, thermal properties) of the resulting SNC were investigated. The SNC were then applied as fillers in three different matrices namely, amadumbe starch, potato starch and soy protein. The influence of the SNC at varying concentrations (2.5, 5 and 10%) on the physicochemical properties of bio-composite films was examined. Amadumbe starch produced a substantially high yield (25%) of SNCs. The nanocrystals appeared as aggregated as well as individual particles. The individual nanocrystals exhibited a square-like platelet morphology with sizes ranging from 50-100 nm. FTIR revealed high peak intensities corresponding to O-H stretch, C-H stretch and H2O bending vibrations for SNCs compared to their native starch counterparts. Both the native starch and SNC exhibited the A–type crystalline pattern. However, amadumbe SNCs showed a higher degree of crystallinity possibly due to the removal of the armorphous material during acid hydrolysis to produce SNCs. Amadumbe SNC showed slightly reduced melting temperatures compared to their native starches. The SNC presented similar thermal decomposition properties as compared to their native starches. In general, the inclusion of SNCs significantly decreased water vapour permeability (WVP) of composite films whilst thermal stability and tensile strength were increased. The degree of improvement in the physicochemical properties of the films varied with the type of matrix as well as the concentration of the nanocrystals. It generally seemed that the enhancement of the physicochemical properties of starch matrices occurred at a lower SNC concentration in comparison to that of soy protein films. Amadumbe SNC can indeed potentially be used as a filler to improve the properties of biodegradable starch and protein films
Characterization and application of bambara groundnut starch-lipid complexes
(2017) Oyeyinka, Samson Adeoye; Amonsou, Eric Oscar; Singh, Suren
Bambara groundnut (Vigna subterranea) is an indigenous underutilised leguminous crop to Africa. It is a good source of protein and carbohydrate including starch. Bambara groundnut is a traditional crop grown mainly for subsistence in Southern Africa. Bambara groundnut has the advantage of being drought tolerant and can thrive in hot temperatures and poor soil conditions. Therefore, it has great potential as an alternative crop to soya bean and peanuts for cultivation and utilisation. Bambara groundnut starch can potentially be used for various industrial applications. However, native starches are not suitable for most industrial applications, hence the need for modification. Bambara groundnut starch has been previously modified using physical and chemical modification methods. Natural alternatives such as the use of lipids are being sought to modify starches due to the associated risk with chemically modified starch. In this research, Bambara groundnut starch was modified with lipids to improve functional properties, utilisation and application. Specifically, the physicochemical properties of native Bambara groundnut starch obtained from five Bambara groundnut genotypes and three landraces (maroon, brown and cream) were determined. Bambara groundnut starch was modified with lipids (palmitic acid, stearic acid, oleic acid, linoleic acid and lysophosphatidylcholine) and the physicochemical properties of the modified starch were investigated. Further, the influence of high-pressure homogenization on complexation of Bambara groundnut starch with lipids was assessed in comparison with maize and potato starches. Lastly, an application of modified Bambara groundnut starch in biofilm production was also studied. Bambara groundnut landraces generally showed higher amylose contents (approx. 33%) than the genotypes (approx. 28%). Differences were observed in the crystalline patterns of these starches. Bambara groundnut genotypes exhibited the C-type-crystallinity, while the landraces showed the unusual A-type pattern. In terms of functionality, landrace starches showed better swelling than the genotypes. Subsequent studies on modification used maroon Bambara groundnut starch since the amylose content was higher than other landraces and there was a consistent supply of the grains during the period of the study. Generally, Bambara groundnut starch showed higher complexing ability with all the lipids than maize and potato reference samples. These differences in complexing ability among the starches could be due to the variation in amylose contents (Bambara groundnut starch: 31.5%, maize: 22.5% and potato: 24.6%). Fatty acids complexed better with Bambara groundnut starch than lysophosphatidylcholine, which could be due to the structural differences in comparison with the lysophosphatidylcholine molecule. The number of fatty acid in the glycerol backbone and the additional steric hindrance of the polar phosphatidic acid group in the lysophosphatidylcholine may have reduced its complexing ability. Among the fatty acids, palmitic acid complexed better than stearic and the unsaturated fatty acids, possibly due to its short chain length compared to other fatty acids. Bambara groundnut starch showed reduced peak and setback viscosities in the presence of stearic acid, linoleic acid and lysophosphatidylcholine, suggesting the formation of V-amylose complex. Bambara groundnut starch pasted with lipids displayed reduced gelling ability compared to their unmodified counterparts. XRD studies of freeze-dried paste revealed peaks at 2Ѳ = 7.4, 12.9 and 19.9o confirming the formation V-amylose complexes in Bambara groundnut starch. Modification of Bambara groundnut starch with lipids resulted in reduced digestibility. High-pressure homogenization significantly increased the complexing ability of Bambara groundnut starch with lipids. Homogenized Bambara groundnut starch-lipid complexes generally exhibited higher complex index than their unhomogenized counterparts. The higher complexing ability could be attributed to the effect of high-pressure which may have enhanced greater dispersion of lipids in the starch-water system. X-ray diffraction studies also revealed the formation of higher complexes as shown by high intensities at peaks (2Ѳ= 7.4, 12.9 and 19.9o) corresponding to V-amylose complexes. Bambara groundnut starch-lipid complexes displayed significantly higher melting temperatures (95.74-103.82oC) compared to native uncomplexed starch (77.32oC). Homogenized Bambara groundnut starch complexes were non-gelling while the unhomogenized types produced weak gels, with G′ ˃ G″ in the range of 0.1- 10 Hz. Complexation of Bambara groundnut starch with lipids using high-pressure homogenization may be employed in the production of modified starch with non-gelling properties and higher thermal stability suitable for certain industrial application, such as fat replacers in mayonnaise, frozen foods and desserts for a better mouth feel. The physicochemical and mechanical properties of biofilm prepared from Bambara groundnut starch modified with stearic acid at varying concentrations of 0, 2, 4, 6, 7 or 10% were further studied. By SEM, Bambara groundnut starch films containing stearic acid (˃ 2%) showed a progressively rough surface compared to those with 2% stearic acid and the control. The addition of 2% stearic acid to Bambara groundnut starch film reduced water vapour permeability by approximately 17%. However, mechanical properties of starch films were generally negatively affected by stearic acid. Bambara groundnut starch film may be modified with 2% stearic acid for improved water vapour permeability and thermal stability with minimal effect on tensile strength.
