Ammonia is found in both grape juice and wine. It is an important nutrient for yeast during primary fermentation.
The amount of NADH consumed is measured at 340 nm and is stoichiometrically related to the amount of ammonia present.
The Yeast Available Nitrogen (YAN) content of the juice can be determined by adding the Ammonia Nitrogen (AN) content to the Primary Amino Acid Nitrogen (PAAN) content.
