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Yeast Pitch Rates

If I add one pouch to 5 gallons of wort, what is the resulting pitch rate?

11 million cells/ml

Million cells/ml? Million cells/ml/ºP? Why the two different units of measurement for pitching yeast?

Cells/ml alone does not take into consideration the amount of sugar we want the yeast  to consume during fermentation. Incorporating ºP (Degrees Plato or %sugar) is a more effective way of accounting for the amount of “work” each cell must perform to reach attenuation.

How much yeast is in the Imperial Pitch Right pouch?

200 billion cells, designed to inoculate 5 gallons (19L) of standard gravity wort.

My yeast viability is low. Can I just pitch more yeast to make up for it?

Yes, pitch rate can and should be adjusted to account for viability. There is a limit, though on reusing lower viability yeast. We recommend only using yeast that is  >80% viable.

Keep in mind using low viable yeast increases the amount of dead or dying yeast cells, potentially resulting in off-flavors indicative of autolysis such as “meaty” or “soy sauce.”

Can you pitch too little yeast?

Yes. Pitching rates (along with fermentation temperature and strain selection) have a large impact on beer flavor and aroma.

Pitching too little yeast may increase ester and higher alcohol profiles and/or extend VDK (diacetyl) reduction times. Low pitch rates can also lead to long fermentation times, stalled or incomplete attenuation, long tank residency, and potential over carbonation in packaged beer.

Can you pitch too much yeast?

Yes. Pitching rates (along with fermentation temperature and strain selection) have a large impact on beer flavor and aroma.

Pitching too much yeast may reduce ester profile and promote sulfur compounds. Over pitching decreases cell growth resulting in a final population of yeast with a higher percentage of older  and potentially unhealthy yeast cells.

Over time, this may contribute to sluggish fermentations, extended VDK (diacetyl) reduction times, shifts in pH, changes in beer profile, and/or the development of “meaty” off flavors indicitive of autolysis.

If I know my desired pitch rate, how do I determine how much yeast to use?
    • First determine the following Variables
      • Wort Volume in milliliters (ml)
      • Wort original gravity in degrees Plato (ºP)
      • Desired pitch rate (see chart of recommended pitch rates)
      • Slurry cell count
        • Imperial Yeast Slurry
          • 1.29 billion cells per ml (1.29E+9 cells per ml)
      • Cell count of your harvested slurry
    •  Then calculate the Total Number of Cells needed for your batch
      • Total Cells = Wort Vol (ml) x Plato x Pitch Rate (Million cells/ml/ºP)
    • Finally, determine total Volume of Slurry Needed
      • Vol Slurry = Total cells needed / Slurry cell count
      • Let us do it for you.  Check out our handy pitch rate calculator.


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What’s the best way to quantify my yeast?

The best way to quantify yeast (viable cell per ml) is to perform cell count and viability assessments. This can be done with basic laboratory equipment, including a microscope, hemocytometer and methylene blue.

This method requires accurate dilution of a homogeneous sample of yeast slurry, then basic microscopy to count and determine yeast cell viability. Cell count along with the yeast slurry weight, allows you to consistently hit your desired pitch rates every time. 

Let us show you how.  Imperial offers cell counting classes and equipment packages.

Contact us to inquire about participating in the next class. We hope to see you there.

Yeast Use & Storage

Do I need to make a starter before pitching the yeast?

If you are brewing more than 5 gallons (19L), making a high gravity wort (above 17 °P or 1.070 SG), or have a pack that is older than 4 months then we recommend making a starter. Pitch one pack into either a stirred 2L starter or an unstirred 4L starter.

Do I still need to aerate or oxygenate my wort if I’m using the Pitch Right pouch?

Yes, absolutely. Standard fermentations require around 12-15 ppm wort DO. When using A38 Juice, it's important to increase this to at least 20-25 ppm wort DO, or increase the oxygen flow regulator to 50% higher than normal.

How long can I store Imperial Yeast Pitch Right pouches prior to use?

We recommend using the freshest possible yeast and we back our yeast for 4 months from the manufacture date on the front of the pouch. If you find yourself with a pouch past its expiration date, we recommend making a starter.

