A modified laboratory canning protocol for quality evaluation of dry bean (Phaseolus vulgaris L.)

The effects of calcium (Ca2+) level in the soak water, blanch water and brine, blanching temperature, and total seed solids on dry bean canning quality were investigated to optimise a laboratory canning protocol. A linear increase in the Ca2+ level of soak water, blanch water and brine resulted in a linear decrease in hydration coefficient and percent washed drained weight but a linear increase in texture. Low Ca2+ level (10 mg kg(-1)) reduced the hydration time for dry bean seed from 14 to 1 h. Blanching temperatures of 50, 70 and 88 degrees C had non-significant effects on canning quality traits. Branching for 30 min at 70 degrees C for black bean or at 88 degrees C for navy bean and pinto bean resulted in percent washed drained weight greater than or equal to 60, as required by the Canada Agricultural Products Standards Act. Seed solids levels of 95-97 g per 300 x 407 (14 fl oz) can were sufficient to attain a percent washed drained weight of 60. It was confirmed that the thermal processing conditions (115.6 degrees C retort temperature, 45 min) used in this study were sufficient to achieve commercial sterility. The optimised lab protocol for evaluation of the canning quality of dry bean breeding Lines is as follows. Seed containing 95 g of solids for pinto bean, 96 g for navy bean and 97 g for black bean is soaked in water for 30 min at 20 degrees C and blanched for 30 min at 70 degrees C for black bean and 88 degrees C for navy bean and pinto bean in water containing 10 mg kg(-1) of Ca2+. The seed is then transferred to a 300;; 407 can, filled with brine containing 10 mg kg(-1) of Ca2+, 1.3% (w/v) of NaCl and 1.6% (w/v) of sugar. The can is then sealed, processed in steam at 115.6 degrees C for 45 min and cooled at 20 degrees C for 20 min. Cans are stored for at least 2 weeks prior to quality evaluation of the canned product. Canning of dry bean seed according to this protocol results in precise estimation of canning quality traits, particularly percent washed drained weight. (C) 2000 Society of Chemical Industry.