Effects of flaxseed and soybean supplementation on the nutritional and antioxidant properties of mahewu – a South African beverage

Abstract

In this study, mahewu, a fermented cereal-based South African beverage was supplemented with soybean and flaxseed in different combinations: C1 (maize), C2 (sorghum), C3 (1:1 of maize and sorghum), C4 and C5 (8:8:3:1 and 6:6:6:2 of maize: sorghum: soybean: flaxseed). Subsequently, the nutritional and health benefits of the fortified samples were compared to that of the original beverage. Proximate composition of raw flours showed high carbohydrate content in maize (78.55 ± 0.32%) and sorghum (71.98 ± 0.46%), while soybean and flaxseed had high contents of protein (48.94 ± 0.09%) and fatty acids (43.56 ± 0.13%), respectively. In addition, significant differences (p < 0.05) and improvements were observed in crude protein, fat, micronutrients as well as the phenolic content and antioxidant activity of the fortified mahewu combinations. Furthermore, the enhanced nutritional quality of the supplemented samples was also evidenced by the improved rheological behaviour, syneresis, colour profile and sensorial characteristics of C4 and C5 combinations. These findings demonstrate that soybean and flaxseed could be used as dietary supplements to improve the nutrient deficiencies of staple foods such as maize and sorghum and their processed products. This research could also serve as the foundation for developing new combinations of staple foods with nutritionally rich soybeans and flaxseeds to increase the protein and healthy fat content, along with essential micronutrients.