This increase is the result of a recent extensive study conducted with multiple strains over the course of several months. We found that the impact on viability was negligible for all our strains at four months from the printed manufacture date. This applied retroactively to all yeast in the marketplace. Expect to see the same reliable, healthy and happy fermentations that you have come to expect from Imperial Yeast.

Yeast Nutrition

Do I need to use yeast nutrient?

Zinc and Magnesium are critical cofactors in many cellular fermentation pathways and are often at deficient levels in wort. Supplenting yeast with bioavailable nutrients increases healthy new cell growth and the odds for a successful fermentation.

See Imperial Yeast Nutrient specification and dosage rates.

At what point in the process should I add my yeast nutrient?

We recommend adding yeast nutrient directly to the boil kettle during the last fifteen minutes of the boil. This ensures adequate mixing and sterilization. We do not recommend adding supplemental nutrition directly to yeast or the fermentation vessel.

Do I need to adjust dosage rates of yeast nutrient for different beers?

Yeast nutrient dosage rates do not typically need to be adjusted for most all-malt worts. However, for worts higher in gravity, or high in adjuncts and/or sugars such as dextrose, dosage rates may need to be adjusted.  See Imperial Yeast Nutrient specification and dosage rates.


How much oxygen does my yeast need?

Saccharomyces & Brettanomyces - We recommend measuring dissolved oxygen during knockout, just before wort enters the fermentation vessel (FV).

  • Lager: 8-10ppm
  • Ale: 12-14ppm
  • A38 Juice: 20-25ppm

Lactic Acid Bacteria - Do not oxygenate or aerate wort.

Dial in your DO with our Dissolved Oxygen Calculator.

What are the differences between using pure O2 and sterile air?

The solubility of oxygen into wort is dependent on several factors including Oxygen % (Pure O2 or Sterile Air), wort gravity (sugar content), and temperature.

Sterile air contains ~21% Oxygen (78% Nitrogen) and dissolves into 15ºP wort at 68ºF at a maximum of around 8ppm DO.

Pure oxygen dissolves into 15ºP wort at 68ºF at a maximum of around 30 ppm DO. Additional factors affecting oxygen levels are flowrate of gas and surface area and porosity of the sintered stone.

What PSI/LPM do I need to run my oxygen at? 

PSI is an inaccurate way of measuring oxygen delivery. It is best to measure oxygen by flow rate in liters per minute (LPM) using an oxygen flowmeter like the one linked here  Oxygen flowmeter.

The delivery of oxygen to the oxygen flowmeter should be no less than 30 psi. If an oxygen tank is running low and the delivery of oxygen to the flowmeter is less than 30 psi, the actual amount of LPM may be inaccurate while visually displaying bubbles through a sight glass.

It is important to regularly check the incoming psi of an oxygen tank to the oxygen flow meter. 

Why do I need to add oxygen at knockout?

Oxygen is required for yeast membrane unsaturated fatty acid (UFA) and sterol synthesis which help maintain cell flexibility and permeability. 

UFA and sterol content is the primary factor limiting cell growth. With each cell doubling, UFA and sterol content is diluted until it reaches a critical point where the cells can no longer divide. 

Without proper oxygenation and subsequent UFA/Sterol synthesis, less growth occurs reducing the amount of yeast available to do the work. This can result in impacts on beer flavor and aroma,  extended VDK (diacetyl) reduction times, long fermentation times, stalled or incomplete attenuation, long tank residency, and potential over carbonation in packaged beer.

What is LPM? Why is this preferred over PSI? How do I measure it?

LPM stands for liters per minute. LPM measures oxygen flow rate. PSI measures oxygen pressure. Flow rate delivers a set amount of oxygen to a specific volume of wort over a measured amount of time.

To measure LPM, we recommend an oxygen flowmeter like the one linked here  Oxygen flowmeter.  Visit our Dissolved Oxygen Calculator to estimate DO levels.

Is it bad to add oxygen after the fermentation has started?

Generally, adding oxygen post onset of fermentation should be avoided due to the potential impacts on beer flavor and aroma.  However, in extreme situations of lagging or stuck fermentation it may be advised to add additional oxygen to stimulate cell growth.

Reach out to Imperial Customer Service to discuss if this is the right option.  We are happy to help.

How should Oxygen be added to wort?

We recommend adding pure oxygen inline through a sintered stainless steel stone during knockout using an oxygen flow meter measuring in liters per minute (LPM).

