Failed primary fementation - repitch?

Yeast: Mangrove Jack's M44 - US West Coast

Yesterday I brewed an IPA recipe but had a couple of issues when it came to pitching the yeast.

The first was that I could not get the wort temperature below 23.9ºC (75F).

The second was that I cooled the re-hydrated yeast too far, to 19.1ºC (66F), as I expected to get the wort down to 21ºC-ish (70F). When I could not get the wort temperature any lower, after using the chiller for almost an hour, I decided to warm the yeast up slightly to 21-22ºC (70-72F) so I could pitch at a slightly higher than normal temperature. Mistakenly I warmed the yeast far too quick by placing the re-hydrated container of yeast in a saucepan of water on the hob. In the space of 10-15 seconds it warmed from 19.1ºC (66F) to 22.3ºC (72F).

At pitching the temps were:
Wort - 23.7ºC (75F)
Yeast - 22.3ºC (72F)

18 hours later the bucket appears to be doing nothing. The airlock is inactive and the lid is not even bulging slightly to indicate a build up of pressure. I have ordered another sachet of M44 yeast which will hopefully arrive tomorrow.

Questions:

  1. Is the higher than optimum pitching temperature likely to delay the start of the primary fermentation?
  2. Will the temperature shock of quickly warming the yeast by 3.2ºC (5F) in 10-15 seconds have likely damaged the yeast?
  3. How long should I wait before determining whether I should pitch the additional yeast?
  4. If I pitch another sachet of yeast will there be any effects on the end flavour?

Topic pitching repitch pitch yeast homebrew

Category Mac

1
answered at

An update to my original question in case anyone stumbles across this in the future.

Around 24-36 hours after asking this question the primary fermentation began - indicated by a krausen which formed at the top. This is the slowest start to a fermentation I have had and I can only assume is down to conditions described in the OP damaging the yeast somewhat.

A further 24 hours after that the new yeast arrived. Given that the primary fermentation had begun I opted not to pitch the additional yeast.

However, there was still no build up of pressure or any airlock activity. After a much closer inspection just now - 5 days after pitching - I noticed the seal where my probe thermometer breaches the lid has split slightly with a 1mm crack on either side of the probe. I could see straight through to the wort below. I have hastily applied silicone around the gap to create a seal and have placed my other lid in sterilization fluid, and will switch them around shortly just in case the drying silicone can cause any issues.

From here all I can do is hope that the beer hasn't been contaminated and carry on as before.

To the next brew...

For the issues of cooling in hot weather I am going to look into the options of a heat exchanger / plate chiller.

1
answered at

If the water in the sauce pan was hotter than 80°F. I'm thinking it was since it only took a few seconds for a few° rise.

What mostlikley happened is most of the yeast in closest contact to the pan water was instantly killed. The other yeast also would have experienced a rapid expansion damaging the cell walls.

Repitch it. This time just put your yeast next to your fermentor until they both have the same temp.

1
answered at

From my perspective, you're taking this temperature thing way too seriously. I mean, it is important to respect temperatures when brewing, (especially for mashing) but in the fermentation process, you should not see any significant differences within the range of 2-3°C.

  1. your yeast performs best in the range 18-23 degrees, a 0.9°C difference should not change anything (are you even sure that your thermometer handles that kind of precision ?)

  2. 3.2°C is not really a shock for your yeast, it is not that much

  3. Wait another day or two and test your gravity, no bubbling does not mean no fermentation.

  4. It depends on the volume of wort, for a 20L wort, 2 packages of dry yeast is not too much.

My guess is that your problem comes from somewhere else:

  • Are you sure your yeast was not expired ?

  • Did you make a starter to pitch the correct amount ?

  • Did you aerate your wort correctly ?

  • Maybe your wort is fermenting? check your SG after few days

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