Abstract:
Rice (Oryza sativa L.) is one of the important raw materials for production of rice wine
that is an alcoholic beverage. In this study, the quality of rice wine, as affected by rice
cultivars, was investigated in order to screen non-glutinous Thai rice cultivars that are suitable
for rice wine production. Eight Thai rice cultivars were selected for comparison in this
experiment, Phitsanulok 2 (26.90), Pathum Thani 1 (16.19), Khao Dawk Mali 105 (14.85) and
RD6 (6.43), Suphan Buri 1 (22.07), Suphan Buri 3 (28.74), Suphan Buri 60 (25.46), and
Suphan Buri 90 (29.84). Rice wine was produced by using pure cultures of fungi Amylomyces
rouxii (TISTR3182) and yeast Saccharomyces cerevisiae (IFO10217) incubated under the
condition of 30oC for 13 days. The chemical components, e.g., amylose, lipid and protein
contents, of rice grains prior to autoclaving were analyzed. The metabolic products, e.g.,
glucose, ethanol, volatile and organic compounds, occurring during the rice wine production
process, were monitored as the quality index of the rice wine. The relationships among rice
cultivars were examined by principal components analysis and cluster analysis. On day 13 of
fermentation, ethanol concentrations in 8 Thai rice wines were the highest when using
Phitsanulok 2 and Pathum Thani 1 rice cultivars (18.2-19.9% (v/v)) and were at a high level
when using Khao Dawk Mali 105 and RD6 (16.1-16.3% (v/v)), compared with the other rice
cultivars. The rice wines could be characterized by their metabolites on the final day of
fermentation into 3 groups; (group 1) Suphan Buri 90 and Suphan Buri 60, (group 2) Suphan
Buri 3, (group 3) Phitsanulok 2, RD6, Pathum Thani 1, Khao Dawk Mali 105, and Suphan
Buri 1. The results from cluster analysis and principal components analysis indicated that
glucose, volatile compounds, and organic compounds on the final day of fermentation might
not be dominated by only amylose and amylopectin contents.