Polyphenol Content Dynamics in Hydrodistillation Water Residues of Lamiaceae Species

Abstract

Lamiaceae herbs are a rich source of volatile oils with multiple benefits mainly for pharmaceutical and cosmetic industry. By-products from the hydro distillation process also represent a valuable source of phenolic compounds which can be turned into antioxidant agents for various purposes, contributing to a complete capitalization of these plants. This study aimed to show the variation of polyphenol content of some spray-dried aqueous extracts obtained before (group 1) and after (group 2) separation of volatile oil, in order to assess the influence of hydro distillation parameters on phenolics recovery. Spectrophotometric analysis of spray-dried extracts before and after hydro distillation, revealed a highest total polyphenol content expressed as rosmarinic acid obtained from Origanum vulgare and Melissa officinalis, with slight differences (0.6-11 %) between the both extraction methods used. Hydrodistillation has a strong influence on the polyphenol composition in all studied Lamiaceae species and important compounds are lost due to solubilization or degradation processes. In our study, caffeic acid was the most labile compound, with even 89.2 % losses after hydro distillation in the case of Thymus species. In comparison, its derivative, rosmarinic acid, with a more complex structure, reached equilibrium between content gaining and losses, depending on the species tested. It can be concluded that for Lamiaceae species, widely known as volatile oil bearing species, capitalization of hydro distillation by-products represents a value-added process for obtaining natural and active ingredients for pharmaceutical, cosmetic and food industries.