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51. Developing a screening system for the brewing ability of non-Saccharomyces yeasts

M. MICHEL (1), F. Jacob (1), M. Hutzler (1); (1) Research Center Weihenstephan for Brewing and Food quality, TU München, Freising, Germany

Yeast, Fermentation, and Microbiology II
Saturday, October 10
8:30–10:15 a.m.
Grand 6–8

The brewing sector is ruled by Saccharomyces species. Besides spontaneous fermentation, there is very little use of non-Saccharomyces yeasts all around the beer industry. There are approximately 670,000 species of yeasts in different habitats, where of only 20 species are being used for industrial needs. The possibility of a lot of new aroma compounds produced by this huge variety of yeasts is unimaginable. To make use of this big field of unknown species, aromas, and maybe new aspects of taste or functionalities for more mouthfeel or higher pressure-resistant yeasts, a screening system is being developed. The screening system includes preliminary biochemical tests to make sure the investigated yeasts can survive in beer wort and, of course, ferment it. This includes the carbohydrate fermentation of wort sugars, hop resistance, and ethanol resistance, as well as different combinations. It is continuous with the propagation ability and flocculation behavior, as well as different brewing trials with the observation of all important beer characteristics. It also includes precursor tests for phenolic off-flavors by sensory evaluations. The further goal is to improve the fermentation ability and special flavor forming of the curtain yeasts found to be feasible for brewing. A bioflavoring for new tastes in beer, as well as new beer types, are being looked for. First trials were done with 12 different Torulaspora delbrueckii and 12 different Hanseniaspora uvarum strains from various habitats like the wine and cheese industries, as well as spontaneous banana wine fermentations. These yeasts have already been used in the wine industry for more fruitiness in certain wines. There has been very little effort to produce beer. The tests and trials show large differences in just one species when it came to sugar fermentation and ethanol formation as well as flavors. The flavor varies from honey-like to pear- or apple-like fresh fruitiness. The brewing ability seems to be present. More yeast strains are being looked at from different spontaneous fermented beverages around the world as well as spoilage yeasts. The screening system is being updated constantly to improve the finding of new yeasts for the brewing industry.

Maximilian Michel finished his studies in brewing and beverage technology with a Dipl.-Ing. degree from TU München in 2014. He wrote his diploma thesis on heat resistance of beer spoilage bacteria. He then started a Ph.D. program at the Research Center Weihenstephan for Brewing and Food Quality, TU München with the aim of developing a screening system for non-Saccharomyces yeasts for the beer industry. He also works as a counselor for breweries at the Research Center Weihenstephan.

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