Many Belgian beers have sugar as one of their ingredients. The sugar percentage can easily reach 25% or more of the total fermentables in some beers. When fermenting a high gravity beer that has a lot of sugar, it is important to help the yeast along and get as clean and complete fermentation as possible. Table or cane sugar is made up of sucrose. Sucrose is a disaccharide; it has one molecule of glucose and one molecule of fructose. It must be broken apart into those molecules before the yeast can metabolize or eat them. An acidic boil will usually break most of the sucrose apart but the wort pH must be acidic for the invertase to form. If one uses lots of sucrose and it doesn’t invert; the resulting beer can stresses yeast; cause an incomplete fermentation and result in a sweet beer.
Invertase is a readily available enzyme which breaks down the table sugar into glucose and fructose. You can find it on Google, Ebay, Amazon, or in some candy making stores. Unless you brew as much as Beanie (he inverts), your cost will range from about 5 cents to 50 cents per use (depending on how much sugar you invert). All you have to do is dissolve 1 pound of sugar into 1 gallon of water. Heat the water to 140 degrees and lower the pH to the 3.5-5.5 range. Lactic acid works well for that. Then add invertase at the rate of .05 oz per pound of sugar. Let it sit for 30-45 minutes and you’re done. I usually invert my sugar a few days before I brew.
After the inverting process is done, I’ll boil the sugar down to concentrate it. You can easily concentrate 5 pounds of sugar into a gallon. When you get to the 8 pounds per gallon level, the sugar will start to caramelize. Great for Dark Strong Belgians, but you better turn down the heat or you can scorch it. The longer you go, the hotter the sugar mixture gets and the darker and richer the caramel becomes. I’ve found that if you add boiling water to the caramelized sugar before it hardens, it is easier to store and brew with. Do it slowly. When I’m done inverting and concentrating/caramelizing my sugar, I’ll just pour it into a gallon glass jar and cap it. No need to refrigerate it. When brewing, just add it to the boiling wort.