ABSTRACT
Changes in the protease-gluten protein system of wheat endosperm during post-maturity germination (and sprouting) were investigated in relation to "sprouting damage" of breadmaking potential. Protease activity, which is negligible in sound wheat, increased substantially during germination under laboratory conditions. Endoprotease activity increased more than exoprotease activity. Concomitant changes in the flour proteins were consistent with the observed increase in proteolytic activity. The most significant change, in relation to breadmaking potential, was the gradual decrease in the proportion of insoluble glutenin and an equivalent increase in the proportion of soluble glutenin plus low MW. protein components. The observed changes in breadmaking potential were consistent with the changes in protein solubility. In the case of the standard quality Canadian bread wheat variety (cv. Neepawa), breadmaking potential (loaf volume) deteriorated with degree of sprouting damage. On the other hand, the variety with very strong gluten (cv. Glenlea) showed an improvement in breadmaking potential with limited sprouting damage and a subsequent deterioration with additional sprouting damage. It is concluded that changes in the protease-gluten proteins system contribute significantly to the loss of breadmaking potential during sprouting and that wheat varieties can be selected, in terms of gluten strength, for improved tolerance of sprouting damage.
