IMPACTS OF GERMINATION ON THE PHYSICOCHEMICAL PROPERTIES, NUTRITIONAL QUALITY AND BREAD MAKING PERFORMANCE OF YELLOW PEA AND FABA BEAN FLOURS

Abstract

The overarching goal of this thesis research was to examine the impacts of germination on the chemical composition, functionality and nutritional properties of pea and faba bean flours, and their application value in a model dough/bread system. The first study aimed to investigate the changes in the proximate composition, functional properties and nutritional attributes of yellow pea (CDC Amarillo variety) and faba bean (CDC Snowdrop variety) flours as a function of germination time (0, 24, 48 and 72 h). Alpha-amylase activity in the yellow pea and faba bean flours increased gradually during germination, whereas negligible changes were found in their chemical composition. Soaking (0-h germination) and 24-h germination showed a noticeable increase in the pasting viscosities of the pulse flours, whereas longer germination times led to a decrease in their viscosities due to the increased endogenous alpha-amylase activity. Germination was found to enhance the emulsifying and foaming properties of both pulse flours. With respect to their nutritional value, improvements were observed in the in vitro digestibility of starch and protein of the flours after germination; germination, however, did not enhance the in vitro protein digestibility corrected amino acid scores (IV-PDCAAS). In the second study, raw and germinated (72-h) yellow pea and faba bean flours were used to replace hard wheat flour at 10% and 20% levels for bread making. In comparison to the 100% wheat flour control, the incorporation of germinated pulse flours at both levels decreased the falling numbers and pasting viscosities. The composite flours tended to require a shorter mixing time to reach optimum dough development, and the generated doughs were stickier than the control dough. Farinograph and rheology results indicated that the doughs formed with the addition of raw/germinated pulse flours were less elastic and possessed a weakened gluten network as compared to the control wheat dough. In addition to the changes observed in flour and dough properties, bread baked from the composite flours displayed reduced loaf volume and decreased slice area, but increased firmness. This study revealed the influence of short-term germination on the functional characteristics and nutritional profiles of pulse flours, and showed the potential of using the modified pulse flours in bread and other bakery goods.