Characterization and modification of Bambara groundnut globulin fractions for the enhancement of functional properties
(2023-05) Alabi, Opeyemi Olaitan; Amonsou, Eric Oscar
There is a growing interest in the utilization of leguminous grain proteins for food and industrial applications. Bambara groundnut is a xerophyte pulse grain and a potential source of protein that can replace soybean protein, a trusted and widely used food ingredient in the food industry. However, the use of Bambara groundnut proteins including the subunits (legumin and vicilin) is limited in food applications. The understanding of the composition of Bambara groundnut proteins at the subunit level is vital to unlocking their potential and facilitating utilization. In this study, Bambara groundnut globulin is characterized in terms of the structures, composition, and physicochemical properties at the subunit level, and then modified using atmospheric plasma and enzymatic hydrolysis. Bambara globulin consisted of about 70% vicilin, whilst legumin protein was found in relatively low quantity. Gel electrophoresis revealed three major protein bands in globulin similar to vicilin with predominant β-sheet structures. The presence of a disulfide bond was also revealed in legumin. Bambara globulin showed major vicilin (7S, Mw: 120 kDa) and minor legumin (11S, Mw: 410 kDa) components. Fluorescence and hydrophobicity data suggested a folded structure for the legumin fraction dominated by the helical secondary structure compared to the vicilin fraction. Bambara proteins contain an appreciable amount of methionine that is even higher than the FAO/WHO recommended value. Bambara vicilin had the highest amount of negatively and positively charged amino acids compared to globulin and legumin. This coincides with its high solubility profile (approximately 82% at pH 3.5). The least gelation concentration (LGC) significantly increased in the order of globulin (8%) < legumin (18%) < vicilin (20%) at pH 7. Bambara groundnut proteins formed weakly structured gels as indicated by the frequencydependent behaviours of both the storage (Gʹ) and loss (Gʺ) moduli with a difference of lesser than 1 log cycle. The highest Gʹ of vicilin gel indicated more firmness of the gel compared to the gel formed by globulin and legumin. The sol-gel transition temperatures increased in the order of globulin (40℃) < legumin (50℃) < vicilin (80℃). The Gʹ and Gʺ of globulin showed relatively low dependency on heating time beyond the gel point compared to legumin and vicilin subfractions, suggesting a more rapid establishment of its gel network during gelation. Vicilin gel consisted of a microporous structure with a small lath sheet-like structure compared to globulin and legumin. Emulsifying stability of the proteins significantly differed (p < 0.05) at pH 7. The foaming capacity of the vicilin fraction was significantly (p < 0.05) higher than that of the storage protein at pH 3, 7, and 9. Atmospheric cold plasma-activated water (PAW) and enzymatic modification of Bambara groundnut globulin were further assessed. The cold plasma treatment resulted in the loss of the helical structure of Bambara globulin. The plasma treatment increased the hydrophobicity of Bambara globulin indicating an unfolded structure that was also reflected in the observed redshift in fluorescence intensity. No major changes were observed in gel electrophoresis, protein surface charge, and solubility profiles, except for about a 20% reduction in the glutamic acid content of the amino acid profile. Bambara globulin had reduced emulsifying capacity after treatment with PAW. However, foaming capacities were significantly better and stable at up to 15 mg protein/mL. Hydrolysates produced from Bambara groundnut globulin and vicilin, respectively using a combination of pepsin and pancreatin were investigated for ACE and renin inhibitory activities. The hydrophobic amino acid residues in both globulin and vicilin hydrolysates are high, improving the entry of their peptides into target organs via hydrophobic associations. Surface hydrophobicity increased significantly (p<0.05) with an increase in peptide size from <1 to <3 kDa with that of vicilin hydrolysate and membrane fractions having the highest values. The low molecular weight peptide (<1 kDa) membrane fractions from globulin at 1 mg/mL exhibited significantly higher (p<0.05) invitro ACE inhibitory activities compared to vicilin hydrolysate and its fractions. However, higher molecular peptide fraction (<3 kDa) favoured renin inhibitory activity at the same concentration. Vicilin is the major protein fraction of Bambara groundnut globulin. Bambara groundnut globulin was stabilized by disulfide linkages from the legumin, a minor fraction of the storage protein. Bambara globulin and its subfractions formed a weakly structured gel with the dominance of an elastic structure. The dominancy of the β-sheet structure in vicilin protein and the high crosslink density of the vicilin gel could be related to the firmness of the vicilin gel. The variations in the gel points of Bambara globulin and the subfractions were linked to the differences in their amino acid and subunit composition, the thermal unfolding properties of the protein fractions, and the presence of disulfide linkages. Modification of Bambara groundnut globulin using cold plasma-activated water treatment and enzymatic hydrolysis, respectively increased the hydrophobicity of the protein and influenced the emulsifying and foaming properties and the invitro angiotensin-converting enzyme (ACE) and renin inhibitory activities. Therefore, Bambara groundnut globulin could be a potential functional ingredient in the food system. The low molecular weight peptide (<1 kDa and <3 kDa) membrane fractions from globulin have the potential to serve as functional bioactive peptides against hypertension.
