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Nonconventional Yeasts and Bacteria

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Hanseniaspora
Some species of this genus cannot ferment maltose or maltotriose, which make up the majority of sugar in brewer's wort. For example, Bellut et al. (2018) found that one strain each of the species ''H. vineae'' and ''H. valbyensis'' that were both isolated from kombucha could not ferment these complex sugars (including sucrose), but could ferment cellobiose. This is due to the lack of a maltose transporter and the enzyme maltase. As such, they have been proposed as being potentially useful in non-alcoholic beer fermentation. Additionally, these species were able to grow in 7◦ Plato wort with a range of IBU (50 IBU was the maximum IBU tested), indicating that IBU's don't impact the growth of these species. They also lacked the ability to produce phenols. ''H. vineae'' was moderately flocculant, while ''H. valbyensis'' had poor flocculation, with the flocculation depending on the ''FLO'' gene and the presence of calcium in the wort (the same as ''Saccharomyces''). They produced much less higher alcohols (n-propanol, isobutanol, and isoamyl alcohol) than the WLP001 control yeast. ''H. vineae'' produced slightly more ethyl acetate than WLP001 (6 mg/L vs 4.05 mg/L), while ''H. valbyensis'' produced above threshold diacetyl (0.21 mg/L), however, due to the worty taste of the ''Hanseniaspora'' species which didn't highly attenuate the wort, the sensory differences were negligible. Both species of ''Hanseniaspora'' produced lower levels of ethyl formate and about half the amount of acetaldehyde as WLP001 <ref name="Bellut_2018">[http://www.mdpi.com/2311-5637/4/3/66 Application of Non-Saccharomyces Yeasts Isolated from Kombucha in the Production of Alcohol-Free Beer. Konstantin Bellut, Maximilian Michel, Martin Zarnkow, Mathias Hutzler, Fritz Jacob, David P. De Schutter, Luk Daenen, Kieran M. Lynch, Emanuele Zannini, and Elke K. Arendt. 2018. DOI: https://doi.org/10.3390/fermentation4030066.]</ref>.
A 2020 Portuguese study researched Co-fermentation potential between ''Hanseniaspora'' and other yeast species, and ''Saccharomyces'' (US-05) found the potential to increase flavour compounds compared to a single Saccharomyces fermentation. ''H. guilliermondii'' IST315 , ''H. opuntiae'' IST408 (Ho) and ''T. delbrueckii'' IST314 were selected as producing the most desirable aroma profile, described as having ‘fruity’, ‘toffee’, and ‘honey’ notes <ref name="Bourbon-Melo_2020">Bourbon-Melo, N., Palma, M., Rocha, M. P., Ferreira, A., Bronze, M. R., Elias, H., & Sá-Correia, I. (2020). Use of Hanseniaspora guilliermondii and Hanseniaspora opuntiae to enhance the aromatic profile of beer in mixed-culture fermentation with Saccharomyces cerevisiae. Food Microbiology, 103678. 2020. DOI: doi:10.1016/j.fm.2020.103678 </ref>. ''H. guilliermondii'' IST315 is isolated from grapes, namely the "D. Maria grape variety (Achada, Portugal)", while ''H. opuntiae'' IST408 was also isolated from grapes, "D. Maria grape variety (Extremoz, Portugal)".
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