The effect of formulation and fermentation process on gluten level and some quality characteristics of Maraş type tarhana

Maraş tarhana chip is a traditional fermented product prepared with wheat and yoghurt that contains gluten by nature. In this study, the effect of different proteolytic enzyme concentrations on gluten levels of tarhana chips produced using einkorn wheat, which is known to have some nutritional benefits, was investigated. For this purpose, tarhana doughs were prepared applying five different formulations, namely the control group (K), 200 µl (E1), 400 µl (E2), 800 µl (E3) and 1600 µl (E4) enzyme supplemented doughs. These were subjected to fermentation at 45 °C for 24 hours and after pasting were dried at 60 °C for 24 hours to obtain samples of tarhana chips. Gluten analyses were performed using the R5 antibody-based Sandwich and Competitive ELISA methods. As the enzyme concentration increased, a significant decrease in gluten level was detected with both assays. It was observed that the legal limit of <100 ppm (low gluten) for labelling was met for the sample with the highest enzyme concentration by Sandwich ELISA method. As a result, a significant change in gluten content of tarhana chips was obtained with Flavourzyme®, a fungal peptidase mixture. On the other hand, chemical properties such as pH, titration acidity, dry matter, protein, fat, free and total amino acid content as well as physical properties such as texture and color were examined in the samples within the scope of the study. When the free amino acid profile is evaluated, the quantities of proline and glutamic acid, which are the most common amino acids in the gluten structure, increase as the enzyme concentration increases, which supports the decrease in gluten level. Furthermore, the detected protein (total nitrogenous compound) and fat contents indicate that a product with superior nutritional value can be developed compared to conventional Maraş tarhana chips. It was also observed that as the enzyme concentration increased, the hardness value measured instrumentally decreased. The color measurement results show that as the enzyme concentration increased, the L* (brightness) value decreased, while the a* and b* values increased. Sensory evaluation revealed that the favourite sample scored by the panelists was E2. The fact that the enzyme-added samples were generally appreciated much higher than the control group shows that a snack made by einkorn wheat with reduced gluten could be a product preferred by consumers.