Cysteine Induced Odor Intensification in Onions and Other Foods

SUMMARY— Adding cysteine to food products prepared from onion and other species of the genus Allium results in lo‐to 40‐fold increase in odor intensity and in alteration of GLC patterns of the volatiles. Other nonvolatile sulfhydryl compounds, but not ascorbic acid, also intensify the odor. The reactions responsible for this cysteine effect are not directly enzymatic in nature and appear, at least in part, to involve a series of sulfhydryl‐disulfide type interchanges among cysteine and the sulfur‐containing products of the enzymatic breakdown of flavor precursors in these foods.