Classification of African Native Plant Foods Based on Their Processing Levels.

With increasing advocacy for plant food consumption, the sub-Saharan Africa landscape is home to diverse plant-based food commodities. The need to leverage the advantages of unprocessed/minimally processed foods (PFs) over ultra-processed foods (UPFs) is a system that requires exploitation. Most of the crops produced in the continent are either classified as traditionally or moderately PFs. However, the rise in industrialization and formalization of markets is impacting and marginalizing traditional food processing (FP). Current FP classification frameworks are briefly discussed. The level of processing of cereals, grains, fruits, vegetables, roots, and tuber crops in the continent requires intervention from nutritionists, food scientists, and scientific and governmental bodies to gain a holistic view and tackle the issue of food insecurity in Africa. This study reviews the levels of processing of African foods, challenges, and future directions.

Wheat Bran Modifications for Enhanced Nutrition and Functionality in Selected Food Products.

The established use of wheat bran (WB) as a food ingredient is related to the nutritional components locked in its dietary fibre. Concurrently, the technological impairment it poses has impeded its use in product formulations. For over two decades, several modifications have been investigated to combat this problem. Ninety-three (93) studies (review and original research) published in English between January 1997 and April 2021 reporting WB modifications for improved nutritional, structural, and functional properties and prospective utilisation in food formulations were included in this paper. The modification methods include mechanical (milling), bioprocessing (enzymatic hydrolysis and fermentation with yeasts and bacteria), and thermal (dry heat, extrusion, autoclaving), treatments. This review condenses the current knowledge on the single and combined impact of various WB pre-treatments on its antioxidant profile, fibre solubilisation, hydration properties, microstructure, chemical properties, and technological properties. The use of modified WB in gluten-free, baked, and other food products was reviewed and possible gaps for future research are proposed. The application of modified WB will have broader application prospects in food formulations.

In Vitro Starch Digestibility and Glycaemic Index of Fried Dough and Batter Enriched with Wheat and Oat Bran.

A deep-fried dough/batter food (magwinya) consumed across different age groups and social strata in South Africa was investigated in this study for digestibility and estimated glycaemic index (eGI). In this research, we investigated the influence of bran type-wheat bran (WB) and oat bran (OB), and concentration (0-20% w/w) on the starch digestibility and eGI of magwinya. Rapidly available glucose (RAG) of control fried dough (60.31 g/100 g) was 33% less than fried batter (90.07 g/100 g). There was a significant reduction in RAG and an increase in slowly available (SAG) and unavailable glucose (UG) content of the fried products with OB and WB addition. The highest SAG content was observed in WB fried dough. Control fried batter had the highest eGI value (80.02) and control fried dough had medium eGI value (58.11). WB fried dough, fried batter, and OB fried dough were categorised as medium GI foods at eGI range of 56.46-58.39, 65.93-68.84 and 56.34-57.27, respectively. The eGI values of OB fried batter ranged from 73.57 to 80.03 and were thus classified as high GI foods. UG showed significant correlation with eGI (r = -0.892, -0.973, p < 0.01) and fat content (r = -0.590, -0.661, p < 0.01) for WB and OB fried products. These results reveal that ingredient modification through bran enrichment is effective for the regulation of starch digestion and reduction of eGI of deep-fried dough/batter foods.

Confocal Laser Scanning Microscopy and Image Analysis for Elucidating Crumb and Crust Microstructure of Bran-Enriched South African Fried Dough and Batter.

A double staining protocol for image acquisition using confocal microscopy (CLSM) coupled with image analysis was employed to elucidate the crust and cross-sectional properties of fried dough. Penetrated oil by image analysis (POia), porosity and pore features were quantified from the cross-section micrographs. Crust surface roughness was measured using fractal metrics and fat content was determined by solvent extraction using the American Association of Cereal Chemists method. Crumb porosity ranged between 54.94%-81.84% and reduced (p < 0.05) with bran addition. Crumb pore sizes ranged from 0-475 µm with <1 circularity, indicating elliptical shape. POia values were notably higher (p < 0.05) than PO by Soxhlet extraction (POsox), except for wheat bran (WB) fried dough where the values of POia and POsox were closely ranked. The linear effect of initial moisture content and bran concentration showed a significant impact on the image properties. The mean fractal dimension (FD) decreased as initial moisture increased. The addition of WB caused a significant reduction in the FD of fried dough, while the opposite effect was noted for its oat bran counterpart. Due to non-collinearity of image properties (FD, POia and porosity), data were fitted to cubic polynomial regression with R2 values > 0.70. CLSM and image analysis were effective in measuring oil absorption and interpreting crumb properties of fried dough. The protocol used in this study can be applied to other thick deep-fried foods for qualitative observation and quantitative measurement of a specific physical or chemical property.

Effect of Wheat Bran Incorporation on the Physical and Sensory Properties of a South African Cereal Fried Dough.

This study investigated the effect of wheat bran (WB) supplementation on the physical and sensory properties of a South African cereal fried dough (magwinya). The physical properties, instrumental texture, and sensory profile were determined for magwinya (100:0, control) and for wheat flour to wheat-bran ratios of 95:5 (MWB5), 90:10 (MWB10), 85:15 (MWB15), and 80:20 (MWB20). An increase in the proportion of WB in the fried dough showed no significant difference on the specific volume (1.47-1.54) of samples. The chroma value (30.19-22.29), lightness (35.92-28.98), and hue angle (55.03-47.77) decreased, while ∆E increased distinctly with the addition of WB. Magwinya supplemented with WB was less cohesive and easy to chew. Significant correlations were found between instrumental hardness and sensory springiness (r = -0.63; p < 0.05), as well as between instrumental cohesiveness and chewiness (r = -0.71; p < 0.01). Two principal components were identified, which accounted for 85.1% of the variance in the instrumental data. A substitution level of 5 and 10% WB was similar to the sensory properties of the control in taste, texture, and overall acceptability and can replace part of the wheat flour in the cereal fried dough production.