Originally Posted by jwbeard
Everything I've read on amylase (beta and alpha) says that the primary denaturing mechanisms are temperature and pH, and often the reference will include a note about denaturing time for certain conditions (e.g. at 153 F, alpha-amylase will become denatured after two hours, etc).
Is there a temperature at which amylase (or other enzymes in the process) won't denature regardless of time, or will the enzymes get 'worn out' and denature after a certain number of reactions regardless of conditions? I'm curious because I may need to add an amylase powder to a fermentation to bring down a (very high) FG to a decent level.
If even a minuscule amount of enzyme will eventually be able to convert the entire wort into a fermentable form, I'll just drink it as is. But if the enzymes denature at *some* point at room temperature, I don't mind adding small small amounts and titrating the gravity down to the desired point...
I'm not sure where to begin on this one. If you wanted to make more fermentable wort, you would want to add beta-amylase, not alpha-amylase. Beta-amylase produces short chain sugars that are readily fermentable by yeast. Alpha-amylase produces wort with higher order sugars that are less fermentable and contribute to body. However, instead of adding enzyme (which just sounds silly to me), why not just mash at a lower temperature (148-150 F) to yield better beta-amylase activity and more fermentable wort? Take advantage of the enzymes in your grain. There should be more than enough enzyme present to convert starches to sugars.
Your FG problems really come down to a matter of mash temperature, fermentation temperature, and yeast strain used:
If you mash on the high end (158-160 F) you will get less fermentable wort, resulting in a higher FG. If you mash at the low end (148-150 F), you wil get more fermentable wort and lower FG.
If you ferment on the high end for the yeast strain, you will likely get better attenuation and lower FG due to higher metabolic activity. If you ferment on the low end of the yeast strain, you will get less attenuation and higher OG owing to lower metabolic activity.
This one is self explanatory. High attenuators yield lower FG and low attenuators yield higher FG.
Have you looked into the mash temperature? The yeast used? The fermentation temperature? How do you monitor mash temperature? Are your thermometers calibrated correctly? What is your water profile? What is your mash pH? How do you monitor fermentation temperature? How do you monitor fermentation progression? Do you take gravity readings throughout, or are you a bubble watcher?
It sounds like you need to take a solid look at your process before looking into adding enzyme (which again is just silly for brewers to do).