Browsing by Author "HOHLBERG, AI"

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    HARD-TO-COOK DEFECT IN BLACK BEANS - PROTEIN AND STARCH CONSIDERATIONS
    (1987) HOHLBERG, AI; STANLEY, DW
    Black beans (Phaseolus vulgaris) was stored for 10 months under three environmental conditions [high temperature/humidity (HTHH: 30.degree.C, 85% RH); medium temperature/humidity (MTMH: 25.degree.C, 65% RH); low temperature/humidity (LTLH: 15.degree.C, 35% RH)] in order to determine changes in starch and protein and to assess their contribution in textural defects. Hard-to-cook defect developed in HTHH-stored seeds and partially in MTMH samples. An increase in the DSC peak starch gelatinization temperature during storage at all three conditions was not related to hardening. Five protein fractions were separated by gel filtration. A significant increase (p < 0.05) was found during storage for a low-MW fraction of HTHH and MTMH extracts. At the same time a high-MW fraction decreased significantly (p < 0.05), suggesting the breakdown of large proteins. After 10 months of storage, free aromatic amino acids increased significantly (p < 0.05) with increasing temperature and humidity of storage. The coincidence of the appearance of small polypeptides and aromatic amino acids with the development of the hard-to-cook defect suggested a relation between these phenomena.