Effects of processing on the thiamin, riboflavin and protein contents of cowpeas (Vigna unguiculata (L) Walp) II. Alkali (‘potash’) treatment

Summary Alkali treatment of cowpeas using ‘potash’(sodium sesquicarbonate) and sodium bicarbonate caused severe losses of thiamin and riboflavin but had no significant effect on the protein content in terms of total nitrogen. The vitamin losses were not dependent on the pH but on the concentration of the alkaline solutions. The reduction in cooking time by the use of alkali was significant only at high concentrations but the resultant products were not acceptable organoleptically. As the vitamin losses were high even with low concentrations of alkali the traditional Nigerian use of ‘potash’ is not advocated. In addition, there is a possible latent danger to health with ‘potash’ treatment of cowpeas because of the possible undesirable formation of lysinoalanine.