engleski

Antibacterial effect of dried aromatic herbs and their extracts on cheese starter culture in vitro - preliminary results

The application of natural compounds from aromatic herbs in cheese production has been studied mainly in the context of improving cheese quality. Their antimicrobial capacity should also be considered from hygienic and technological aspects. In this work, the effect of cold-sterilized Dalmatian aromatic herbs - sage (Salvia officinalis L.), immortelle (Helichrysum italicum (Roth) G. Don), rosemary (Rosemarinus officinalis L.) and their extracts - against commercial cheese starter culture Lactobacillus helveticus/Lactobacillus lactis in pasteurized milk was tested. Dried herbs were irradiated (8 kGy, P = 5.23 Gy/s) at the panoramic Co-60 source in the Radiation Chemistry and Dosimetry Laboratory of the Ruđer Bošković Institute in Zagreb, Croatia. Herbal extracts were prepared according to the Soxhlet protocol, filtered, and evaporated in rotary vacuum. Different concentrations of sterilized herbs and extracts (0.25, 0.5, and 1% v/w) were added to pasteurized milk inoculated with a starter (103 CFU/ mL) and incubated at 30 ºC for 24 hours. Lactobacillus helveticus/Lactobacillus lactis reached a counts of 7.4 log CFU/mL in pasteurized milk at 30 ºC/24h. When dried herbs were applied, the growth of the milk culture was not affected, regardless of the concentrations applied. The higher the concentration of sage and immortelle extracts, the lower the number of starter cultures, which was, however, within the growth rate of the control sample. These preliminary results show that dried sage, immortelle and rosemary and their extracts have no negative effects on the targeted starter culture Lactobacillus helveticus/Lactobacillus lactis, which is preliminarily important for their use in pilot cheese production.

aromatic herbs ; cheese ; starter culture ; antibacterial effect

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