Partial purification of components in rye water extractables which improve the quality of oat bread

Unlike wheat bread, the dough of which has a visco-elastic network and high gas-holding capacity, oat bread generally has a low volume and a dense structure. We showed earlier that including rye water-extractable components in an oat bread batter recipe increases loaf volume by ca. 30% (Pauly and Delcour, submitted as back-to-back publication). We here report on efforts to identify the active factor(s). Anion exchange chromatography allowed enriching the active factor(s). This and the fact that only a limited volume increase was observed when oat batter was supplemented with boiled rye extract indicate that proteins are likely the most important components responsible for the volume increase. While the most active factor(s) had a pI below 4.5, components with pI values between 4.5 and 8.5 also contributed to oat loaf volume. Alkaline rye components (pI > 8.5) or rye arabinoxylan had no impact. Rye water-extractable components smaller than 6-8 kDa also had a positive impact on loaf volume.