An insoluble α-Ketoglutarate salt coated onto an inert high surface area solid support prevents autoxidation of neat citrus oil

Abstract

Terpene hydroperoxides (THPs) have been reported to be skin sensitizers, so their elimination from citrus oils is desirable for consumer safety. Previously, we reported that treatment of citrus-based perfumes with pyruvic acid and α-ketoglutaric acid (AKG) or their salts was effective at removing existing THPs, measured by peroxide value (POV) titration. AKG salts, if soluble, were effective in neat citrus oil as well, but an insoluble AKG salt was only moderately effective. However, contact with an insoluble salt did prevent further autoxidation of the citrus oil. Herein, we report that coating an inert solid support with an insoluble AKG salt, made from either N-methyl diethanolamine or 1-[bis[3-(dimethylamino)propyl]amino]-2-propanol, produced an easily handled device for insertion into a container of citrus oil; the device was highly effective at maintaining a low POV in fresh orange oil for an extended storage period. Such devices offer a promising mode of preventing autoxidation in fresh citrus oil raw materials.