Measurements of pH, total acidity, total soluble solids, residual
sugars, and ethanol were performed as described by Song et al.
(2014). Volatile flavor compounds were analyzed using an automated
Purge & Trap Sampler JTD-505III (Japan Analytical Industry,
Tokyo, Japan) for the purge and trap sampling of gas, and a GC/MS
QP 2010 plus (Shimadzu, Kyoto, Japan) for quantification and
qualification (Chung et al., 2010) with 2-methyl-3-heptanone as an
internal standard. Each physicochemical analysis was performed in
triplicate, and the results were expressed as mean ± standard
deviation.