This is my 3rd batch of beer with the first two coming out really good so I'm hoping to get some troubleshooting help on my 3rd batch, a hefeweizen, which I just sampled after 11 days of fermentation at 72' and 6 days in the bottle, and found a nice banana nose, good carbonation and first swallow tastes good, but leads to a medium tart/sour aftertaste. I'm worried the sourness if from an infection, but hoping it is just the tang of the yeast for the style.
The recipe was a simple 6.6 lbs of Breiss Wheat LME and 1 oz Hallertau, but here's where it may get a little tricky. I am new to home brewing, but there is an experienced brewer in my neighborhood who brews about 300 gallons a year. He brewed a fantastic hef with yeast (originally White Labs WLP300) which he has re-used about 5 times and brewed with this yeast as recently as 8 weeks ago. He told me to use his yeast and save some money so I did.
I made a starter about 36 hours before and pitched room temp yeast into room temp (72') wort and it took off after 7 hours and didn't stop for 5 days. Possible starter infection? I waited until day 11 to bottle because of time constraints. I am pretty meticulous with cleaning and sanitizing.
I am wondering, and hoping, that I simply sampled the beer too early at 6 days and letting it sit in bottles for another couple of weeks will help mellow the tangy aftertaste. But I am also concerned that there may be an infection or that the re-used yeast mutated over time.
I am hoping to get your thoughts as my home brewer friend is out of town. Thank you.