Maturation Accelerator is an acetolactate-decarboxylase (ALDC) enzyme that converts vicinal diketones (VDK) precursors directly into the flavor-free end-products of acetoin and 2,3-pentanediol, reducing maturation time by 2-14 days. It is recommended to use Maturation Accelerator with every brew.
VDKs don't taste good in your final beer. These are characterized by a butterscotch or movie theater popcorn taste that is buttery and off putting and not found in properly produced commercial beer. Some yeast strains, like US-05, produce a lot of VDK precursors and can benefit greatly from Maturation Accelerator. Exposure of the beer to oxygen, which can happen when dry hopping, can force the VDK precursors to convert to VDKs, leaving strong off flavors in the final beer.