PRODUCTION OF LACTIC ACID WORT-BASED BEVERAGES WITH MINT ESSENTIAL OIL ADDITION

Abstract

Lactic acid wort-based beverages are functional, non-alcoholic, with low pH value and produced by the fermentation of wort by lactic acid bacteria. They are not well accepted by consumers because of their poor sensory characteristics. Therefore, 0.025 and 0.05 % (v/v) mint (Mentha piperita) essential oil was used as a tool for improvement of lactic acid wort-based beverages organoleptic profile. Wort was produced by 60% Pilsen malt, 20% Vienna malt, and 20% Caramel Munich ІІ malt. It was inoculated with probiotic lactic acid bacteria Lactobacillus casei ssp. rhamnosus LBRC11 at a concentration of 107 cells/ml and fermentation was carried out at constant temperature of 25°C. The dynamics of pH, concentration of viable cells, phenolic compounds and antioxidant activity were monitored and the beverages obtained were evaluated by a tasting panel. The results showed that addition of mint essential oil in concentration of 0.025 and 0.05 % (v/v) inhibited lactic acid fermentation but improved the sensory profile of the beverage obtained only when 0.025% mint essential oil was added. Mint essential oil addition led to an increase in the total phenolic compounds concentration, phenolic acids and flavonoid phenolic compounds, measured by Folin–Ciocalteu and modified Glories method but resulted in a decrease in the antioxidant activity, measured by the DPPH radical scavenging assay, cupric reducing antioxidant power (CUPRAC) and ferric reducing antioxidant power (FRAP). The antioxidant activity measured by the ABTS radical scavenging assay was almost equal for the beverages with and without mint essential oil addition. The results obtained will be used for modeling of lactic acids fermentation with addition of mint essential oil for the production of functional wort-based beverages. Keywords: lactic acid fermentation, wort, mint essential oil, phenolic compounds, antioxidant activity