Sourdough cultures as reservoirs of maltose-negative yeasts for low-alcohol beer brewing. (April 2021)

• Record Type: Journal Article
• Authors: Johansson, Linnea; Nikulin, Jarkko; Juvonen, Riikka; Krogerus, Kristoffer; Magalhães, Frederico; Mikkelson, Atte; Nuppunen-Puputti, Maija; Sohlberg, Elina; de Francesco, Giovanni; Perretti, Giuseppe; Gibson, Brian
• Is Part Of: Food microbiology. Volume 94(2021)
• Publication Date: 2021-04
• Subjects: Sourdough -- Low-alcohol beer -- Next-generation sequencing -- Flavour -- Kazachstania servazzi -- Pichia fermentans; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2020.103629
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: De novo sourdough cultures were here assessed for their potential as sources of yeast strains for low-alcohol beer brewing. NGS analysis revealed an abundance of ascomycete yeasts, with some influence of grain type on fungal community composition. Ten different ascomycete yeast species were isolated from different sourdough types (including wheat, rye, and barley) and seven of these were screened for a number of brewing-relevant phenotypes. All seven were maltose-negative and produced less than 1% (v/v) alcohol from a 12 °Plato wort in initial fermentation trials. Strains were further screened for their bioflavouring potential (production of volatile aromas and phenolic notes, reduction of wort aldehydes), stress tolerance (temperature extremes, osmotic stress and ethanol tolerance) and flocculence. Based on these criteria, two species ( Kazachstania servazzii and Pichia fermentans ) were selected for 10 L-scale fermentation trials and sensory analysis of beers. The latter species was considered particularly suitable for production of low-alcohol wheat beers due to its production of the spice/clove aroma 4-vinylguaiacol, while the former showed potential for lager-style beers due to its clean flavour profile and tolerance to low temperature conditions. Highlights: De novo sourdough cultures were prepared under laboratory conditions for isolation of novel, low-alcohol, beer-brewing strains. Next generation sequencing revealed that the Ascomycota was the most abundant phylum present. Fifty-six isolated yeasts belonged to ten different species. All showed some potential for low-alcohol wort fermentation. Isolates differed in their ability to reduce aldehyde compounds and generate volatile aromas during fermentation. Selected strains showed potential for industrial application.