Characterization of aroma profile and characteristic aromas during lychee wine fermentation

Characteristic aroma substances of cis-rose oxide imparts the odorant of "lychee-like," while of citronellol is the precursor of it in lychee. The characterization of volatiles of lychee wine fermentation using headspace solid-phase microextraction gas chromatography-mass spectrometry combined with headspace gas chromatography-ion mobility spectrometry were done to regulate processing. Results indicated that the total of 97 volatiles (38 in common) were observed during fermentation, including 39 terpenoids, 5 alcohols, 22 esters, 4 acids, 7 alkenes, 4 ketones and ethers, 3 sulfur compounds and others. Losses of characteristic aromas mainly occurred during primary fermentation more than threefold decrease. The volatility of cis-rose oxide was stronger than citronellol, which implied that more gentle processing should be performed to protect lychee flavor. Cis-rose oxide was a mixture of monomer and dimer with unequal proportion, while citronellol was a monomer in lychee. The work provides important new information on aroma development during fermentation. Practical applications Fruit consumption, among which tropical fruit-based products have gained huge popularity in the recent years. The main high value-added processed products of lychee pulp are lychee wine and vinegar; however, the typical aroma always decreased or disappeared during fermentation. Therefore, this study aims at providing more information for product improvement and process development.