[erockrph]

I've used WY1469 fairly often. Normally I get a bit of a subdued "stone fruit" ester, i.e., not quite nectarine, not quite cherry, not quite almond, but if you used any of those terms I wouldn't disagree. Last night I just kegged a batch of bitter that I brewed with 1469, and the sample I poured had a rather intense cherry pie aroma, reminiscent of Orval. I was taken aback by how intense it was. There was no acidity, barnyard, grass, goat, diacetyl, or other sign of Brett/bacterial contamination. Aside from the ester, it tastes just as I would expect a young, moderate-gravity bitter to taste.

The recipe is below. I ferment 3 gallon batches in a 5 gallon keg with a PRV set to about 2 PSI (just enough to keep it closed). Once the PRV stops hissing audibly, I'll pull it off altogether. The beer doesn't end up fully spund-carbonated, but it's at least partly there and it takes a lot less CO2 to finish carbing in the keg. From there, I do a closed transfer into a purged keg.

I did pitch a bit less than usual this time around (about 2/3 of a fairly fresh smack pack, no starter. I usually pitch a full pack). I also fermented at 70F rather than 66F. Other than that, I can't think of any changes to my process that could impact ester formation. I actually quite enjoy this flavor, but it's so drastically different than usual and I'm at a loss as to how it happened. Has anyone else gotten this flavor from 1469? Any thoughts on what caused this? Could a 4 degree F fermentation temp increase and a slightly lower pitch rate be enough to explain this?

Title: Pale Bitter

Brew Method: BIAB
Style Name: Ordinary Bitter
Boil Time: 60 min
Batch Size: 3.9 gallons (ending kettle volume)
Boil Size: 4.3 gallons
Boil Gravity: 1.033
Efficiency: 80% (ending kettle)

STATS:
Original Gravity: 1.041
Final Gravity: 1.012
ABV (standard): 3.92%
IBU (tinseth): 32.67
SRM (morey): 7.02
Mash pH: 5.35

FERMENTABLES:
4 lb - Sugar Creek Ye Olde Pale Ale (76.2%)
4 oz - Briess Caramel Malt - 60L (4.8%)
8 oz - Flaked Corn (9.5%)
8 oz - Becker - Invert Sugar #1 - (late boil kettle addition)  (9.5%)

HOPS:
1 oz - Challenger, Type: Pellet, AA: 4.5, Use: Boil for 60 min, IBU: 25.45
1 oz - Northdown, Type: Pellet, AA: 6.4, Use: Boil for 5 min, IBU: 7.22
1 oz - Target, Type: Pellet, AA: 10.3, Use: Boil for 0 min

OTHER INGREDIENTS:
4 g - Gypsum, Time: 60 min, Type: Water Agt, Use: Mash
1.5 g - Salt, Time: 60 min, Type: Water Agt, Use: Mash
1.16 ml - Lactic acid, Time: 60 min, Type: Water Agt, Use: Mash

YEAST:
Wyeast - West Yorkshire 1469

PRIMING:
CO2 Level: 1.02 Volumes

MASH GUIDELINES:
1) Temperature, Start Temp: 147 F, Target Temp: 162 F, Time: 60 min, Amount: 17 qt, Ramp through sacc rest

[reverseapachemaster]

Expressive yeast can sometimes create wildly different results with small changes. I've had Belgian strains underpitched and underoxygenated unload so much orange flavor into a beer it tasted like I tossed in a bottle of Grand Marnier and British strains cough up aggressive apricot flavor. I've only gotten those once. I've had more than a few come out with very little fruit flavor.

I would say with a high level of confidence based on my experience that you wouldn't get cherry pie flavor out of a wild yeast invasion unless the beer sat after exposure for months, maybe years.