I'm trying to make sense of a series of problems I've been having in a series of recent beers that haven't been a big issue previously. I am now attributing them to stressed yeast. I should say that I have been transitioning from brew-in-a-bag, which I have been doing for several years, to traditional mashing during this time. I don't think that has much, if anything to do with it because some of these issues bridge that transition. I should also say that, except for one circumstance that is noted below, I always grow starters, usually from large inoculations of pure yeast cultures of various types. My pitching rate is usually between 200 and 300 billion cells per 5 gallons. Next, all of the beers in question have been fermented in a modified refrigerator at 65-68F.
There are two issues that have reared their ugly heads.
First, I have had a number of poorly attenuated beers. Although some have been quite high gravity (1.08-1.09), others have been my typical 1.05-1.07 range. Most were fermented with WLP001 or similar (rescued from Ballast Point Sculpin). One, a 1.09 IPA, I tried to kickstart using a late addition WLP090 with relatively little success. The beer ultimately did mature into a very malty but not worty IPA that I have enjoyed drinking but it took nearly two months. Most of my fermentations are complete within 2 weeks and then conditioned and dry hopped as necessary. On those that were stuck, I have also tried bumping the temperature up to 70F after 5 days of fermentation with relatively little success.
Second, and much more disturbing have been a couple of very estery beers. First, I had a 1.065 IPA fermented with US-05, a yeast I hadn't used before but pitched dry after disposing of a starter I suspected of being contaminated. That beer was bursting with ethyl butyrate, tropical fruity esters, much more than I had ever tasted in any beer. Although knowing I pitched this directly into the beer, that result wouldn't have surprised me, but I know a couple people who do that routinely and brew very quaffable beer. Again, I had controlled temperature during the entire fermentation. More recently I brewed a Belgian pale with around the same OG using a yeast recovered from North Coast Pranqster that I have used many times with great success to give a mildly estery Belgian character. I tastes that yesterday after two weeks between 65 and 68F and found it to overwhelmingly isoamyl acetate imitation banana flavored. Esters attack again! Although I can't be certain about the pitching rate (the settled starter seemed a little low in yeast), it was not excessively low.
My assessment of the composite of these problems is poor aeration. Although I have always found my fermentations to go well with most yeast with just a vigorous shaking of the carboy before pitching, I am suspecting that, for whatever reason, my luck with that has run out. I have decided that I am going to aerate using pure o2 and pitch a little more aggressively and see where that leads me both in terms of attenuation and in terms of esters. I am wondering what folks think of this assessment and whether they have other suggestions.
There are two issues that have reared their ugly heads.
First, I have had a number of poorly attenuated beers. Although some have been quite high gravity (1.08-1.09), others have been my typical 1.05-1.07 range. Most were fermented with WLP001 or similar (rescued from Ballast Point Sculpin). One, a 1.09 IPA, I tried to kickstart using a late addition WLP090 with relatively little success. The beer ultimately did mature into a very malty but not worty IPA that I have enjoyed drinking but it took nearly two months. Most of my fermentations are complete within 2 weeks and then conditioned and dry hopped as necessary. On those that were stuck, I have also tried bumping the temperature up to 70F after 5 days of fermentation with relatively little success.
Second, and much more disturbing have been a couple of very estery beers. First, I had a 1.065 IPA fermented with US-05, a yeast I hadn't used before but pitched dry after disposing of a starter I suspected of being contaminated. That beer was bursting with ethyl butyrate, tropical fruity esters, much more than I had ever tasted in any beer. Although knowing I pitched this directly into the beer, that result wouldn't have surprised me, but I know a couple people who do that routinely and brew very quaffable beer. Again, I had controlled temperature during the entire fermentation. More recently I brewed a Belgian pale with around the same OG using a yeast recovered from North Coast Pranqster that I have used many times with great success to give a mildly estery Belgian character. I tastes that yesterday after two weeks between 65 and 68F and found it to overwhelmingly isoamyl acetate imitation banana flavored. Esters attack again! Although I can't be certain about the pitching rate (the settled starter seemed a little low in yeast), it was not excessively low.
My assessment of the composite of these problems is poor aeration. Although I have always found my fermentations to go well with most yeast with just a vigorous shaking of the carboy before pitching, I am suspecting that, for whatever reason, my luck with that has run out. I have decided that I am going to aerate using pure o2 and pitch a little more aggressively and see where that leads me both in terms of attenuation and in terms of esters. I am wondering what folks think of this assessment and whether they have other suggestions.
