Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Other
Publication Acceptance Date: 2/9/1995
Publication Date: N/A
Interpretive Summary: Dry beans (Phaseolus vulgaris L.) are often stored for several months before they are sold and/or eaten by consumers. Bean storage is of a particular concern in tropical climates. Because of the high humidities and high temperatures under which they are held in the tropics, beans that are stored for periods of time exceeding 3 months often become hard-to-cook kand increasingly indigestible. An experiment was conducted to study the cooking time of beans grown and stored for up to 9 months in Tanzania, and East African tropical country. A second objective was to see if some beans had stable cooking times despite the regime under which they were stored. Eight varieties of beans adapted to local conditions in the bean growing areas of Tanzania were stored for 3, 6, and 9 months under prevailing temperatures and humidity. After each storage period a bean sample was cooked in open pots on a stove top. The cooking time of the bean varieties stored for 9 months increased, on average, by 6 minutes over those stored for 3 months. Some varieties took the same time to cook regardless of the storage time. The production and use of bean varieties with stable cooking times allows growers to store beans for prolonged periods and take advantage of the higher price during periods of bean scarcity without fear of consumer rejection because of unfavorable cooking time. Beans that cook quickly can be prepared with reduced firewood usage and, thus, conserve a valuable natural resouce. The time saved in preparing beans for consumption could be used to expand other income producing activities.
Technical Abstract: Dry seeds of common bean (Phaseolus vulgaris L.) are underutilized as a food on a world basis. Part of the problem of dry bean underutilization in developing countries is due to storage conditions which often cause grains to become hard-to-cook and increasingly indigestible. Another problem associated with storage in developing countries is that farmers generally save a portion of the seed they produce for planting in the next season. The reliability of obtaining a crop in the season subsequent to harvest depends on the viability of seed during storage. An experiment was conducted to ascertain the stability of dry bean cooking time after storage under tropical conditions and assess seed viability. Eight cultivars of dry bean with high consumer acceptance in Tanzania were grown in the field near Morogoro, harvested and threshed. The seed was stored at 73 RH for 3, 6, and 9 months. Cooking time was determined with a pin-drop apparatus. Samples of 400 seed of each cultivar were placed on moist paper towling to assess the percentage germination. Beans stored for 9 months took longer to cook than those freshly harvested or stored for 3 and 6 months. The cooking time of the cultivars stored for 9 months ranged between 48 and 86 minutes. In all cases, beans stored for 9 months had considerably lower germination percentages than those of freshly harvested and seed stored for 3 and 6 months. Stable variability for genotypes that maintained their cooking time after 9 months storage indicated that genetic selection in breeding populations will be successful in developing cultivars with shorter cooking times. Since germination is reduced after storage, farmers should consider overplanting beans in the season subsequent to harvest in order to compensate for the decrease in germination.