Effect of Starch Damage Degree of Rice Flour on Bread-making Properties and Temporal Changes of Wheat Flour and Rice Flour Blended Bread

Abstract

The purpose of this study was to investigate the effects of two types of rice flour, with different starch damage degrees, on bread-making properties and temporal changes in bread crumb rheological properties. The subject of this study was wheat flour and rice flour blended bread, in which rice flour was used to replace 40% of the wheat flour. It was found that rice flour with a high degree of starch damage had high water retention capacity. Also, differences in the shape and surface microstructure of rice flour particles were observed. When producing the subject bread on a laboratory scale, it was found that replacing 25% or 50% of low starch damage rice flour with high starch damage rice flour reduced the temporal changes in bread crumb rheological properties compared to the product made using only rice flour with a low degree of starch damage (2.7%). With the aim of simulating mass production, the subject bread was produced on an experimental factory scale with each rice flour type at a ratio of 50% (starch damage degree 8.2%). Results showed that when the starch damage degree increased, dough hardening was suppressed and temporal changes in the rheological properties of the subject bread crumb (firmness and cohesiveness) decreased. It was speculated that as the starch damage degree increased, α-amylase, which was added during the dough mixing stage, acted more easily.