AROMA OF VIRGIN OLIVE OIL - BIOGENESIS OF THE GREEN ODOR NOTES

The enzymes acylhydrolase, lipoxygenase, and fatty acid hydroperoxide lyase were found in cell-free extract of olive fruit. Triacylglycerols and phospholipids are hydrolyzed to free fatty acid, mainly polyunsaturated, by acylhydrolase. From linoleic and linolenic acids 9- and 13-hydroperoxides were formed by lipoxygenase. The lyase cleaves the 13-hydroperoxides of linoleic and linolenic acids to form the volatile aldehydes hexanal and cis-3-hexenal, respectively; the enzyme does not act on 9-hydroperoxides of these acids. Incubation of ripe olive fruit tissue disks resulted in biological conversion of hexanal and trans-2-hexenal to corresponding alcohols. Hexyl alcohols were converted to their acetate esters during the incubation with olive fruit tissue. A sequential enzymatic pathway for the formation of green odor compounds in virgin olive oil is proposed.