THE HARD TO COOK DEFECT IN COMMON BEANS: UNDERSTANDING THE EFFECT OF S TOR AGE CONDITIONS ON PHYSICAL, COOKING AND NUTRITIONAL PROPERTIES

Abstract

Common beans are highly nutritious and widely consumed in Kenya. Storage of common beans under adverse conditions of high temperature (≥25°C) and high humidity (≥ 65%) renders them susceptible to the hard-tocook (HTC) defect. This results in increased cooking time, fuel and water use. This has a negative effect on acceptability and utilization of beans. The objective of this study was to determine effects of storage temperature and relative humidity on development of the HTC defect in common beans and subsequent physical and nutritional quality changes. Rose coco and Red kidney bean varieties were obtained from Kenya Agricultural Research Institute (K ARI) - Thika. The beans were subjected to combination of varying temperature (35˚ C and 45˚ C) and relative humidity (75% and85% RH). Beans from each treatment condition were sampled at an interval of zero, two, four and six months followed by analysis of physical, cooking and nutritional properties. There w a s a significant i n c r e a se i n conductivity and leached solutes. Significant decrease was observed in hydration and swelling coefficients of beans under each storage condition. Characteristic dimensions and one hundred seed weight were not significantly different among the various storage conditions. Based on the results of this study, it was concluded that adverse storage conditions of temperature (35˚ C and 45˚ C) and relative humidity (75% and85% RH) cause development of the HTC defect which in turn affects physical properties and cooking quality of common beans.