Beer > Amateur

What is brewer's yeast?

Brewer's yeast is used to make beer, wine, bread and any other fermented beverage, food or product. Brewer's yeast is a single celled fungus that ferments from the top or the bottom and reproduce asexually by budding. They are unique in the world of yeast and have essentially been domesticated. Certain strains work best with certain beers and other products, contributing the flavors the public anticipates.


Is your yeast kosher?

White Labs' brewing and distilling yeast was certified kosher in 2013.

I operate a store that sells White Labs yeast. Do you have suggestions for how I should ship the yeast to my customers who order by phone or online?

White Labs is committed to producing the highest quality of yeast in the world.  It leaves our laboratory having undergone the most rigorous standards of quality control. But much can happen in the shipping process, and to remain its best, it’s important to be handled the best. To ensure the yeast reaches your customers in the same quality as when it left our laboratory, we’ve put together a set of shipping guidelines.

1. The most important rule, keep it cold. Yeast needs to be stored in a refrigerator at all times, 40 F (4 C).  Its shelf life can decrease dramatically when left outside of this range. Too cold is just as damaging as too hot; it should never be frozen. Yeast looses 10% viability each time it is frozen.

2. Insulation and Ice Packs. The more insulation inside the package when shipping the better.  Insulation is used both as padding for protection, and to regulate the internal temperature.  At White Labs, we ship in boxes lined with styrofoam, and pack each shipment with ice packs to ensure it will stay cool during transit.

Provided here is a table of the recommended ratio of home brew vials to ice packs needed when shipping.

VIALS     ICE PACKS (normal)     ICE PACKS (hot months)     
1-4                    1                                 2
5 to 9               2                                 4
10 to 19           3                                 5

3. Packing Sequence.  Be sure to remove the yeast from the refrigerator right before packing it in a box. Ice packs only keep the yeast at its current temperature, it will not chill the yeast.  If you package the yeast at 40oF (4oC) with ice packs and insulation, it will stay close to that temperature for the first 24 hours. If the yeast temperature rises to 50oF (10oC) before packaging, it will never get back to 40oF (4oC).  The ice packs will maintain it at the higher temperature, and  the yeast will rise to higher temperatures more quickly than if packed at 40oF (4oC). 

4. We recommend shipping everything 1 to 2 days.  Be aware of weekends and holidays where shipments can be delayed.  Plan your shipments during the week to ensure delivery before the weekend.

5. Make sure to let you customers know that it needs to be refrigerated upon arrival.

By following these recommendations, you will pass on the highest quality of our product to your customers.  We thank you for taking the time to ensure these steps are followed.

I have heard that Rochefort has two strains. How would I go about selecting those as two different strains (separating them)? How do you differentiate between the different strains?

This is a topic that is subject to a lot of rumors as well. Also, you can find multiple strains in a yeast slurry, but it can still be one strain that is doing all or most of the fermentation. If you wanted to look at Rochefort, if you had the yeast slurry you could plate a bunch of times and select individual colonies, do fermentation and taste the results. You can also do differential plates or giant colony plates but that is more involved. If you have yeast from the bottle, there is really little you can do because often you find a lot of other yeast and organisms in the bottle that are not intended to be there.

I have just tasted some of my 005 yeast out of the vial, and it tastes sour. I just wanted to know if this is normal.

People are often surprised by the way the yeast smells or tastes out of the vial; it is hard to judge since it is a concentrated yeast slurry. It is not going to taste like beer.  The pH is also lower, so the higher acidic flavor can taste sour. You really cannot tell purity by smell or taste, although it is not a bad practice to try and become familiar with what is normal. The only way to know purity is to plate the yeast on to special media, which is what we do on all of the lots at White Labs.

I live in India, and I recently got a couple of vials from an American homebrew store. They were in shipping for about 5 days and with an ice pack. Once they arrived, I put them in my refrigerator right away. Today, I used it for a batch of American Brown Ale I made. I had several questions about the yeast.

1. It was not white in color, and the yeast appeared brownish.

This is normal - we package the yeast with protein and lipids to keep them healthy in shipping.

2. I shook the vial (after removing from the fridge) and left it at room temp. When I opened the vial, there was a lot of frothing.

It built up pressure during shipping and warming to room temperature. One tip is to break the cap when you first take it out of the refrigerator, while most of the CO2 is still in solution. Then vent the cap periodically as the yeast warms up.

