Production of Kefiran in Kefir Grains and its Effects on the Rheological Properties Low Protein Wheat Dough and Quality of France Bulky Bread

Abstract

Kefiran is an exogenous microbial metabolite which is produced principally by lactic acid bacteria and fungi and molds throughout growth. Exo polysaccharide of kefiran was extracted from kefir grains and in status of gel was added at 1, 2, 3% concentrations (w/w flour basis) to wheat flour to evaluate its effects on rheological properties of weak wheat dough. The rheological measurements of the dough were investigated using Farinograph and Extensograph instruments. Results of Farinograph evaluation of dough showed that adding of kefiran and increase in its levels leads to increase in the water absorption capacity, dough development time and departure time, while the dough degree of softening after 20 min and mixing tolerance index were decreased in comparison with the control sample. The study on Extensograph behavior of the dough containing kefiran showed that resistance to extension at 45 and 90 min resting times was increased by increasing the percentage of the added kefiran. Longer fermentation time for each level of kefiran led to decrease of resistance to extension. Significant difference was observed in the resistance to extension of the dough containing different levels of kefiran and the control sample. Addition of kefiran to the dough after 45, 90 and 135 min resting times significantly decreased the extensibility, also with an increase in resting time from 45 to 135 min, the extensibility decreased for both the control and kefiran samples. Generally, addition kefiran at 45, 90 and 135 min resting times led to a significantly increase in resistance to extension ratio. Energy input increased at 45 and 90 min resting times, whereas chaotic effect was shown at time of 135 min restig time. Therefore, kefiran can be used to playing an important role in improving of rheological properties of weak dough and its processing conditions.