Isolation and identification of yeasts during Kargi Tulum cheese production in Turkey

This study investigated yeast diversity and physicochemical changes during the production of Kargı Tulum cheese, a traditional Turkish cheese. Samples were collected at six key stages, from raw milk to the final product, and analysed for parameters including pH, titratable acidity, dry matter, fat, salt, protein, water-soluble protein and maturation index. During ripening, pH values ranged from 3.03 ± 0.017 to 3.70 ± 0.017, while titratable acidity increased from 0.91% ± 0.16% to 3.33% ± 0.17%. Dry matter and fat content increased significantly, reaching 50.41% ± 1.56% and 33.50% ± 5.41%, respectively. Salt content ranged from 0.58% ± 0.08% to 3.03% ± 0.58%, and protein content from 3.70% ± 0.93% to 20.63% ± 1.16%. The maturation index increased from 5.54% ± 0.71% to 16.26% ± 4.35%, indicating ongoing proteolysis. A total of 42 yeast isolates were phenotypically characterized and grouped by sugar fermentation ability, growth and salt tolerance. Internal transcribed spacer region sequencing identified key yeast species, including Kazachstania unispora, Pichia fermentans, Kluyveromyces lactis, Pichia membranifaciens and Geotrichum candidum. These species play significant roles in cheese maturation, contributing to flavour and texture. The results emphasize the importance of indigenous yeast populations in traditional cheese production and offer insights for improving fermentation and ripening processes to enhance cheese quality.