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Glycosides

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Aglycones can be released from glycosides via a low pH. Generally, this occurs at lower pH's, but different types of glycosides are more readily broken down at different pH's. For example, ocimenols (lemon, lime <ref>[http://www.thegoodscentscompany.com/data/rw1020581.html "Ocimenol". The Good Scents Company. Retrieved 06/26/2017.]</ref>) are formed from glycoside breakdown at a pH of 1, but terpenes such as linalool, nerol, and geraniol (commonly found in hops and other plant material) are formed at a pH of 3, and alpha-terpineol was formed at both pH values. The acidic breakdown of these glycosides were found to contribute to the flavor of wine during aging <ref name="Maicas"></ref>.
In beer, it was found that the lower the pH of the beer the higher the amount of the ketone damascenone (floral, rose <ref>[https://en.wikipedia.org/wiki/Damascenone "Damascenone". Wikipedia. Retrieved 06/26/2017.]</ref>) and dimethyl trisulfide (sulfury cooked onion <ref>[http://www.thegoodscentscompany.com/data/rw1008101.html "Dimethyl trisulfide". The Good Scents Company. Retrieved 06/26/2017.]</ref>). In one study, at a pH of 3, damascenone was reported to be ~27 ppb and dimethyl trisulfide was reported to be 650 ppt. At a pH of 4.2, they were 17 ppb and 300 ppt respectively. At a ph of 5, beta-damascenone was around 12 ppb and dimethyl trisulfide 50 ppt. This was believed to be due to the acidic hydrolysis of glycosides, and it was speculated that other glycosides could have a flavor impact on beers that contain fruit or herbs due to acidic hydrolysis of glycosides <ref>How Low pH Can Intensify ?-Damascenone and Dimethyl Trisulfide Production through Beer Aging. L AURENCE G IJS LAURENCE GIJS, F ABIENNE C HEVANCE FABIENNE CHEVANCE, V ESNA J ERKOVIC VESNA JERKOVIC, AND S ONIA C OLLINSONIA COLLIN. 2002. DOI: 10.1021/jf020563p.</ref>.
* See also: [[Hops#Glycosides|Glycosides In Hops]].

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