Effect of Kefiran on physicochemical characteristics of wheat and flour and rheological properties of dough

Kefiran is an exopolysaccharide which is produced mainly by lactic acid bacteria and fungi in kefir grains during growth. In this study، kefiran was added at levels of 1، 2 and 3% w/w (flour basis) to wheat flour and its effects on physicochemical characteristics of wheat and flour and rheological properties of dough was investigated. Physicochemical properties of wheat and its flour were analyzed by inframatic and the rheological of dough by farinograph and extensograph instruments. The results of physicochemical properties of the tests wheat and its flour showed that wheat had hectoliter and thousand seed weight، water absorption، flour yield and falling number higher than standards، whereas its hardness، wet gluten، moisture and protein content along with zeleny index and SDS-sedimentation height were higher than those of standards. Results of farinograph evaluation of dough showed that addition of kefiran significantly (P<0. 05) increased dough water absorption، dough development time، departure time and valorimeter value، while decreased mixing tolerance index and dough degree of softening after 10 and 20 minutes. Nevertheless، dough stability did not change significantly (P<0. 05). The results of extensograph showed that kefiran significantly (P<0. 05) increased resistance-to-extension and energy for extension in over the time while، dough extensibility was significantly (P<0. 05) decreased due to increasing levels of kefiran. It was concluded even though kefiran had no significantly effect on dough stability، could significantly increase resistance-to-extension and decreased mixing tolerance index and dough degree of softening after 10 and 20 minutes. Therefore، kefiran can be used to improve rheological properties of weak dough and its processing conditions.