There should be at least 10 ft. of hose between stone and tank to limit O2 breakout. This method allows the brewer to achieve accurate and consistent DO levels with the delivery of a set amount of oxygen to a specific volume of wort.

DO levels can be verified by using a DO meter like this Portable Dissolved Oxygen Meter to ensure proper oxygenation.

For more information see “How much oxygen does my yeast need?” and visit our Dissolved Oxygen Calculator to estimate DO levels.

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Can I just blow O2 into the FV after KO?

It is possible to oxygenate after knockout by adding oxygen through the bottom port of the fermentation vessel, or through a carb stone, at 1LPM/minute/BBL. 

For example, a 30 barrel batch would receive 30 minutes of oxygen at a flow rate of 1 liters per minute (LPM). However, this is not always an accurate or efficient method for dissolving oxygen into solution. Instead, we recommend adding pure oxygen through a sintered stainless steel stone inline during knockout using an oxygen flow meter measuring in liters per minute (LPM).

This method allows the brewer to achieve accurate and consistent DO levels with the delivery of a set amount of oxygen to  a specific volume of wort.

Visit our Dissolved Oxygen Calculator to estimate DO levels.


Should I warm my yeast to room temperature before pitching?

We do not recommend warming yeast to room temperature before pitching. As yeast warms they become active. If this happens in an environment without oxygen, nutrition and food, they may begin depleting their internal stores of glycogen.

This process can degrade viability and lead to fermentation issues, such as slow or stalled fermentations, long VDK reduction times, and/or poor flocculation characteristics.

Can I freeze my yeast?

Yeast should be stored between 33ºF and 38ºF and should not be allowed to freeze.

Yeast cells contain water. When frozen, water forms crystalline structures that may rupture the cell wall affecting viability. If a container of yeast freezes, allow it to thaw at refrigeration temperature.  Once it thaws, perform a viability test to determine if it is acceptable to use.

Can I ferment my lager warm (over 58oF)?

Yes, it is possible to ferment lager yeast above traditional lager temperatures.  Higher temperatures will increase fermentation speed as well as reduce VDK rest times, however may result in increased levels of esters and higher alcohols.  Lager yeast should be propagated warm to ensure efficient cell growth with each step.

What temperature should I ferment Kveik?

Kveik yeasts are capable of a wide range of fermentation temperatures.

Depending on the desired profile, strains like A44 Kveiking can ferment up to 95ºF producing intense fruity and tropical esters. Other Kveik strains, such as A43 Loki, can ferment as low as 55ºF producing a clean “pseudo lager” profile.

For individual strain information and descriptions, check out our full selection of brewers' yeast strains.

For Lagers, what temperature should I perform a diacetyl rest and when?

Increasing the temperature towards the end of fermentation decreases VDK (diacetyl) reduction times and can be helpful with Lager or colder fermentations. Raising the temperature to 70ºF when the gravity reaches 70-80% of attenuation will help expedite the VDK rest.

That said, maintaining Lager temperature throughout diacetyl rest will eventually have the same result, just slower.  Regardless, we always recommend performing a VDK (Diacetyl) Test before crashing to cooler temperatures to ensure that VDK reduction is complete.

Temp control wasn’t set or failed after pitching my yeast. What should I do? Is the beer ruined?

Not necessarily. If the wort is allowed to ferment without temperature control, then the temperature will increase slowly as yeast become metabolically active.  If caught early, the yeast (and beer) should be fine.  However, as the temperature rises, yeast that become too hot can experience rapid growth.  This may lead to high levels of stress and potentially lower viabilities.

Higher temperatures also often result in rapid fermentations with higher levels of alcohols and esters. In some beer styles this may be acceptable. In other beer styles it may not be acceptable. Taste the beer several times throughout the day to determine the impact.  Many times, the beer turns out just fine.  Deciding what’s “ruined” and what is not depends on each individual situation.

Should I increase the fermentation temperature for a diacetyl rest when brewing an Ale?

Increasing the temperature towards the end of fermentation decreases VDK (diacetyl) reduction times and can be helpful with colder fermentations. Ale fermentations, however, are typically warm enough (≥60ºF) for an efficient diacetyl rest and do not require temperature increase.

