Systematic Review of the Literature to Inform the Development of a South African Dietary Polyphenol Composition Database.

Comprehensively compiled dietary polyphenol data is required to compare polyphenol content between foods, calculate polyphenol intake and study its association with health and disease. The purpose of this review was to identify data on the presence and content of polyphenolic components in South African foods, with the aim of compiling the data into a database. An electronic literature search was conducted up until January 2020 using multiple databases. Additional literature was sourced from South African university repositories. A total of 7051 potentially eligible references were identified, of which 384 met the inclusion criteria. These studies provided information on food item name, geographical distribution, polyphenol type, quantity, and quantification method. Data for 1070 foods were identified, amounting to 4994 polyphenols. Spectrophotometry was the main method used for quantification of gross phenolic content in various assays such as total phenolic content (Folin-Ciocalteu assay), total flavonoid content (AlCl3 assay) and condensed tannin content (vanillin-HCl assay). Phenolic acids and flavonoids were the main polyphenol classes identified. This review highlights that South Africa has abundant information on the polyphenol content of foods, which could be utilised within a food composition database for the estimation of polyphenol intake for South Africa.

Production, health-promoting properties and characterization of bioactive peptides from cereal and legume grains.

The search for bioactive components for the development of functional foods and nutraceuticals has received tremendous attention. This is due to the increasing awareness of their therapeutic potentials, such as antioxidant, anti-inflammatory, antihypertensive, anti-cancer properties, etc. Food proteins, well known for their nutritional importance and their roles in growth and development, are also sources of peptide sequences with bioactive properties and physiological implications. Cereal and legume grains are important staples that are processed and consumed in various forms worldwide. However, they have received little attention compared to other foods. This review therefore is geared towards surveying the literature for an appraisal of research conducted on bioactive peptides in cereal and legume grains in order to identify what the knowledge gaps are. Studies on bioactive peptides from cereal and legume grains are still quite limited when compared to other food items and most of the research already carried out have been done without identifying the sequence of the bioactive peptides. However, the reports on the antioxidative, anticancer/inflammatory, antihypertensive, antidiabetic properties show there is much prospect of obtaining potent bioactive peptides from cereal and legume grains which could be utilized in the development of functional foods and nutraceuticals.

Stability of ß-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 ß-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 ß-carotene during baking and the contribution of OFSP-wheat composite breads to vitamin A requirements were evaluated. The retention of all-trans-ß-carotene in breads containing 10, 20 and 30% OFSP flour was 62.7, 71.4 and 83% respectively, after baking. Breads containing 20% and 30% OFSP flour could be used for the eradication of vitamin A deficiency as they were found to meet 29 and 89.2% (100g portion) respectively, of the recommended dietary allowance (RDA) of vitamin A amongst children aged 3-10years. The latter would meet nearly a half of the RDA of vitamin A for pregnant and lactating women.

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. Micronisation changes the physicochemical properties of cowpea seeds, which may affect the sensory properties of cooked cowpeas. Consumer acceptance and utilisation of micronised cowpeas depend on their sensory properties. Micronised and unmicronised samples of Blackeye, Bechuana white, Glenda and Dr Saunders cowpeas were subjected to cooking time, descriptive sensory and colour analyses. RESULTS: Micronisation significantly reduced cowpea cooking time by 28-49%. There were significant (P < 0.05) increases in roasted aroma and flavour, mushy texture and splitting in all micronised samples. Bechuana white was more mushy and split than others. There were significant decreases in firmness, mealiness and coarseness after micronisation for all cowpea types. Micronised cowpeas were darker (lower L* values) than unmicronised cooked cowpeas. Darkening was more evident in light-coloured than dark-coloured cowpeas. CONCLUSION: Micronisation reduces cowpea cooking time but also affects sensory properties of cowpeas such as introducing roasted flavours that may not be familiar to consumers. This might have an influence on consumer acceptance of micronised cowpeas.

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. 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. RESULTS: 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. CONCLUSION: 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.