Assessment of the Baking Properties of Rye Flour Based on the Polysaccharide Content and Properties

Abstract

This study aimed to determine the baking quality of rye flour in terms of the content and properties of its polysaccharides, i.e., starch and pentosans. The study materials were low- and high-extract rye flours produced in industrial mills from the rye grain of two growing seasons (2019 and 2020). The results of the starch content, falling number, amylograph properties, DSC test, content of pentosans, swelling curve test, and laboratory baking test were determined. It was found that the type of flour had a greater impact on the baking quality of rye flour than the year of its production. Research has shown that the most frequently used parameters, such as the falling number and the maximum viscosity of starch paste, are not good indicators for assessing the baking value of currently produced rye flours. From the parameters used for evaluating the properties of the starch–amylolytic complex, the initial and onset temperatures for starch gelatinization were the best indicators for evaluating the baking quality of rye flour. This study revealed a significant correlation between the pentosan content (total, water soluble, and insoluble), swelling curve parameters and quality parameters of rye bread, such as the specific bread volume, bread crumb moisture, and bread crumb hardness. Assessment of the baking value of rye flour based only on the evaluated properties of the starch–amylolytic complex is currently not sufficient to determine the baking quality of rye flour and predict the quality of rye bread. This study on the baking quality of rye flour should be extended to include the assessment of the dough properties related to the pentosan content and the enzymes that degrade these components. It was shown that the properties of rye dough related to the content of pentosan can be characterized based on the swelling curve test as a method that, together with the initial and onset starch gelatinization temperatures, allows better assessment of the baking quality of the commercial rye flour and its suitability for the good-quality rye bread production.

Keywords

• rye flour
• swelling curve
• pentosans
• alpha-amylase activity
• rye bread