Some chemical options for the control of hard to cook and the associated browning in boiled cowpea (V. unguiculata)

Long cooking time is a problem militating against a wider dietary exploitation of the high protein contents of many grain legumes. Addition of CaHCO3 (calcium bicarbonate) and a crude rock salt of carbonates (kaun) are the traditional methods of alleviating this problem in most Nigerian homes. However, this treatment also enhances browning; hence it is important to look for alternatives to the carbonates. The effects of some salts and organic acids on the cooking quality of a white variety of cowpea (V. unguiculata) was studied. The cookweights increased by 13.5, 23.8 and 28.7% with addition of hydrogencarbonate, carbonate and hydroxide of sodium, and by 16.65, 21.1 and 21.5% with addition of the hydrogencarbonate, hydroxide and carbonate of potassium. Addition of chlorides of sodium, potassium and calcium decreased the cookweight by 0.5, 8.5 and 13.5%, respectively (p>0.05). Addition of the carbonates of sodium and potassium increased the browning of the grains (p<0.01), but addition of organic acids and chloride salts of sodium, potassium and calcium, respectively, reduced the browning (A430 nm) (p<0.01). Citric acid was suggested as an alternative to the traditional use of carbonates for boiling cowpea.