ANTIMICROBIAL EFFECTS OF SELECTED PLANT EXTRACTS ON THE SHELF LIFE OF GOAT WHEY

One of the possibilities, how we can increase the shelf life of whey, as well as food in general, is using of essential oils and extracts. The aim of this paper was to evaluate the possibility of addition of an aqueous plant extracts to goat whey to ensure its microbiological stability and prolongation of its shelf-life. There were chosen these herbs: lemon balm (Melissa officinalis L.), wild garlic (Allium ursinum L.), rosemary (Rosmarinus officinalis L.) and Baikal skullcap (Scutellaria baicalensis L.). The aqueous extracts in the amount of 5% were added into goat whey. These samples were stored at 6 degrees C for four weeks. The microbiological analysis (determining the groups: total plate count, coli-form bacteria, enterococci, thermo-resistant microorganisms), measuring of pH and titratable acidity were performed during storage. The rosemary extract was the only one that significantly reduced the titratable acidity of goat whey. The other three extracts showed mild decrease of titratable acidity. The pH came into lower undesirable values in all prepared samples with the addition of aqueous plant extracts. The results of microbiological analyses suggested that the aqueous extract of rosemary was inappropriate. It contributed to an increase of the number of microorganisms in all the studied groups. A clear opinion cannot be expressed for the other three extracts. To increase the dose of aqueous extracts of selected plants in goat whey would be probably more appropriate performing the results of future experiments devoted to antimicrobial activity of plant extracts.