Development of a Semi-Industrial Kefalotyri-Type Cheese Using Thermized Milk from Native Epirus Sheep Breeds and Autochthonous Starter and Adjunct Cultures

Autochthonous starter and adjunct cultures have gained increasing practical research interest for use in traditional cheese-making in recent years. This study evaluated the performance of a native starter comprising Streptococcus thermophilus ST1 and two wild Lactococcus lactis strains, including the M78 nisin A-producer, during the semi-industrial production of Kefalotyri cooked hard cheese from thermized sheep milk (TM; 65 °C, 30 s) in the absence (C-cheese) or presence of the native adjunct strains Lactiplantibacillus plantarum H25 and Leuconostoc mesenteroides KFM7 + KFM9 (N-cheese). The growth of the native starter was optimal in all three cheese trials within the first 24 h of processing, but afterward, ST1 failed to exceed 8 log CFU/g in favor of total mesophilic LAB, comprising both L. lactis starter strains, and the prevalent (ca. 8.5 log CFU/g) H25 adjunct in the ripening N-cheeses. Instead, in the C-cheeses, indigenous non-Enterococcus NSLAB survivors from TM prevailed, whereas enterococci failed to increase above 6 log CFU/g in all cheeses. Although the mature (90-day-old) N-cheeses presented no statistically significant differences regarding the pH value, gross composition, and hydrophobic (HO)/hydrophilic (HI) peptide ratios from the mature C-cheeses, they had lower total LAB counts and contained less residual lactose, more acetate, and an overall less diversified volatilome (VOC) profile. The most abundant VOCs in both cheeses were acetone, butyric acid, methyl butyrate, ethyl ether, and ethanol. All mature cheeses were safe and graded of ‘excellent quality’ (i.e., moisture < 35%; fat-in-dry-matter > 47%).