Abstract
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.
Highlights
Beer is traditionally brewed from malted barley, water and hops using Saccharomyces cerevisiae, which produces flavour-active substances during wort fermentation, giving beer its flavour profile
The aim of this study is to evaluate the potential of a novel yeast Williopsis saturnus var. mrakii NCYC 500 to produce fruity beer
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
Summary
Beer is traditionally brewed from malted barley, water and hops using Saccharomyces cerevisiae, which produces flavour-active substances during wort fermentation, giving beer its flavour profile. These substances include esters, alcohols, aldehydes and ketones, volatile sulphur compounds and fatty acids, etc. Acetate esters are produced via alcoholysis from alcohols and acetyl coenzyme A (CoA) catalysed by alcohol acetyl transferases. Ethyl esters are secondary metabolites produced by both S. cerevisiae and non-Saccharomyces yeasts. These ethyl esters can be formed by esterification or alcoholysis. Important ethyl esters in beer include ethyl octanoate, ethyl hexanoate and ethyl decanoate [5]
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