Volatile compounds of volatile oils and hydrosols: intra-specific comparison in seven Lamiaceae species.
Özliman S
Essential Oils
The fragrant water left in your pot after steaming lavender or rosemary is packed with unique aromatic compounds you won't find in the essential oil — and this study confirms it's worth collecting and using, not pouring down the drain.
When you steam-distill herbs like lavender, peppermint, or rosemary to make essential oil, you also get a fragrant leftover water called a hydrosol. Scientists tested both products from seven popular culinary and medicinal herbs and found they smell and behave differently because they carry different chemical compounds — the oil holds oily, volatile molecules while the water holds gentler, more water-soluble ones. This means hydrosols aren't just watered-down essential oils; they're genuinely distinct aromatic products with their own uses in cooking, skincare, and natural fragrances.
Key Findings
Hydrosols from all seven herb species showed a higher relative proportion of polar, water-soluble oxygenated compounds (such as alcohols and oxides) compared to their matched essential oils.
Essential oils were dominated by less polar, highly volatile compounds including monoterpene hydrocarbons and certain esters and ketones — categories less prominent in hydrosols.
Across all seven Lamiaceae species tested — including lavender, peppermint, oregano, and three sage varieties — oxygenated monoterpenes were the dominant chemical class in both distillation products.
chevron_right Technical Summary
Researchers compared the chemical profiles of essential oils and hydrosols — the aromatic water left over after steam distillation — from seven common herb species in the mint family. They found that hydrosols are chemically distinct from essential oils, carrying more water-friendly aromatic compounds that make them useful ingredients in their own right.
Abstract Preview
Aromatic plants of the Lamiaceae family are widely recognized as major natural sources of volatile oils (VOs), with broad applications in pharmaceutical, cosmetic, and food systems. In contrast, hy...
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Lavandula is a genus of 47 known species of perennial flowering plants in the sage family, Lamiaceae. It is native to the Old World, primarily found across the drier, warmer regions of the Mediterranean, with an affinity for maritime breezes.