Effects of gamma-irradiation on cotyledon cell separation and pectin solubilisation in hard-to-cook cowpeas.

Background: Cowpeas stored under high temperature and humidity develop the hard-to-cook defect (HTC). This defect greatly increases cooking times and energy costs. To better understand the mechanisms involved in the HTC defect development, the effects of gamma-irradiation on cotyledon cellular structure and pectin solubility in two cowpea cultivars with different susceptibility to HTC defect were investigated.

Influence of extraction pH on the foaming, emulsification, oil-binding and visco-elastic properties of marama protein.

Background: Marama bean protein, as extracted previously at pH 8, forms a viscous, adhesive and extensible dough. To obtain a protein isolate with optimum functional properties, protein extraction under slightly acidic conditions (pH 6) was investigated.

Results: Two-dimensional electrophoresis showed that pH 6 extracted marama protein lacked some basic 11S legumin polypeptides, present in pH 8 extracted protein.

Stability of β-carotene during baking of orange-fleshed sweet potato-wheat composite bread and estimated contribution to vitamin A requirements.

Orange-fleshed sweet potato (OFSP) is known to be a rich source of β-carotene, a precursor of vitamin A and a potential tool for fighting vitamin A deficiency (VAD) in developing countries. OFSP flour was incorporated into wheat flour at 10, 20 and 30% (w/w) substitution levels. The stability of β-carotene during baking and the contribution of OFSP-wheat composite breads to vitamin A requirements were evaluated.

Effects of micronisation and dehulling of pre-soaked bambara groundnut seeds on microstructure and functionality of the resulting flours.

Functional properties of flours from pre-soaked and micronised (130°C) whole and dehulled bambara seeds (5, 10 and 15min) were determined. An increase in micronisation time significantly reduced the pasting viscosity of the flours. Significant reductions in the differential scanning calorimetry endothermic peak enthalpies and loss of birefringence in the starch were found, indicating starch pre-gelatinisation when micronised.

Emerging Early Actions to Bend the Curve in Sub-Saharan Africa's Nutrition Transition.

Background: Sub-Saharan Africa is the last region to undergo a nutrition transition and can still avoid its adverse health outcomes.

Objective: The article explores emerging responses to "bend the curve" in sub-Saharan Africa's nutrition transition to steer public health outcomes onto a healthier trajectory.

Methods: Early responses in 3 countries at different stages of food system transformation are examined: South Africa-advanced, Ghana-intermediate, and Uganda-early.

Sorghum-cowpea composite porridge as a functional food, Part II: Antioxidant properties as affected by simulated in vitro gastrointestinal digestion.

The effect of compositing red non-tannin sorghum with brownish-cream cowpea and in vitro gastrointestinal digestion on total phenolic and flavonoid contents and antioxidant properties of a sorghum-cowpea composite porridge was studied. Maize-soybean composite porridge was used as a reference sample. Antioxidant properties were studied using radical scavenging activities against the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), peroxyl and NO radicals as well as inhibition of low density lipoprotein (LDL) oxidation and oxidative damage of vector DNA.

Effects of stearic acid and gamma irradiation, alone and in combination, on pasting properties of high amylose maize starch.

The effects of stearic acid and gamma irradiation on pasting properties of high amylose maize starch (HAMS) were studied. Stearic acid (0%, 1.5%, and 5%) was added to HAMS, and then irradiated at 0, 30, and 60 kGy before pasting.

Sensory and physicochemical analyses of roasted marama beans [Tylosema esculentum (Burchell) A. Schreiber] with specific focus on compounds that may contribute to bitterness.

The role of phenolics and saponins in contributing to bitterness in marama beans, an underutilized legume, especially when roasted, was investigated. Marama beans were roasted at 150°C for 20, 25 or 30 min, then dehulled to separate cotyledons, and pastes were prepared from these. Water extracts were prepared from full fat and defatted flours from roasted and unroasted marama cotyledons.

Novel in situ evaluation of the role minerals play in the development of the hard-to-cook (HTC) defect of cowpeas and its effect on the in vitro mineral bioaccessibility.

Cowpea is a nutritionally important drought-resistant legume in sub-Saharan Africa. It is, however, underutilised, in part due to the hard-to-cook (HTC) defect caused by adverse storage conditions resulting in seeds not softening during cooking. This study introduced a novel evaluation of the potential role that minerals play in the development of the HTC defect.