A comparative microbiological assessment of river basin sites to elucidate fecal impact and the corresponding risks
(2017) Sithebe, Ayanda; Stenström, Thor-Axel; Singh, Gulshan; Bux, Faizal
The study aims to assess and compare the concentration of microbial contaminants, their sources and distribution in surface water and sediment, and to determine the impact of seasonal variations and corresponding risks of faecal contamination using conventional and molecular methods. Historical data analysis was conducted using E. coli values from the eThekwini Water and Sanitation (EWS) department for 66 months (2009-2014). E. coli and Enterococci were analysed in surface water and sediment samples using the mFC/ spread plate and Colilert-18 (IDEXX) methods. The impact of seasonal variations was assessed using E. coli and Enterococci data collected during rainfall and no rainfall events, using an auto-sampler and sediment trap in parallel. Conventional standard membrane filtration methods using mFC agar, Slanetz & Bartley/ Bile Esculin and Brilliance E. coli selective agar were compared to the enzymatic Colilert-18 and Enterolert (IDEXX) test methods along the Isipingo and Palmiet Rivers. In addition, comparison of the analytical performance of droplet digital PCR (ddPCR) and qPCR for the detection of Salmonella targeting ttr gene in river sediment samples collected from the four sites of the Palmiet River in Durban, South Africa was done. In order to assess the public health risk associated with exposure of men, women and children to microbial pathogens in polluted surface water during recreational activities, the QMRA tool was employed in relation to the risk exposure to pathogenic E. coli, Campylobacter, Salmonella and Shigella. Also, the risk associated with crop irrigation (on farmers) as well as the consumption of crops irrigated with surface water from the Isipingo river was determined. Analysis of the historical data gave a baseline of the two rivers of interest, thus helps understand the current situation of the rivers enabling researchers to pick up potential gaps. In this study after the analysis of the historical data it was evident that at the Palmiet river, microbial analysis must be conducted around the QRI settlements which is a major pollution source. Also, from this study it was found that sampling points situated close to wastewater treatment plants, pump stations or informal settlements were of major concern, thus were considered for the study. It was found that sediment exhibited higher microbial concentrations than surface water, which was observed in both rivers. Also, rainfall had a significant impact on microbial variability. Higher microbial concentrations (indicator organisms) were observed in surface water after a heavy rainfall as appose to when there was no rainfall. This was due to contamination that is washed off into the river and sediment resuspension. Methodology comparison revealed that Colilert-18 and Brilliance E. coli were more selective compared to mFC agar. Brilliance E. coli /Coliform agar was comparable with Colilert-18 IDEXX, which was also observed with Slanetz & Bartley and Enterolert IDEXX. However, when mFC agar was compared with Colilert-18 IDEXX, significant difference was observed. In comparison of two Molecular methods, ddPCR were found to be fully amenable for the quantification of Salmonella and offer robust, accurate, high-throughput, affordable and more sensitive quantitation than qPCR in complex environmental samples like sediments. Quantitative Microbial Risk Assessment (QMRA) relating to recreational and occupational exposure showed that children were at the highest risk of getting infected. Also, it was observed that the probability of infection upon exposure to surface water from the Isipingo and Palmiet rivers was significantly high, hence exceeded the WHO guidelines values. Risk assessment on crops revealed that pathogenic bacteria may pose a risk to the consumer, however, a 9-log reduction may be achieved according to the WHO multi-barrier approach which involves proper washing and proper cooking of the crop before ingestion. Overall the sampling points that had the highest pollution level and constantly exceeded the WHO and DWAF guidelines at the Isipingo river were the points situated and named “Next to the WWTP”, and “Downstream of QRI” at the Palmiet River.
Composition and functional bioactive properties of bambara groundnut protein and hydrolysates
(2016) Arise, Abimbola Kemisola; Amonsou, Eric Oscar; Ijabadeniyi, Oluwatosin Ademola
Bambara groundnut (Vigna substerranea) is an indigenous legume of African origin which is currently experiencing a low level utilisation. It is tolerant to drought and can grow under poor soil conditions in which other lucrative crops such as groundnut cannot grow. Bambara is a good source of protein comparable to that of cowpea and slightly lower than soya bean. In order to assess the potential use of bambara protein as a functional ingredient in food systems and as an important ingredient for the formulation of therapeutic product, the knowledge of its protein composition, structure and functionality becomes important. The main goal of this thesis was to determine the composition and bioactive properties of bambara protein and its hydrolysates. Specifically, a comparative study was carried out on the protein content, yield and functional properties of protein concentrates prepared from three different bambara landraces using different extraction methods (Salt solubilisation and Acid precipitation). There was no significant difference in protein content, yield and functional properties of the landraces. However, the method of extraction had an influence on their physicochemical and functional properties. Acid precipitation produced bambara protein concentrates with high protein content and yield (79% and 52% respectively) when compared to salt solubilisation (protein content - 57% and yield - 25%). Protein concentrates prepared through salt solubilisation method exhibited better functional properties in terms of water absorption capacity, oil absorption capacity, foaming capacity, foaming stability and emulsion activities when compared to concentrates obtained through acid precipitation. Furthermore, the composition of bambara proteins produced through isoelectric precipitation was determined. SDS PAGE revealed four major bands; a broad band at 55 kDa which was analysed to be vicilin, two medium bands at 62 kDa and 80 kDa and a high molecular weight (HMW) protein at 141 kDa. Further investigation of bambara protein revealed vicilin (55 kDa) with two sub units as the major protein in bambara and this was also confirmed by the proteomic map. The proteomic map revealed acidic amino acids as the major protein of bambara which is characteristic of vicilin, the map also showed that there were differences in the number of spots across the landraces with 77 spots matching each other. Circular dichroism spectroscopy exhibited reductions in α-helix, and β-pleated sheet conformations as pH varies. In addition, the tertiary structures as observed from the near-UV CD spectra were also influenced by shifts in pH conditions. Differential scanning calorimetry thermograms showed two endothermic peaks at around 67 and 81oC respectively. These can be attributed to thermal denaturation of vicilin and the HMW protein. Subsequent studies used isolates from red bambara since the composition of the landraces were similar. Bambara protein isolate was subjected to enzymatic hydrolysis using three proteases (alcalase, pepsin and trypsin) to produce various bambara protein hydrolysates (BPHs). BPHs were investigated for antioxidant and antihypertensive activities. The in vitro structural and functional characteristics of bambara protein and its enzymatic protein hydrolysate revealed that bambara groundnut possessed antioxidant properties against a variety of physiologically relevant free radicals. High surface hydrophobicity and the molecular size of the peptide seem to be important for scavenging of hydroxyl radicals, ferric reducing power and metal chelation. BPHs and peptide fractions were able to scavenge DPPH radicals with greater affinity for smaller size. Less than 1 and 1-3 kDa pepsin fraction was able to scavenge DPPH radical more than glutathione, BPHs and its fractions scavenge ABTS•+ three folds than the isolate. Scavenging of superoxide radicals was generally weak except for 5-10 kDa peptide fractions. All BPHs inhibited linolenic acid oxidation with greater affinity for the lower molecular size peptide. BPHs showed potential antihypertensive properties because of the in vitro inhibition of activities of angiotensin converting enzyme (ACE) and renin inhibition. The molecular size had significant effect on the ACE inhibitory properties with low molecular weight peptide (<1 kDa) fractions exhibiting significantly higher (p<0.05) inhibitory activities. However, enzyme type had synergistic effects on renin inhibition with alcalase hydrolysate showing highest inhibition at 59% when compared to other hydrolysates and their membrane fractions. The fractions with <1 and 1-3 kDa peptides showed a higher potential as antihypertensive and antioxidant peptides. Based on this study, incorporation of bambara protein isolate as an ingredient may be useful for the manufacture of high quality food products. Likewise, the bambara protein hydrolysates, especially the <1 kDa and 1-3 kDa fraction represent a potential source of bioactive peptides in formulating functional foods and nutraceuticals.
