A KINETIC INTERPRETATION OF TEXTURAL CHANGES IN BLACK BEANS DURING PROLONGED STORAGE
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1987
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Abstract
Control and roasted (80.degree.C), dry black beans (Phaseolus vulgaris) were stored for 9 months at 8, 10, 12, and/or 14% moisture content and 8.5.degree., 25.degree., and 40.degree.C. Similarly, beans heated in a solid-to-solid roaster to 51.degree., 61.degree., 72.3.degree., 80.degree., 85.5.degree., 89.5.degree., 101.degree., and 111.degree.C were maintained at 8% moisture and 25.degree.C. Final hardness increased with moisture content and temperature. Hardening at 8.5.degree. and 25.degree.C proceeded initially almost linearly reaching a constant value after 4 to 6 months while at 40.degree.C it was sigma-shaped. A pseudo-zero order kinetic model fitted for initial rates had an activation energy of 6-11.8 kcal/mol. The hardening rate at 25.degree.C paralleled the shape of the sorption isotherm.