Development of cereal flakes using sprouted red cowpea [Vigna unguiculata (L.)] and flattened rice flakes flour through manual dough flattening

Abstract

The study was conducted at Pambahinna, Sri Lanka (6.72◦ N, 80.78◦ E). Red cowpea (Vigna unguiculata) is a vastly nourishing legume usually used for culinary purposes, but remains less widespread as a component in food product development in Sri Lanka. Sprouting improves the nutritional value and digestibility of legumes. This study emphasises the development of cereal flakes using sprouted red cowpea flour (SRCF), flattened rice flakes flour (FRFF), dehydrated banana slices, and sesame seeds, addressing the rising demand for healthier food choices. SRCF and FRFF were mixed in three proportions: 75:25, 50:50, and 25:75, while maintaining consistent quantities of dehydrated banana as a natural sweetener and sesame seeds. The flakes were produced through manual dough flattening, without the use of extrusion or high-pressure cooking technologies commonly used in commercial flake manufacturing, which limits the textural properties of the product. Sensory evaluation was conducted using a 5-point hedonic scale, supported by one-way ANOVA and Tukey’s test, at a significance level of 0.05, identifying the 50:50 SRCF-FRFF blend as the most acceptable formulation. Chemical analyses showed the flakes contained 4.17±0.18% crude fibre, 2.59±0.1% crude fat, and 3.43±0.12% total ash. Functional properties revealed water absorption capacity of 196.67±4.16%, with milk absorption capacities of 92.67±2.52% (whole milk) and 82±2% (sweetened milk). The initial pH and water activity were 6.51±0.03 and 0.63±0.01, respectively. Texture profile analysis described a product hardness of 591.6±49.5 g and fracturability of 588.3±48.9 g, signifying a relatively firm texture attributed to the manual flaking process instead of extrusion, and adhesiveness of 0.09±0.05 mJ, gumminess of 533.83±5.69 g, and deformation of 0.09±0.01 mm. By measuring shelf life through water activity, pH, and microbiological tests, specifically the total plate count method and the yeast and mould method, it was determined that the best packaging material for storing cereal flakes was aluminium-coated packaging. This study demonstrates that sprouted red cowpea flour can be successfully incorporated into cereal flakes, thereby providing a nutritious and marketable alternative to conventional products.