Design and operation of a laboratory scale photobioreactor for the cultivation of microalgae
(2011) Bhola, Virthie; Bux, Faizal
Due to greenhouse gas emissions from fossil fuel usage, the impending threat of global climate change has increased. The need for an alternative energy feedstock that is not in direct competition to food production has drawn the focus to microalgae. Research suggests that future advances in microalgal mass culture will require closed systems as most microalgal species of interest thrive in highly selective environments. A high lipid producing microalga, identified as Chlorella vulgaris was isolated from a freshwater pond. To appraise the biofuel potential of the isolated strain, the growth kinetics, pyroletic characteristics and photosynthetic efficiency of the Chlorella sp was evaluated in vitro. The optimised preliminary conditions for higher biomass yield of the selected strain were at 4% CO2, 0.5 g l-1 NaNO3 and 0.04 g l-1 PO4, respectively. Pulse amplitude modulation results indicated that C. vulgaris could withstand a light intensity ranging from 150-350 μmol photons m-2s-1. The pyrolitic studies under inert atmosphere at different heating rates of 15, 30, 40 and 50 ºC min-1 from ambient temperature to 800 oC showed that the overall final weight loss recorded for the four different heating rates was in the range of 78.9 to 81%. A tubular photobioreactor was then designed and utilised for biomass and lipid optimisation. The suspension of microalgae was circulated by a pump and propelled to give a sufficiently turbulent flow periodically through the illuminated part and the dark part of the photobioreactor. Microalgal density was determined daily using a Spectrophotometer. Spectrophotometric determinations of biomass were periodically verified by dry cell weight measurements. Results suggest that the optimal NaNO3 concentration for cell growth in the reactor was around 7.5 g l-1, yielding maximum biomass of 2.09 g l-1 on day 16. This was a significant 2.2 fold increase in biomass (p < 0.005) when compared to results achieved at the lowest NaNO3 cycle (of 3.8 g l-1), which yielded a biomass value of 0.95 g l-1 at an OD of 1.178. Lipid accumulation experiments revealed that the microalga did not accumulate significant amounts of lipids when NaNO3 concentrations in the reactor were beyond 1.5 g l-1 (p > 0.005). The largest lipid fraction occurred when the NaNO3 concentration in the medium was 0.5 g l-1. Results suggest that the optimal trade-off between maximising biomass and lipid content occurs at 0.9 g l-1 NaNO3 among the tested conditions within the photobioreactor. Gas chromatograms showed that even though a greater number of known lipids were produced in Run 8, the total lipid percentage was much lower when compared to Runs 9-13. For maximal biomass and lipid from C. vulgaris, it is therefore crucial to optimise nutritional parameters such as NaNO3. However, suitable growth conditions for C. vulgaris in a tubular photobioreactor calls for innovative technological breakthroughs and therefore work is ongoing globally to address this.
