The Effect of Selected Herbal Extracts on Lactic Acid Bacteria Activity

This study aimed to investigate the effect of plant extracts (valerian Valeriana officinalis L., sage Salvia officinalis L., chamomile Matricaria chamomilla L., cistus Cistus L., linden blossom Tilia L., ribwort plantain Plantago lanceolata L., marshmallow Althaea L.) on the activity and growth of lactic acid bacteria (LAB) during the fermentation and passage of milk through a digestive system model. The tested extracts were also characterized in terms of their content of polyphenolic compounds and antioxidant activity. It was observed that the addition of the tested herbal extracts did not inhibit the growth of LAB in fermented milk drinks, such as yogurts. However, they can gradually inhibit fermentation when added at concentrations above 2% by weight, and hence should be used in limited amounts. The microflora of yogurts containing the tested herbal extracts did not die during digestion in model digestive juices, and no stimulating effect of the added plant extracts was noted either. Nevertheless, due to the antioxidant properties, a slight addition of the herbal extracts containing polyphenols to different kinds of food products can increase the nutritional quality, thus making them functional foods.