Ayran production with reduced lactose content

In this study, the effects of using milk with different proportions of reduced lactose content (0%, 50% and 100%) and salt in different ratios (0.3%, 0.6% and 0.9%) on the physicochemical, microbiological and sensory properties of ayran were determined during storage. The ayran samples were stored in plastic packaging of 200 grams at 4°C for 30 days. Physicochemical, microbiological and sensory properties of ayran samples were determined on the 1st, 15th and 30th days of the storage. The effects of reduction rate of lactose content, salt ratio and storage period on the titration acidity, pH, serum separation and apparent viscosity values of the ayran samples were found be statistically significant P<0.001. It was determined that the proteolytic activity values increased in all samples during the storage. The effects of reduction rate of lactose content, salt ratio and storage period on the proteolytic activity values of ayran samples were determined as statistically significant. The proteolytic activity values of ayran samples decreased with increasing salt content. Based on the results of the rheological analyses made during the storage period, the power law model was fit to the ayran samples. The ayran samples produced from milk with reduced lactose content of 100% were found to have the lowest consistency coefficient, flow behavior index and thixotropy values. The thixotropy values of ayran samples containing 0.3% and 0.6% salt were higher than that containing 0.9% salt. In the ayran samples, the flow behavior index values decreased with increasing salt content. The flow behavior index and thixotropy values in the ayran samples decreased during storage period. Lactose, glucose and galactose contents of the ayran samples produced from milk with reduced lactose content of 50% were 0.61%, 0.62% and 1.28%, respectively, while lactose, glucose and galactose contents of the ayran samples produced from milk with reduced lactose content of 100% were 0.03%, 0.95% and 1.61%, respectively. The lactose, glucose and galactose contents in the ayran samples decreased during the storage period. The highest number of Lactobacillus ssp. delbrueckii bulgaricus was determined in the ayran samples produced from milk with reduced lactose content of 100%. As the lactose content of milk used in the ayran production decreased, the number of Streptococcus thermophilus in the ayran samples increased. While the salt content of the ayran samples increased, it was determined that there was a significant (P<0.05) decrease in the number of Lactobacillus ssp. delbrueckii bulgaricus, whereas the change in salt content did not cause a significant difference among the numbers of Streptococcus thermophilus in the ayran samples (P>0.005). During the storage period, the numbers of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus in the ayran samples decreased. According to results of sensory analyses of ayran samples, the effects of salt ratio and storage period on the appearance scores of the ayran samples were found statistically significant (P<0.001) and the effect of reduction rate of lactose content was not significant (P>0.05). The effects of reduction rate of lactose content and storage period on the taste scores of the ayran samples were not significant (P>0.05), while the effect of salt ratio was significant at the P<0.001 level. In addition to this, there were no significant effect (P>0.05) of reduction rate of lactose content, salt ratio and storage period on the texture scores of the ayran samples.