Development and acceptability of a cost-effective, energy-dense snack suitable for the National School Nutrition Programme
(2020-11-13) Hassanally, Saffia; Naicker, Ashika; Singh, Evonne
Background: The National School Nutrition Programme (NSNP) was established in South Africa (SA) to ensure that hunger will not be a barrier to learning among school learners attending quintile one to three schools and aims to provide a free, nutritious meal for all 189 school days. The NSNP currently does not have a solution to ensure that all learners are suitably sustained until the main NSNP meal can be served. With the increase in food insecurity levels, the need for the development of an energy-dense snack item for school learners is critical, in the effort of combatting hunger and ensuring learners have the necessary energy to sustain their concentration until their next meal. Aim: This study aimed to develop a suitable, cost-effective, energy-dense snack item for learners as a supplement to the NSNP, to assist learners in reaching their recommended dietary requirements. Methodology: The snack product development was informed by a cross-sectional snack preference survey, as well as a scoping review of the literature on school feeding programmes and past snack interventions that have shown success in South Africa and other developing countries in Africa. Through informed consent, 85 primary school learners between the age group of nine to thirteen that were part of the NSNP from two quintile three schools in KwaZulu-Natal participated in the snack preference survey whilst 81 learners participated in the consumer sensory evaluation. The snack preference survey and scoping review of past snack development interventions were conducted, to decide on a suitable, cost-effective snack for development, for the learners of the primary schools. The developed snack product then went through sensory evaluation, using trained personnel and, thereafter, for microbiological testing, to deem the product safe for consumption. The product then underwent nutritional analysis, to determine the nutritional properties of the snack item and shelf-life testing. Lastly the product was presented to the learners for final sensory analysis, to determine sensory acceptability of the developed snack, using a 7-point facial hedonic scale. Results: Analysis of the reviewed articles inferred that the most appropriate snack product to develop for this study was a biscuit. Results from the snack preference survey showed that muffins were the most preferred snack (57.1%) by both girls and (55.8%) boys, respectively. Biscuits were the second most preferred snack (32.6%) by both girls and (33.3%) for boys, respectively. There was no significant relationship between gender and choice of snack (p=1.000) and no significant relationship between age and choice of snack (p=0.141). The literature results showed biscuits to have a longer shelf life than most other snacks. It can be emulated with ease and can carry many nutrients, while being cost-effective. Trained sensory panellists, comprising of consenting Food and Nutrition staff and students, were used to evaluate the sensory acceptability of the trial recipes, during development. Following the systematic steps of food product development, at the end of the trained sensory tests, a crispy, flavourful biscuit was developed. The final recipe yielded 20 portions of 22g biscuit dough, of which the final weight of the biscuit was reduced to 20g, due to moisture loss during baking. The microbial analysis deemed the product to be safe to consume, as total counts of coliform bacteria were zero, showing no bacterial growth. The nutritional analysis showed that fat contributed the most energy (61.0%). The Recommended Dietary Intake (RDI) percentage values of the biscuit amounted to 14.3% for girls and 14.2% for boys, which is in-keeping with the first objective of creating an energy-dense product. When compared to two other products of a similar nature on the market, the developed biscuit was found to be the most cost-effective (R0.79 for 20g portion). The shelf stability of the product proved that the product is highly shelf stable, remaining fresh for five weeks and can last up to five months, under proper storage conditions. Following the consumer sensory evaluation, a significant number (69.1%) of children found the snack to be ‘Super good’ (p<.0005), 14.8% rated the product as ‘Good’ and 12.3% rated the product as ‘Really good’. There was no significant difference in sensory scores across age groups (p=0.706). Conclusion: It is well established that school feeding programmes create a positive impact on school children, as it enriches their lives and provides them with much needed nutrients. In SA, the well-established NSNP does have challenges one of which is the shortfall of -providing 30.0% of the Recommended Dietary Allowances (RDA) to learners. Although there are existing snack development studies, this study is unique, in the sense that it is designed to assist the NSNP to fill the current gap in the RDA for the children of SA. All objectives of this study were reached, and a suitable, cost-effective, energy-dense snack biscuit was developed in a systematic process. This snack can be a potential solution to sustain children that come to school hungry. This study will be brought to the attention of NSNP stakeholders, in the hope of the programme adopting this solution, to fill the RDA gap in the NSNP.
Development and optimization of technology for the extraction and conversion of micro algal lipids to biodiesel
(2015) Ramluckan, Krishan; Moodley, Kandasamy Govindsamy; Bux, Faizal
Fossil fuel reserves have been diminishing worldwide thus making them very scarce in the long term. These fuel sources and their by-products which are used commercially tend to produce large quantities of emissions. Some of them are believed to be toxic to flora and fauna. It is primarily for this reason that researchers worldwide have begun to seek out alternative sources of environmentally safe fuel. Biodiesel from algae is one of these sources that have been examined over the last few decades. Biodiesel has been produced from other plant-based material and waste oils in countries like America and Japan. However, the use of food based crops for biodiesel production has been challenged as it has an impact on food production on an international scale. Algae have only recently been investigated for their feasibility for biodiesel production on a large scale. The aim of this study was to investigate and develop technologies for biodiesel production from algae. The species of algae chosen were chlorella sp and scenedesmus sp., since they are indigeneous to Kwazulu Natal in South Africa. Samples were obtained from a local raceway pond and prepared for analysis. Drying protocols used freeze, oven and sun drying for initial preparation of the samples for analysis. Sun drying was the least energy intensive but most time consuming. At laboratory scale, oven drying was chosen as the best alternative. Lipid extraction methods investigated were the separating funnel method, the soxhlet method, microwave assisted extraction (MAE) and the expeller press. Thirteen solvents covering a range of polarities were used with the extraction methods to determine the efficiency of the solvent with these methods. Optimization of the MAE method was conducted using both the one factor at a time (OFAT) method and a design of experiment (DOE) statistical method. The shelf life of algal biomass was determined by ageing the samples for approximately three months. Direct and in-situ transesterification of lipid extracts to produce biodiesel was investigated using both acid and base catalysis. Qualitative and quantitative analyses were conducted using Fourier transform infra-red (FTIR) and gas chromatography (GC). Chemical and physical characterization of the biodiesel produced from the algal lipid extracts were compared to both local and international standard specifications for biodiesel. In terms of extraction efficiency, it was found that soxhlet and microwave assisted extraction methods were almost equally good. This was proved by the MAE method yielding an average of 10.0% lipids for chloroform, ethanol and hexane after 30 mL of solvent was used in an extraction time of 10 minutes, while the soxhlet method yielded 10.36% lipids using an extraction volume of 100 mL of solvent with an extraction time of 3 hours. Chloroform, ethanol and hexane were more efficient than the other ten solvents used. This was shown by these three solvents producing lipid quantities between 10% to 11% while all the other solvents produced lipid quantities between 2 and 10 %. The best extraction efficiency was achieved by the binary solvent mixture made up of chloroform and ethanol in a 1:1 ratio. Under the conditions optimized, this solvent ratio yielded a lipid content of 11.76%. The methods chosen and optimized for extraction are very efficient, but the actual cost of production of biodiesel need to be determined. Physical methods like the expeller press are not feasible for extraction of the type of biomass produced unless algae are pelletized to improve extraction. This will impact on the cost of producing biodiesel. The transesterification protocols investigated show that the base catalysis produced biodiesel with a ratio of saturates to unsaturates conducive to a good fuel product. The direct esterification method in this study proved to be better than the in-situ method for biodiesel production. The in-situ method was also more labour intensive. Chromatography was found to be a fast and efficient method for qualitative and quantitative determination of biodiesel. Characterization tests showed that the quality of biodiesel produced was satisfactory. It also showed that the methods used in this study were feasible for the satisfactory production of biodiesel which meets local and international specifications.
