A fast laboratory procedure to assess the hard-to-cook tendency of common bean varieties

Abstract

Common beans ( Phaseolus vulgaris L.) develop the hard-to-cook (HTC) defect during storage at high temperatures and relative humidities. The objective of this work was to develop a fast laboratory procedure to assess the tendency of common bean seeds to become HTC. Four samples of common beans (cv Flor de Mayo, Mayocoba, MAM-13 and MX 2340-5) were grown under irrigation (Etzatlán and Cocula conditions) and rain-fed (Etzatlán) conditions. Two hardening procedures were used: (1) Storage hardening. Samples were stored at 33–35°C, 76% relative humidity for 120 days, sampling every 20 days; (2) Chemical hardening. Materials were soaked in 0·1 m acetate buffer, pH = 4·0, at 37°C for 1–7 h. For both hardening procedures, changes in cooking time and hardness were mathematically estimated with a relative percentage deviation of 4·8–6·0% and 1·8–5·8%, respectively. Chemical hardening might be useful for screening new bean varieties; its advantage over the storage method is its rapidity.