I keep some on hand and use it occasionally if I feel like doing something crazy. I've used it in a 50% corn cream ale, and a 50% potato beer. I just add it to my mash. I don't know how to calculate efficiency with odd ingredients like these, but it definitely converted the starch, and it's always been good beer.
I've used Alpha-Galactosidase once for a light beer. I bought it from a homebrew shop. It was 3 tablets (crushed) per 5 gal batch. I bought some Beano to try instead. It is the same stuff (exactly?). I'll be brewing up another batch soon, trying the beano instead
I use Amylase in my light beers with good results. It produces a dry crisp beer but can take a long time. I've also used it in high percentage wheat beers as cheap insurance for getting full conversion.
Well what enzymes you use depends on what you are trying to accomplish.
If you are trying to break down whole gelatinized starch, or convert larger sugars into smaller more fermentable sugars. For the former, I would recommend an alpha-amylase enzyme. Those are typically found in homebrew shops listed as "amylase enzyme", which is misleading. The easiest alpha-amylase to find is usually a bacterial one that works within the 120-165 F range. Depending on the concentration of the enzyme (it can be altered by the supplier or the provider by adding more maltodextrin) dosage can be a few grams to a full ounce. This is typically called the "liquefaction" process of converting starch into dextrins (random sugars). Some commercial products are "Termamyl SC" or "SEBamyl BA".
To further break down the dextrins, or to make a "light" beer, a glucoamylase will be required. This enzyme works below 135 F, on even down to ale fermentation temperatures. This enzyme will break down the larger sugars into glucose, provided enough exposure, can make a 90-95% fermentable mash. Glucoamylase is also known as amyloglucosidase as their scientific names. Some commercial products are "Convertase AG" or "Ultra-Ferm".
Malted barley provides alpha-amylase and beta-amylase to the mash, which means it, converts itself with its own "liquefaction" and "saccharification" steps.
Alpha-amylases can be found in three different temperature ranges: Low, medium, and high. But like I said before, most distributors only have the medium temp one (it is the cheapest).
Hope this helps more than confuses, if you require more information look up "Liquefaction" or "liquefaction enzymes" in Google, there are some good papers on that. Also "The complete joy of homebrewing" 3rd edition has some notes on enzyme uses around pg.218 I think.
P.S. Sorry if I am not allowed to mention brand names, but there is usually some confusion as to whether the name describes a function or was made up on the fly. All those products are from different providers, so hopefully that makes it better...
So what's the consensus on quantities needed for 5 gal and 10 gal batches? Let's say you do a 90% wheat beer? 80% wheat? 60% wheat? etc... Somebody should really come up with a chart with percentages of major adjuncts along one side and quantities of alpha and beta amylases on the other.
That would make life too easy. That is actually one of the things that enzyme providers do on purpose usually. They change or mask the activity of their enzyme through various means so that "no one knows" the activity except them.
Some companies do not release their activities to the public, only dosing scales (from which you can guess), while others go to the lengths of inventing whole new evaluation units for their enzyme activities, so then you need to figure out a standard conversion. It gets really complicated really fast.
Not to mention that but wheat varies in quality, varies in starch content, where it is grown will affect its makeup, winter versus spring, and red versus white...
In general though, you can "guesstimate" and get pretty close, enzyme are relatively cheap on a small scale, so overdosing is not a big deal. Typically the dosing is based on the starch content of the mash, so you would have to know the starch content of the wheat you are working with (usually listed on the grain makeup from the provider).
10 lbs. of wheat that contain 75% starch = 7.5lbs of starch.
From there you can calculate dosing at roughly 0.25-0.5ml/lb. of starch. Or 0.25-0.5g/lb. of starch.
That would go for most amylases that fall into the availability to homebrewers.
I use amylase enzyme when I make a light beer, I rack on top of 1 tsp in the secondary. These light beers regularly finish at, or very close to, 1.00. I can't take credit, I found it here in the recipe section under Light Hybrid Beer. Look for a recipe called Miller Lite(Really Triple Hopped) by Schlenkerla. I've made several variations of his recipe and non craft beer drinkers like them quite a bit.
i tried out the Diatase enzyme from eckrauss website. it says it is alpha and beta amylase. i am seeing if it will make extract more fermentable. (the DME i have found here in Central america has only been fermenting down from 1.060 to 1.030.
my first attempt was yesterday - i put 3 tsp of the enzyme in 2 gallons of water with 6.5 lbs of extract. brought it up to 150 degrees and let it sit for 45 minutes. (the temp slowly went down to 142 over the course of the 45 minutes.
then added 3 more gallons of water and brought up to a boil to denature the enzyme and continued to brew my Pale ale recipe.
ill update how this enzyme works for extract brewers. Is there anyone with any experience with enzymes in this nature?