|MadSci Network: Chemistry|
This is a big question. For a thorough understanding of the process, try consulting a homebrewing book...the Joy of Homebrewing by Charlie Papazian is a good one. Overall, several steps make up beer production. Grains which contain starches are used to produce sugars, which are then acted upon by yeasts to generate alcohol, carbon dioxide and water. Various flavors including hops are added. Final carbonation occurs either by forcing carbon dioxide into the beer (what happens to most of the beers that you buy in the store) or by addition of a little sugar to the bottle just before bottling (called "bottle conditioned beers") which is further acted upon by the yeast to yield carbonation. The grains contains starches, which the yeast is unable to act upon. The grains also contain enzymes, which are species which can convert the starches to sugars. You have enzymes in your saliva, for example. These enzymes in the grains become activated when they are warmed. Hence, the grains are soaked in warm water to generate sugars ("food" for the yeasts). Flavors include hops (a bitter herb) and roasted grains. I hope this helps. Please email me if you have further questions: email@example.com Best Regards, Mike
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