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Dimethyl Sulfide

46 bytes added, 11:48, 21 March 2016
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===Using Just Half-Life===
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 different value of DMS. Using this equation might be more accurate for no-boil wort since it uses Mark Hammond from MTF used a computer program to model the conversion of SMM to DMS. The model takes into consideration the half-life directly instead of averaging out the starting and ending temperaturesSMM at any given time. WeHammond assumed a linear heating rate, and used Newton'll use 95 minutes as our time (35 minutes s Law of Cooling for heating the cooling rate. By observing these estimations, it can be seen that no-boil or "raw ale", and pasteurizingwort boiled for short durations, 60 minutes for cooling):predict less DMS than what is predicted using the traditional model.
<code>[[File:DMS Pasteurization.png|none|thumb|500px|SMM into the fermenter = 1conversion to DMS during a 20 minute heat up,000 µg/L x 2<sup>-(95 min/300 min)</sup> = 115 minute pasteurization at 82°C,000 x 2<sup>-0and 60 minute cool down to 20°C.32</sup> = 1,000 x 0 Graph created and provided by Mark Hammond.8 = 800 µg/L </code>]]
and In the above computer generated graph, using only the half-life rates of SMM, only ~60 µg/L of SMM is converted into ~60 µg/L of DMS. This is below the recommended threshold of 100 µg/L of DMS going into the fermenter <ref name="Scheuren2016mbaa"></ref>.
<code>DMS into the fermenter = 1Hammond also generated graphs for a 15 minute boil and a 0 minute boil (wort heated to 100°C,000 µg/L - 800 µg/L = 200 µg/L </code>then immediately cooled). These graphs are seen below:
Another example will show that cutting the time down that the wort is exposed to 82°C will also lower the [[File:DMS15MinBoil. We'll estimate that it takes 45 minutes png|none|thumb|500px|SMM conversion to DMS during a 35 minute heat the wort to 82°Cup, pasteurize for 15 minutesminute boil at 100°C, and then 60 minute cool down to 20°C. Graph created and provided by Mark Hammond.]][[File:DMS 0MinBoil.png|none|thumb|500px|SMM conversion to pitching DMS during a 35 minute heat up to boiling temperature (all heating and 100°C), then immediate cooling time will be calculated at 82°C for simplicity):60 minutes to 20°C. Graph created and provided by Mark Hammond.]]
<code>SMM into In the case of the fermenter = 115 minute boil,000 approximately 400 µg/L x 2<sup>-(45 min/300 min)</sup> = 1,000 x 2<sup>-0.15</sup> = 1,000 x 0.9 = 900 of SMM is converted into approximately 400 µg/L </code> and  <code>of DMS into . During the fermenter = 1boiling process,000 µg/L - 900 µg/L = 100 µg/L </code> Considering again the large impact it could be assumed that temperature has on much of the half-life of SMM, 100 µg/L DMS is still probably a gross overestimation of DMSvolatilized due to the boil. To demonstrate this, we'll calculate this again, but at 76°C (~600 minute half-life): <code>SMM into In the case of the fermenter = 1,000 µg/L x 2<sup>-(45 min/600 min)</sup> = 1,000 x 2<sup>-"0.075</sup> = 1minute" boil,000 x 0.95 = 950 approximately 175 µg/L </code> and  <code>DMS of SMM is converted into the fermenter = 1,000 approximately 175 µg/L - 900 µg/L = 50 µg/L </code> We could break up the SMM conversion to of DMS into many steps by measuring how much time the wort sits at the different temperatures ranges based on the [[Dimethyl_Sulfide#Mashing_and_Boiling|half-life table above]], and calculating how much SMM is converted at the different half-lives.
===Kettle Souring and Effects of pH===

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