Exploration of sake yeast from olive on Kagawa prefecture and application in product development

Olive, which have been cultivated in Kagawa Prefecture since 1908, have a strong brand name both inside and outside of the prefecture, and brewing sake with yeast isolated from olive will enable the development of a new sake product that highlight the uniqueness of Kagawa. This study was conducted with the aim of commercializing a highly original sake using yeast isolated from olive. Yeasts (OY-4 and -5) were isolated from olive flowers, fruits, and two strains of Saccharomyces cerevisiae with the ability to produce ethanol at 15 ºC were obtained. However, their ethanol production were lower than that of Kyokai-kobo No. 9. To solve this, we attempted to obtain a strain with higher ethanol productivity by selecting alcohol-resistant strains from OY−4 or −5. Yeast were cultured on agar medium containing ethanol, and 5 strains that could be grown on 17 % ethanol were obtained. Among them, OY-04-2 was selected for its high alcohol productivity and good sensory characteristics. OY-04-2 was named “Sanuki Olive Yeast”, and 4 sake products made with the yeast have been on the market since April 2020. These sake products have been highly praised for their fruity aroma and refreshing acidity.