Comparison of the impact of Lactobacillus casei and Lactobacillus rhamnosus on acrylamide reduction in flat and bulk bread

The effect of yeast and lactic acid bacteria (LAB), Lactobacillus casei and Lactobacillus rhamnosus fermentation, on reducing acrylamide and physicochemical properties of the Iranian flat bread named, Sangak and bulk bread were studied. Bread containing whole grain such as Sangak bread contains a high level of enzymes and nutrients related to the bran and outer layers of the grain. In this study, the activity of amylase in whole wheat flour was 19.8% higher than to white wheat flour, based on falling number analysis. Results showed after 24 h of fermentation, in similar temperature, the pH values of the sourdoughs made from whole wheat flour were higher, compared to sourdoughs prepared from white wheat flour. Acrylamide formation was affected (r= 0.69) by pH of sourdough. In addition, moisture and water activity of bread reversely influenced (r=-0.807 and -0.588, respectively) the formation of acrylamide in bread. As an important result, acrylamide content of Sangak bread in all cases was lower than in the bulk bread. According to a sensory analysis, Sangak and bulk bread leavened with LAB starters had the most acceptable to yeast starter. The addition of sourdough starters decreased pH of bread, which causes of enhancing the texture and sensory properties, as well as reducing of contaminants like acrylamide.