Abstract:
Sato is a traditional Thai alcoholic beverage product from fermentation of steamed glutinous rice mixed with Loogpang which is a starter culture. The main problem in commercial Sato production is the quality consistency between batches. In Sato brewery, fermentation temperature is one of the most important parameter for development of alcoholic fermentation since it affects kinetics of the process in term of duration, rate of fermentation and the final chemical composition of the wine. In this research, Sato was produced using the mixed culture starter. This study focused on the effect of fermentation temperature at 18 oC, 30 oC and 40 oC respectively. The Sato samples were taken during fermentation and determined for total acidity, reducing sugar, ethanol, higher alcohol (iso-amyl alcohol) and aldehyde compound. Among three different fermentation temperatures, the highest reducing sugar content (5.51 mg/ml) was found at 40 oC on day 16, while others fermentation temperatures at 18 oC and 30 oC gave the result of reducing sugar on day 16 (1.64 and 1.26 mg/ml, respectively). The highest ethanol level in SATO was 6.49 % on day 12 of fermentation, which was no significant difference (P<0.05) from samples obtained at 30 oC (5.86%) but higher than those obtained at 18 oC (4.53%). On the final day of fermentation (day16), the highest of iso-amylalcohol level (88.88 mg/l) was obtained from fermentation temperature at 40 oC, which was no significant difference (P<0.05) from those obtained at 30 oC (76.20 mg/l) but significant difference from samples obtained at 18 oC (43.96 mg/l). The acetaldehyde level at the final day of fermentation was highest (147.58 mg/l) when the fermentation was carried on at 30 oC. The investigations on changes of iso-amylalcohol and acetaldehyde during 12 days of Sato fermentation were done. It was found that fermentation at 40 oC has the highest level of iso-amylalcohol concentration (41.93-56.96 mg/l), and fermentation at 18 oC has the lowest level of acetaldehyde concentration (32.96-75.44 mg/l)