EFFECT OF PROCESSING ON SOME PROPERTIES OF COWPEA (VIGNA-UNGUICULATA), SEED, PROTEIN, STARCH, FLOUR AND AKARA

Large brown eye Kano white cowpea (Vigna unguiculata) seeds were proce ssed into three batches of flour by wetting, drying individually at 30 , 80, and 120 degrees C, decorticating and dry milling. Starch was ext racted from the cowpea seed and protein from the flour using water as solvent. The water-extractable proteins were purified by dialysis and analysed by electrophoresis. The cowpea flour was used to produce akar a balls (fried paste). The microstructure of the cowpea cotyledon, flo ur, starch and akara crumb were examined with a scanning electron micr oscope (SEM). Electrophoretic separation revealed that some of the pro tein fractions from the sample extracted from 30 degrees C dried cowpe a were absent in the sample extracted from the 80 degrees C and 120 de grees C dried cowpeas or their quantities had decreased. In the SEM st udy, no difference was observed in the microstructure of the three flo ur samples except in the size and shape of the starch granules and par ticles of protein and cell wall material. The starch granules from the cowpea dried at 120 degrees C had surface defects. Cavities occurred in the cotyledons of the 80 and 120 degrees C dried cowpea seeds, some starch granules, protein matrix and sometimes the entire cell content s were lost from the cell. The protein sheet in the akara crumb became thicker as temperature increased to 80 and 120 degrees C.