ANTIOXIDANT AND ANTIMICROBIAL PROPERTIES OF TEA AND AROMATIC PLANT EXTRACTS AGAINST BACTERIAL FOODBORNE PATHOGENS: A COMPARATIVE EVALUATION

摘要

Phenolic compounds exhibit noteworthy antioxidant and antimicrobial properties and are abundant in tea and aromatic plants. In this study, we investigated the differences in the antioxidant capacity (AC) and total phenolic content (TPC) between aqueous and methanolic extracts of different types of tea (i.e. green and black tea) and aromatic plants. We also evaluated the relationship between the AC and TPC of the extracts with their antimicrobial activity against bacterial strains of selected foodborne pathogens. Methanolic tea extracts presented notable antibacterial effects and showed a significantly increased AC compared to the methanolic aromatic plant extracts (p<0.05), whereas TPC of the green tea extracts was higher compared to black tea and aromatic plant extracts in all the extraction conditions tested. TPC ranged from 579.7 to 7051.5 and from 72.8 to 990.6 mg gallic acid litre(-1) in tea and in aromatic plant extracts, respectively. The correlation analysis performed between the antioxidant properties and the antimicrobial activity of the methanolic extracts revealed negative correlations in certain cases, while signs of intraspecies specificity regarding the antibacterial activity of the extracts were suggested. These findings indicate not only the benefits in human health that the potential application of the studied herbal infusions may confer in foods, but also the need for effective and efficient pathogen control from the use of such plant derivatives as natural preservatives in food products.