Molecular level protein composition of flour mill streams from a pilot-scale flour mill and its relationship to product quality

Flour mill streams prepared from two Australian and two New Zealand wheat cultivars using a pilot-scale roller mill were analyzed for rheological and baking quality characteristics and for protein composition using size-exclusion HPLC. Differences in mill stream protein composition, on an industrially relevant scale, and the relationships between the distribution of proteins (and their degree of thiol exposure) and the technological quality of the floor mill streams were examined. Consistent, significant differences were observed in the physicochemical and processing characteristics of the flour streams. Between mill streams, changes in the quantities of the storage protein groups were more marked than for nonstorage protein groups, Changes in protein composition differed between the break and reduction Stream flours. In contrast, the degree of exposure of thiol groups on the various protein groups followed different patterns between mill streams, Numerous significant relationships were observed between dough mixing and Product bilking tests and the composition and thiol exposure state of the various protein classes. These relationships are discussed in context of manipulating the processing quality of floor-based products using mill streaming, A possible role for exposed thiol groups oil storage proteins in the phenomenon of flour aging is suggested.