Development of a sensorially acceptable food product from Cissus quadrangularis to create awareness among young adults
(2021) Singh, Vihara; Naicker, Ashika; Palmer, Karina
Among the main causes of food insecurity in Africa is drought which results in poor harvests for farmers. Drought tolerant plants are environmentally sustainable and show great promise in improving food security and preventing malnutrition. South Africa has a wide range of drought tolerant indigenous plants that possess both medicinal and nutritional value. However, most of these indigenous plants are used by older generations and are unfamiliar to younger generations. With the revival of indigenous knowledge systems and botanical decolonisation, the potential of indigenous plants as functional foods has come to the fore. Aim: The aim of this study is to develop a sensorially acceptable food product with Cissus quadrangularis and to create awareness of Cissus quadrangularis among young adults. Methodology: This food product development study was informed by key informant interviews as well as a desktop study on food and nutrition trends. Through informed consent, ten elderly community members participated in the key informant interviews and shared their knowledge, uses and perceptions of Cissus quadrangularis. The developed food product underwent pilot and final sensory evaluation through a 9- point hedonic scale and a paired preference test. For the sensory evaluation, 110 participants were used, 10 for the pilot and 100 for the final sensory evaluation. The food product also underwent microbiological testing, nutrient analysis, and shelf-life testing. Once this was conducted, an awareness tool was developed. The awareness tool underwent pilot and final evaluation via a Likert scale. For the awareness tool survey, 110 young adult participants residing in KZN were used, 10 for the pilot and 100 for the final instrument. Results: Analysis from the key informant interviews indicated that the participants viewed Cissus quadrangularis as a medicinal plant, used to treat sprains, inflammations, broken bones, cholesterol, and ulcers. The participants cooked the plant in curries, pastes or fried doughs and some participants boiled it and drank the water. The desktop study on food and nutrition trends displayed key food trends for 2019 and 2020 such as zero-waste foods, botanical beverages, alternative ingredient, sustainability, plant-based foods, and natural remedies, less sugar, health convenience items, and texture. The results from the key informant interviews and desktop study on food and nutrition trends informed the development of the food product with Cissus quadrangularis. Following the steps of product development, a trendy energy bite infused with Cissus quadrangularis was developed. The energy bite yielded 10 portions of 21.5g each. Analysis from the microbial test indicate that the microbial count in the product was high averaging between 1000 to 5000 cfu/g which was within acceptable limit. However, the product was suitable for a short shelf-life of three days. Potassium sorbate was added to the energy bite infused with Cissus quadrangularis for the second microbial test. The second test results indicated that the microbial count found in the developed product was low and that there were no microorganisms present. The Cissus quadrangularis infused energy bite (both samples) indicated that the product was to some extent high in sugar (4g: 3.4g / 6g: 3.48g per 21.5g). The nutrient analysis showed that the product was relatively low in fat and sodium. The energy bite carbohydrate level was relatively low as it contributed (Women: 6.72 %/ Men: 6.32%) to the Dietary Reference Intake (DRIs) of women and men aged 19-30 years old. The amount of dietary fibre present in this study; in both samples was high (4g: 4.02 / 6g: 4.16 per 21.5g), contributing well to both women and men DRIs of dietary fibre, respectively (Women: 16.08 % / Men: 10.94%). The protein value in the energy bite was significantly low only contributing Women: 3.17% / Men: 2.6% to the DRIs of women and men, respectively. The vitamins and minerals tested in the nutrient analysis were not present in notable amounts, contributing low percentages to both women and men’s DRIs. Analysis from the pilot and final sensory evaluation showed that both the 4g and 6g sample of the developed food product was liked, however, the 4g sample was preferred. The final sensory evaluation showed that 27% of participants chose “like extremely” for the 4g sample whilst 18% of participants chose “like extremely” for the 6g sample. The Wilcoxon signed ranks test indicated that there was no significant difference between the 4g and 6g sensory rating score (p=0.066) indicating that there was a marginal preference of sample 1 (4g) over sample 2 (6g). There was no significant difference in the sensory rating of these products across gender for the 4g (p=0.521) and 6g (p=0.673) sample. The last objective of the study was to develop an awareness tool using the developed food product to create awareness of Cissus quadrangularis among young adults. The pilot and final awareness tool survey showed that the majority of participants found the awareness tool to be informative and that the participants involved were willing to make the recipes using Cissus quadrangularis. The final awareness tool results indicate that a significant 93% either liked or extremely enjoyed the video (p<.0005). Analysis with Pearson’s chi-square (Fisher’s exact test) of the cross-tabulation of responses with demographics shows that there was a significant relationship between gender and video rating, Fisher’s exact = 11.129, (p=.007). The results indicated that 57.1% of male participants extremely enjoyed the video whereas 59.3% of females only liked the video. Conclusion: The development of a trendy and sensorially acceptable food product with Cissus quadrangularis as a main ingredient and the development of an awareness tool created awareness to this unfamiliar indigenous plant with various health benefits among young people. Food product development using indigenous edible plants can be seen as sustainable measure and can contribute towards food security initiatives in South Africa. Awareness tools that appeal to the youth can help educate young adults on various indigenous foods reducing the vulnerability of food and nutrition insecurity.
Development of a starter culture for the production of Gari, a traditional African fermented food
(2010) Edward, Vinodh Aroon; Singh, Suren; Franz, Charles M. A. P.; Van Zyl, Petrus J.
