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Dimethyl Sulfide

56 bytes added, 12:08, 23 March 2016
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Using the exact same wort composition but with a 60 minute boil, this example in "Principles of Brewing Science: A Study of Serious Brewing Issues" computes only 92 µg/L of DMS, mostly because a lot more of the SMM is converted to DMS during boiling, which is then volatilized during the boiling, and leaving less SMM to convert to DMS during cooling. Even with the higher SMM during cooling in our heat pasteurized wort example, that hardly seems fair considering that the half-life of SMM is ~300 minutes at the pasteurization temperature of 82°C.
===Using Just Half-Lifeand New Volatilization Equations===
If instead we just use the first equation that predicted how much SMM is decomposed into DMS during the heat pasteurization time, we get a much lower value of SMM that is decomposed into DMS. This approach takes into consideration the [[Dimethyl_Sulfide#Mashing_and_Boiling|half-life of SMM]] at any given temperature rather than taking the average of the starting temperature and ending temperature during cooling. [https://www.facebook.com/mark.hammond.1253 Mark Hammond] from MTF used a computer program to model the conversion of SMM to DMS based on SMM half-life at any given temperature. The new equations from Hammond assumed a linear heating rate, and used Newton's Law of Cooling for the cooling rate. By observing these estimations, it can be seen that no-boil or "raw ale", and wort boiled for short durations, we predict less DMS than what is predicted using the traditional model.
[[File:DMS Pasteurization.png|none|thumb|500px|SMM conversion to DMS during a 20 minute heat up, 15 minute pasteurization at 82°C, and 60 minute cool down to 20°C. Graph created and provided by Mark Hammond.]]

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