Changes induced by infestation on some chemical properties of cowpea seeds

Three cowpea varieties were used in the present study,Insect susceptible popular variety, `Ife-brown' (IFB), an improved varietyfor insect resistance IT 81D-975 (1975) and a local black cowpea varietywith a white hilium adapted to diverse habitats, `Akidi' (AKD).Cowpea seeds were infested with Callosobruchus maculatus. Crudeprotein content of infested and uninfested whole cowpea flour and proteinconcentrate was determined. Prolamin contents of flour and proteinconcentrates were evaluated. Fat content, free fatty acid and peroxidevalues of cowpea seeds were also determined. All determinations werecarried out in infested and uninfested cowpea seeds in 3 replicates for eachdetermination. Emulsion properties of cowpea seeds stored in 3 containers,plastic cans (PC) and polyethylene bags (white and black WPB/BPB) weremonitored on a biweekly basis for 24 weeks.Varietal differences existed in the protein, fat and prolamin contents ofcowpeas. Infestation reduced the contents of these nutrients in all cases. Free fatty acid contents and peroxide values were increased by >100%. Infestation reduced the prolamin content by > 25% inall cases. Varietal differences also existed in emulsion capacities of cowpeaflours; IFB and 975 formed better and more stable emulsions than AKDflour. Storage in plastic cans led to better retention of the emulsionproperties of the cowpeas.