How to Use Wyeast Activator Packs

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Wyeast Activation Instructions

Using liquid yeast is an excellent way to brew beers with authentic style-specific flavors that usually cannot be achieved using dried yeast. Unlike dried yeast, however, using liquid yeast does requires extra attention. While we love the Wyeast liquid smack packs and the excellent results they produce, we feel the package instructions are not detailed enough to eliminate possible problems. Liquid yeast must be properly activated before use. A properly activated pack will rise and swell. You must make sure your yeast has been properly activated and swelled before you brew. Please follow the instructions below.

  1. When you receive your yeast, either through shipment or when returning from the store, you must immediately refrigerate the yeast until you're ready to activate it.
  2. Before you activate the yeast, first examine the package's manufacturing date. Stamped on the front of the Wyeast Activator pack is the packaging date of the yeast. For example, a pack that reads "MFG 28MAY19" was packaged on May, 28, 2019. Wyeast states that the package is best used within 6 months of the manufacturer's date when stored in the refrigerator. While this is theoretically true, it has two basic shortcomings.
    1. Very young yeast (approximately 2 months old or less) may be activated on the day you brew. Usually by the time you have brewed and your wort has cooled, the package will have inflated and is ready to go. Older yeast will require a longer activation time. We wish we could specifically tell you how far in advance to activate, but this estimation skill is somewhat of a black art which you gain with brewing experience. In general, however, a packet that is between 2 - 3 months old should be activated approximately 24 hours in advance. A packet that is between 4 - 6 months old may need to be activated 2 days or more in advance.
    2. A yeast that has been mail-ordered my not retain complete yeast viability for the full six months. For example, you receive a Wyeast smack pack that is fresh (1 month old). However, the yeast sat in the shipping box without an ice pack at room temperature or warmer for 4 - 5 days. The yeast will still be alive, but you should not expect it to retain viability for the next five months. You should not store this yeast in the refrigerator for four more months before you brew. Instead, you should try to brew with this yeast sooner rather than later.
  3. Activate the yeast. You must activate the yeast before you brew. Activation is the process whereby you break open the inner nutrient pouch to feed and activate the yeast. The yeast will consume the nutrients and become over one-thousand percent more metabolically active than they are in their dormant state. This is a good thing.
    1. The Wyeast package states, "To Activate, locate and move inner packet to a corner. Place this area in the palm of one hand and firmly smack the package with the other hand to break the inner nutrient packet. Confirm the inner packet is broken." It is very important to confirm you have broken the nutrient packet. Feel around until you're sure you've broken it. Otherwise, the yeast does not have a chance to feed, and the pack will not swell. Shake the pack to release and mix the nutrients.
    2. The Wyeast package states, "Allow the package to incubate and swell for 3 hours or more at 70 - 75 degrees F." As discussed above, this might not be enough time. Always base this incubation time on the age of the packet, which you've determined by examining the manufacturing date. Remember, older packets may require 1 or more days. What if your room temperature is too cool for proper incubation? We like to place the activated packet on top of a cable or satellite box. The heat from the electronics helps keep the packet warm. The Wyeast packet also states, "it is not necessary for this package to fully swell before use." While this is true, you must make sure that the pack has indeed swelled. A common mistake that we often hear is that the brewer "thinks" the pack has swelled. If you've waited long enough, you will have no doubt.
  4. Use sanitizing solution to sanitize the package before opening. This is important. You don't want to pick up any stray bacteria when you're pouring the liquid yeast. If you're using scissors to cut open the pack, it's advisable to use clean and sanitized scissors. We like to use scissors specifically dedicated to brewing, since our regular scissors at home seem to be coated in various impressive layers of toxic waste that I doubt can ever be cleaned.
  5. Shake the pouch, open and pour. Like you need instructions on how to do this. But the pouch-shaking part is important. Them yeast are sticky little critters. Shaking the pack helps dislodge them from the sides. And we feel that the extra calories burned justifies pouring another beer. We're just sayin'. Also, Wyeast recommends (and so do we) oxygenating your wort just prior to pitching the yeast. You don't have to get fancy here with direct oxygen injection, but shaking your cooled wort to mix in some air is important. The yeast needs that oxygenation at the time of pitching to reproduce to greater numbers and form a healthy, happy colony. Keep the yeast happy. Aerate your wort.
  6. High gravity alert! Be aware that the yeast cell count of a single Activator pack is designed for worts with specific gravities of 1.060 or less. If you're doing a higher alcohol "high gravity" beer, we, they and everyone who's anyone recommends adding more yeast, usually from having done a yeast starter. If you under-pitch your wort, you risk sluggish fermentation and poor attenuation (the beer doesn't ferment down to your expected final specific gravity).
  7. Don't shoot yourself in the foot. Wyeast recommends pitching the yeast when the wort is between 65-72°F and then maintaining this temperature until you begin to see bubbling through the airlock. This, too, is important. It is during this "lag phase" prior to fermentation that the yeast is reproducing and invading your wort. You want the yeast to invade quickly, and the warmer temperatures help a lot. We personally like to pitch the yeast when the wort is 75°F and then wrap the fermenter with blankets to act as insulation to keep the wort temperature at 75°F. Once we see airlock activity, we'll move it to a location with our desired fermentation temperature.