Particle Size Distribution of Commercial Cowpea (Vigna unguiculata (L) Walp.) Flour and Sensory Properties of Akara

Abstract

Cowpea (Vigna unguiculata (L) Walp.) is an indigenous African legume. It is an important source of protein in the diet of West Africans. In Nigeria, large proportion of cowpea is consumed as a deep fat fried foam product (akara), after the beans had been soaked in water, manually dehulled and made into paste. The inconvenience of these procedures each time is a major constraint in the utilization of cowpea and has led to considerable effort towards production of ready-to-use cowpea flour which can be hydrated into paste for akara. Consistency, dispensability and the frying characteristics of cowpea paste, reconstituted from cowpea flour, and the quality of the resulting akara balls, are influenced among others by particle size distribution of the paste. In this study, particle size distribution of commercially produced cowpea flour was determined and the sensory properties of akara made from it were compared with that prepared using a traditional method. The commercial cowpea flour notably had finer particles than the traditional paste. Over 40% of the commercial cowpea flour had particles finer than 0.75x10-4m as against 25% of the traditional paste. The concentration of particles intermediate between flour and grits (i.e. in the 2x10-4m - 6.0x10-4m pore region) was higher in the traditional paste (44.72%) than the commercial cowpea flour (18.36%). All the akara had high scores for colour, while the commercial cowpea flour akara had significantly (p?0.05) lower scores for texture, flavour and overall acceptability. The commercial flour akara was dry and dense with tough outer surface, and beany flavour. Texture and flavour are very important determinants of akara quality.