Post
by Graham » Wed Oct 21, 2009 11:30 pm
As others have already said, BYO has to be uncomplicated and easily accessible for the beginner. Much of the advice given in the book is the result of sticking as close as possible the basics.
However, one thing to beware of is that some authors give the impression that some limiting factor takes place by varying mash temperature (or pH); that the mash enzymes magically stop working when the sugar balance is correct. They don't. There is a time factor involved which many authors forget to mention.
All that happens when mash temperature is varied is that the two major enzymes work much faster at a high temperature than a low temperature. The enzymes do not get used up, nor do they stop working (unless the temperature is at destructively high levels), but will continue to work until the mash is deliberately stopped. Given enough time the alpha-amylase will convert all the starch into dextrin, and the beta-amylase will convert as much of the dextrin that it can into maltose - typically 62% of it. No matter what the temperature may be, the mash will get to the same point sooner or later, and will limit when about 62% of the total sugars are fermentable. This is the standard balance for almost all beers. The only way to alter this sugar balance is to forcibly stop the mash, early, by rapidly raising its temperature to about 76 degrees to arrest beta-amylase activity. Not only do home brewers not usually do this, but choosing the correct point to stop the mash is fraught with difficulty. How does one know when the mash is at the correct sugar balance? A degree or two difference in temperature or a small difference in pH will throw the timings wildly out. Jiggling with mash temperature and pH is ineffective without appropriate timing, and that is a risky strategy.
On here we sometimes see full-mashers ending up with what is called a stuck fermentation, but in my view this is down to attempts to cut down on mash time, which is also fairly common on here. This stuck fermentation is because the beta-amylase has not been given enough time to convert all the dextrin to maltose. In the book the mash time is standardised on 90 minutes. This is because if the mash temperature drops more than expected, or the pH is way out, there is still enough time for that magical 63% fermentability to be reached.
After reading the intial descriptions i.e fruity dry etc im not sure how this is achieved as some homebrew books say the temperature has a lot to do with the malty / dry character of the beer. Have i misunderstood this 
I learn more by trying / failing than getting it exactly right, which is lucky as i tend to fail at most things 
, but i may go for Daniels "Designing Great Beers" as it nearly that time and everyone asking what they can buy, may make for some interesting bedtime reading....i have always been an isomniac 
