Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cook... more Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cooked cowpeas
Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cook... more Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cooked cowpeas
The morama bean is an underutilized leguminous oilseed native to the Kalahari Desert and neighbor... more The morama bean is an underutilized leguminous oilseed native to the Kalahari Desert and neighboring sandy regions of Botswana, Namibia, and South Africa (Limpopo, North-West, Gauteng, and Northern Cape provinces), and forms part of the diet of the indigenous population in these countries. It is also known as gemsbok bean, moramaboontjie, elandboontjie, braaiboonjie, marama, marumana, tsi, tsin, gami, and ombanui. It is reported as an excellent source of good quality protein (29-39%); its oil (24-48%) is rich in mono- and di-unsaturated fatty acids and contains no cholesterol. Morama is a good source of micronutrients such as calcium, iron, zinc, phosphate, magnesium, and B vitamins including folate. It is also reported to be a potential source of phytonutrients including phenolic compounds (e.g., tannins), trypsin inhibitors, phytates, and oligosaccharides, components which have been shown in other foods to contribute to health in particular, prevention of noncommunicable diseases such as cardiovascular diseases, diabetes, and some cancers. From a nutritional and health perspective, the morama bean has potential commercial value as a cash crop and value-added products, particularly in the communities where it is found.
Steeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. N... more Steeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. NaOH steeping substantially reduced assayable total phenols and tannins in both Type III and Type II sorghums and with Type III sorghum caused a 60-80% reduction in α-amylase inhibition compared to a 20% reduction by water steeping. NaOH treatment also reduced starch liquefaction time and increased free amino nitrogen. Type II tannin sorghum did not inhibit α-amylase and consequently the NaOH treatment had no effect. HPLC and LC-MS of the tannin extracts indicated a general trend of increasing proanthocyanidin/procyanidin size with increasing NaOH concentration and steeping time, coupled with a reduction in total area of peaks resolved. These show that the NaOH treatment forms highly polymerised tannin compounds, too large to assay and to interact with the α-amylase. NaOH pre-treatment of Type III sorghums could enable their utilisation in bioethanol production.
ABSTRACT The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize... more ABSTRACT The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize starch digestion in vitro were studied using floury and vitreous endosperm flours. Starch digestion was significantly higher in floury sorghum endosperm than vitreous endosperm, but similar floury and vitreous endosperm of maize. Cooking with 2-mercaptoethanol increased starch digestion in both sorghum and maize, but more with sorghum, and more with vitreous endosperm flours. Increasing cooking time progressively reduced starch digestion in vitreous sorghum endosperm but improved digestibility in the other flours. Pressure-cooking increased starch digestion in all flours, but markedly more in vitreous sorghum flour; probably through physical disruption of the protein matrix enveloping the starch. Irrespective of vitreousness or cooking condition, the alpha-amylase kinetic constant (k) for both sorghum and maize flours remained similar, indicating that differences in their starch digestion were due to factors extrinsic to the starches. SDS-PAGE indicated that the higher proportion of disulphide bond-cross-linked prolamin proteins and more extensive polymerisation of the prolamins on cooking, resulting in polymers of Mr>100k, were responsible for the lower starch digestibility of the vitreous sorghum endosperm flour.
Previously, we reported that starch-related functional properties of cowpea flours and pastes wer... more Previously, we reported that starch-related functional properties of cowpea flours and pastes were modified by 2, 10 and 50 kGy γ-irradiation doses. To elucidate some of the effects of γ-irradiation specifically on cowpea starch as well as the actual contribution of starch to the observed ...
Journal of the Science of Food and Agriculture, 2010
The edible seeds of marama beans are a good source of protein and fat and can potentially enhance... more The edible seeds of marama beans are a good source of protein and fat and can potentially enhance the nutritional quality of sorghum products. Utilisation of marama flour in a composite porridge depends on sensory acceptance. Heating of marama beans before milling is used to inactivate trypsin inhibitors. Defatting of marama flour would improve shelf life. In this study, marama/sorghum composite porridges (10% solids) were prepared and subjected to descriptive sensory analysis, consumer acceptance testing, texture analysis, pasting and colour measurements. Composite porridges had less cooked sorghum aroma/flavour but more intense overall aroma/flavour and were less viscous and less firm than sorghum porridge. Composite porridges prepared with flour from heated marama beans had a roasted nut flavour and were darker in colour compared with porridges prepared with unheated marama beans, which had a strong boiled nut aroma/flavour. Composite porridges from full-fat marama flours tasted more buttery/creamy. A bitter aftertaste was perceived in porridges from defatted marama flours. The 100% sorghum porridge and the composite porridge with full-fat flour were more acceptable to consumers. Combining sorghum meal with full-fat marama bean flour has the potential to improve the sensory quality of sorghum porridge as a staple by providing acceptable sensory appeal.
This paper reviews the literature on African leafy vegetables (ALVs) consumed in sub-Saharan Afri... more This paper reviews the literature on African leafy vegetables (ALVs) consumed in sub-Saharan Africa. The aim is to evaluate the nutritional value of these plant.
Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cook... more Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cooked cowpeas
Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cook... more Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cooked cowpeas
The morama bean is an underutilized leguminous oilseed native to the Kalahari Desert and neighbor... more The morama bean is an underutilized leguminous oilseed native to the Kalahari Desert and neighboring sandy regions of Botswana, Namibia, and South Africa (Limpopo, North-West, Gauteng, and Northern Cape provinces), and forms part of the diet of the indigenous population in these countries. It is also known as gemsbok bean, moramaboontjie, elandboontjie, braaiboonjie, marama, marumana, tsi, tsin, gami, and ombanui. It is reported as an excellent source of good quality protein (29-39%); its oil (24-48%) is rich in mono- and di-unsaturated fatty acids and contains no cholesterol. Morama is a good source of micronutrients such as calcium, iron, zinc, phosphate, magnesium, and B vitamins including folate. It is also reported to be a potential source of phytonutrients including phenolic compounds (e.g., tannins), trypsin inhibitors, phytates, and oligosaccharides, components which have been shown in other foods to contribute to health in particular, prevention of noncommunicable diseases such as cardiovascular diseases, diabetes, and some cancers. From a nutritional and health perspective, the morama bean has potential commercial value as a cash crop and value-added products, particularly in the communities where it is found.
Steeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. N... more Steeping milled sorghum in up to 0.4% NaOH was investigated as a method of tannin inactivation. NaOH steeping substantially reduced assayable total phenols and tannins in both Type III and Type II sorghums and with Type III sorghum caused a 60-80% reduction in α-amylase inhibition compared to a 20% reduction by water steeping. NaOH treatment also reduced starch liquefaction time and increased free amino nitrogen. Type II tannin sorghum did not inhibit α-amylase and consequently the NaOH treatment had no effect. HPLC and LC-MS of the tannin extracts indicated a general trend of increasing proanthocyanidin/procyanidin size with increasing NaOH concentration and steeping time, coupled with a reduction in total area of peaks resolved. These show that the NaOH treatment forms highly polymerised tannin compounds, too large to assay and to interact with the α-amylase. NaOH pre-treatment of Type III sorghums could enable their utilisation in bioethanol production.
ABSTRACT The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize... more ABSTRACT The effects of endosperm vitreousness, cooking time and temperature on sorghum and maize starch digestion in vitro were studied using floury and vitreous endosperm flours. Starch digestion was significantly higher in floury sorghum endosperm than vitreous endosperm, but similar floury and vitreous endosperm of maize. Cooking with 2-mercaptoethanol increased starch digestion in both sorghum and maize, but more with sorghum, and more with vitreous endosperm flours. Increasing cooking time progressively reduced starch digestion in vitreous sorghum endosperm but improved digestibility in the other flours. Pressure-cooking increased starch digestion in all flours, but markedly more in vitreous sorghum flour; probably through physical disruption of the protein matrix enveloping the starch. Irrespective of vitreousness or cooking condition, the alpha-amylase kinetic constant (k) for both sorghum and maize flours remained similar, indicating that differences in their starch digestion were due to factors extrinsic to the starches. SDS-PAGE indicated that the higher proportion of disulphide bond-cross-linked prolamin proteins and more extensive polymerisation of the prolamins on cooking, resulting in polymers of Mr>100k, were responsible for the lower starch digestibility of the vitreous sorghum endosperm flour.
Previously, we reported that starch-related functional properties of cowpea flours and pastes wer... more Previously, we reported that starch-related functional properties of cowpea flours and pastes were modified by 2, 10 and 50 kGy γ-irradiation doses. To elucidate some of the effects of γ-irradiation specifically on cowpea starch as well as the actual contribution of starch to the observed ...
Journal of the Science of Food and Agriculture, 2010
The edible seeds of marama beans are a good source of protein and fat and can potentially enhance... more The edible seeds of marama beans are a good source of protein and fat and can potentially enhance the nutritional quality of sorghum products. Utilisation of marama flour in a composite porridge depends on sensory acceptance. Heating of marama beans before milling is used to inactivate trypsin inhibitors. Defatting of marama flour would improve shelf life. In this study, marama/sorghum composite porridges (10% solids) were prepared and subjected to descriptive sensory analysis, consumer acceptance testing, texture analysis, pasting and colour measurements. Composite porridges had less cooked sorghum aroma/flavour but more intense overall aroma/flavour and were less viscous and less firm than sorghum porridge. Composite porridges prepared with flour from heated marama beans had a roasted nut flavour and were darker in colour compared with porridges prepared with unheated marama beans, which had a strong boiled nut aroma/flavour. Composite porridges from full-fat marama flours tasted more buttery/creamy. A bitter aftertaste was perceived in porridges from defatted marama flours. The 100% sorghum porridge and the composite porridge with full-fat flour were more acceptable to consumers. Combining sorghum meal with full-fat marama bean flour has the potential to improve the sensory quality of sorghum porridge as a staple by providing acceptable sensory appeal.
This paper reviews the literature on African leafy vegetables (ALVs) consumed in sub-Saharan Afri... more This paper reviews the literature on African leafy vegetables (ALVs) consumed in sub-Saharan Africa. The aim is to evaluate the nutritional value of these plant.
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