Physicochemical and Microbiological Properties of Ayran Produced from Milk Treated with Different Microbial Transglutaminase

In this study, ayran was produced from milk treated with microbial transglutaminase (MTG) under different conditions. The aim of this work was to determine the effect of treating milk with two different MTGs (MTG-MP and MTG-YG), either before or after heat treatment at different conditions (at 4°C for 12 h, at 38°C for 3 h, and at 50°C for 1 h), on the physicochemical and microbiological properties of ayran. The highest number of grains and mean perimeter of grains were determined as 140.8 per 3 mL of the sample and 3.8 mm, respectively, in ayran samples produced from milk treated with MTG-MP at 50ºC for 1 h before heat treatment. During storage, the apparent viscosity and consistency coefficient values of ayran drinks ranged from 0.10 to 0.26 Pa.s and from 1.05 to 4.13 Pa.sn, respectively. In comparison to ayran drinks produced from milk treated with MTG before heat treatment and after heat treatment, the latter had higher apparent viscosity and consistency coefficient values, as well as lower number of grains, mean perimeter of grains, visual roughness, syneresis, and flow behaviour index values. Considering the physicochemical properties of ayran, treating milk with MTG-MP at 38°C for 3 h prior to heat treatment might be preferable in comparison to treating at 4°C for 12 h or at 50°C for 1 h. Similarly, treating milk with MTG-YG at 50°C for 1 h prior to heat treatment might be preferable compared to treating it at 4°C for 12 h or at 38°C for 3 h. This study demonstrated that changing the type of MTG used and the treatment condition of MTG to milk used in ayran production resulted in insignificant differences in microbiological properties.