In this article the term ‘African leafy vegetables’ was adopted to refer to the collective of plant species which are used as leafy vegetables and which are referred to as morogo or imifino by African people in South Africa. Function is central in this indigenous concept, which is subject to spatial and temporal variability in terms of plant species that are included as a result of diversity in ecology, culinary repertoire and change over time. As a result, the concept embraces indigenous, indigenised and recently introduced leafy vegetable species but this article is concerned mainly with the indigenous and indigenised species. In South Africa, the collection of these two types of leafy vegetables from the wild, or from cultivated fields where some of them grow as weeds, has a long history that has been intimately linked to women and their traditional livelihood tasks. Among poor people in remote rural areas the use of these types of leafy vegetables is still common but nationwide there is evidence of decline, particularly in urban areas. Cultivation of indigenous or indigenised leafy vegetables is restricted to a narrow group of primarily indigenised species in South Africa. Seven groups of indigenous or indigenised African leafy vegetables that are important in South Africa were given special attention and their local nomenclature, ecology, use and cultivation are discussed.

Thesis(M.Sc.(Agriculture Horticulture)) -- University of Limpopo, 2019 / Innovative methods of preserving the quality of traditionally processed green leafy vegetables are underway in Africa. Improvement of processing and preservation methods of leafy vegetables is another way of overcoming perishability restrictions and guaranteeing continued quality food supply in rural areas. The objectives of this study were: to determine the effect of time-based oven-drying on (1) mineral composition, (2) proximate composition and (3) microbial profiling of cowpea (Vigna unguiculata). Separate experiments were conducted for raw and cooked cowpea leaves with four treatments, viz 0 (sun dried), 24, 48 and 72 hours of oven-drying, arranged in a randomised complete block design with 5 replications. In raw cowpea leaves, relative to control (sun-drying), oven-drying period 48hrs, significantly decreased Potassium (K), Manganese (Mn), and Sodium (Na) content in raw cowpea leaves by 6, 9 and 13%, respectively. Similarly, oven-drying period 72hrs significantly decreased Ca, Fe, Mg, Zn, P and S by 5, 11, 16, 18 and 57%, respectively. In cooked cowpea leaves, relative to control (sun-drying), oven-drying period 24hrs significantly increased Na by 18%. Similarly 48hrs oven-drying periods increased Fe and K by 6 and 8%, respectively. Similarly, oven-drying period 72hrs significantly increased Ca, Mg and Mn by 8, 8 and 3%, respectively. In contrast, oven-drying period 72hrs significantly reduced Zn, P and S by 16, 10 and 39%, respectively. Relative to control (sun-drying), oven-drying period 24hrs significantly increased fat by 46% in raw cowpea leaves, however oven-drying period 72hrs significantly decreased protein, moisture, ash, fibre and carbohydrate by 10, 29, 18, 0.5, and 7% respectively. In contrast, relative to control (sun-drying), 72hrs increased energy by 3%. In cooked cowpea leaves, relative to control (sun-drying), oven-drying period 24hrs significantly increased energy by 1%. In contrast, relative to control (sun-drying) 72hrs oven-drying period decreased energy by 1%. Similarly, ovendrying 72hrs significantly decreased protein, moisture, ash, fat, fibre and carbohydrate by 8, 14, 13, 19, 0.4 and 10% respectively. Relative to control (sun-drying), oven-drying periods 24hrs significantly increased Staphylococcus spp. in raw cowpea leaves by 6%, respectively. Relative to control (sun-drying) 72hrs oven-drying period significantly decreased Shigella spp. by 92%, respectively. In cooked leaves, relative to control (sundrying), 72hrs drying periods decreased both Shigella spp. and Staphylococcus spp. by 99 and 21%, respectively. Total coliforms unit of Salmonella spp, Escherichia coli, Pseudomonas spp, and Bacillus cereus were absent and/or at an undetectable level according to the Tempo Biomerieux system results. In conclusion, cooked leaves retained most essential mineral elements as compared to raw when subjected to 72hrs of oven-drying as there was an improvement in the concentration of Ca, Fe, K, Mg, Mn and Na. However, in both raw and cooked cowpea leaves proximate composition was negatively affected as there was a decrease in protein content. Oven-drying period of 24 hours can be used to minimize the loss of protein. Cooked cowpea leaves subjected to 72hrs of oven-drying had least total coliforms for both Shigella spp and Staphylococcus spp, therefore have potential to serve as an alternative to sun-drying to reduce microorganism causing spoilage in leafy vegetables. Drying raw cowpea leaves under oven-drying periods less than 72 hours should be avoided as it reduces the mineral concentration and increase microbial count of microorganisms responsible for spoilage. / National Research Foundation

Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Objectives: The aim of this study was to assess the bioaccessibility of iron and zinc in African leafy vegetables (ALV) and maize porridge composite dishes using an in vitro dialysability assay and to estimate the antinutrient content in ALV and maize porridge composite dishes. Methods: ALV leaves were collected, cooked and mixed with either cooked fortified or unfortified maize porridge to simulate the way it is usually consumed. Mineral and antinutrient levels were determined using standard methods and the bioaccessibility of iron and zinc was determined using an in vitro dialysability assay. Findings: The findings of the present study indicated that ALV dishes contain a reasonable amount of iron and zinc, but combining the ALV dishes with unfortified maize porridge resulted in dilution and hence a lower iron content. The amaranth-pumpkin dish contained most iron (24 mg/100 g). ALV dishes in the study had zinc contents ranging from 2.6 to 3.2 mg/100 g, with amaranth mixed with spider plant having the highest zinc content. Regarding antinutrients, the amaranth-cowpea dish had the highest phytate content of 2078 mg/100 g dry weight. ALV dishes also contained tannins and phenolic compounds. Iron percentage bioaccessibility was high in an amaranth-spider plant dish (25%), while other dishes had lower iron bioaccessibility of less than 11%. The percentage bioaccessibility of zinc in ALV dishes ranged from 7 to 8%. The amaranth-spider plant dish had higher zinc bioaccessibility when composited with fortified maize meal (13%). The percentage zinc bioaccessibility is negatively associated with phytate:zinc and phyate-calcium:zinc molar ratios. Conclusions: ALV and maize meal composite dishes have a high iron and zinc content, though they also have a high antinutrient content that has some inhibitory effects. Despite the inhibiting factors, the amount of bioaccessible iron and zinc from ALV and maize porridge composite dishes could play a significant role in planning food security strategies. However, there is a need to understand the possible effects of consuming them in different combinations with other foods. / MSc (Nutrition), North-West University, Potchefstroom Campus, 2015

Using farmer surveys the smallholder commodity systems of Brassica rapa L. subsp. chinensis and Solanum retroflexum Dun. in Vhembe District, Limpopo Province, South Africa were described and analysed. Production, transaction and consumption of the two vegetables were deeply embedded in the food, trade and farming systems of local people. The cultivation systems, which appeared effective, were developed by borrowing elements from the systems of other crops to which new knowledge specific to B. chinensis and S. retroflexum were added. Several elements of the production systems that could benefit from scientific enquiry were identified. These included genetic improvement and the optimisation of planting density and nutrient supply.

Food insecurity remains a major challenge affecting the rural poor households in South Africa. The consumption of green leafy vegetables is important to address micronutrients deficiency in rural communities and, at the same time, it contributes to fibre intake. This study investigated the people’s attitude towards the cultivation and utilisation of ILVs in rural communities. A cross-section survey study was conducted among 1 000 respondents in randomly selected households in communities. The majority of respondents were not willingly consuming ILVs. This is because most consumers were black and of the low-income group. ILVs that are consumed grow mainly in the wild. The regular consumption of these vegetables as indicated in this study is interesting, as this will help in mitigating micronutrient deficiency. Furthermore, these vegetables could be incorporated in formulated food to improve iron and zinc, especially in infant foods formulation. Based on the findings of this study it would be important to find ways of encouraging cultivation of ILVs for both nutrition and as income generating activities. / Business Management / M. Consumer Science

