Development of Hom Nil and Hom Ubon Rice Wine

Abstract

Thai aromatic rice is one of the well-renowned rice varieties which is an essential crop in Thailand. Hom Nil rice (HNR) and Hom Ubon rice (HUR), aromatic black and brown rice, that are generally rich in nutrients are potential to be used as the raw material for wine fermentation in order to add value to the product. This study, thus, aimed to develop the rice wine produced by using HNR and HUR. Results indicated that, of both rice wine samples, as the fermentation time increased, the total soluble solids (TSS) content decreased, while their pH and alcohol content increased. HNR and HUR wine fermented for seven days had the lowest TSS (7.6% and 7.8%, respectively) (p<0.05). The highest alcohol content of HNR wine (13.7%) and HUR wine (13.2%) was found on the seventh day of fermentation. HNR wine was higher in phenolic compound and antioxidant activity than HUR wine (p<0.05). Phenolic compound and antioxidant activity of the samples increased with a longer fermentation period. The highest phenolic compound and antioxidant activity were determined when fermenting HNR (340.52 mg GAE/l; 158.47 mg Trolox/l) and HUR (299.78 mg GAE/l; 57.97 mg Trolox/l) for eight days. However, HUR wines fermented for seven and eight days were not statistically different in the antioxidant activity. The sensory evaluation revealed that HNR and HUR wine with eight days of fermentation received the highest sensory acceptability scores (ranked between like slightly to like moderately), rated by 30 untrained panelists on a 9-point hedonic scale, among other samples with a shorter fermentation period, but not statistically different from those fermented for seven days. Therefore, such fermentation period was selected to evaluate the sensory acceptability when a black mint flavor (BMF) was added to the samples. Accordingly, a BMF increased the score of flavor and aroma of both samples. HNR wine with a BMF received the highest overall sensory acceptability scores (like slightly) (p≥0.05). Thus, HNR and HUR could be used as an alternative source of raw material for wine production, which would be beneficial for adding value to the Thai aromatic rice crop and improving the health advantages of the rice wine.