Effect of using kefir in the formulation of traditional tarhana

Abstract

Tarhana is known as a fermented cereal product made traditionally from wheat flour and yoghurt. As a novelty, kefir was used as substitute for yoghurt in tarhana production partially and completely to investigate the effects on fermentation activity, nutritional, sensory and rheological properties of tarhana. Addition of kefir increased the fermentation activity as raise in acidity values was observed compared to tarhana samples prepared with yoghurt. Regarding dry tarhana samples, the highest acidity degree, protein, ash and phenolic contents were detected in samples prepared with 100% kefir. Counts of LAB groups (M17 and MRS agar) of tarhana enriched with 100% kefir was higher than that of other tarhana samples during the fermentation period. Moreover, kefir affected the scores of sensory properties of tarhana soups. Tarhana soups prepared with kefir gave the highest scores for mouth feel, odour and consistency attributes. Tarhana soup prepared with 50% yoghurt and kefir showed the lowest viscosity probably due to synergistic effect on starch hydrolysis by bacterial population from both ingredients. These results suggest that replacement of yogurt with kefir in the formulation of Tarhana may enhance some properties of the soup.