Improvement of Fresh Ovine Tuma Cheese Quality Characteristics by Application of Oregano Essential Oils

In the present work, oregano essential oils (OEOs) were applied to process the fresh ovine cheese Tuma obtained by pressed cheese technology. Cheese making trials were performed under industrial conditions using ewe's pasteurized milk and two strains of Lactococcus lactis (NT1 and NT5) as fermenting agents. Two experimental cheese products (ECP) were obtained through the addition of 100 (ECP100) and 200 (ECP200) & mu;L/L of OEO to milk, while the control cheese product (CCP) was OEO-free. Both Lc. lactis strains showed in vitro and in vivo ability to grow in the presence of OEOs and to dominate over indigenous milk lactic acid bacteria (LAB) resistant to pasteurization. In the presence of OEOs, the most abundant compound found in cheese was carvacrol, constituting more than 65% of the volatile fraction in both experimental products. The addition of OEOs did not influence ash, fat, or protein content, but it increased by 43% the antioxidant capacity of the experimental cheeses. ECP100 cheeses showed the best appreciation scores by the sensory panel. In order to investigate the ability OEOs to be used as a natural preservative, a test of artificial contamination was carried out, and the results showed a significant reduction of the main dairy pathogens in OEO-added cheeses.

Automated summary

In this study, oregano essential oils (OEOs) were used to process fresh ovine cheese. Cheese making trials showed that two strains of Lactococcus lactis were able to grow in the presence of OEOs and dominate over indigenous milk lactic acid bacteria. Carvacrol was the most abundant compound found in the cheese, constituting over 65% of the volatile fraction. Adding OEOs increased the antioxidant capacity of the cheese by 43%. Sensory evaluation showed that ECP100 cheeses were preferred by the panel. Artificial contamination tests demonstrated a significant reduction in dairy pathogens in OEO-added cheeses.