Production of cheese with high cla content by propionibacterium isolated from Mihaliç cheese

Mihaliç cheese which is given characteristic properties by Propionibacterium species (PAB), is one of the most important traditional cheeses in Turkey. The objectives of this research are the isolation of PAB from Mihaliç cheeses, the identification of them by MALDI-TOF-MS, and the production of functional Mihaliç cheese with PAB having a high potential of conjugated linoleic acid (CLA) production. To isolate PAB, 25 different Mihaliç kinds of cheese were purchased from the local producers and sellers. A total of 21 PAB were identified by MALDI-TOF-MD and 57% of them Propionibacterium freudenreichii subsp. freudenreichii, 33% Propionibacterium freudenreichii subsp. shermanii and 10% of Propionibacterium thoenii. The sensitivity of PAB against linoleic acid, pH, and salt was evaluated and then Propionibacterium freudenreichii subsp. shermanii and Propionibacterium thoenii were chosen as a starter culture for cheese production because of their high CLA potential and resistance to pH and salt. Milk was fortified with pure linoleic acid or black seed oil with high linoleic acid content in order to produce CLA enriched cheese. Chosen PAB isolates were added to milk separately and together and uncultured cheese was also produced as a control. The highest level of CLA was determined in the cheese produced with pure linoleic acid. When P. freudenreichii subsp. shermanii alone or combined with P. thoenii resulted in the highest CLA production. CLA ratios of cheeses varied between 3,93-6,28 mg/g fat at the end of the ripening period. The cheese produced by using both cultures together, from milk supplemented with linoleic acid contains 17,8% more CLA than the uncultured control cheese. There was also a positive effect of linoleic acid addition (%26,8) on CLA content. When compared with cheese produced without any linoleic acid and culture, the amount of CLA increased by 59,8%. Ripening did not have a significant effect on the CLA content of cheeses. It is obvious that the addition of linoleic acid or CLA producing cultures to the cheese production process altered the CLA level certainly. Taken together, these results suggest that there is a relation between linoleic acid fortification and CLA producing cultures causing the synergistic effect on CLA elevation in cheese.