Effect of local food processing on the inositol phosphate contents in lima bean (Phaseolus lunatus L.); pigeon pea (Cajanus cajan); African yam bean (Sphenostylis sternocarpa) and jackbean (Canavalia ensiformis)

Abstract

The effects of cooking in water or alkaline solution, soaking and germination on the individual inositol phosphates (IP3 to IP6), and total inositol phosphates (IP) content of lima bean, pigeon pea, African yam bean, and jackbean were investigated. Inositol triphosphate was not detected in any of the legumes studied. The predominant inositol phosphate in all the legumes was inositol hexaphosphate (IP6). Raw white lima bean contained the highest quantity of IP6, 0.350 mg/100 mg. Pigeon pea contained 0.289 mg/100 mg IP6 in the brown and cream varieties. Jackbean contained 0.242 mg/100 mg IP6 while African yam bean had the lowest IP6 content of 0.139 mg/100 mg. All processing methods reduced the total IP to various extents. Germination led to a reduction of 85% of total IP in white lima bean. Cooking reduced IP6 by 39–65% in all the grain legumes while cooking in alkaline solution reduced total IP up to 80% in cream pigeon pea.