Utilization of the Japanese Peppermint Herbal Water Byproduct of Steam Distillation as an Antimicrobial Agent.

The present study provides valuable data that the herbal water byproduct of Japanese peppermint, produced during the steam distillation extraction of an essential oil, can be utilized as an antibacterial agent. The major ingredient in the herbal water from Japanese peppermint 'Hokuto' was menthol, with a concentration close to its water solubility. The herbal water produced showed excellent antibacterial efficacy against typical gram-negative and gram-positive bacterial strains of Escherichia coli and Staphylococcus aureus, respectively, and the antibacterial efficacy was maintained even when the herbal water was diluted up to an appropriate concentration of 50%.