Field-isolated brewing yeast produces wheat beer flavor without wheat ingredients

This study explored the potential of 120 wild yeasts obtained from eight different fruits, with particular emphasis on Saccharomyces cerevisiae S-1. This strain demonstrated remarkable attributes, notably its superior alcohol tolerance when compared to the conventional yeast, US-05. Significantly, the S-1 yeast unveiled its ability to produce three distinct aroma compounds—isoamyl acetate, β-phenylethyl acetate, and ethyl decanoate— not typically found in beer brewed with US-05 stain. These compounds are essential for enriching the sensory experience of beer drinkers. Further investigation revealed that the diminsihed expression of Leu2 in US-05 hindered metabolite synthesis, resulting in the absence of these aroma compounds. In contrast, S-1 exhibited approximately three times higher Leu2 expression, which may explain the observed differences in aroma compounds production. This sheds light on the potential mechanism behind the disparity in aroma profiles between the two strains. Overall, the study highlighted S-1’s capacity to enhance beer flavor and aroma. It suggested that wild yeast strains, such as S-1 yeast isolated from grapes, present innovative opportunities for the brewing industry. The hightened Leu2 expression and synthesis of unique aroma compounds in S-1 yeast underscore the latent capabilities of wild yeast strains in elevating beer characteristics.