3. There was a peculiar smell which I haven’t got from any dry yeast.

This is normal for people to think it smells different; concentrated liquid yeast will have a different aroma. When yeast grows in beer, it smells different for a number of reasons, including the presence in beer of hops.

How can I pitch 1 million cells per ml per degree Plato?

Some homebrewers now want to pitch more yeast in 5 gallons then a pint starter. An often quoted number is to pitch 1 million cells/ml/degree Plato of beer, which equals about 250 billion cells for 5 gallons. That is okay, more cells are not detrimental until about 400 billion cells. For those that enjoy yeast culturing and want 250 billion cells, one vial can be added directly to 2 liters of wort starter, and after two days of incubation, will be equal to roughly 250 billion cells. Is this necessary? Every brewer will have a different opinion, but here is some information:

a. The source of the 1 million cells/ml/degree Plato figure: Professional brewery literature.
Most professional breweries re-pitch their yeast because they have the fermentor design and facilities to reuse yeast. So most brewery pitches are actually re-pitches, and only 2-10% of brewery pitchings are using freshly propagated yeast. One of the main sources of contamination in a brewery is the pitching yeast. So in order to out-compete other organisms, large quantities of yeast must be pitched. When propagated by a professional yeast laboratory, the yeast is grown under sterile conditions, sterileoxygen and special nutrients are used to improve cell construction and performance. This does not occur in a brewery, so numbers they use to "pitch" take into account the inadequacy of their brewers yeast. The yeast is also unhealthy due to prolonged growth without oxygen and nutrients. In addition, brewers yeast will always contain some contaminants that need to be out-grown, and 1 million cells per ml per degree Plato has been found to be the best marriage of high pitching rates and no negative flavor effects (Higher pitching rates can lead to unhealthy yeast and a "yeasty" off bite). Liquid yeast grown by a professional laboratory should have no contaminants, so out competing contaminants found in the pitching yeast is not a concern.

One thing that contributes to flavor contribution in beer is yeast growth. If less yeast is pitched into beer, more yeast growth takes place, so more flavor compounds such as esters are produced. Depending on the amount produced, this is how pitching rates can have a direct effect on flavor profile. If 5 to 10 billion cells are pitched into wort, this definitely has a negative flavor impact in terms of higher ester levels and potential for bacterial contamination. But does a pint starter worth of yeast (30-50 billion cells) pitched into beer tasted different then 2 liters worth of yeast (250 billion cells)? Sounds like more homebrew has to be made to get to the bottom of this! Your feedback is appreciated.

Do you have a map between your yeast strains and others?

No, we do not have a direct "correlation chart". Some of our strains are similar to those offered by other companies, but some are different. Even for the strains with similar origin, they have been obtained at different times from different locations. They are stored different, grown in different conditions and different media. Each yeast strain produced by White Labs has been carefully selected from breweries worldwide, and further selected for advantageous brewing characteristics. In general, yeast strains of similar origin exhibit similar, but not exact, properties. In our descriptions of the yeast strains, we describe the area of origin and the flavor profile parameters of each strain.

How can I obtain White Labs yeast if my local homebrew shop doesn’t carry it?

If your local homebrew shop does not carry our yeast, you can simply order the yeast you need off the order now section of this website.

What is the shelf life of White Labs Yeast?

Quick Answer: 4 Months
Long Answer: Yeast is a living organism. As such, it needs to be in the right conditions to survive. Dry yeast can stay alive for one year, but yeast left in liquid form, even though it's a better product in terms of taste and performance, is more perishable. At White Labs, we are constantly working on our recipe to maximize the viability of the yeast in long term storage. The longer we can make the yeast last in the vial, the better shape it will be in for fermentation. After 30 days in the vial, the viability of our yeast is 75-85%, which is very high for liquid yeast. Yeast that is harvested after a brewery fermentation will typically have a viability of less then 50% after 30 days. Our high viability is due to the health of the yeast and nutrient content of our liquid at packaging.  After 6 weeks, lag time before active fermentation is usually between 15-20 hours.  The shelf life for White Labs Yeast is four months.  Yeast used after this point is usually fine, but lag times will be longer. There will be living yeast in most vials for 6-12 months, so if a starter is made to activate the yeast, successful fermentations can be carried out with aged yeast.

How can I increase the oxygen level in the wort?

Most homebrewers add oxygen into wort by shaking the carboy. This can only achieve 10-30% of desired dissolved oxygen levels. Commercial brewers force oxygen into wort using an inline aeration stone. Homebrewers can find oxygen stones at most homebrew shops.

How should I store my yeast?

