Molecular characterization of yeast flora and quality attributes of traditional gravyer cheese

This study aimed to characterize the yeast flora of traditional Kars Gravyer cheese produced in Türkiye using molecular methods, alongside evaluating its physicochemical and microbiological quality attributes. Thirty cheese samples were collected from retail points. DNA was isolated from 150 yeast colonies (5 per sample). Species identification was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis of the ITS1-5.8 S-ITS2 region and 26 S rDNA sequencing. Additionally, pH, dry matter, color parameters, and microbial counts were analyzed. Biotechnological analyses revealed that Debaryomyces hansenii was present in 20 cheese samples (66.7%), Cryptococcus laurentii in 8 cheese samples (26.7%), and both yeasts concurrently in two cheese samples (6.6%). In Gravyer cheeses, where the mean pH and dry matter values ​​were determined as 5.96 ± 0.17 and 67.25 ± 2.12%, respectively, the count of lactic acid bacteria (7.45 ± 0.42 log CFU/g) was higher than the count of Micrococcus/Staphylococcus (5.65 ± 0.97 log CFU/g). The mean yeast-mould count was 4.48 ± 1.16 log CFU/g, with yeasts being more predominant than moulds in the samples, and no mould growth was observed in three samples. The Enterobacteriaceae count was found to be below 2.00 log CFU/g in 20 samples, whereas the average in 10 samples was 3.33 ± 1.13 log CFU/g. The inner and rind surfaces of the Gravyer cheese have different color values (P < 0.01), and the L* and b* values ​​of the inner surface were higher than those of the rind surface (P < 0.05). As a result of the current study, Debaryomyces hansenii was identified as the predominant yeast species in the traditional Gravyer cheese. Yeast flora in traditional Gravyer cheeses was detected for the first time in this study. Yeast species of isolates was determined using the PCR technique following sequencing of the ITS1-5.8S-ITS2 and 26 S rDNA regions. The dominant yeast flora in Kars Gravyer cheeses was detected as Debaryomyces hansenii. Lactic acid bacteria and Micrococcus/Staphylococcus was the predominant microbial population in Kars Gravyer cheeses. Among Kars Gravyer cheese samples showed significant differences in color, pore structure, and shape.