Authors of a recent study suggest that leafy herbal tea (LHT) extracts may soon be used as a functional ingredient to kill cariogenic bacteria in the mouth or as a natural antimicrobial preservative in foods.
The LHT extracts used in the study consisted of 11 popular teas brewed from leafy herbs: green, black, rooibos, rosemary, lemongrass, mulberry leaf, bamboo leaf, lotus leaf, peppermint, persimmon leaf, and maté.
Scientist Oh Jungmin and colleages from Sungkyunkwan University’s food science and biotechnology department published their study in the October 2012 issue of Food Control. In the study, researchers extracted samples of each LHT using 80C water and 20C ethanol.
Highest Antioxidant Activity
For the study, scientists defined antioxidant activity as the inhibition of oxidation of lipids, proteins, DNA, or other molecules that block the propagation step in oxidative chain reactions. Researchers measured for levels of Total Phenolic Content (TPC), Total Flavonoid Content (TFC), two extremely effective antioxidant compounds that prevent the release of free radicals.
The green tea ethanol extract showed the highest antioxidant activity in all trials, except the ferrous ion-chelating test.
Highest Antimicrobial Activity
Jungmin and his team also examined the antimicrobial effects of the 11 tea extracts on three common foodborne pathogens- Listeria monocytogenes (Listeria), Shigella flexneri (Dysentery) and Salmonella eterica (Salmonella). The tea extracts were also tested against two oral pathogens, Steptococcus mutans and Streptoccoccus sobrimus, the two leading causes of tooth decay.
Shigella Bacteria x1000
Among the tested LHTs, green tea ethanol extract had potent antimicrobial activity against all five pathogens,” wrote Jungmin.
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