If I want to have a beer ferment in less time would doubling the amount of yeast I pitch help? Will there be any consequences of doing so? Does it matter if I make a starter for them both?

4 Answers 4


If you are already pitching the correct amount of yeast, pitching more will not make the beer ferment faster. In addition, there are negative flavor consequences to pitching too much yeast. Having proper yeast growth in the fermenter is a big factor in ester production or lack thereof. I used to pitch an entire slurry from a previous batch into the next batch. When I started using 1/3 to 1/2 of the slurry the beer flavor improved considerably. According to Dr. Clayton Cone of Lallemand, the same enzyme, Co-Enzyme A, is responsible for both cell growth and ester production and when it's doing one it won't be doing the other. Therefore, allowing for cell growth means that you will fewer esters produced and a cleaner beer. This contradicts some other theories, but it's what I've found to be true in my own brewing. You can read more about it here yeast growth and esters. So, to sum up, pitching twice as much yeast won't speed up fermentation and might have negative impact on beer flavor.

  • Excellent article, and excellent information. I believe I fixed your link, it originally led to a great collection, but not the specific article. I've never pitched anywhere near the full slurry before, what exactly did you notice different?
    – Mlusby
    Mar 30, 2011 at 0:56
  • I re-read the article you linked to, and he also specifically mentions that increasing the pitching rate is done by commercial breweries to decrease total fermentation time. Way more complicated than I thought, and I knew it was complicated.
    – Mlusby
    Mar 30, 2011 at 2:23
  • Thanks for fixing my link, although that whole collection has some great info! I noticed that when I used only a partial slurry that my beers seemed to have a cleaner and crisper flavor.
    – Denny Conn
    Mar 30, 2011 at 15:33
  • I thought that the point of using the wyeast activator packs was that they have a greater cell count and faster fermentation (more cells working on the same amount of sugar). This is just a marketing thing?
    – drj
    Mar 30, 2011 at 23:00
  • 2
    @drj - There's a balance you have to strike in cell count, you don't want too much, nor do you want to little. Regarding the smack-pack, I've seen Wyeast microbiologist Greg Doss mention in a video that the yeast doesn't actually increase in cell count, its metabolism just gets a kick-start so it's not dormant when you pitch it. Link: youtube.com/…
    – Room3
    Mar 31, 2011 at 20:21

Making a starter is all about increasing your yeast cell count.
There is no reason to use more than one packet of yeast if you're making a starter. If you need more yeast, you can split the starter to get even more.

It might technically decrease the amount of time needed, but likely only by a few hours, not days, if you're normally pitching a dry packet, smack pack, or vial per 5 gallons. What you're doing by introducing a larger yeast population is ensuring that it will be dominant and healthy, very important for higher gravity beers, and probably never a bad idea.

There are several good questions already about starters:

Should I always use a starter

Making a Yeast Starter

Starter and smack Packs


As mentionned by Denny and Mlusby, adding more yeast is not the way to go to speed up things.

Yeast can be more productive at certain temperature, so I would rather focus on controlling the temperature in my fermenter.

Making a yeast starter can also save so time in the process.


The reason I use about a quarter packet is that yeast reproduces asexually, by fission or budding. The cells mature and divide in two. Two divide to four, then eight, sixteen, and in a day there’s billions, depending on food, trace elements like calcium, and temperature. My wort is always going like mad the next day. Using two packets over a quarter-packet saves you about four yeast reproduction cycles, or a couple hours.

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