Evaluation of Beer Fermentation with a Novel Yeast
Williopsis saturnus

The aim of this study is to evaluate the potential of a novel yeast Williopsis saturnus var. mrakii NCYC 500 to produce fruity beer. Fermentation performance of W. mrakii and beer volatile composition were compared against that fermented with Saccharomyces cerevisiae Safale US-05. ^oBrix, sugar and pH differed significantly between the two types of beer. A total of 8 alcohols, 11 acids, 41 esters, 9 aldehydes, 8 ketones, 21 terpenes and terpenoids, 5 Maillard reaction products and 2 volatile phenolic compounds were detected. Yeast strain Safale US-05 was more capable of producing a wider range of ethyl and other esters, while yeast strain NCYC 500 produced significantly higher amounts of acetate esters. Strain NCYC 500 retained more terpenes and terpenoids, suggesting that the resultant beer could possess more of the aromatic hint of hops. This study showed that W. saturnus var. mrakii NCYC 500 could ferment wort to produce low-alcohol beer with higher levels of acetate esters, terpenes and terpenoids than yeast S. cerevisiae Safale US-05.