Addition of yogurt to wort for the production of spirits: Evaluation of the spirit aroma over a two‐year period

Abstract

Triggered by the development of lactic acid bacteria (LAB) during the production of Scotch whisky, this study examined the influence of yeast and LAB inoculation on whisky flavor. Four new spirits were produced using the same process. LAB were added as a form of a Greek yogurt's live culture. In each category (barley and rye), one sample was fermented with Greek yogurt while the other was fermented without it. The spirits were matured and analyzed at five different points. Results from gas chromatography‐mass spectrometry (GC‐MS) analysis showed basic volatile compounds, along with some important extra compounds with yogurt culture. The most obvious differences were observed in the concentration of butanoic acid, a characteristic acid in spirits undergoing lactic acid fermentation: to identify esters such as ethyl butanoate, ethyl isobutanoate, isoamyl butanoate, and 2‐phenylethyl butanoate, they are not typical compounds in whisky.

Co-Fermentations of Kveik with Non-Conventional Yeasts for Targeted Aroma Modulation

“…Therefore, yeasts that generate copious volatile aromas may be favorable. Flavor contributions of other organisms have been viewed as spoilage, but recently they have also been looked at more positively [ 15 , 32 ]. The use of different lactic acid bacteria (LAB) in malt whisky fermentations has been studied.…”

“…These bacteria may develop as the wort is not boiled in contrast to beer fermentations and selection of Lactobacilli may contribute beneficial flavors to whisky [ 14 , 33 ]. Particularly, ethyl butanoate has been valued for its positive influence on the whisky aroma with its fruity flavor (orange, pineapple) [ 15 , 34 ]. However, inclusion of LAB will result in the formation of lactic acid and its ester ethyl lactate (buttery, creamy odor), which did not occur in our co-fermentations with NCYs.…”

“…Non-sterile fermentations, such as in whisky production, require fast fermenting strains with high temperature and high ethanol tolerance. The presence of bacterial strains is tolerated and may be associated with positive aroma contribution [ 14 , 15 ]. The limitations of the use of Saccharomyces in fermentations, compared to some successful spontaneous fermentations that are based on a much broader biodiversity, have led to an interest in employing NCYs in beverage productions.…”

Temperature‐dependent alcohol acyltransferase reactions as the main enzymatic way to produce short‐chain (C4–C8) and medium‐chain (C9–C13) esters over the whole Daqu‐making process

“…8,9 Owing to the time-consuming production of Daqu, up to now, advances have been only achieved in revealing the correlations between environmental factors and specific communities during SSF, 4,10 while detailed information about the main enzymatic ways and key environmental factors for ester formation over the whole Daqu-making process has not been thoroughly investigated, which is necessary for the generation of methods to enhance the flavor profile of Baijiu, as in other brewing liquors. 11,12 Therefore, the aims of this study were focused on identifying the main enzymatic ways as well as their dependent environmental factors for the formation of specific categories of esters over the whole Daqu-making process. We carefully examined the change profiles of volatile esters, substrate indices, representative ester-formatting enzyme activities and important environmental factors over the whole making process in two types of Daqu and analyzed the influence of the environmental factors on the formation of specific categories of esters by the random forest machine learning algorithm.…”

“…Nevertheless, some studies showed that the sum volatile esters in Daqu could be affected by ESTs, but the short‐chain (C4–C8) and medium‐chain (C9–C13) esters had little relationship with ESTs and might be contributed by other ester‐synthesis enzymes 8,9 . Owing to the time‐consuming production of Daqu , up to now, advances have been only achieved in revealing the correlations between environmental factors and specific communities during SSF, 4,10 while detailed information about the main enzymatic ways and key environmental factors for ester formation over the whole Daqu ‐making process has not been thoroughly investigated, which is necessary for the generation of methods to enhance the flavor profile of Baijiu , as in other brewing liquors 11,12 …”