Thymus capitatus essential oil ameliorates pasteurization efficiency.

This work aims to characterize Thymus capitatus essential oil and to investigate its preservative effects on raw milk quality alone or combined to pasteurization heat treatment. To study its preservative effect, 1 mg l-1 of T. capitatus essential oil, characterized by GC-MS, was added to pasteurized or raw milk. The evaluation of milk quality was made by consulting samples total acidities, peroxide values and their total microbial counts, as compared to control milks. Assays were made immediately and after every 48 h of incubation at room temperature throughout 6 days. Results showed that the incorporation of T. capitatus EO to pasteurized milk was the most efficient treatment that inhibited milk deterioration. Combining pasteurization to EO incorporation into raw milk inhibited completely the contaminant bacterial growth to the second day of incubation. Moreover, until the fourth day, no statistical differences have been recorded on the total acidity of incorporated and pasteurized milk samples, while raw milk acidity exceeded 55 g of lactic acid equivalent l-1. Considering milk fat oxidation, adding T. capitatus EO to pasteurized milk has significantly retarded milk peroxide production to day 4. In conclusion, Thymus capitatus essential oil, combined to pasteurization, presents an interesting potency to act as milk stabilizer.