I think this should be labeled as "not very fermentable" instead of "un-fermentable." The first time I used it, I added it just prior to bottling along with the usual amount of corn sugar. One bottle actually exploded and the rest were all foam. I could pour a 12 oz bottle into a liter pitcher and it would FILL it with foam! The next time, I added it into the secondary and had no problem, so just beware how you use it.