Yeast: not behaving like it read the rule book

[Sea brewer]

Hi All

First timer here. Done two tentative homebrews. Both BIAB. Loved every aspect so far. The smells are fantastic. But one aspect isn’t going to plan. Yeast.

On my first brew I got rather carried away. I added my packet of WyeYeast at 70-80oC, forgetting to let the wort cool properly. The packet had swollen nicely and I thought what the heck, we need to meet friends in an hour so let’s just chuck it in and tidy up. I came back a few hours later to a very active fermentation. The gravity stopped dropping five days later and by looks, smell and a cheeky taste it seems good. But all the forums and articles state that my yeast should have failed.

On my second batch I was much more patient and calm. But my WyeYeast pack wouldn’t expand despite several smacks. I opened it (the sachet had mixed) and poured it in with the wort at 22oC. Nothing. 3 days later, still nothing. I then added bread yeast (sure, my wife said, what’s the worst that can happen?) and within twelve hours I got proper fermentation.

So what’s the deal? Should 70-80oC mean dead yeast? If so what happened? Do WyeYeast packets always work? Does yeast understand it’s not funny to behave this randomly? Have I made some runny bread?

Thanks in advance.

 

[NormanHurst]

Generally speaking yeast behaves fairly predictably - in the right conditions it will grow in number, eat sugar and leave behind alcohol and carbon dioxide.

And that's kind of all yeast cares about: eating and reproducing.

As a brewer, whilst you want the sugar to turn into alcohol, you also want to try and ensure the yeasts' behaviour doesn't negatively impact your beer. Remember yeast is responsible for much of the flavour in beer - either by actively adding something (English bitters, Hefeweizens, Belgian ales) or by keeping squeaky clean and unobtrusive (lager, some modern hoppy ales).

To achieve your goal, you need to know how your chosen strain reacts to variables such as pitching rate, temperature, time, wort strength etc

Control the environment and limit the variables to increase the chances of the yeast behaving how you want it to rather than just how it wants to.

Pitching at such a high temperature as your first batch is definitely not recommended. Your yeast were lucky to survive. You don't mention how the beer turned out (or what it was) but the chances of the yeast being stressed and producing off flavours are very high. Well done if you dodged a bullet here, but I wouldn't take that as encouragement to repeat the experiment.

With batch 2, you don't state how you knew the yeast wasn't doing anything. A bubbling air lock on a plastic fermentation bucket is a lovely reassuring plip ploppy thing, but sometimes there are no blips - yet the yeast is still working away happily. The only true way to know would be to measure your gravity. Had it budged since you pitched the yeast?

As for adding the bread yeast - on the one hand it is all Saccharomyces cerevisiae. On the other hand, there's a reason Wyeast don't do a Hovis strain. It will do the basic sugar into booze thing, but it might not get you the beer you want.

Next time you could pick up a spare sachet of Nottingham or US05 dry yeast if you think you need an emergency back up. These are neutral strains that are at least intended to make beer rather than bloomers.

The whole liquid v dry yeast thing is also worthy of some time. Both have advantages and draw backs. One draw back of liquid yeast is viability based on age and storage. Despite the Smack Pack theory and marketing, many here would always make a starter to ensure there are enough yeast cells to do the job.

The perceived lack of fermentation in the second batch could have been the result of a pack that (for whatever reason) just didn't have sufficient cells to get going.

If you want to really dive into the topic then "Yeast: The Practical Guide to Beer Fermentation" by Chris White and Jamil Zainasheff is a great book. You can pick it up for less than a tenner and it will tell you more than you need to know on the subject as a homebrewer. You'll fall asleep dreaming about oxygenation rates.

 

[Clarence]

On my first brew I got rather carried away. I added my packet of WyeYeast at 70-80oC, forgetting to let the wort cool properly. The packet had swollen nicely and I thought what the heck, we need to meet friends in an hour so let’s just chuck it in and tidy up. I came back a few hours later to a very active fermentation.

No you didn't. I don't know of any yeast that can survive that temperature. They'll all be dead at less than 60C. Do you mean70-80F?

So what’s the deal? Should 70-80oC mean dead yeast? If so what happened? Do WyeYeast packets always work? Does yeast understand it’s not funny to behave this randomly? Have I made some runny bread?