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No. of bitstreams: 1 silva_phs_me_jabo.pdf: 1324447 bytes, checksum: 0a31631931bf7d8856203d7c9fcd70a5 (MD5) Previous issue date: 2017-11-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O nitrogênio é um elemento requerido em maior quantidade pela maioria das culturas e o segundo mais acumulado pela rúcula. Neste contexto, o trabalho foi realizado com o objetivo de avaliar o efeito de doses de nitrogênio no crescimento e na produtividade da rúcula. O delineamento experimental utilizado foi o de blocos casualizados, com quatro repetições. Foram avaliados seis tratamentos (0, 50, 100, 150, 200 e 250 kg ha-1 de N). A rúcula caracteriza-se por apresentar crescimento inicial lento, tendo maior exigência nutricional no final do ciclo, com isso, as melhores respostas foram obtidas aos 35 dias após a emergência. O teor máximo de nitrato estimado foi de 2,1 g kg-1 de massa seca obtido com aplicação da dose de 250 kg ha-1 de N, que corresponde a 146 mg kg-1 de massa fresca e está muito abaixo do limite máximo tolerável. As doses crescentes de nitrogênio pronunciaram-se positivamente sobre a altura de plantas, número de folhas, área foliar, massa fresca e seca da parte aérea. A máxima produtividade de rúcula (4,53 kg m-2) foi obtida com 223 kg ha-1 de nitrogênio. O teor de nitrato na dose que maximiza a produtividade não é uma característica que prejudica a qualidade da rúcula. / Nitrogen is an element required in greater quantity by most of the crops and the second most accumulated nutrient by rocket. In this context, this study aimed to evaluate the effect of different nitrogen rates on rocket growth and productivity. A randomized complete block design with four replications. Six treatments were evaluated (0, 50, 100, 150, 200 and 250 kg ha-1 of N). Rocket is characterized as a vegetable which presents slow initial growth, having a higher nutritional requirement at the end of its cycle. Therefore, the best plant responses in this study were obtained at 35 days after the emergence of seedlings. The maximum estimated nitrate content was 2.1 g kg-1 of plant dry mass obtained with the application of 250 kg ha-1 of N, which corresponds to 146 mg kg-1 of plant fresh mass. This is considered below the maximum tolerable limit. The increasing nitrogen doses in this study were positively correlated with plant height, number of leaves, leaf area, and fresh and dry mass of the crop canopy. Rocket maximum yield production in this study (4.53 kg m-2) was obtained with 223 kg ha-1 of N. The nitrate content in the dose which maximizes the productivity is not a characteristic that negatively affects rocket quality.

Phenolic compounds in African green leafy vegetables (GLVs) may have a significant impact on human health. However, there is little information on the phenolic composition, antioxidant properties, as well as biological and cellular protective effects of these vegetables. The effects of boiling and extraction solvent on these compounds and on their antioxidant properties are also unknown. Phenolic content, antioxidant activity and cellular protective effects of four African GLVs in comparison with spinach, an exotic GLV, was determined. African GLVs had appreciable levels of total phenolics and antioxidant activity and in higher quantities compared to spinach. Boiling decreased the antioxidant content and activity of these vegetables and 75% acetone was more effective in extracting antioxidants from the GLVs compared to water. GLVs with high levels of phenolics also contained higher levels of antioxidant activity, suggesting that phenolics are likely to have contributed to radical scavenging activity of these vegetable extracts, even though the degree of scavenging varied in each extract of the vegetable species. The flavonoid compositions of raw and boiled African GLVs and spinach were determined using high-performance liquid chromatography. Epicatechin and rutin were the most dominant flavonoids found in both water and 75% acetone extracts. Among water extracts, pumpkin contained higher concentrations of detected flavonoids, while among the acetone extracts, cowpea exhibited higher concentrations. The effect of boiling was dependent on the type of vegetable and the specific flavonoids. There were no major differences observed between the type of flavonoids detected in extracts of African GLVs and those in spinach. However, similar to the results of total phenolics and antioxidant activity, the 75% acetone extracts of African GLVs also exhibited higher amounts of flavonoids than spinach. The protective effects of GLVs against oxidative haemolysis were dependent on the type of vegetable species. Boiling had variable effects depending on the species. The highest level of protection of erythrocytes against oxidative damage was offered by amaranth extracts, while extracts of raw jute mallow contributed to the damage of erythrocytes. The highest antioxidant protection activity against oxidative damage in plasmid DNA was offered by extracts of jute mallow and lowest by spinach.<p. For the cell viability assays, GLVs were evaluated to determine their cytotoxicity levels and functional role in oxidative damage. The results of the long-term cell viability (i.e. MTT, NR and CV) assays indicated no cytotoxicity, while the short-term cell viability (i.e. DCF) assay indicated that all extracts of raw GLVs were significantly (p < 0.05) cytotoxic to SC-1 fibroblast and human adenocarcinoma colon cancer (Caco-2) cells than extracts of cooked samples, and the levels of toxicity in the extracts of spinach was higher than in African GLVs. These results indicate that there was an initial cytotoxic effect as extracts of raw GLVs were added to the cells. However, after about 72 h, the cells recovered from the initial shock and started proliferating as usual. In the presence of peroxyl radicals, extracts of African GLVs exhibited higher protective effects against oxidative damage in both types of cell cultures than extracts of spinach. These results indicate that these protective effects could be attributed to the presence of phenolics and antioxidant properties of these extracts. Although boiling reduced the antioxidant content and activity of African GLVs, the levels remained higher than in spinach. Boiling also decreased the cytotoxicity and cell damage caused by extracts of raw GLVs samples. African GLVs are consumed after boiling, and therefore the observed cytotoxicities might not be experienced in practical terms. African GLVs have therefore a potential to reduce the risk and development of diseases associated with oxidative stress in communities that consume these vegetables. / Thesis (PhD)--University of Pretoria, 2012. / Centre for Nutrition / PhD / Unrestricted

