148 Swelling index of glutenin and wheat flour quality.

Ch. WANG and M. I. P. Kovacs. Agriculture & Agri-Food Canada, Cereal Research Centre, 195 Dafoe Road, Winnipeg, Manitoba, Canada R3T 2M9.

Here we would like to show that the increased flour quality value is due chiefly to the increased imbibitional power of the proteins, mainly the gluten components. Small scale tests for the prediction of wheat baking quality and dough properties have been widely used in wheat breeding and wheat protein studies. These methods are indirectly or directly based on the amount of insoluble protein in wheat. In this study, a micro method was developed to measure the swelling capacity of glutenin in flour in different solvents to predict dough properties according to the amount of insoluble glutenin in the flour. Flour of 40mg was hydrated in distilled water and swollen in non-reducing solvents (SDS-lactic acid) followed by a low speed centrifugation. The swelling index of glutenin (SIG) was calculated as the weight of the residue divided by the original weight of the sample. The SIG tests were compared to other small scale tests using a set of samples, consisted of 20 cultivars ranging in flour dough quality properties. The SIG tests showed a strong correlation with gel protein and insoluble glutenin tests (r = 0.85, r = 0.91, p < 0.01 respectively) and also with SDS and Zeleny sedimentation tests (r = 0.74, r = 0.72, p < 0.01, respectively). This method has the potential for analyzing large numbers of samples within a short time with good reproducibility. The SIG test is suitable for predicting flour quality in the early generations of a breeding program.