Hydrolates: By-products of essential oil distillation: Chemical composition, biological activity and potential uses

Abstract

Hydrolates, also referred to as hydrosols, floral or distillate waters, as well as aromatic waters, are produced in the same isolation process with essential oils by steam distillation. A small amount of essential oil constituents is dissolved in hydrolates providing specific organoleptic properties and flavor, as well as biological activity which makes them useful as raw material in many industries. Their popularity is still on the rise, especially in aromatherapy. The objective in this review is to analyze the chemical compositions of hydrolates and their corresponding essential oils, as well as biological activity of hydrolates (antimicrobial, antioxidant and antiinflamatory) and potential uses, not only in food industry for flavoring, and preservation of fresh-cut fruits and vegetables, but also as functional (soft) drinks. However, hydrolates can be used in aromatherapy and cosmetics, as well as in organic agriculture and aquaculture.

Headspace/GC–MS Analysis and Investigation of Antibacterial, Antioxidant and Cytotoxic Activity of Essential Oils and Hydrolates from Rosmarinus officinalis L. and Lavandula angustifolia Miller

“…As reviewed by D'Amato et al [31], the antibacterial and antifungal, as well antioxidant, properties of the Hys were demonstrated for different plant species, and their uses and applications could be evaluated to control microorganism growth and oxidative processes in food shelf-life. Furthermore, Hys were demonstrated to be active against biofilm production [59,60], and thus could be used as a natural antimicrobial agent for food production [54]. As reported by Šilha et al [53], no antibacterial effect of L. angustifolia Hy was detected against eight strains of Arcobacter-like bacteria and against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli and the yeast Candida albicans.…”

“…Of interest, L. angustifolia Hy from Croatia [53] was characterized by linalool (23.2%) when steam distillation was used to obtain the extract, and by 1,8-cineole (20.6%) through hydrodistillation. In fact, the chemical profile of Hys can also vary according to the distillation method used [54].…”

“…Generally, Hys exert their biological activities at high concentrations, reflecting their low terpene amount. Since they are aqueous solutions, the hydrophilic environment likely facilitates the terpenes' availability, enhancing their biological activity [54].…”

Biological activity and profiling of Salvia sclarea essential oil obtained by steam and hydrodistillation extraction methods via chemometrics tools

“…However, it is well known that S. sclarea EO is mainly obtained by SD on commercial scale. Vegetal waste material after processing of S. sclarea could be converted into “green” bioactive particles with high biomedical value, 66 as well as into hydrolate, which as by‐product during SD also has commercial value on the market 67,68 …”

Evaluation of antimicrobial activities of plant aqueous extracts against Salmonella Typhimurium and their application to improve safety of pork meat

“…Τhe collected hydro-distilled extracts were odorless since the essential oil was removed and, thus, they can be used without compromising the sensory characteristics (odor and flavor) of the food products. Industrial hydrolate collected as by-product of steam distillation, the most commonly applied method of essential oil production 34 , can contain only a small amount of essential oils, that is usually discarded 35 . Although the odor of the hydrolate can vary, it is far from the strong scent of essential oils that can cause headache, eye and skin irritations, etc.…”