Power ultrasound to enhance the fermentation process of traditional Taiwanese rice wine
Authors: Gavahian Mohsen , Ratchaneesiripap Paphawarin 
Published: March 2022

Rice wine is a fermented product that can be distilled to produce rice spirit, which is an ingredient in several Asian dishes. The industry usually uses traditional practices for rice wine production. This study aims to evaluate the possibility of enhancing Taiwanese rice wine fermentation through the application of ultrasound as an emerging technology. In this regard, in an academic‐industrial cooperation, a commercial process was modified by incorporating a 550‐W power horn ultrasound treatment after the saccharification step. Independent parameters were sonication times of 0, 3, 6, 9, and 12 min (referred to as control, US3, US6, US9, and US12, respectively) and fermentation time (0, 2, 4, 6, qnd 8 days), and dependent parameters were total phenolic content (TPC), total acidity, alcohol content, CIE color values, pH, total acidity, electrical conductivity (EC), and refractive index (RI). The results showed that US3 provided the highest alcohol content while the physical characteristics, including pH, total acidity, EC, and RI, were not significantly different from those of the control sample. At the same time, sonication alters color values (L*, a*, b*, color intensity, and overall color changes) and TPC. Besides, US12 treatment yielded a rice wine with the highest TPC, that is, 306.77 ± 1.90 mg GAE/L sample. Therefore, sonication conditions can be optimized to achieve the desired properties such as the highest alcohol content or highest TPC. This study revealed that a relatively mild sonication process can enhance the fermentation process to achieve higher alcohol content which could be related to the stress‐response of yeast (Saccharomyces cerevisiae) and modification of fermentation medium. This can be considered an effort to contribute to sustainable development goals (SDGs) and sustainability by increasing resource efficiency. Besides, a more intense sonication resulted in a fermented product with higher amounts of bioactive compounds through the improved extraction process. According to the observations, power ultrasound is a promising pretreatment to boost the fermentation process and rice wine quality through positive effects on both brewer's yeast and fermentation substrates.

Practical Applications

The wine processing industry is seeking innovative approaches to enhance the fermentation yield, reduce fermentation time, and enhance the production capacity. In this sense, the results of this industrial‐academic collaborative research showed that power ultrasound has the potential to improve rice wine fermentation to meet the above‐mentioned industrial demands. This emerging technology at appropriate processing conditions enhanced the percentage of alcohol in the final product which could be considered as an approach to enhance the profit of wineries through enhancing the resource efficiency, that is, more amount of product from the same amount of raw materials. At the same time, this sonication‐based technique did not negatively affect the physicochemical properties of the rice wine. The production platform explored in this study is scalable and can be implemented at industrial levels in wineries.