STORAGE‐INDUCED HARDENING IN 20 COMMON BEAN CULTIVARS

Twenty cultivars of common bean (Phaseolus vulgaris L.) varying in color and size were grown in three consecutive growing seasons at different locations and then stored for 6 months at 30°C/85% RH to induce hardening. Bean hardness was measured instrumentally following soaking and cooking. All cultivars increased in hardness during storage by a factor ranging from 1.54 to 2.47. Significant sources of variation in hardness included cultivar, environment and, largest, cultivar × environment interaction. Of the various chemical and physical tests conducted on beans before and after storage, those important in determining final hardness included fluorescence intensity (a predictor of a phenol polymerization‐type reaction), phytate level, seed volume (larger cultivars hardened less) and water relationships (storage reduced the amount of bound water). The amount of water absorbed following storage was related to cultivar color, seed volume and hilum area but not seed coat thickness.