Abstract
Fresh soybean samples were subjected to either an accelerated storage regime at 30°C and 79% relative humidity, or soaking in calcium chloride solution to induce the hard-to-cook (HTC) defect. The stored samples registered a five-fold increase in hardness after three months. This was attributed mainly to the alteration in the nature and bonding interactions of cell wall structural polymers. These structural polymer interactions whose thermal degradations lead to softening (or decrease in cotyledon hardness) were referred to as ‘softening substrates’. Four such softening substrates were identified on the graph of peak compressive force versus cooking time using a stepwise degradation model, and these substrates were characterized in terms of their apparent activation energies. Two of these substrates could be directly linked to β-eliminative reactions of pectic substances. Therefore, storage-induced factors influencing pectic β-degradation reactions may be one way that directly leads to the development of the HTC defect in soybean cotyledons.
