White Labs

FAQ for Craft Brewers
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Brewers often ask us the following questions. We hope our answers are helpful to you. Use your browser's search function to find keywords that are associated with your question. If you have a different question, please email us.

Craftbrewer FAQs

What is comparable to liter measurement?

The White Labs barrel (BBL) system is comparable to the hectoliter measurement by the ratio of 1 to 1. Example: 1 HL = 1 BBL (approx.). Our BBL measuring system was designed to make it easier for the professional brewer to order the proper quantity of yeast needed for their brewing system.

How long can I wait to use White Labs Pure Brewers Yeast?

White Labs Pure Brewers Yeast leave our lab at 95%+ viability. We suggest you use it the day after you receive it. Do not try to brew on the same day of receipt of the yeast. We have great success with our shipping companies getting you the yeast on time but we would hate to have you knocking out and the yeast has not arrived. If you need to wait longer than the day after receipt we suggest using it within 7 days. The fresher the better.

How many generations should I use my yeast?

We recommend 6-10 generations per strain. Three main reasons yeast should be replaced on a regular interval are bacterial contamination, yeast cell mutation, and yeast fatigue.
Bacterial contamination is largely responsible for off flavors. Bacteria grow at an exponential rate in comparison to the yeast.
Yeast cell mutation. Yeast cells will adapt to their environment, this could dramatically or subtly change the characteristics of the beer.
Yeast fatigue. Beer is a hostile environment for the yeast. Healthy yeast requires oxygen and food (malt). CO2 and alcohol are detrimental to the overall health of the yeast.

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 %.

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.

What is Servomyces?

Servomyces is a nutritional yeast supplement (GMO free) that 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
Increase yeast production for a better harvest
Improve the quality of the finished product
Servomyces can be used in all fermentations, including beer, wine, cider and mead.

Does a professional brewer need to propagate when using White Labs yeast?

For breweries our BBL packaging already contains enough yeast cells to accommodate the brewers needs. When ordering the pitchable amount, the yeast can go directly into the full batch. This saves the brewer time and money. Since the yeast does not require propagation, extra tanks are not necessary and time can be better spent brewing or cleaning instead of waiting for the yeast to propagate.

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 temperature should I pitch a lager yeast?

There are two different methods of pitching lagers. Brewers use each method with success, but every brewer has their preference. The easiest method is (A).
A) Start the yeast warm and lower to 50-55F after the start of fermentation. The yeast should be pitched at 70 to 75 degrees Fahrenheit. Once you see active fermentation, bring the temperature of the wort down 10 degrees per 12 hours until the desired fermentation temperature has been achieved. This method works well without forming high amounts of esters because most esters are produced after the first 12 hours.
B) Pitch the yeast at the desired fermentation temperature (48-55 Degrees F). Lager yeast ferment well at this temperature, but they grow very slowly. If you are using this method, understand that you may not see signs of activity for 48-72 hours. If starting the fermentation cold, we recommend you make a 1-2 liter starter per 5 gallons, or if a commercial brewery, a starter 10% of the batch size.

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.

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 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.

How often should I test for contamination?

In the brewery, an overall Quality Control checkup is recommended every one to two months. Most brewers schedule monthly testing for aerobic bacteria, anaerobic bacteria, and wild yeast. Testing frequency depends on the size of the brewery and how often you brew. (Most mid-sized to large breweries test for contamination on every batch.)

How can I avoid contamination in the brewery?

Proper cleaning practices are the most important way to avoid contamination in the brewery. Since breweries are a sanitized environment and not a sterile environment, proper testing should be performed regularly throughout the entire brewery. Preventative measures, like testing for contamination, is the best way to avoid dumping a bad batch of beer.

How will contamination affect the end product?

If the beer experienced contamination at any point in the brewing process, off flavors would be evident and spoiled beer may have been produced. We recommend that brewer’s test for contamination regularly to avoid any unexpected problems.

What are White Labs test kits and how can they help?

White Labs offers three test kits, which allow the brewer to test for anaerobic bacteria, aerobic bacteria, or wild yeast. They require no special skills. All that is needed is a little time to read the instructions, and a microwave oven. These tests can be beneficial to the brewer for preventative maintenance in the brewery or to locate the physical location of an existing infection.

What is meant by "certified pure?"

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.

What is the lowest temperature I can ferment ale at?

Ale strains are most commonly fermented between 68 and 72 degrees Fahrenheit. It is not recommended that you try and ferment ale below 65 degrees Fahrenheit. The ale strains have a much harder time fermenting wort at the lower temperatures.

What is the lowest temperature I can ferment a lager?

Lager strains are most commonly fermented at 50 to 55 degrees Fahrenheit. At 45 degrees Fahrenheit the lager strains will slow down and fermentation maystop. There is some variation between strains so it is recommended to follow the temperature ranges on the vial or strain descriptions.

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.

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.

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 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.

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.

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.

What are anaerobic bacteria?

Anaerobic bacteria do not require oxygen to grow. In the brewery, the most common types of anaerobic bacteria are pediococcus and lactobacillus. Good cleaning practices and frequent testing are the best ways to avoid contamination in the brewery.

What are aerobic bacteria?

Aerobic bacteria require oxygen to grow. In the brewery, the most common types of aerobic bacteria are acetic acid and enterobacteriaceae. Good cleaning practices and frequent testing are the best ways to avoid contamination in the brewery.

What is acid washing for yeast?

Acid washing is done to cleanse the yeast slurry before repitching into the next batch of wort. Acid washing consists of adding food grade sulfuric or phosphoric acid to the yeast until the pH level reaches 2.5. At this level of pH most bacteria are killed. Acid washing does not kill wild yeast cells which could still contaminate your wort.

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.

Is it best to store yeast under beer?

Yes, the best way to store yeast is under finished beer. It is best to remove yeast from the fermentor because high pressure and heat that can affect yeast in a fermentor.

Is your yeast gluten free?

Thank you for your inquiry. Our yeast is low in gluten and is below the European standard for being labeled as gluten free; the American standards are still being developed. The European standard for gluten free is below 20 ppm. Our yeast analysis:

Yeast slurry in package: 12 ppm

When our yeast is used with ingredients such as sorghum to make gluten free beer: 2 ppm

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