Yeast should be stored in the refrigerator prior to use. Remove the yeast from the refrigerator approximately two to six hours before pitching and allow the yeast to come up to room temperature. The reason for this is to prevent a temperature shock when the yeast is pitched.

Can I use your liquid yeast to make bread?

Yes you can use our yeast to make bread. It will take longer to rise, perhaps overnight, but you will have interesting almost beer like flavors in your bread.

What is flocculation?

Flocculation refers to the clumping of yeast cells at the end of fermentation. Strains are separated into three main degrees of flocculation- High, Medium, and Low. An example of a highly flocculent strain would be our English Ale yeast, which will settle at the bottom of the fermentation tank. An example of a low flocculent strain would be our Hefeweizen yeast.

Why does the vial look different?

The vials sometimes come in slightly different sizes depending on availability from suppliers. Update in October 2012: The vials are slightly shorter with a bigger top rim than the previous model. The internal volume is the same.

Is overpitching yeast harmful?

If the beer is overpitched, yeast do not grow though a complete growth cycle. This results in few new yeast cells, which makes for unhealthy yeast and low viability by the end of fermentation.

What is diacetyl?

Diacetyl is a natural byproduct of yeast. It is most commonly recognized as a butterscotch or buttered popcorn flavor in the beer. To minimize the diacetyl attributes in beer, it’s recommended that the fermenting wort rest once the beer has reached terminal gravity for 48 hours at 62-70 degrees prior to crashing the temperature. This stage allows to yeast to reabsorb the diacetyl.

Can I combine yeast strains?

Yes, some brewers like to combine strains for more unique flavor profiles. For example, a mellow hefeweizen beer can be produced by combining WLP001California Ale Yeast with WLP300 Hefeweizen Yeast.

        Will there be any benefits or drawbacks from this?

Some of the benefits of blending yeast strains would be to blend flavors or aromas of different strains. Over time one strain can dominate the other so the consistency of flavors would be lost over time. If flocculation is different between the strains, it is hard to collect an equal amount of each strain.

Why does my beer have a high ester and/or sulfur level?

High ester and sulfur levels are most commonly associated with high fermentation temperatures. Different types of strains also produce different ester and sulfur attributes. Make sure you choose the proper yeast for the style of beer you are making and ferment the wort within the recommended temperature ranges.

Why is my beer under-attenuating?

Low oxygen levels may be one of the primary reasons for under-attenuation. Another factor could be under pitching. If an insufficient amount of yeast is added to wort, than you should expect a much longer fermentation time. White Labs yeast nutrient can also assist the yeast performance by adding additionalvitamins and amino acids into the wort. This will give the yeast more food and can jump-start a stagnant fermentation.

Why is my beer over-attenuating?

Over attenuation can occur from wild yeast contamination, or from a warm fermentation. Also, the mash profile creates different types of sugars, which the yeast consume differently.

How can I increase the alcohol level in my beer?

Alcohol is a byproduct of the yeast cells consumption of the sugars in the wort. As the alcohol level rises in the wort, the fermentation begins to slow down. Adding yeast nutrients to the wort can give the yeast new food allowing for an extended fermentation period. Yeast nutrient also helps to create stronger cell walls, which make yeast less susceptible to alcohol death. Another way to increase the alcohol level in the beer is to add yeast with a higher alcohol tolerance towards the end of fermentation.

What is meant by "certified pure yeast"?

White Labs certifies the yeast to be free from aerobic bacteria, anaerobic bacteria, and wild yeast contamination through a series of tests performed by our lab. Yeast does not leave our facility unless it is free of contaminants, and at least 95% viable. A signed report is shipped with each batch of yeast to commercial breweries. For homebrewers, the yeast vials come from a lot that is tested, and the report is housed at White Labs.

Why is the fermentation not starting in the recommended time?

The most common causes are oxygen limitation and temperature. Low dissolved oxygen levels may cause a long lag at the start of fermentation. Oxygen is a primary element needed for yeast to be able to produce cell walls. Temperature of the wort when the yeast is pitched is also critical. If the wort is above 85-90°F, this may decrease the cell viability. If the wort is too cold it can cause the yeast to slow down, therefore increasing the overall time needed for fermentation to start.

What is meant by pitchable quantities?

At White Labs we package our yeast with a concentrated cell count which does not require any additional propagation time. Therefore, our vials can be directly pitched into a five-gallon batch of wort, giving you approximately a 5-15 hour lag time. Our barrel (BBL) system designed for the professional brewers also has the appropriate cell count for their specified sizes.

