13,696
edits
Changes
grammar
The same strain of ''B. custersianus'' was screened for beta-glucosidase activity and aglycone byproducts during the refermentation of sour cherries in beer (a very small amount of the byproducts were manufactured by the yeast ''de novo'', particularly linalool, alpha-terpineol, alpha-ionol, and a precursor that leads to beta-damascenone under low pH conditions). Different portions of the cherries were tested: whole cherries with stones (pits), cherry pulp without stones, cherry juice without stones or other solids from the fruit, and the stones alone. Benzaldehyde (almond, cherry stone flavor) was produced during fermentation in all cases, and reduced to benzyl alcohol (almond flavor) and benzyl acetate (fruity, jasmin flavor) by the end of fermentation. There were higher levels of these benzyl based compounds in the whole cherries and cherry stone alone samples, indicating that cherry stones make a big impact on the almond flavors found in cherry sour beers. Methyl salicylate, linalool, alpha-terpineol (pine), geraniol (rose, lime, floral) and alpha-ionol (floral, violet), eugenol (spicy, clove, medicinal) and isoeugenol (fine delicate clove) levels increased in all forms of cherries added except for stones alone, indicating that these aglycones are more present in the flesh and juice of the cherries <ref name="Daenen2"></ref>.
Many strains of ''B. bruxellensis'' have also been found to have varying degrees of intracellular or parietal (attached to the cell wall) beta-glucosidase activity. ''Brettanomyces'' has more strains that can produce beta-glucosidase than other genre genera of yeast, and the strains generally also have a higher rate of beta-glucosidase activity than other genre 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>. 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 the possess an extra gene for beta-glucosidase enzyme production <ref name="Crauwels1"></ref>.
====See Also====