Review: Pure non‐Saccharomycesstarter cultures for beer fermentation with a focus on secondary metabolites and practical applications

Abstract

Recently there has been increased interest in using non‐Saccharomyces yeasts to ferment beer. The worldwide growth of craft beer and microbreweries has revitalised the use of different yeast strains with a pronounced impact on aroma and flavour. Using non‐conventional yeast gives brewers a unique selling point to differentiate themselves. Belgian brewers have been very successful in using wild yeasts and mixed fermentations that often contain non‐Saccharomyces yeasts. Historically, ancient beers and beers produced before the domestication of commonly used Saccharomyces strains most likely included non‐Saccharomyces species. Given the renewed interest in using non‐Saccharomyces yeasts to brew traditional beers and their potential application to produce low‐alcohol or alcohol‐free beer, the fermentation and flavour characteristics of different species of non‐Saccharomyces pure culture yeast were screened for brewing potential (Brettanomyces anomalus and bruxellensis, Candida tropicalis and shehatae, Saccharomycodes ludwigii, Torulaspora delbrueckii, Pichia kluyveri, Zygosaccharomyces rouxii). Alcohol‐free beer is already industrially produced using S. ludwigii, a maltose‐negative species, which is a good example of the introduction of non‐Saccharomyces yeast to breweries. Overall, non‐Saccharomyces yeasts represent a large resource of biodiversity for the production of new beers and have the potential for wider application to other beverage and industrial applications. Almost all of the trials reviewed were conducted with varying fermentation parameters, which plays an important role in the outcome of the studies. To understand these impacts all trials were described with their major fermentation parameters. Copyright © 2016 The Institute of Brewing & Distilling

Conventional and Non-Conventional Yeasts in Beer Production

“…These compounds are desirable; if present in moderate levels, they help increase the flavor complexity of beers, whereas high amounts affect negatively beverage aroma, conferring undesirable, solvent-like buttery and medicinal notes [30]. Otherwise, most authors reported very low quantities of isoamyl acetate, which could be explained by the ability of B. bruxellensis to break down this aroma compound, which is highly desirable in wheat beer [31].…”

“…Torulaspora delbrueckii, a common contaminant in the brewing environment and suggested as a potential brewing yeast firstly by King and Dickinson [36], has been shown to be able to produce high levels of amyl alcohol (fruity flavours) [31] and is often associated with wheat beer, a style typically associated with pronounced fruit notes. This yeast species has the additional advantage of being resistant to the various stresses encountered during brewing, although different strains exhibited different abilities to ferment wort sugars, and this characteristic may explain the variable performance observed in different studies [31,37,38].…”

“…This yeast species has the additional advantage of being resistant to the various stresses encountered during brewing, although different strains exhibited different abilities to ferment wort sugars, and this characteristic may explain the variable performance observed in different studies [31,37,38]. Tataridis et al [37] tested T. delbrueckii as a yeast for producing German wheat beer, in comparison to a top-fermenting S. cerevisiae strain.…”

Spent Yeast from Brewing Processes: A Biodiverse Starting Material for Yeast Extract Production

“…The altered yeast metabolism during high-gravity fermentation not only changes the quality of the finished beer but also the material composition of the yeast [10,18]. In addition, the biodiversity of the generated spent yeast in breweries is increased through the use of various alternative non-Saccharomyces strains as pure starter cultures for beer production [19,20]. Improper storage or handling of the spent yeast can result in contamination with various microorganisms, which can impact the subsequent yeast extract production process [21].…”

Microbial and Chemical Diversity of Traditional Non-Cereal Based Alcoholic Beverages of Sub-Saharan Africa

“…This is the most important group of secondary metabolites essential for aromatic characteristics as they impart a fruity and sweet note to alcoholic beverages during fermentation. Esters are divided into acetate esters (synthesized from a higher alcohol or ethanol with acetic acid) and medium-chain fatty acid ethyl esters (made from a medium-chain fatty acid and an ethanol radical) [111,112].…”