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update to Activity of Brettanomyces and Saccharomyces on mogrosides
Many strains of ''B. bruxellensis'' have also been found to have varying degrees of intracellular (produced inside the cell only) or parietal (attached to the cell wall) beta-glucosidase activity. At least one mutant strain of ''B. bruxellensis'' found in wine (''D. bruxellensis'' BCRC920084 from the Bioresource Collection and Research Center, Hsin-Chu, Taiwan) has been reported to have high extracellular (excreted out of the cell) production of beta-glucosidase that was very efficient at breaking down a glycoside called "piceid" that released resveratrol, which has been marketed as a dietary supplement <ref>[https://www.ncbi.nlm.nih.gov/pubmed/29389552?dopt=Abstract Characterization of an extracellular β-glucosidase from Dekkera bruxellensis for resveratrol production. Kuo HP, Wang R, Huang CY, Lai JT, Lo YC, Huang ST. 2018.]</ref><ref>[https://en.wikipedia.org/wiki/Resveratrol Wikipedia. "Resveratrol" article. Retrieved 02/09/2018.]</ref>. ''Brettanomyces'' has more strains that can produce beta-glucosidase than other genera of yeast, and the strains generally also have a higher rate of beta-glucosidase activity than other genera of yeast <ref>[http://link.springer.com/article/10.1038/sj.jim.2900720 Quantification of glycosidase activities in selected yeasts and lactic acid bacteria. H McMahon, B W Zoecklein, K Fugelsang, Y Jasinski. 1999.]</ref><ref name="Mansfield"></ref>. Strains with higher beta-glucosidase activity have been isolated from lambic, suggesting that these strains may have an adapted ability to utilize sugar from glycosides <ref name="Vervoort">[http://onlinelibrary.wiley.com/wol1/doi/10.1111/jam.13200/abstract Characterization of the recombinant Brettanomyces anomalus β-glucosidase and its potential for bioflavoring. Yannick Vervoort, Beatriz Herrera-Malaver, Stijn Mertens, Victor Guadalupe Medina, Jorge Duitama, Lotte Michiels, Guy Derdelinckx, Karin Voordeckers, and Kevin J. Verstrepen. 2016.]</ref>. Some ''Brettanomyces'' strains may only be capable of beta-glucosidase activity, and not the other enzymes which are needed to break down disaccharide type glycosides. Additionally, cell death and autolysis can result in an increase in beta-glucosidase activity in solution due to the cell contents being released into solution <ref name="Mansfield"></ref>. Strains that can metabolize cellobiose tend to also have higher beta-glucosidase activity because they possess an extra gene for beta-glucosidase enzyme production <ref name="Crauwels1">[http://link.springer.com/article/10.1007/s00253-015-6769-9 Comparative phenomics and targeted use of genomics reveals variation in carbon and nitrogen assimilation among different Brettanomyces bruxellensis strains. S. Crauwels, A. Van Assche, R. de Jonge, A. R. Borneman, C. Verreth, P. Troels, G. De Samblanx, K. Marchal, Y. Van de Peer, K. A. Willems, K. J. Verstrepen, C. D. Curtin, B. Lievens. 2015]</ref>.
Sensory analysis of beers with cherries or hops have shown that there is a significantly detectable difference between cherry beers that have been exposed to beta-glucosidase from one strain of ''B. anomalus'' versus not exposed to the enzyme, but no significant difference was found in beers hopped with pellets. The cherry beers exposed to the enzyme contained more and above odor threshold eugenol (clove, honey aroma), benzyl alcohol (sweet, flower), benzaldehyde (almond, cherry) than cherry beers that were not exposed to the enzyme. The cherry beers exposed to the enzyme were not only identified in a blind tasting, but were also preferred to the cherry beers without exposure to the enzyme, indicating that beta-glucosidase activity in cherry beers provides a significant flavor difference. Other types of beta-glucosidase enzymes released different levels of different flavor compounds, indicating that the source (bacteria or yeast) of the enzyme make a significant difference in the flavors that are produced <ref name="Vervoort"></ref>.
The effects of beta-glucosidase on hops may be limited even in ideal conditions using pure beta-glucosidase that is highly efficient in beer where beta-glucosidase activity by yeast is suppressed. Sharp et al. (2017) determined that hops contain such a small amount of glycosides that their release doesn't contribute much to hop flavor and aroma. While previous studies focused on hop extracts, they studied glycosides in whole leaf hops for the first time and found non-significant levels of hop -derived monoterpenes from glycosides even when using pure beta-glucosidase extracted from almonds. For example, linalool was increased by 16.5 μg/L when using the highest hopping rate, but this amount has little impact on the overall aroma and flavor of the beer. Terineol, citronellol, nerol, and geraniol were also not increased in significant amounts, however 1-octanol (waxy, green, citrus, orange, aldehydic, fruity <ref>[http://www.thegoodscentscompany.com/data/rw1021071.html Octanol. The Good Scents Company. Retrieved 03/31/2017.]</ref>) was increased significantly <ref name="Sharp_2017" />. Wang et al. (2018) reported another type of glycosidic activity in one strain of ''B bruxellensis'' which is the conversion of the glycoside "mogroside V" into an artificial sweetener called siamenoside I. Other yeast and bacteria species were tested and did not find this particular glycosidic activity. [https://en.wikipedia.org/wiki/Mogroside Mogroside V] is found naturally in some fruit, specifically, an Asian fruit called [https://en.wikipedia.org/wiki/Siraitia_grosvenorii Lo Han Kuo (''Siraitia grosvenorii'')]. The artificial sweetener siamenoside is 563 times sweeter tasting than 5% sucrose. The specific enzyme responsible for this conversion that this strain of ''B. bruxellensis'' produced is called ''Db''Exg1 <ref>[https://www.sciencedirect.com/science/article/pii/S0308814618317473 Dekkera bruxellensis, a beer yeast that specifically bioconverts mogroside extracts into the intense natural sweetener siamenoside I. Reuben Wang, Yi-Chieh Chen, Yun-Ju Lai, Ting-Jang Lu, Shyue-Tsong Huang, Yi-Chen Lo. 2018. DOI: https://doi.org/10.1016/j.foodchem.2018.09.163.]</ref>.
See also [[Hops#Glycosides|Glycosides in Hops]].