Non-alcoholic beers have seen steady growth in recent years and are attracting customer interest. At the same time, consumer demand for non-alcoholic beers is rising. While wort-like flavors are often criticized in beer and also regarded as off-flavors, there is growing demand for beer flavor diversification. The latest research results prove that certain non-Saccharomyces yeast species can produce distinctive fruity flavor profiles during wort fermentation. In this study, 15 different yeast strains were evaluated for their suitability to produce novel flavor profiles during fermentation in wort from malt extract while being tested for their ability to produce less than 0.5% (v/v) ethanol. The yeast strains were therefore analyzed for their sugar utilization and were compared with the maltose-negative reference yeast strain Saccharomycodes ludwigii TUM SL17. Following the fermentation experiments, the beers were analyzed for secondary metabolites and ethanol content before being tasted by trained assessors. The results reveal that all 15 yeasts are suitable for the production of non-alcoholic beers based on their sugar utilization. Particularly promising flavors were produced by three yeast strains of the species Cyberlindnera saturnus, which were reminiscent of cool mint sweets, pear, and banana. Two further yeasts of the species Kluyveromyces marxianus and Saccharomycopsis fibuligera also produced a wide range of pleasant fruity flavors. Although the secondary metabolites were mostly below the odor thresholds based on regular alcoholic beers, this study reveals that the thresholds in non-alcoholic beers can be classified as significantly lower. Supplemental data for this article is available online at https://doi.org/10.1080/03610470.2021.2012747 .

Non-Saccharomyces yeasts have aroused interest in brewing science as an innovative and seminal way of creating new beer flavors. A screening system for potential brewing strains of non-Saccharomyces yeasts was set up to investigate the yeast’s utilization of wort sugars and to examine the effect of hop acids as well as ethanol on the growth of different yeast strains. Additionally, phenolic off-flavor (POF) and sensory odor tests of fermented wort samples were performed. The promising strains were further investigated for their propagation ability and for following fermentation trials. The produced beers were analyzed for secondary metabolites, ethanol content and judged by trained panelists. Subsequently to the screening, it was discovered that among the 110 screened yeast strains, approx. 10 strains of the species Saccharomycopsis fibuligera, Schizosaccharomyces pombe and Zygosaccharomyces rouxii generate promising fruity flavors during fermentation and were able to metabolize maltose and maltotriose as a prerequisite for the production of alcoholic beers. Consequently, the screening method described in this study makes it possible to investigate a tremendous number of different non-Saccharomyces yeasts and to test their brewing ability in a relatively short period of time.

The diversification of beer flavor is becoming increasingly popular, especially in the field of non-alcoholic beers, where sales are growing steadily. While flavor substances of traditional beers can largely be traced back to defined secondary metabolites, the production of non-alcoholic beers with non-Saccharomyces yeasts generates novel fruity flavors, some of which cannot yet be assigned to specific flavor substances. In a recently published study, besides pear, cool mint sweets, and banana-like flavor, distinctive red berry and apple flavors were perceived in a non-alcoholic beer fermented with the yeast strain Cyberlindnera saturnus TUM 247, whose secondary metabolites were to be elucidated in this study. The trials were carried out using response surface methodology to examine the fermentation properties of the yeast strain and to optimize the beer with maximum fruitiness but minimal off-flavors and ethanol content. It turned out that a low pitching rate, a moderate fermentation temperature, and an original gravity of 10.5 °P gave the optimal parameters. Qualitative analysis of the secondary metabolites, in addition to standard analysis for traditional beers, was first performed using headspace-gas chromatography with olfactometry. (E)-β-damascenone emerged as the decisive substance for the red berry and apple flavor and so this substance was then quantitated. Although (E)-β-damascenone is a well-known secondary metabolite in beer and this substance is associated with apple or cooked apple- and berry-like flavors, it has not yet been reported as a main flavor component in non-alcoholic beers.

Nonalcoholic beers are becoming increasingly popular, in part due to consumers’ awareness of a healthier lifestyle. Additionally, consumers are demanding diversification in the product range, which can be offered by producing nonalcoholic beers using non-Saccharomyces yeasts for fermentation to create a wide variety of flavors. So far, little is known about the nutritionally relevant byproducts that these yeasts release during wort fermentation and whether these yeasts can be considered safe for food fermentations. To gain insights into this, the B vitamins of four different nonalcoholic beers fermented with the yeast species Saccharomycodes ludwigii, Cyberlindnera saturnus (two strains), and Kluyveromyces marxianus were analyzed. Furthermore, a total of 16 beers fermented with different non-Saccharomyces yeast strains were analyzed for biogenic amines. Additionally, stress tolerance tests were performed at 37°C and in synthetic human gastric juice in vitro. B vitamins were found in the four nonalcoholic beers in nutritionally relevant amounts so they could serve as a supplement for a balanced diet. Biogenic amines remained below the limit of determination in all 16 beers, and thus likely had no influence, while the stress tolerance tests gave a first indication that seven yeast strains could possibly tolerate the human gastric juice milieu.