A Comparative Study on Yayık Butter Produced with Commercial and Endemic Yogurt Starter Culture Strains

Starter cultures are involved in biochemical reactions during fermentation resulting in the diversity of foods. They are also used for aroma/flavor, texture, nutritional quality enhancement, and shelf-life extension. This study aimed to evaluate the effects of using four different starter culture combinations of which two were isolated starter cultures of Streptococcus thermophilus (St) and Lactobacillus delbrueckii subsp. bulgaricus (Lb) and two were commercial cultures of the same bacteria in Yayık butter characteristics. For this purpose, four different yogurt samples were prepared and then churned to obtain four different Yayık butter samples. Physico-chemical analysis, free fatty acids, volatile compounds, and sensory analysis were performed on the 1st, 30th, and 60th days of storage. No significant differences were observed in moisture, fat, titratable acidity, acid degree, and peroxide value between the samples (P>0.05). However, endemic isolated combined cultures showed better performance in terms of free fatty acid formation and sensorial attributes. The serum pH differed significantly among the samples with higher values in isolated cultures (P<0.05). Storage time was significantly effective on the titratable acidity (°SH) of all Yayık butter samples (P<0.01). The peroxide values were lower than the threshold value of 2.0 meq O2/kg fat. Acid degree varied between 1.70-1.75 mg KOH/g during the storage period. Endemic isolated cultures exhibited the highest free fatty acid accumulation. In the Yayık butter samples, a total of 31 volatile compounds were quantified. The highest number was detected in the butter samples produced with isolated strains (27St/27Lb and 27St/ALb). Yayık butter samples produced with 27St/27Lb contained 16, while with 27St/ALb had 7 compounds identified. Butyric acid and hexanoic acid were the most abundant carboxylic acids while ketones were the predominant volatile compound detected in all Yayık butter samples. This study highlights the importance of preserving traditional culture strains and offers another perspective on using them in dairy industry.