Does a sorghum-cowpea composite porridge hold promise for contributing to alleviating oxidative stress?

The effect of compositing red non-tannin sorghum with cream-coloured cowpea and porridge preparation on phenolic profile and radical scavenging activity was studied. A maize-soybean composite porridge representing a similar product on the South African market was used as reference sample. UPLC-QToF-MS-ESI was used to determine phenolic composition of the grain flours, their composites and porridges.

Relating physico-chemical properties of frozen green peas (Pisum sativum L.) to sensory quality.

Background: The acceptability of frozen green peas depends on their sensory quality. There is a need to relate physico-chemical parameters to sensory quality. In this research, six brands of frozen green peas representing product sold for retail and caterer's markets were purchased and subjected to descriptive sensory evaluation and physico-chemical analyses (including dry matter content, alcohol insoluble solids content, starch content, °Brix, residual peroxidase activity, size sorting, hardness using texture analysis and colour measurements) to assess and explain product quality.

Phenolic composition and inhibitory effect against oxidative DNA damage of cooked cowpeas as affected by simulated in vitro gastrointestinal digestion.

Cowpeas contain phenolic compounds with potential health benefits. The effect of simulated gastrointestinal digestion on phenolic composition of cooked cowpeas and the ability of the digests to inhibit radical-induced DNA damage was determined. A red and a cream-coloured cowpea type were used.

Effect of micronisation of pre-conditioned cowpeas on cooking time and sensory properties of cooked cowpeas.

Background: Cowpea is mostly utilised as cooked whole seeds. This is often achieved only after boiling for up to 2 h, resulting in high energy consumption and a long time for food preparation. Micronisation of pre-conditioned cowpeas reduces their cooking time.

Highly viscous dough-forming properties of marama protein.

Marama bean is an indigenous southern African oilseed legume with an unusual protein composition. Hence, its rheological properties were studied. Marama protein formed a highly viscous and extensible dough when compared to soya and gluten.

Micronisation and hot air roasting of cowpeas as pretreatments to control the development of hard-to-cook phenomenon.

Background: Cowpeas stored under conditions of high temperature and high relative humidity (HTHH) develop the hard-to-cook (HTC) defect. Cowpeas with HTC defect require long cooking times, limiting their utilisation. Heat pretreatments are aimed at inactivating the enzymes responsible for HTC defect development.

Effect of kafirin protein coating on sensory quality and shelf-life of 'Packham's Triumph' pears during ripening.

Background: Pears are exported in large quantities from South Africa, resulting in large revenues. Minimisation of quality losses once the fruit has reached the export destination is as important as following strict export and distribution protocols. Kafirin can form edible films.

The morama bean (Tylosema esculentum): a potential crop for southern Africa.

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.

Sensory quality of marama/sorghum composite porridges.

Background: 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.

Kafirin microparticle encapsulation of catechin and sorghum condensed tannins.

To exploit the porous nature of previously developed kafirin microparticles, encapsulation of the bioactive polyphenols, catechin and sorghum condensed tannins, was investigated. The antioxidant release profiles of the encapsulated substances were studied under simulated gastric conditions. Kafirin microparticles encapsulating catechin or sorghum condensed tannins were similar in size to control kafirin microparticles (5-6 mum).

Preparation of free-standing films from kafirin protein microparticles: mechanism of formation and functional properties.

A method of preparing free-standing films using kafirin microparticles made by phase separation from acetic acid is described. Film preparation involved the suspension of the microparticles in acetic acid solution containing plasticizer. On evaporation of the acetic acid, a complete, smooth, flexible, transparent film was formed.

Use of γ-irradiation to reduce Clostridium perfringens on ready-to-eat bovine tripe.

The aim of this study was to determine the effect of gamma irradiation at a target dose of 9kGy and storage at 5 and 15°C on the safety of ready-to-eat (RTE) tripe with respect to Clostridium perfringens count (CC) and aerobic plate count (APC), and to determine the effect of boiling (1h) and irradiation (9kGy) on Cl. perfringens ATCC 13124 spore structure. Irradiation significantly reduced APC stored at 5 and 15°C for 7 days.