Citrus hydrosols as useful by-products for tyrosinase inhibition

Hydrosols are coproduced during water or steam distillation of plant material. Three kinds of citrus hydrosols (CIHS) were assessed for anti-tyrosinase (TYR) activity using spectrophotometric assays and terpene content as quantified by gas chromatography (GC). All of the distillate waters were found to inhibit commercial mushroom tyrosinase at varying levels (21.8-68.9%) depending on substrate type and concentration. The GC analysis indicated that a number of known tyrosinase inhibitors including myrcene, sabinene, geraniol and citral were present in CIHS, which behave as mixed-type inhibitors towards tyrosinase. Industrial relevance: Citrus hydrosols have great potential to meet the demands of the food and cosmetic industries, since they are not only easy and inexpensive to produce but also without any perceivable hazard for humans. In addition, since citrus hydrosols can be extracted from the discarded peels of citrus fruits, their use as anti-browning agents would allow the repurposing of what has typically been considered a biological waste product.