June 26, 2015 by fhsteinbart
For years, brewers have asked for lower protein malted barley’s for brewing beer. While the farmers were more than happy to cooperate with this venture, and the maltster’s also contributed to the lower protein demands of brewers, there’s a caveat For if you decrease the protein, you also decrease the free amino nitrogen. Free amino nitrogen (FAN) is essential for proper yeast growth and development. Without sufficient FAN, the yeast will have insufficient food for proper growth and development, and may result in a stuck fermentation, or even worse still, an abnormal fermentation. Yeast need approximately 150 parts per 1,000,000 (PPM) or 150 mg per liter of FAN in wort in order to have the optimal amount nutritional needs met. Unfortunately, we need decrease the levels of protein in barley and consequently and malt, you also decrease the FAN. Since most home brewers do not use a protein rest in brewing are all green beers, yeast nutrient must be added to compensate for the decrease level of FAN. Doing a protein rest will encourage the formation of free amino nitrogen, which would be sufficient supplementation for the yeast. So the basic choice comes down to either doing a protein rest, or adding yeast nutrient to the wort. While the former is more preferred, the latter is just as effective and will save time, energy, and make for a simpler brew day.