Why should I use liquid yeast as opposed to dry yeast?

Purity and variety of liquid cultures. Currently, dry yeast contains some level of contamination because the drying technology is not available to create a sterile product. White Labs takes an extra step by testing each batch of yeast produced to ensure that you receive a product that is free of contamination. There is more variety with liquid yeast because only certain strains of yeast can be dried. Even if they could be dried, most yeast strains do not have the demand to make a large batch of dry yeast economically viable. An increased variety of liquid stains also gives the brewer the flexibility to produce many different beer styles.

At what temperature should I pitch ale yeast?

The yeast should be pitched at 70 to 75 degrees Fahrenheit, 21.1 to 23.9 Centigrade. Once you see active fermentation, bring the temperature to the desired fermentation temperature.

What is White Labs yeast nutrient?

White Labs Yeast Nutrient is a complex blend of nitrogen, vitamins, and co-factors. We designed it specifically for White Labs Yeast to increase vitality and viability in our yeast propagations. It is different from other nutrients in the market is because of the increased amount and variety of amino acids and cofactors. This increases the rate of metabolism, which results in faster fermentation and greater yeast viability. I t is an affordable way to increase the success of your brew. Our brewers have found it very beneficial for first generation, stuck fermentation and high gravity beers. Yeast nutrient can also be helpful when brewing high gravity beers. For commercial breweries, we package it in dry form in vials that are re-measured for 5 barrels. Nutrient is good for every generation and a must for beers above 1.070 SG or 17 Plato.

How long does the fermentation take to complete?

Most fermentations will be complete within 14 days. Lager fermentions can take up to one month, plus aging time. The typical ale profile is to ferment very actively for 1-4 days, which is called the "exponential" or "log" phase. Then the yeast enter a stationary phase, which helps to mature the beer and can last from 3-10 days. The beer should be ready to bottle at this time. It is important to check the final gravity (FG), and calculate the percentage attenuation to make sure the fermentation is complete. If the particular yeast strain is not very flocculent, it is hard to gauge when fermentation is complete without calculating attenuation %.

Why does my vial look different?

The vials sometimes come in slightly different sizes depending on availability from suppliers. Update in October 2012: The vials are slightly shorter with a bigger top rim than the previous model. The internal volume is the same.

What is Servomyces?

Servo is yeast and is propagated in a micronutrient rich environment then, and is killed off prior to packaging. Boiling incorporates the Servo into the wort. The benefit of Servo is that micronutrients, e.g. zinc, are able to pass through its cell walls to your live yeast cell, thereby delivering the micronutrients without toxicity. Because this system is so effective in eliminating autolysis and improving the health of your yeast, it should be used in every batch.

Servomyces is GMO free and was originally developed for German brewers by Weihenstephan and the Munich University. It conforms to the restrictions of Reinheitsgebot. Servomyces enables any yeast strain's ability to incorporate essential nutrients into its cellular structure. Tested in breweries around the world, it has been proven to:

* Cut down fermentation time
* Increase flocculation
* Greatly reduce harsh sulfur notes
* Improve the health and viability of yeast
* Reduce levels of diacetyl at the end of primary fermentation
* Produce faster, more complete attenuations

Each retail packet contains 6 capsules, which can each be used for a 5-gallon (20-25L) batch of beer, wine mead or cider. The instructions are listed below:

1.) Add 1 capsule 10 minutes prior to the end of the boil.
2.) If your fermentation does not require a boil, open the capsule and pour in the Servomyces, since the capsule
requires boiling to melt.
3.) Only one capsule is required per 5-gallon (20-25L) batch.
4.) Servomyces can be used an all fermentations, including beer, wine, cider and mead.

I am curious to know how your nutrient may differ from Servo? That is what I use now, but since I hope to switch to White Labs yeast exclusively in the future, I was wondering if the WL product may be superior.

Our nutrient (WLN1000) has amino acids, so if your wort is deficient in nitrogen, our nutrient helps a lot. When trying to grow more yeast as done in propagation, our nutrient can really help. But most of our customers use Servo. It has a lot of usable zinc and zinc is a great source of fermentation power. If that doesn't work, it may be a nitrogen problem, and they try our nutrient.

What is attenuation?

Attenuation is the percentage of sugars that the yeast consume during fermentation. If the fermentation went to 1.000 gravity, that would be 100% attenuation. Understanding the different attenuation ranges of each strain will help determine the terminal gravity of the beer.

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