This study investigated the effects of 2
nd stage mash pH on the fermentation process, volatile compounds, and the sensory quality of sweet potato
shochu. The initiation of fermentation was delayed when the pH of 2
nd stage mash was pH 3.3, 3,6 or 5.4 compared with pH 4.3 as the control, but the overall fermentation process was not significantly changed by the mash pH. The numbers of total cell and living cell in fermented mash decreased under a lower pH(pH 3.3 or 3.6). The alcohol content of fermented mash decreased with a lower pH(<4.5). Volatile acidity of mash increased with pH. A GC-MS analysis showed that higher alcohols, acetate esters, rose oxide, and citronellol increased slightly with mash pH. Concurrently, β-damascenone and aldehydes increased with a lower pH. Mash pH significantly affected the concentration of α-terpineol, nerol, linalool, nerolidol, and nerol oxide. As the result of a sensory test,
shochu distilled from lower pH mash was described as “floral” and “citrus-like”, and that from higher pH mash was described as “steamed sweet potato-like” and “yellow
koji-like”.
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