Investigation on the effects of kefiran on bulky bread quality and its shelf life

Kefiran is a microbial exopolysaccharide (EPS) which is produced by acid lactic bacteria and fungi during their growth. In this study, kefir grain cultivation and its kefiran extraction was carried out, respectively. Kefiran was added at the rate of 1%, 2% and 3% (w/w flour basis) to the dough and its effects on the quality properties and shelf life of bulky bread was evaluated using a completely randomized design with four treatments of kefiran (control, 1%, 2% and 3%) and in triplicates. The staling, shelf life and volume of bread were analyzed by Instron texture analyzer machine, Incubator and rapeseed displacement method, respectively. Analysis of variance and the Duncan’s multiple range test were used by SPSS Software (v.16.00 INC, USA) to analyze the data (P < 0.05). The results for dye to physicochemical properties of wheat and its flour showed that wheat had high hectoliter weight, water absorption, flour yield and falling number and in contrast, low hectoliter weight, hardness, thousand seed weight, gluten, moisture, protein, zeleny index and SDS-Sedimentation height. The results of staling tests done in three times, 24, 48 and 72 hours showed that addition of kefiran (1%, 2%, 3%) on dough, decreased significantly (p<0.05) the rate of breads crumb staling. Also, breads containing kefiran had lower rate of staling compared to control samples, as bread sample containing 3% kefiran and control sample had the least and the most staling rate respectively. The results of technological properties showed that increase of kefiran levels led to significantly (p<0.05) decrease of breads cooking loss in comparison with control samples. Addition of kefiran (1%, 2% and 3%) caused a significant (p<0.05) increase and decrease in breads volume and specific volume, respectively. The results of sensory evaluation of bread samples showed from a quality point of view, the desirable level of kefiran was 3%. The addition of kefiran increased the shelf life of the breads and extended the shelf life of the bread 3% to 8 days compared with control sample. Based on the results, application of kefiran is recommended in bakery industry to increase quality and shelf life of bulk bread.