Not a question of "should". Beer can be pasteurised around that temperature with about 30 seconds contact.
Wyeast, in my experience, always works. But not always on demand. You may have to wait days for the pack to swell depending on the temperature and the age of the pack. I always make a starter up from mine. I'd say they're not for beginners. There are plenty of dry yeasts on the market and the quality is generally very good indeed, If I were starting from scratch 'd be using a sachet of dry yeast.

 

[Sea brewer]

No you didn't. I don't know of any yeast that can survive that temperature. They'll all be dead at less than 60C. Do you mean70-80F?

Not a question of "should". Beer can be pasteurised around that temperature with about 30 seconds contact.
Wyeast, in my experience, always works. But not always on demand. You may have to wait days for the pack to swell depending on the temperature and the age of the pack. I always make a starter up from mine. I'd say they're not for beginners. There are plenty of dry yeasts on the market and the quality is generally very good indeed, If I were starting from scratch 'd be using a sachet of dry yeast.

Hi Clarence.

No, it was oC. I do everything in metric. The only thing I can think of is some steep temperature differences in my tub. I used a metal steamer to prevent my bag touching the heating element. I believe this led to hot spots and cold spots. Perhaps my yeast touched the cooler zones.

Thanks for the advice.

Owen

 

[Sea brewer]

Generally speaking yeast behaves fairly predictably - in the right conditions it will grow in number, eat sugar and leave behind alcohol and carbon dioxide.

And that's kind of all yeast cares about: eating and reproducing.

As a brewer, whilst you want the sugar to turn into alcohol, you also want to try and ensure the yeasts' behaviour doesn't negatively impact your beer. Remember yeast is responsible for much of the flavour in beer - either by actively adding something (English bitters, Hefeweizens, Belgian ales) or by keeping squeaky clean and unobtrusive (lager, some modern hoppy ales).

To achieve your goal, you need to know how your chosen strain reacts to variables such as pitching rate, temperature, time, wort strength etc

Control the environment and limit the variables to increase the chances of the yeast behaving how you want it to rather than just how it wants to.

Pitching at such a high temperature as your first batch is definitely not recommended. Your yeast were lucky to survive. You don't mention how the beer turned out (or what it was) but the chances of the yeast being stressed and producing off flavours are very high. Well done if you dodged a bullet here, but I wouldn't take that as encouragement to repeat the experiment.

With batch 2, you don't state how you knew the yeast wasn't doing anything. A bubbling air lock on a plastic fermentation bucket is a lovely reassuring plip ploppy thing, but sometimes there are no blips - yet the yeast is still working away happily. The only true way to know would be to measure your gravity. Had it budged since you pitched the yeast?

As for adding the bread yeast - on the one hand it is all Saccharomyces cerevisiae. On the other hand, there's a reason Wyeast don't do a Hovis strain. It will do the basic sugar into booze thing, but it might not get you the beer you want.

Next time you could pick up a spare sachet of Nottingham or US05 dry yeast if you think you need an emergency back up. These are neutral strains that are at least intended to make beer rather than bloomers.

The whole liquid v dry yeast thing is also worthy of some time. Both have advantages and draw backs. One draw back of liquid yeast is viability based on age and storage. Despite the Smack Pack theory and marketing, many here would always make a starter to ensure there are enough yeast cells to do the job.

The perceived lack of fermentation in the second batch could have been the result of a pack that (for whatever reason) just didn't have sufficient cells to get going.

If you want to really dive into the topic then "Yeast: The Practical Guide to Beer Fermentation" by Chris White and Jamil Zainasheff is a great book. You can pick it up for less than a tenner and it will tell you more than you need to know on the subject as a homebrewer. You'll fall asleep dreaming about oxygenation rates.

Thanks, I was using a hydrometer to check for continual reduction in gravity. I keep my hydrometer in the fermenter rather than take it out and steriliser it all the time. Hope that's an okay approach. Really helpful response by the way, and if I can't crack this third time around then I'll be buying that book! I will also get some US05 as a back-up.

 

[klaus]

I don't really delve into the scientific details, just keep an eye on what's happening. I have pitched yeast at temp 28C and worked like a steam engine, after two days no apparent activity, left for another 10 days, beer perfect. Another brew, yeast active and threatening to foam into airlock for a week, another 10 days looking all quiet, beer perfect. Maybe I was just lucky but I never had a beer that failed, some didn't taste as expected. If you ensure that the basics are under control you'll always have a nice beer.

 

[MashBag]

Serious point. Try dried yeast. It is not the enemy.

 

[MashBag]

And that's kind of all yeast cares about: eating and reproducing.

Sounds like a mate of mine!