Changes in flavor compounds of dry-cured Chinese Jinhua ham during processing

Sixty experimental Jinhua hams were processed by a traditional method using green hams from local Liangtouwu cross-bred pigs. Samples of Biceps femoris were taken from five hams randomly at each of the key stages of production, i.e., green ham, end of salting, end of sun-drying, middle of loft-aging, end of loft-aging, post-aging-1 and post-aging-2. Analysis of flavor compounds showed 89 compounds at the green ham stage and at the end of salting, 90 at the end of sun-drying, 91 at the middle of loft-aging, 96 at the end of loft-aging, 93 at the post-age-1 and 94 at the post-age-2. The flavor compounds could be clustered in the following chemical families: alkanes and alkenes, aromatic hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, esters, oxygenous heterocycle compounds, nitrogenous compounds, sulphur compounds, chloride compounds, amides, and terpenes. During processing, the concentrations of aldehydes and carboxylic acids increased; while the concentrations of alcohols, ketones, alkanes, alkenes, aromatic and cyclic hydrocarbons decreased. Sulphur compounds and pyrazines were formed and increased continuously during processing. In the final Jinhua ham, the contents of aldehydes, carboxylic acids, alcohols and ketones were 45.07%, 18.39%, 13.93% and 9.00% of the total flavor substances, respectively. The first principal component was a group dominated by five unbranched aldehydes; the second principal component was a group dominated by five branched and unbranched alcohols, two branched ketones, toluene, hexane and 4-nitrophthalamide. The two principal components explained 90.6% of the total flavor variance in Jinhua ham.