The influence of the alcoholic extract of lemon balm on the growth of Lactobacillus helveticus MDC 9602 and the technological, physicochemical, organoleptic, and antioxidant properties of fermented milk.

This study assessed the impact of Lemon balm ethanolic extract (LBEE) on the technological, physicochemical, functional, and sensory properties of a functional sour milk drink fermented solely by Lactobacillus helveticus MDC 9602. Using a modified critical dilution method, LBEE was found to significantly enhance the growth of L. helveticus MDC 9602 within a specific concentration range. Incorporating the optimal stimulating concentration of LBEE (0.25%) during milk fermentation by L. helveticus MDC 9602 accelerated milk acidification, reduced coagulation time, increased viable starter count and viscosity, and notably boosted the product's antioxidant activity. Despite LBEE's high antioxidant potential from phenolic compounds, its actual contribution to the antioxidant activity of fermented milk remains minimal due to the low amounts used (< 0.5%). The addition of LBEE resulted in enhanced probiotic content, increased antioxidant activity, improved viscosity, reduced syneresis, and better resistance to cold stress throughout the product's shelf life. Moreover, LBEE enhanced the sensory properties of the yoghurt, particularly aroma and texture. These findings indicate that the impact of low doses of LBEE on yoghurt quality is primarily functional rather than flavor-oriented.

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