Tracing the geographical origin of raw wheat flour in prepared mix containing milk and/or egg by analyzing the electrophoretic band patterns and stable isotope ratios of glutenin fractions

Abstract

Abstract To trace the origin of raw wheat flour in prepared mix for bread and confectionery, the electrophoretic band patterns and stable isotope ratios of glutenin fractions extracted from prepared mix powders, including milk and/or egg were analyzed. The presence of auxiliary materials, such as sugar, salt, non-fat dry milk powder, emulsifier, thickener, and yeast, had little influence on the protein composition and the carbon and nitrogen isotope ratios of the wheat glutenin fractions extracted from the prepared mix. On the other hand, the electrophoretic band patterns and the carbon and nitrogen isotope ratios of glutenin fractions extracted from the prepared mix containing dried whole-egg powder were different from those extracted from wheat flour. However, in the presence or absence of auxiliary materials containing skimmed milk powder and/or dried whole egg powder, the electrophoretic patterns of the glutenin fraction had some characteristic bands. The results revealed the presence of characteristic protein bands depending on the wheat flour variety. Moreover, the glutenin fraction extracted from the prepared mix for confectionery was divided into high-molecular-weight (HMW-GS) and low-molecular-weight glutenin subunit (LMW-GS) fractions. The LMW-GSs was observed to reduce the effect of egg-derived proteins on electrophoretic band patterns, and stable isotope ratios. The carbon and nitrogen isotope ratios of LMW-GSs extracted from Japanese flour were significantly lower compared to wheat flour from US. Therefore, our study suggests that the electrophoresis of the glutenin fractions and the stable isotope ratios of LMW-GSs would be useful tool for discriminating varieties of wheat flour and prepared mix samples including milk and egg.