Cassava, (Manihot esculenta Crantz), is used for the production of a variety of West African foods and ranks fourth in the list of major crops in developing countries after rice, wheat and maize. Gari is one of the most popular foods produced from cassava. Cassava may contain high levels of linamarin, a cyanogenic glucoside, which in its natural state is toxic to man. Therefore, some processing methods that can enhance the detoxification of cassava and lead to the improvement of the quality and hygienic safety of the food are vitally important for less toxic products to be obtained. Quality, safety and acceptability of traditional fermented foods may be improved through the use of starter cultures. There has been a trend recently to isolate wild-type strains from traditional products for use as starter cultures in food fermentation. A total of 74 bacterial strains and 21 yeast strains were isolated from a cassava mash fermentation process in a rural village in Benin, West Africa. These strains were assessed, together with 26 strains isolated at the CSIR from cassava samples sent from Benin previously, for phenotypic and technological properties. Twenty four presumptive lactic acid bacteria (LAB) were selected for further phenotypic, genotypic and technological characterization during a research visit to the BFE (now Max Rubner Institute of Nutrition and Food). After assessment, the strains VE 20, VE 36, VE 65b, VE 77 and VE 82 were chosen for further study as starter cultures. These L. plantarum strains were chosen on the basis of predominance and possession of suitable technological properties. The investigation of this study was complemented by further, similar studies on further Gari isolates in Germany by the BFE. That study was done independently from this study, but both studies served to select potential starter cultures for cassava fermentation for the production of Gari, as this was the common goal of the project. Thus, a wider final selection of potential starter cultures was decided on at the project level and this selection was further tested in fermentation experiments. A total of 17 strains were grown in optimized media in 2 L fermenters. These strains were freeze-dried and thereafter tested in lab-scale cassava mash fermentation trials. xiii The strains performed well in the small scale bucket fermentations. There was a rapid acidification evidenced by the increase in titratable acidity, ranging from 1.1 to 1.3 % at 24 hours, and 1.3 to 1.6 % at 48 hours. The effect of the starter was obvious in that it lowered the pH much faster and to lower levels than the control. It appeared that both the processing and starter culture addition played a role in the removal of cyanide during processing of the cassava into Gari. This was evident from the lower cyanide values obtained for fermentations that included starter cultures. The study also showed that especially the L. plantarum group strains could be produced as starter cultures at lower costs than compared to L. fermentum, W. paramesenteroides or L. mesenteroides strains. Overall the results of this study were crucial for the project in showing that a starter culture which is easy and economical to produce and which has the desired attributes is a feasible possibility for application in the field.
Development of electrochemical biosensors for sweeteners using engineered nanomaterials supported by computational modelling
(2024-05) Hloma, Phathisanani; Bisetty, Krishna; Sabela, Myalowenkosi Innocent; Uwaya, Gloria Ebube
Electrochemical immunosensors are a powerful tool in analytical applications. The current methods for the isolation and detection of artificial and natural sweeteners suffer from challenges in sample preparation and a lack of specificity. However, electrochemical immunosensors offer a sensitive, economical, and selective analytical solution to analyse these commonly used sweeteners, such as aspartame. The author of this work developed electrochemical immunosensors for the food and beverage industries to use in the detection and measurement of aspartame, a non-nutritive sweetener, and rebaudioside A, a natural sweetener. Most artificial sweeteners are low-calorie options that are suggested for ailments linked to health. These sweeteners' ability to remain stable at even high temperatures has greatly expanded the range of meals that can use them. Aspartame and rebaudioside A have not been linked to any health risks, although regulation is still necessary because of their extensive use in the food industry. The developed immunosensors for the detection of aspartame and rebaudioside A were achieved and presented as three case studies in this study. In the first case study, the immunosensor was achieved by fabricating green synthesized PVP capped silver nanoparticles (PVP-AgNPs) with functionalized multi-walled carbon nanotubes (fMWCNTs) and immobilizing the human sweet tase receptor T1R2 in a glassy carbon electrode (GCE), resulting in GCE/PVP-AgNPs/fMWCNTs/T1R2. The electrochemical assessment of aspartame was achieved using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV), respectively, under optimum pH 8 in a 0.1 M phosphate buffer with reference to the Ag/AgCl reference electrode. The electro-oxidation of ASP was noticed by a well-defined oxidation peak potential at 1.4 V. The immunosensor sensor showed a linear dynamic range of 2.89 to 27.61 μM (R 2 = 0.9170) based on differential pulse voltammetry, with limits of detection (LOD) and quantification (LOQ) (S/N = 3) of 0.40 μM and 1.34 μM, respectively. The second case study focused on the indirect electrochemical detection of rebaudioside A in the presence of ferro/ferricyanide as a redox probe. The immunosensor was developed by fabricating GCE with zeolitic imidazolate framework-67 (ZIF-67) in combination with fMWCNTs and the immobilization of the T1R2 receptor. The qualitative and quantitative analysis of rebaudioside A was done using CV, EIS, and DPV utilizing a 5 mM [Fe (CN)6] 3-/-4 redox probe. The stable electrode had an exponential dynamic range of 0.9901 µM to 8.2569 µM (R2 = 0.9996). The LOD and LOQ were computed to be 1.10 µM and 3.33 µM, respectively. This case study also used Patch Dock and PyRx to better understand the interactions between Reb A and T1R2. The final case study employed a platinum electrode (PtE) as the working electrode (WE) for the electrochemical immunosensing of aspartame. The modification of PtE involved the utilization of a nanocomposite consisting of PVP-AgNPs and reduced graphene oxide (rGO), with T1R2 immobilized. The electrochemical detection of aspartame was achieved under optimized conditions at pH 8 in a 0.1 M phosphate buffer, utilizing CV, EIS, and DPV as electrochemical tools. The PVP-AgNPs/rGO/T1R2 was used to fabricate Pt and the electrode performed well with a linear increase in oxidation peak currents as aspartame concentrations were increased from 2.38 µM to 25.78 µM (0.9529). The LOD and LOQ were calculated to be 5.85 µM and 17.73 µM, respectively. The synthesized nanoparticles and nanocomposites (PVP-AgNPs/fMWCNTs, ZIF 67/fMWCNTs, and PVP-AgNPs/rGO) were characterized using conventional techniques such as UV-Vis spectroscopy, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), field flow fractionation (FFF), single particle inductively coupled plasma mass spectrometry (sp-ICPMS), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM). In addition to the experimental results, computational chemistry methods were undertaken. These included adsorption assessments, density functional theory (DFT), and molecular docking techniques. These techniques were all aimed at achieving a deeper molecular-level understanding of the interactions among the analytes (Aspartame and Reb A), T1R2, and the nanocomposites employed in the modification of the working electrodes (GCE and Pt-E)
Development of nutrition education material for caregivers of immune compromised children in children's homes in the Durban area
(2011) Grobbelaar, Hendrina Helena; Oldewage-Theron, Wilna; Napier, Carin E.
