Protein: Difference between revisions
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===Wort nitrogen levels===
===Wort nitrogen levels===
Nitrogen is present in many forms in wort. All-malt wort contains about 65–100 mg nitrogen per 100 mL of which about 20% is proteins, 30–40% is polypeptides, 30–40% is free amino acids, and 10% is nucleotides and other nitrogenous compounds.<ref name=lei>Lei H, Zheng L, Wang C, Zhao H, Zhao M. [https://www.sciencedirect.com/science/article/abs/pii/S0168160512006150 Effects of worts treated with proteases on the assimilation of free amino acids and fermentation performance of lager yeast.] ''Int J Food Microbiol.'' 2013;161(2):76–83.</ref>
Nitrogen is present in many forms in wort. All-malt wort contains about 650–1000 mg/L nitrogen, of which about 20% is proteins, 30–40% is polypeptides, 30–40% is free amino acids, and 10% is nucleotides and other nitrogenous compounds.<ref name=lei>Lei H, Zheng L, Wang C, Zhao H, Zhao M. [https://www.sciencedirect.com/science/article/abs/pii/S0168160512006150 Effects of worts treated with proteases on the assimilation of free amino acids and fermentation performance of lager yeast.] ''Int J Food Microbiol.'' 2013;161(2):76–83.</ref>


Free amino nitrogen (FAN) is a measure of the low molecular weight substances, mainly amino acids, which are needed to support yeast growth and metabolism.<ref name=bsp>Briggs DE, Boulton CA, Brookes PA, Stevens R. [[Library|''Brewing Science and Practice.'']] Woodhead Publishing Limited and CRC Press LLC; 2004.</ref> FAN has long been regarded as a predictor of healthy yeast growth, viability, vitality, fermentation efficiency, and beer quality and stability.<ref name=lekkas>Lekkas C, Hill AE, Stewart GG. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2014-0113-01 Extraction of FAN from malting barley during malting and mashing.] ''J Am Soc Brew Chem.'' 2014;72(1):6–11.</ref> This is because FAN is used to provide not only nitrogen to the yeast cells for growth but also the wort nitrogen content or its metabolic products which affect beer flavor compounds and overall stability. The desired concentration of 200–250 mg/L free amino acids is typically available even without the proteolytic activity during mashing.<ref name=kuhbeck/> Around 88% of the total yeast utilizable nitrogen is produced during malting and 12% is produced during mashing (on average, with some variation between malts). This means that brewers producing all-malt wort generally don't need to worry about supplementing yeast nutrition as long as good practices are used for brewing and pitching. The FAN level of wort is fairly consistent (when produced within the standard pH range, which is optimal for FAN production) regardless of whether a protein rest is performed.<ref>De Rouck G, Jaskula B, De Causmaecker B, et al. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2013-0113-01 The influence of very thick and fast mashing conditions on wort composition.] ''J Am Soc Brew Chem.'' 2013;71(1):1–14.</ref><ref name=kuhbeck/><ref name=schwarz>Schwarz KJ, Boitz LI, Methner FJ. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2012-1011-02 Release of phenolic acids and amino acids during mashing dependent on temperature, pH, time, and raw materials.] ''J Am Soc Brew Chem.'' 2012;70(4):290–295.</ref>
Free amino nitrogen (FAN) is a measure of the low molecular weight substances, mainly amino acids, which are needed to support yeast growth and metabolism.<ref name=bsp>Briggs DE, Boulton CA, Brookes PA, Stevens R. [[Library|''Brewing Science and Practice.'']] Woodhead Publishing Limited and CRC Press LLC; 2004.</ref> FAN has long been regarded as a predictor of healthy yeast growth, viability, vitality, fermentation efficiency, and beer quality and stability.<ref name=lekkas>Lekkas C, Hill AE, Stewart GG. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2014-0113-01 Extraction of FAN from malting barley during malting and mashing.] ''J Am Soc Brew Chem.'' 2014;72(1):6–11.</ref> This is because FAN is used to provide not only nitrogen to the yeast cells for growth but also the wort nitrogen content or its metabolic products which affect beer flavor compounds and overall stability. The desired concentration of 200–250 mg/L free amino acids is typically available even without the proteolytic activity during mashing.<ref name=kuhbeck/> Around 88% of the total yeast utilizable nitrogen is produced during malting and 12% is produced during mashing (on average, with some variation between malts). This means that brewers producing all-malt wort generally don't need to worry about supplementing yeast nutrition as long as good practices are used for brewing and pitching. The FAN level of wort is fairly consistent (when produced within the standard pH range, which is optimal for FAN production) regardless of whether a protein rest is performed.<ref>De Rouck G, Jaskula B, De Causmaecker B, et al. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2013-0113-01 The influence of very thick and fast mashing conditions on wort composition.] ''J Am Soc Brew Chem.'' 2013;71(1):1–14.</ref><ref name=kuhbeck/><ref name=schwarz>Schwarz KJ, Boitz LI, Methner FJ. [https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-2012-1011-02 Release of phenolic acids and amino acids during mashing dependent on temperature, pH, time, and raw materials.] ''J Am Soc Brew Chem.'' 2012;70(4):290–295.</ref>
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