Yeast Esters

[mrtrav]

I made both a pale ale and a blonde ale with similar profiles (~1.045 OG). I used US-05 on both and dumped the dry yeast directly into the wort (was told to do this by the LHBS). Pitch temp was 60 degrees and stayed between 60-64 throughout. Now they both have tremendous strawberry/banana esters. I would usually attribute this to a warmer fermentation, but these two fermented on the lower range.

Could this be attributed to not hydrating the yeast and/or not doing a starter? My other guess is oxygenating the wort may prevent this as well. Any input from the experts?

 

[brewguyver]

I wouldn't do a starter with dry yeast - that could stress the yeast out more. Rehydrating and aerating would make a difference. Strawberry is an odd flavor though.

 

[flars]

US-05 can produce off flavors in some beers, when fermenting in the low 60° range. Usually it is described as a peach flavor. Amount and type of hops could change the perceived flavor.

 

[mrtrav]

Interesting, I used Galaxy for bothering and Citra for late additions. The pale was cascade throughout and Citra dry hopped. I'm going to let them age for a few weeks and see how they are then. In the mean time I'm switching back to liquid yeast with a starter.

 

[Natdavis777]

Ive heard of peach with 05 fermenting low, but never experienced it personally. I always rehydrated though. I still got esters with a higher gravity beer by not pitching enough. Try the same beers but use liquid yeast and make a starter and compare the results.

 

[WoodlandBrew]

How long did the yeast float after being added to the wort? You might try the manufacturers instructions for rehydration as well. I've found that works very well both in terms of measured viability, fermentation performance, and beer quality.

 

[RM-MN]

Interesting, I used Galaxy for bothering and Citra for late additions. The pale was cascade throughout and Citra dry hopped. I'm going to let them age for a few weeks and see how they are then. In the mean time I'm switching back to liquid yeast with a starter.

Have you used Citra before? I find that it has a strong aroma and I perceive it as mango but you may perceive it as strawberry/banana.

 

[mrtrav]

How long did the yeast float after being added to the wort? You might try the manufacturers instructions for rehydration as well. I've found that works very well both in terms of measured viability, fermentation performance, and beer quality.

Not sure, it was in a conical so I couldn't monitor that aspect of fermentation.

 

[mrtrav]

Have you used Citra before? I find that it has a strong aroma and I perceive it as mango but you may perceive it as strawberry/banana.

I have, the Pale Ale dry hopped with Citra had less esters than the blonde, which were masked by the aroma of the Citra. The strawberry/banana mainly came off the blonde, which wasn't dry hopped at all. I just got an oxygen pump for free to oxygenate the next batch. Going to try the same recipe with a yeast starter and oxygenating the wort and see how it turns out.

 

[WoodlandBrew]

Not sure, it was in a conical so I couldn't monitor that aspect of fermentation.

Well, as long as you sprinkled it across the surface, didn't stir it in, and the temperature was near 80° then viability should be fine.

 

[mrtrav]

Well, as long as you sprinkled it across the surface, didn't stir it in, and the temperature was near 80° then viability should be fine.

Yup, sprinked across the surface and the temperature was mid-60's.

 

[trentm]

I made both a pale ale and a blonde ale with similar profiles (~1.045 OG). I used US-05 on both and dumped the dry yeast directly into the wort (was told to do this by the LHBS). Pitch temp was 60 degrees and stayed between 60-64 throughout. Now they both have tremendous strawberry/banana esters. I would usually attribute this to a warmer fermentation, but these two fermented on the lower range.

Could this be attributed to not hydrating the yeast and/or not doing a starter? My other guess is oxygenating the wort may prevent this as well. Any input from the experts?

There is a lot of evidence that not rehydrating yeast will significantly reduce yeast viability. Here are a couple of links to assessments by homebrewers.

http://seanterrill.com/2011/04/01/dry-yeast-viability/, https://bkyeast.wordpress.com/2013/03/13/more-on-yeast-rehydration/

If the viability of the yeast was reduced enough to be considered underpitching, that could certainly increase ester production.

 

[Talgrath]

It could be the lower fermentation temperature, it could also be due to not rehydrating the yeast (though that should be an overpitch by a lot, so rehydrating shouldn't have changed things that much). Now technically, yes, you can just use the yeast without rehydrating, but it's better to rehydrate. Based on what you said though, I suspect either a bad batch of yeast (what was the manufacture date?) or the low fermentation temperature being the culprit.

 

[desabat]

Could be under pitching yeast due to not re hydrating the yeast and losing cell count