Variability in the Content of Water-Extractable and Water-Unextractable Non-Starch Polysaccharides in Rye Flour and Their Relationship to Baking Quality Parameters

Abstract

The non-starch polysaccharide (NSP) content and composition of rye flours, differing in baking quality, were studied over three consecutive years at three locations. Rye flours were rich in water-extractable NSP and, consequently, rich in water-extractable arabinoxylans (WE-AX). A large variability of both components was observed in water-unextractable fraction, and especially, in the ratio of water-extractable to water-unextractable arabinoxylan content (WE/U-AX). The proportion of WE/U-AX in rye flour was found to be the primary factor contributing to both flour and bread quality parameters. However, the content of WE-AX correlated positively but not significantly, whereas water-unextractable (WU) counterpart was negatively correlated with quality attributes. The data showed that rye flour of high baking quality had a high ratio of WE/U-AX, which was also combined with high values of falling number and amylographic peak viscosity. Significant, positive correlations were also found between ratio of water extract viscosity to water-extractable arabinoxylan content (EV/WE-AX) and overall baking score and bread volume. Our results suggest that some AX populations, of specific structure and/or molecular weight, could be especially important for baking potential of rye flour.