QUANTITATIVE CHANGES OF ASCORBIC ACID AND BETA CAROTENE IN AFRICAN NIGHTSHADE (SOLANUM NIGRUM) AND SPIDER PLANT (CLEOME GYNANDRA) DUE TO TRADITIONAL COOKING METHODS USED IN WESTERN KENYA

African nightshade (Solanum nigrum) and Spider plant (Cleome gynandra) are among African leafy vegetables (ALVs) that are consumed in Kenya. Studies were conducted to establish the traditional cooking methods for ALVs and to determine quantitative changes in ascorbic acid and beta carotene on cooking the two ALVs. Results revealed that the cooking methods had distinct steps. The amount of time and water for cooking were unspecified. Ascorbic acid decreased from 28.2mg/100g to 1.8mg/100g in Spider plant (93.6% loss) and from 19.5mg/100g to 5.8mg/100g in African nightshade (70% loss). Beta carotene decreased from 2.1mg/100g to 0.1mg/100g in Spider plant (94.4% loss) and from 1.8mg/100g to 0.9mg/100g (50.6% loss) in African nightshade. All results were significant (P˂ 0.001). The study concludes that there are existing methods of cooking ALVs. For the two ALVs, cooking led to drastic losses of ascorbic acid and beta carotene. Losses from the African nightshade were generally lower than from the Spider plant for the same nutrient, under similar processing conditions. The study recommends procedural changes in processing methods so as to conserve the two nutrients.