Regardless, we always recommend performing a VDK (Diacetyl) Test before crashing to cooler temperatures to ensure that VDK reduction is complete.

Ordering & Shipping

How is the cost of shipping determined?

We share the discount that UPS extends to us with all our customers.

Where is my tracking number?

All tracking numbers are sent on the invoice- simply open the invoice (sent via email) and click the tracking link which will take you to UPS's site. You can also access this info on our online portal.

How do I place an order?

Follow this link to our online ordering portal, log in, and place your order. You can also call, email, or send a carrier pigeon to us- whatever is easiest for you, though we might not recommend the pigeon idea.

My order is damaged!

Not to worry! We can help, please contact us and we’ll get you taken care of ASAP.

Can I use my own UPS account?

Absolutely! Please let us know if you would like to use your account number, and we’ll make a note on your orders.

My yeast is delayed, and I mashed in, WHAT NOW?!

Well shoot, give us a call.  We will be more than happy to help you through this issue. Also, we do recommend scheduling your yeast to arrive with at least 1 day of buffer in case of delivery delays. 

What carrier do you use to ship orders?

 All domestic and international orders are sent via UPS next day air (commercial) or UPS 2nd day air (retail)

Can I place an order for something that is not guaranteed in stock?

Yes! We have a ton of strains available in the bank, just let us know what you’re looking for and we’ll get it in our propagation queue. Typically, we’ll need about 2-3 weeks lead time and a minimum order of 10L.

Product Info

Is your yeast gluten free?

We offer gluten free yeast upon request with a 6 week lead time.


Can you propagate gluten-free yeast?

Yes! We are happy to propagate gluten-free yeast upon request. Please contact us for details on lead times and placing orders.

How do I become a customer?

You can follow the “where to buy” link in the upper right corner of our website. Or, you can call us or email us! We’re here to make things easy for you.

Can you propagate Certified Organic Yeast?

Yes! We are happy to propagate certified organic yeast upon request. Please contact us for details on lead times and placing orders.

How do I update my profile information?

It’s easiest just to give us a call and provide us with the updated information. We’ll update it on our end, and those changes should be live in your portal within minutes.

What is the best beer style?


Do you have a minimum order?

Professionals- no, you may order any of our guaranteed in-stock strains in quantities of .5L and up.

Retailers- no, we do not have an order minimum. However, we do encourage you to fill out a box to maximize your landed cost. 

Do you offer strain banking?

We sure do! For professional brewers, we offer banking for a one-time fee of $100. Please contact us, and we’ll send you the necessary paperwork for secure, private, and confidential strain banking.

Do you support collabs?

We love to collab with folks in the industry. Get in touch with us and pitch (haha) your idea, and we’ll let you know if we can support your collaboration.

Is yeast magic?

DUH! The gods are kind.

What is the shelf life for professional pitches?

We ask that you use the yeast within two weeks of receipt. Please remove the yeast from the shipping box and place it in the walk-in. Keep an eye on the container and vent any pressure that may form.


What are my payment terms and payment options?

We start everyone out with NET30 terms. From the ‘pay now’ link on your invoice, you can pay via ACH or Linked Bank Account with no additional fees, or via credit card with a processing fee of about 3%. We also accept checks at our main facility address, and can provide bank info for EFT and Wire transfers upon request.

How do I pay my invoice?

The day your order ships, we will send an invoice to the email you designate as your primary Accounts Payable contact. From the email, click to open the invoice PDF file, and then click the gold “pay now” button. You can also log into our online portal and access your invoices there.


I am a homebrewer, can I order directly from you?

We do not sell directly to individuals. Please check out our Where to Buy map to find your nearest retailer.

Do you support homebrew competitions?

Yes! We love homebrewers and love supporting the vibrant homebrewing community. Please shoot us an email with your competition details, dates, and request, and we’ll hook you up with swag.

What is the shelf life for homebrew pitches?

4 months from the MFG date printed on the package.

Retailers - if you have an expired product, please remove it from the shelves and contact us for a credit on your next order.

Homebrewers- if you receive an expired pouch, please give us a call to discuss the next steps.


I am a retailer, can I re-package your nutrient into homebrew-sized containers?

No, we ask that you do not repackage our product. If a professional would like to order nutrients, please have them contact us directly.


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