Hydrolates: a promising ‘new’ type of herbal extracts?

Article in Dutch, journalistic review, 26 refs, in: Ned Tijds Fytoth, 2018(3):14-7.

EB Ass Hydrolaten 2018 3-14-17

Hydrolates are an important part of culinary and medical traditions in the Arab world. For example rose water, lavender water and kekik water (hydrolate of carvacrol and thymol-containing plants) are well-known skin care products and are often used as a folk medicine. In Iran, a lot of different hydrolates are sold as soft drinks in supermarkets. One clinical study showed that the Juglans regia leaf hydrolate, much valued by diabetes patients in Iran, indeed lowered the blood sugar content. The composition of hydrolates can vary according to their preparation. In laboratory conditions the hydrolates content was analyzed and appeared to differ substantially from the volatile oil (hydrophobic) contents. There is uncertainty about the presence of hydrophylic substances in the hydrolate.

Lately, several experiments showed that hydrolates can be potentially of interest for cleaning surfaces (antibiotic, anti-fungal) and also for agricultural applications. Some hydrolates seem to successfully combat well-known fungal pests such as Botrytis cinerea and harvest-damaging insects like Myzus persicae, Aphis gossypii and Tetranychus urticae. In a laboratory setting, it was also shown that mosquito nymphs died when hydrolates of ginger, curcuma or lemongrass leaves were used in concentrations of 15-40%.

The popularity of hydrolates within the aromatherapy community is in sharp contrast with the lack of interest of university scientists. People share many experiences – for example on the internet – but with little research available, it is difficult to distinguish right from wrong. Even more so because there is a lack of clear, generally accepted quality standards for hydrolates.