Dynamics of technological and baking qualities of winter rye grain depending on flour yield and water extract viscosity

Abstract

Dynamics of technological and baking qualities of winter rye grain were studied depending on flour yield and water extract viscosity (WEV). Initial material consisted in six populations of winter rye obtained after ten cycles of divergent selection for WEV, which was carried out on the basis of cultivars Al’fa and Moskovskaya 12. For each cultivar, three populations contrastingly differing for WEV were identified: low viscosity ones (LV) obtained in minus selection, mean viscosity ones (MV) obtained on the basis of the original populations without selection, and high viscosity (HV) ones obtained in plus selection. For each population, three grades of flour were obtained: wholemeal flour (100% yield), medium flour (87% yield), and pure flour (63% yield). Comparative testing was carried out in 2015 and 2016: in a field experiment on 8-m2 plots in three repetitions. The following traits were studied: weight of 1000 grains, nature of grain, glassiness, protein and starch contents, flour whiteness, falling number, amylogram height, starch gelatinization temperature, H/D ratio, bread volume, and crumb porosity. A prominent feature of LV-populations is the trend towards small grains, low grain nature, and lowered starch contents. For most traits, HV-populations were at the level of MV-populations. It was concluded that, during production of pure rye flour, almost all pentosans together with bran are removed from external layers of caryopsis. As a result, the share of pentosans within endosperm essentially increases. These pentosans belong to the water-soluble fraction, which is proven to be true by a sharp increase in WEV in pure rye flour in comparison with wholemeal flour. An increase in WEV in the grades of thin grinding flour occurs due to water-soluble pentosans, which are contained in bran, in deep layers of endosperm. As compared to rough grinding flour (wholemeal flour), thin grinding flour (pure flour) differed by higher whiteness (by 46.6 units), better amylogram (by 46 a. units), higher H/D ratio (by 0.04), volumetric yield (by 38 cm3), and porosity of crumb of a square loaf (by 9.9%). WEV also had significant influence, which, at high expression, positively affected flour whiteness, falling number, amylogram height, starch gelatinization temperature, and shape stability of toppling bread.