The effect of green tea extract on the removal of sulfur-containing oral malodor volatiles in vitro and its potential application in chewing gum.

Increasing pH solution from 7.5 to 8.0 was found to significantly improve the effectiveness of green tea extract for methanethiol removal in vitro. Green tea extract was also found to remove hydrogen sulfide and its effectiveness was greatly improved under alkaline conditions. It was found that with green tea extract, maximum H₂S removal was achieved when the pH was between 8.1 and 8.4 at 37 °C for 5 min. Further increases in pH resulted in decrease of the extract effectiveness. Vegetable acetone powders which contain polyphenol oxidases or peroxidases were found to further enhance the effectiveness for the removal of thiols when used in combination with green tea extracts at body temperature under alkaline conditions. Adding 5% baking soda to green tea extract-containing chewing gum was found to buffer saliva pHs to 8.0 during 10 min of chewing. However, severe discoloration was observed and undesirable bitterness was perceived, most likely due to the polymerization of unencapsulated green tea polyphenols. Therefore, encapsulation of green tea extract is recommended for applications at elevated pHs.