Are You Pitching Enough Yeast?

YeastYeastWhat makes a good beer great?

Proper fermentation! Having the right amount of clean, healthy yeast to get the job done can mean the difference between a good beer and a great beer. Yeast starters can ensure proper fermentation resulting in a beer with the appropriate flavor, body, and aroma. Many homebrewers start with Wyeast ACTIVATOR or White Labs pitchable vial and making a starter for these products can improve the performance of their yeasts.

Keep reading for details on how to make a starter...

When to make a starter

Although it is not necessary for homebrewers to make a starter every time they brew, you should always make a starter if you think the health of your yeast may be low (ie the smack pack doesn’t puff up, if the pack is around 6 months old, or has been warm for a long period of time). Yeast starters (or pitching more than one packet of yeast) should always be made when brewing lagers or ales with gravities higher than 1.060.

Tables one and two were provided to us by Wyeast. These tables provide an excellent place to start when planning your next beer. Based on the recommended pitching rates in table one, you can use table two to choose the appropriate volume of starter to get your yeast cell count to the desired pitching rate. The pitching rate for one Wyeast Activator pack in five gallons of beer is six million cells per milliliter.

Table 1. Recommended Pitch Rates

 STYLE

 GRAVITY

 PITCHING
TEMPERATURE
(°F)

 FERMENTATION
TEMPERATURE
(°F)

 PITCH RATE
(Million Cells/ml.)

Ale

 <1.060 (15P°)

 >65

 >65

 6.00

Ale

 1.061-1.076 (15-19P°)

 >65

 >65

 12.00

Ale

 >1.076 (19P°)

 >65

 >65

 >18.00

Lager*

 <1.060 (15P°)

 >65

<60

 6.00

Lager*

  1.061-1.076 (15-19P°)

 >65

 <60

 12.00

Lager*

 >1.076 (19P°)

 >65

<60

 >18.00

Lager

 <1.060 (15P°)

 <60

 <60

 12.00

Lager

  1.061-1.076 (15-19P°)

 <60

 <60

 18.00

Lager

 >1.076 (19P°)

 <60

 <60

 >24.00

source: wyeastlab.com

Table 2. Propagation/Starters

# of Activators
1
1
2
1
2
3
1
2
3
1
2
3
Volume of Starter (L)
1
2
2
4
4
4
6
6
6
8
8
8
Starter Pitch Rate (mil cells/ml)
120
60
120
30
60
90
20
40
60
15
30
45
Time of Starter to TG (hr)
18
36
18
72
36
20
84
60
36
96
72
48
Pitch Rate (mil cells/ml)
9
12
19
17
25
32
20
30
38
24
35
44

source: wyeastlab.com

When a yeast starter is not necessary?

A yeast starter is not necessary for low gravity session style beers (1.030-1.050). There is a small chance that you can over pitch your yeast for lower gravity beers. Over pitching yeast can cause less than ideal fermentation such as unexpected esters, yeast autolysis flavors, or poor head retention.

When using dry yeast starters are usually not used as it would be easier and inexpensive to pitch 2 pitch two packets of dry yeasts. Making starters with liquid yeast is cheaper than pitching multiple packets.

How to make a starter

A starter is a mini batch of beer that is used to increase the yeast cell count and does not focus on the drinkability of the starter. The gravity of the wort for a yeast starter should be between 1.030 and 1.040. It is not necessary to make a high gravity starter to grow yeast.

Ingredients needed:
a clean and sanitized gallon jug, growler, erlenmeyer flask or any other similar glass container
a funnel
1lb or so of dried malt extract - golden light or pilsen
a clean piece of aluminum foil
yeast nutrient
water

1. Bring 1 liter of water to a boil and stir in 1 cup (3.5ounces by weight) of dried malt extract.

2. Boil for 10 min. Turn off the stove and add a ½ a teaspoon of yeast nutrient. Yeast nutrient is like vitamins for your yeast and ensures they will start off strong and healthy.

3. Fill your kitchen sink with a few inches of cold water and place the pot of wort in the water. Ice can be added to speed the process. Cool to 70 degrees.

4. Pour all of the wort, including the sediment, into sanitized container such as a jug, growler, or erlenmeyer flask. Be sure the temperature of your starter wort is not too hot. Try to keep the fermentation temp around 65 to 75 degrees. This strikes a good balance between quick growth (higher temps) and healthy cell production (lower temps). For lager yeast starts, you can ferment a few degrees cooler.

5. Shake the starter to aerate the wort. You can also add pure oxygen at this point if you have it. Top with a clean and sanitized piece of aluminum foil or cling wrap. Shake it a little to add oxygen every once in a while (a handfull of times in an evening). See table two for times to reach terminal gravity (TG). At TG, pitch or refrigerate immediately.
See Yeast Starter Recipe

How Big of a Starter do I Need?

The above 1 liter recipe is a great place to start if you're just trying to rejuvenate some yeast that you suspect may have lower viability. As you can see from table two, a one liter starter with one activator could at most give you a pitch rate of 9 million cells per ml. Since low viability is suspected, that pitch rate would likely be much lower and might only get you back to your recommended pitching rate for ales under 1.060 (6mil cells/ml).

The above recipe can be doubled, tripled, etc. to meet the needs of your wort. For example, say you are planning an ale over 1.060. Pitch one activator packet into a two liter starter to give you the recommended pitch rate of 12 million cells/ml (see tables 1 and 2). It is recommended to decant the starter beer and just pitch the yeast into your wort, especially as starter volumes increase. Placing the starter in the fridge can speed flocculation (settling of the yeast) and make this process easier. The starter beer will usually have undesirable flavors as the yeast have not had sufficient time to clean up off flavors created during fermentation.

Yeast terminology

Attenuation is the percentage of malt sugar that is converted by the yeast strain to ethanol and carbon dioxide. Most yeast strains attenuate between 67 and 77%. A low attenuating yeast would be 67-70%, medium 71-74%, and high 75-78%. Attenuation also has to do with the fermentability of the wort (i.e. certain malts leave more residual sugar than others).

Flocculation is how fast or how well a yeast settles to the bottom of the fermenter after fermentation is complete. Yeast strains vary in how fast and how much the yeast particles will settle out. High flocculating yeast can sometimes settle out before the yeast has finished fermenting which would leave higher than normal levels of diacetyl or even fermentable sugars. Pitching an proper amount of healthy yeast with adequate aeration will prevent this problem. Low flocculating yeast strains may leave yeast particles in suspension and this may desired for certain styles (ie wheat beers).

Pitching Rate indicates the number of yeast cells to add per volume of wort.

Lag Time is the amount of time that passes between the time the yeast is pitched to when the airlock begins to bubble vigorously. A long lag time of more than 24 hours may mean that wort was poorly aerated, not enough yeast was pitched, and/or the yeast pitched was not healthy.

Types of yeast

Ale yeast is referred to as top fermenting because the majority of the fermentation action takes place on the top of the fermenter. Ale yeast prefer temperatures that are above 55 degrees. Lager yeast seems to prefer the bottom of the fermenter and like temperatures between 40 and 55 degrees. The exception to this is a lager yeast called California Lager which produces a lager at an ale temperature of between 60 and 70 degrees.

By now you should be well on your way to becoming a yeast whisperer. If you're still confused or have questions, call us up at the shop or shoot us a message and we'd be happy to geek out with you.

Sources
This post complied by HBX staff using personal experience, John Palmer’s book How to Brew, wyeastlab.com and mrmalty.com.