Neutrase is a neutral protease produced by a selected strain of Bacillus amyloliquefaciens and used during mashing to increase the level of free amino nitrogen (FAN) in the wort.
Neutrase contains only the neutral part of B. amyloliquefaciens proteases, whereas most other commercial preparations also contain the alkaline protease.
If yeast is not provided with sufficient FAN, the fermentation process will be poor and the beer quality will be inferior. Adding Neutrase at mashing-in can be used to raise the
level of FAN. This is useful when working with poorly modified malt or with high adjunct ratios. With normal malt, no more than 30–40% of the protein is rendered
soluble. With Neutrase, this figure may be brought up to 40–50%, making it possible to use higher ratios of adjuncts such as corn and sorghum, which have relatively inaccessible protein.