Abstract: The differences in the chemical and aroma profiles of moderately and entirely fermented apple vinegar were investigated. The total phenols content, and organic acid and aroma profiles were determined and analyzed using Folin-Ciocalteu colorimetry and high performance liquid chromatography (HPLC), respectively. The volatile aroma components were extracted by headspace solid-phase microextraction (HS-SPME) and identified by gas chromatography-mass spectrometry (GC-MS). The total phenols content in the moderately fermented sample was 21% higher than that in the entirely fermented one. The organic acids species in two vinegar samples were exactly the same, but their contents were different. The moderately fermented vinegar contained higher levels of tartaric acid, citric acid and fumaric acid while the entirely fermented one contained higher levels of pyruvic acid, malic acid, α-ketoglutaric acid, lactic acid, acetic acid and succinic acid. The moderate fermentation could provide the vinegar with more abundant aroma-active compounds. A total of 37 volatile compounds were detected, including citronellol, nerol, butanoic acid ethyl ester, 4-methyl-3-hexyl acetate ester, and 2-methylbutyl acetate, which were also detected in the apple juice. The moderate fermentation method could be an effective way to develop apple vinegar with high quality because of its protective effects on total phenols and aroma compounds.

Key words: apple vinegar, moderate fermentation, entire fermentation, total phenol, organic acid, aroma compounds