Soybean grain storage adversely affects grain testa color, texture and cooking quality

This article determines the effect of postharvest storage time and conditions on soybean rehydration, cooking (texture) quality and testa color. Soybean (Glycine max L.) samples were stored for 12 months (0, 3, 6, 9 and 12 months) at three moisture contents (MC) (9, 11 and 13%) and at three temperatures (10, 20 and 30 C). Soybeans were measured for rehydration, cooked bean texture and testa color. Soybeans stored at increasing MC and temperature, especially at MC 13%, 30 C, exhibited increased hydration after 6 h of soaking, increased cooked bean texture strength, reduced L*, increased a*, reduced b* color values and increased ΔE*ab color difference. This effect increased with increased storage time. Soybean storage at high MC and temperature for extended periods resulted in reduced cooked bean cooking quality and darkening of the soybean testa. This is expected to have a negative effect on soybean processing quality, sensory acceptability and economic value. Practical Applications: This work elucidates the effect of soybean storage for extended periods of time under varying temperatures and MC. Such storage may lead to detrimental changes in the soybean technological and physical properties; the major changes being testa darkening, reduced hydration and loss of cooking quality. Unfavorable soybean storage and related loss of quality will result in lower commercial value and reduced acceptability of soybeans by food processors and consumers. As a consequence, this work will provide information relevant to the formulation of appropriate soybean storage conditions for maintaining good soybean processing quality.