Influence of hardening procedure and soaking solution on cooking quality of common beans

Two common bean (Phaseolus vulgaris) varieties were seeded in the same location, harvested and cleaned. Three hardening procedures were used (soaking in acetate buffer, pH 4.1 at 37 degrees C for 5 h; storage at 37 degrees C, 100% RH for 28 days; and storage at 31-33 degrees C, 76% RH for 120 days) to have seeds in a hard-to-cook (HTC) state. The adverse effects of HTC condition, in terms of cooking time as assessed by a Mattson bean cooker, were practically eliminated by soaking seeds in salt solutions (1% NaCl + 0.75% NaHCO3; and 0.75% NaHCO3) instead of only water. Ultrastructural changes of cotyledon cells from fresh, HTC and softened seeds were observed. Results of this study may be used for the development of a technological procedure to utilize properly HTC beans generated by unefficient storage systems.