If you are just getting started in the world of craft brewing, you must have wondered: What is all this yeast nutrient about, and is it necessary when brewing beer?
In this article, we’re going to go into detail about what yeast nutrient is, its composition, whether or not it is necessary when brewing beer, when to use it, and more!
Without further ado, let’s get started!
Yeast nutrient is only necessary if the yeast is reused multiple times in multiple beer productions, if it has a higher than normal sugar or adjunct content, if the initial gravity is very high, or if a starter is to be used.
Now, let’s take a closer look!
What is Yeast Nutrient?
Brewer’s yeasts perform their biological functions optimally if they develop in an ideal temperature environment and are surrounded by the essential nutrients in sufficient quantities, and this is where yeast nutrient can be useful as it could help us in preparing the yeast to be able to better develop its activity when conditions are not optimal from the beginning.
But what really is yeast nutrient? Yeast nutrient is a complex of vitamins, minerals, and nitrogen responsible for creating an “optimal” environment for the healthy development of fermentation.
Let’s see in more detail how the yeast nutrient is composed:
Each laboratory offers different alternatives to the market, and the composition usually varies according to the nutrient needs required in the different stages of fermentation.
Almost all the formulas we see in the market contain nitrogen and zinc in their composition, two of the microelements that are usually deficient, but we can also find formulas with vitamins and various other minerals.
The most frequent ones are listed below:
- Diammonium Phosphate: Diammonium Phosphate (DAP) is a nutrient used in fermentation processes due to its inorganic nitrogen content (and supply). At the same time, it also provides phosphate, another essential micronutrient that helps in the formation of cellular DNA.
- Yeast hulls: Yeast hulls are essentially dead yeast, composed mainly of Saccharomyces cerevisiae cell walls. It is a source of protein, beta-glucan, and mannan oligosaccharides. Yeast hulls are useful for fermentation as they provide sterols and long-chain fatty acids, useful for the health of yeast cell membranes.
- Vitamins, Thiamine, and Biotin: Vitamins are involved in many enzymatic reactions; yeast cannot synthesize many of them, so they need to be incorporated into the wort externally. Essential vitamins include biotin, nicotinic acid, and pantothenic acid. Biotin is the most important vitamin for yeast and is involved in almost all enzymatic reactions that create critical yeast compounds, such as proteins, DNA, carbohydrates, and fatty acids. Biotin deficiency leads to yeast growth arrest and stuck fermentation.
- Magnesium: Magnesium is a critical and important nutrient in yeast growth, in fact, yeast cannot grow in the absence of this mineral. When magnesium is deficient, yeast cells use alternative routes in an attempt to counteract the lack of this mineral, increasing the concentration of secondary metabolites that affect beer flavor.
- Zinc: Zinc is important in the cell cycle (reproduction) and is a co-factor for alcohol dehydrogenase, the enzyme responsible for alcohol production. Although other metal ions may be present, there is no substitute for zinc.
- Servomyces: Servomyces is a unique supplement that uses a patented process. It is basically yeast cells grown in an environment with excess metal ions, including zinc and magnesium. This process causes most of the minerals to remain within the cell wall and prevents the chelation of the minerals when added to the wort. Servomyces are mainly nutrient-enriched yeasts that have the particularity of higher utilization of nutrients.
It Improves the health of yeast cells
There are critical nutrients involved in yeast reproduction and fermentation. Nitrogen compounds, such as magnesium and zinc, as well as B-complex vitamins (biotin and thiamine), are essential in yeast reproduction since yeast cannot synthesize them autonomously.
These nutrients are involved in the formation of the cell membrane, in the formation of DNA, and also in the development of proteins, fatty acids, etc.
Therefore, ensuring an adequate supply of these nutrients is important for the health of the yeast and for the fermentation to develop optimally, avoiding the development of off-flavors and premature fermentation stops.
All of the above components are involved in chemical reactions that occur during fermentation, mostly in situations of cell growth.
Nutrient requirements are justified in situations where increased cell growth is demanded, such as in original high-gravity beers, when making a starter, and during yeast reutilization.
But it is also justified in situations where it is suspected that the supply of minerals and/or nutrients in the wort is deficient.
It is important to evaluate the situation the yeast is going to face before suggesting the incorporation of nutrients to start fermentation. Here we will name some of the situations that may justify its use:
Very high initial gravity
When the beer has a particularly high initial gravity, greater than 1060 g/dl and/or an alcohol percentage of more than 8% ABV, providing yeast nutrient will help improve alcohol tolerance and decrease the stress of increased sugars. It also avoids stagnation problems in fermentation.
If beer production uses a large proportion of adjuncts:
If the beer uses a lot of adjuncts, particularly sugar, greater than 25%, the wort is likely to be nutrient deficient because sugar alone does not provide the range of nutrients that an all-malt beer does.
In this case, the use of yeast nutrients may be a good choice.
When reusing yeast
New yeasts are enriched with nutrients, vitamins, and minerals that guarantee a healthy fermentation regardless of the wort’s composition. For this reason, when yeasts are fresh, it is not advisable to use nutrients.
When the yeast is reused throughout multiple elaborations, the nutrients may no longer be available, and in this situation, the use of nutrients is justified, mainly through nitrogen compounds, zinc, and vitamins.
When using a starter
When successive yeast replication is required, starting from a minimum yeast population, the addition of yeast nutrients is suggested because successive cell growth increases the demand for these nutrients.
Is it advisable to make a Yeast Starter?
The purpose of starters is to increase the amount of yeast available through reproduction. Starters are advisable when you want to inoculate high-gravity beers, or when you start with a small amount of yeast and want to ferment larger batches than usual.
They are also suggested when a fast fermentation start is desired, or when the yeast’s viability is somewhat questionable.
The starter is not recommended without guaranteed hygienic measures, and also without fundamental elements such as oxygen, nutrients for the yeast, and a controlled temperature.
The amount of nutrients is specified by each manufacturer. Generally, very small amounts of nutrients are required, and exceeding them could generate some problems and off-flavors in the final product.
- Servomyces: 1 to 2 g of nutrients per 26.41 gallons or 100 lts of wort.
- Zinc Chloride/Zinc Sulfate Salts: 1-5 g per 264.2 gallons or 1000 lts of wort.
- Yeast Hulls: 25g per 100 liters or 2 lbs/1000 gal.
It is important that nutrients for the yeast are available at the start of fermentation.
Some people add the yeast nutrient in the last minutes before the end of the boil, but there are also those who add it by sprinkling it directly into the fermenter once the wort has had time to cool down.
Either way can give good results.
Yeast nutrients become more vital for home winemakers and mead producers, where the ingredients are not as nutrient-dense as malted barley and wheat.
When making field wines in which more than 90% of the fermentable sugars come from simple sugars, the yeast needs yeast nutrients to reproduce and thrive.
The same is true for making mead. Honey is a simple sugar and will require a nutrient boost for the yeast to ferment in the best way.
Yeast nutrients are recommended when making cider, wine, and mead in most cases.
Wort made from “all-malt” grains ensures an adequate nutrient profile of the wort.
When beers with high adjunct content are brewed, this nutrient content decreases, which could lead to nutrient deficiencies, therefore, it could be wise to use yeast nutrient to be on the safe side.
On the other hand, there are situations where the use of yeast nutrients is advised regardless of the quality of the wort.
These are situations where rapid cell growth is required, such as in beers with high initial gravity, when yeast is reused, and also when a starter is made from a tiny population of yeast cells.