You can improve your yeast performance by giving it extra nutrients. Yeast has a complex nutritional requirement. Conversion of wort sugar to alcohol is not just one chemical … Yeast Nutrients Make Fermentations Better By Christopher White, Ph.D. Nutritional supplements in human nutrition have become a booming business. Most are not necessary, but some can improve can improve mental and physical performance. The same can be said for brewers yeast. They do just fine by themselves. But adding the right mix of nutrients can …

Does yeast get everything it needs from beer wort? The answer is … yes and no. Can it ferment wort and make beer with no extra nutrients added to all grain wort? The answer is yes. But does the yeast like that? No. You can improve your yeast performance by giving it extra nutrients. Yeast has a complex nutritional requirement. Conversion of wort sugar to alcohol is not just one chemical reaction, as was thought in the early nineteenth century. Hundreds of chemical reactions occur inside a yeast cell. A yeast cell can be thought of as a “bag of enzymes”. Each enzyme catalyzes a different chemical reaction. Each enzyme also has specific mineral requirements for optimum performance. These chemical reactions produce alcohol, flavor compounds, energy for growth, cell wall compounds, and so on. If any of these reactions are compromised, there can be an effect on yeast health and fermentation performance, which has a direct impact on flavor. What does your yeast need? We know yeast needs sugar, and we know sugar is turned into alcohol by yeast. But yeast needs a lot more. They need amino acids to build proteins and ultimately new cells, they need vitamins and minerals to make enzymes work correctly, and they need phosphorus to create new DNA. Exact nutrient requirements vary between ale ( Saccharomyces cerevisiae ) and lager ( Saccharomyces uvarum ), and for each strain within the species. Nutrient requirements can also vary between breweries, even when they are using the same yeast strain. It depends on your water supply, your wort composition, your brewhouse design, environmental conditions such as temperature and humidity, size of your brew, frequency of your brew, the type of beer your producing, and the season of the year. In general, yeast need an adequate supply of sugar, nitrogen, vitamins, phosphorus, and trace metals. Nitrogen makes up approximately 10% of the dry weight of yeast cells. In brewers wort, most of the nitrogen is provided in the form of amino acids. To supplement nitrogen, ammonium sulfate is commonly used. A preferred source however, is amino acids. Yeast grow better on amino acids because amino acids are the building blocks of proteins. There are 20 different types of amino acids, and yeast can either make the amino acids they need or assimilate them from the wort. However, yeast are not capable of producing some amino acids, termed essential amino acids. Essential amino acids must be supplied by the wort. If the wort is deficient, this can create fermentation problems. Even when yeast can produce their own amino acids, it is usually better for the cell to assimilate them. For every amino acid they have to make, they create intermediary compounds that can leak out of the cell. Valine is a classic example. Valine is an amino acid that yeast can either produce autonomously, or assimilate from the wort. An intermediate compound in valine production is acetolactate (Fig. 1). Not all of the acetolactate produced will be converted to valine, some will leak out of the cell and into the beer. This acetolactate is then chemically (not enzymaticly) converted to diacetyl in the beer. The chemical reaction is an oxidation, and high fermentation temperatures favor this reaction. Other factors that will increase diacetyl production in this phase are insufficient nutrients (e.g. the amino acid valine), which forces yeast to manufacture their own. For example, the more valine yeast produce, the more acetolactate intermediate is required, and hence the more diacetyl made. There is also an apparent strain specific phenomena occurring, because given the same conditions, different strains will produce different levels of diacetyl…..

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