Nutrition plays a fundamental role in the care and support of people living with the Human Immunodeficiency Virus (HIV) and children in particular are affected by HIV and the Acquired Immunodeficiency Syndrome (AIDS) epidemic in Africa in various ways. The epidemic puts children at risk physically, psychologically and economically. Children are indirectly affected by HIV and AIDS when the epidemic has a negative impact on their communities and the services these communities provide. Undernutrition is a major problem in HIV-positive children in South Africa with severe malnutrition as a common finding in HIV-positive children. HIV contributes to an increased incidence and severity of undernutrition and micronutrient deficiency. Low serum levels of vitamins A, E, B6, B12 and C, betacarotene, selenium, zinc, copper and iron deficiencies are frequently documented during all stages of HIV-infection. Malnutrition in turn further weakens the immune system which increases the susceptibility to infections and the duration and the severity of infections. Thus, the immune response is less effective and less vigorous when an individual is undernourished. Although guidelines exist for the treatment and management of HIV-infected children, it is clear from the literature that exceptional measures are needed to ensure the health and well-being of the children are met. Furthermore, residential care should not only be considered as a last resort for children’s care, but also as an intervention that requires more than merely addressing children’s basic physical needs. Nutrition education has been utilised globally and in South Africa to address nutrition related problems. The main purpose of nutrition education is to provide individuals with adequate and accurate information, skills and motivation to buy, produce and consume the correct foods to stay healthy and lead an active life. Aim The purpose of this study was to develop reliable and valid nutrition education material for the child care workers (CCWs) of Immune Compromised children vi resident in Children’s Homes in the Durban area in order to maintain the child’s immune system and to optimise their quality of life. Methodology The FAO framework used for planning, implementing and evaluating a nutrition education programme was followed to develop the nutrition education material in this study. Phase I included a situational analysis of the children homes involved. The residential care settings that participated in this study included three Children’s Homes in Durban. The total purposive sample included: boys (5–19 years) n = 112, girls (5–19 years) n = 38 and CCWs n = 40. The sample of HIV-positive children included boys (5–19 years) n = 3 and girls (5– 19 years) n = 6. The physical measurements obtained for this study to determine nutritional status were weight and height. The anthropometric measurements were captured and analysed by the researcher using the World Health Organisation’s AnthroPlus version 1.0.2. Statistical software. The following indices were included: height-for-age (stunting), weight-for-age (underweight) and BMI-for-age (overweight and wasting). The WHO growth standards for school-aged children and adolescents were used to compare the anthropometric indicators. Dietary intake measurements were done by analysing the cycle menus by means of the Food Finder® Version 3 computer software program and comparing the results with the Dietary Reference Intakes (DRIs), specifically the EAR and AI where the EAR were not available. The data were analysed to determine the adequacy of energy and nutrient intake. Average portion sizes were established by the plate waste studies method as well as observation of practices, interviews with the central buyer and focus group discussions with the CCWs. Nutrition knowledge of the CCWs was determined by a self-administered questionnaire developed and tested for reliability and validity. The problems identified in Phase I through the implementation of the questionnaires and other methods directed the design of messages in Phase II. Once suitable media was selected, nutrition education material was developed based on existing guidelines pertaining to HIV and AIDS. The material developed was then tested for reliability and validity before it was produced. vii Results The anthropometric measurements indicated that the majority of the HIV-negative boys and girls were of normal height-for-age and weight-for-age. The results also showed that possible risk of overweight and overweight were more prevalent in girls whereas underweight was more prevalent in boys. Furthermore, the results indicated that a third (33.0%) of the HIV-positive children were stunted and 16.7% was severely stunted. Findings of the menu analysis indicated that both girls and boys consumed three times more carbohydrates than the recommended intake. The DRIs for girls and boys were met for energy and protein in all the age groups except boys aged 14-18 years did not meet the DRI for energy. However, the comparison of the actual intake of the macro nutrients with the WHO guidelines indicated that the protein (10.78%) and carbohydrate (58.07%) is within the recommendations of 10- 15% and 55–75% respectively. This comparison also showed that the total fat intake of 31.15% was above the recommended intake of 15-30%. None of the age groups met the DRIs for fibre. The comparison of the intake with the WHO guidelines also indicated that the total dietary fibre intake was only 19.67g/day and not 27–40g/day. The actual fruit and vegetable intake was a mere 68.64g/day instead of 400g/day as recommended. None of the groups met the DRIs for calcium and iodine. The results clearly showed that micro nutrient inadequacies were more prevalent in the dietary intake of age groups 9-13 and 14-18 years in both girls and boys. Inadequate intake of magnesium, vitamin A, vitamin C, riboflavin, niacin, vitamin B6, pantothenate, biotin, vitamin E and vitamin K were evident in the age group 14-18 year. Overall, it is evident from the results on nutrition knowledge that although the respondents’ knowledge was fair on general nutrition guidelines, the results of the nutrition knowledge questionnaire indicated that knowledge on the importance of a variety in the diet is lacking. The CCWs displayed a very poor knowledge of the recommended number of fruit and vegetable portions per day as well as correct serving sizes of vegetable portions. A very poor knowledge also existed regarding the role of healthy eating in maintaining and supporting the immune system and a limited knowledge on correct hygiene practices was noted. The fridge magnets developed included five messages relating to nutrition and four messages relating to food safety and hygiene. viii Conclusion This study established that malnutrition is apparent in the children’s homes and that there were many gaps in the nutrition knowledge of the CCWs. These gaps included the role of good nutrition in the support and maintenance of the immune system and the importance of adequate intake of fruit and vegetables daily. The NEM developed in this study will address these gaps.