Traditional leafy vegetables (TLVs) have formed a part of rural household food security strategies for generations. In an effort understand their role in household food security, the role and production of TLVs (morogo/ miroho/imifino) were determined in three culturally and agro-ecologically diverse rural communities in South Africa. A questionnaire survey was combined with qualitative methodologies to access the indigenous knowledge associated with the utilisation and production of these crops. TLV production is a female-oriented agricultural activity, as households mainly utilise TLVs for household consumption. Marketing of mainly dried TLVs was limited and income generated from these sales was used to complement household income. The importance of the different TLVs for household consumption varies according to the specific socio-economic situation of the household at a specific time, although they are very important in the period just before other crops are harvested. Cultural beliefs and taboo’s associated with agricultural activities were reported widely. Expenditure on agricultural inputs is low in all three villages. TLVs are commonly intercropped with maize, therefore their production and management practices are linked with maize. Uncultivated TLVs are generally harvested from maize fields and fallow lands. Variations between the villages were found for seedbed preparation, pest control management, fertilisation and irrigation practices. Interactions between crops in the production system and varieties produced had an influence on production decisions made. The socio-economic conditions of households determined the growth stages at which TLVs were harvested. Villages differed with regard to the TLVs mixed into a dish, the proportions of the different TLVs and the plant parts harvested (seed, stalks, flowers, growth points and fruit). Differences in preparation methods of crops existed and were reflected in the preparation method (frying, boiling), type of dish prepared (relish, incorporated into the porridge) and additions to dishes (adding of ash, peanut flour, bicarbonate of soda, mashed pumpkin seed, exotic vegetables, flowers and immature or mature fruit). The types of TLVs dried, preservation methods utilised, storage management and length of storage varied considerably between the three villages. Most of the dried TLVs were stored for up to one year, but the bulk was used within six months. Cowpea was perceived as an ideal dried crop for drought survival strategies as the dried leaves have a long shelf life. Villagers perceived TLVs to be nutritious, but it was not promoted amoungst vulnerable groups. The loss of indigenous knowledge (IK) was identified as a possible cause for this. The decline in utilisation of TLVs found in all three villages is mainly due to poor production systems (drought, low soil fertility, loss of IK and lack of seed). Seed systems for uncultivated plants were unstructured, although the older women had very sophisticated knowledge about seed quality. Differences in the utilisation and production of TLVs were found between the three villages. The main contributing factors towards the utilisation differences are caused by the climate and degree of indigenous knowledge in a specific area. Production differences are influenced by the bio-physical and socio-economic elements in the area. / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Agricultural Economics, Extension and Rural Development / unrestricted

The consumption of indigenous leafy vegetables is a significant tradition and culture of South Africa. The purpose of this research was to investigate the access and consumption of indigenous leafy vegetables in rural and informal settlements of the West Coast District Municipality (WCDM), Western Cape, South Africa. The research identified ILV being available and accessible in WCDM, methods of preparation used as well as the factors influencing the consumption of ILV. A cross sectional descriptive survey design was used and data collection was done using a structured questionnaire. Respondents were randomly selected from the five local municipalities in the West Coast District Municipality. A total of 205 respondents representing 205 households in the rural and informal settlements of the West Coast District Municipality were interviewed. Majority of respondents were black females, unemployed and had no formal qualification. Seventeen indigenous leafy vegetables were identified in the West Coast District and the majority of the respondents consumed indigenous leafy vegetables as part of their diet mainly because of the health benefits and taste. Four methods of cooking, namely stewing, boiling, steaming and frying were used by the respondents to prepare indigenous leafy vegetables and most of the respondents added additional ingredients during cooking such as mealie meal, fish oil and salt. The informal sector was identified as the major source of indigenous leafy vegetables and cultivation of ILV was very limited. The majority of the respondents consumed ILV at least once a week. Preservation of ILV was not a common practice. Factors such as employment status, higher household size and higher income levels did not influence the frequency of ILV consumption. / Life and Consumer Sciences / M. Sc. (Consumer Science)