PHYSICOCHEMICAL AND NUTRITIONAL PROPERTIES OF COWPEAS (VIGNA-UNGUICULATA) HEATED UNDER PRESSURE

Cowpeas (Vigna unguiculata (L) Walp) at four stages of maturity were heated in water at 34.5 kPa for varying times up to 40 min. All measurements except ash were affected by the stage of maturity and time of heating. Changes occurred most rapidly during the first 10 min of heating. The greenness of thc most immature cowpeas was lost. The degrees of firmness of all groups differed initially but decreased rapidly during the first 5 min and more slowly thereafter. Fresh cowpeas were softened sufficiently for eating after 10 min at which time pH increased 0.65 units to pH 6.75 and acidity decreased to 0.17%. In-vitro protein digestibility of the most mature, unheated cowpeas was 70.7% and increased to 83.4% after 10 min heating. Heating decreased the original trypsin inhibitor activity by 81.7% after 5 min and 85.9% after 10 min.