How Much Yeast Nutrient for 5 Gallons of Beer

In this brief article, we will answer the question of how much yeast nutrient is required for 5 gallons of beer, the importance of yeast nutrient, and what it is made of.

How Much Yeast Nutrient for 5 Gallons of Beer?

You should use, according to studies, about 5 g of yeast nutrient for each 5 gallons of beer (5). 

The amount of yeast nutrient required for the production of 5 gallons of beer may vary and the exact dosages of yeast nutrients are generally mentioned on their packaging, so be sure to follow the recommendations from the manufacturer for the best result.

In a study, the amounts of yeast nutrients, including urea and diammonium phosphate (DAP) were used in different proportions to evaluate the optimal concentration and resulting yield of alcohol. 

At DAP concentration of 15 kg/ fermenter 65 m³ working volume, S. cerevisiae F-514 produced 8.9% (v/v) ethanol with remaining sugars, 1.66%, fermentation efficiency of 80.1% final cell count 3.10 × 10⁸ /mL, and dry yeast cells 11.8 g/L (5).

What is Yeast Nutrient?

Yeast nutrient is a preparation containing sources of assimilable nitrogen from low molecular-weight compounds such as ammonium ions and amino acids, salts containing phosphorus, such as diammonium phosphate (DAP), and B vitamins, such as biotin and panthenol (1,2,3). 

The principal raw materials used to brew beer are water, malted barley, hops, and yeast. The brewing process involves extracting and breaking down the carbohydrate from the malted barley to make a sugar solution (called “wort”), which also contains essential nutrients for yeast growth (2). 

However, yeast nutrient will provide more readily assimilable nitrogen from low molecular-weight nitrogenous compounds, which ensures yeast growth and increases fermentation rate (1).

What is Present in Yeast Nutrient?

The most common substrates present in yeast nutrients are (1,2,3,6): 

• Diammonium Phosphate – this is the main salt that provides free amino nitrogen (FAN) to yeast for its optimal growth. Mostly, malt already contains sufficient FAN so DAP often may not be required.
• Yeast Hulls – these are dead yeast cell walls rich in amino acids used as additional sources of nutrients for the production of new yeast cells.
• Vitamins, especially Biotin, Pantothenol and Inositol– yeast also required vitamins for optimal growth, such as the B-vitamins, which may lack in the growth medium.
• Magnesium and Zinc – these minerals are essential for the yeast growth.

The high levels of nutrients and its quality (amino acids, oxygen, lipids, zinc), along with increased temperature and agitation has a major effect on higher alcohol formation (2).

Why is Yeast Nutrient Important for Beer?

Yeast nutrients are used in brewing to increase yeast growth and fermentation rate and to ensure a complete fermentation (1). Yeast Nutrient provides all the essential substrates required for yeast cells to reproduce and stay healthy. 

Even though wort is usually abundant in nitrogen, supplementation with yeast nutrient aids high-gravity beers to achieve fermentation. Assimilable nitrogen from low molecular-weight nitrogenous compounds such as ammonium ions and amino acids is an essential nutrient for yeast growth (1). 

Yeast cells require many compounds to grow and form new cells, such as nitrogen, amino acids, vitamins, and fatty acids. If these substances are absent or present in inadequate amounts when you add yeast to your wort it can cause problems during fermentation, or even inhibit fermentation altogether (6). 

What is the importance of yeast health in brewing beer?

The importance of yeast health in brewing beer is the efficiency of the brewing process, as it is performed by the yeast. Not only does yeast convert sugars into alcohol, but it also produces various other compounds that exert a major influence on the overall flavor of the final beverage. 

A healthy and well-selected yeast is needed for an efficient fermentation and when selecting the strain, attention must be paid to whether the flavor compounds that the yeast produces are of interest or concern. The yeast under stress will not be working at its optimum. A careful choice as to the particular strain and meticulous attention to growth conditions will lead to successful fermentations (3).

Do You Really Need Yeast Nutrient for Beer?

No, you don’t necessarily need yeast nutrient for beer production or yeast growth. Although wort rich in malted barley and molasses contain most of the nutrients required for yeast growth, generally nitrogen and phosphate are added to enhance yeast growth and ethanol production (5).

However, there might be certain cases of brewing particular beers which require adding yeast nutrient. These include:

Brewing a Particularly High-Gravity Beer – In the production of high gravity beer, a beer in higher ethanol concentrations is produced, at the end, the beer is diluted to the desired ethanol content. 

This brewing technology has the advantages of increasing brewery capacity by 20–30% without additional expenditures for facilities, reducing the cost of energy and labor, and improving the beer smoothness, flavor, and haze stability. It requires the use of wort with higher sugar and nutrient concentration, therefore, yeast nutrients should be added (4). 

Brewing a Beer with a High Portion of Adjuncts – if the beer utilizes a high portion of fermentables, particularly those that come largely from plain sugar. Commonly used adjuncts in brewing are corn syrup and molasses, which contain mainly carbohydrates and not other nutrients (4). 

What Happens If You Add Excess Yeast Nutrient to Beer?

The excess of yeast nutrient in beer may lead to the production of carcinogenic ethyl carbamate, which is unacceptable in alcoholic beverages (2). 

Many countries have now banned the use of urea as a yeast nutrient for the production of alcoholic beverages using yeasts because it may lead to the production of small amounts of urethane (ethyl carbamate).

Conclusion

In this brief article, we answered how much yeast nutrient is needed for 5 gallons of beer, the importance of yeast nutrient, and what it is made of.

References:

1. Buescher, W. A., et al. High alcohol wine production from grape juice concentrates. Am J Enol Viticult, 2001, 52, 345-351.
2. Willaert, Ronnie. The beer brewing process: Wort production and beer. Handbook of food products manufacturing 2, 2007, 443.
3. Russell, Inge. Understanding yeast fundamentals. The alcohol textbook 4, 2003,  531-537.
4. Piddocke, Maya P., et al. Physiological characterization of brewer’s yeast in high-gravity beer fermentations with glucose or maltose syrups as adjuncts. App Microbiol Biotechnol, 2009, 84,  453-464.
5. Fadel, M., et al. High level ethanol from sugar cane molasses by a new thermotolerant Saccharomyces cerevisiae strain in industrial scale. Biotechnol res intern, 2013.  
6. Beukes, Louisa. Impact of complex yeast nutrient products on selected non Saccharomyces yeasts. Diss. Stellenbosch: Stellenbosch University, 2020.