Off Flavors and need help

[Boston85]

I have done about 5 AG batches now, but they all seem to have some type of off flavor. I can't really describe it, but it just is not a clean taste. On average, I feel like my mashes wind up a little lower than they should. I shoot for 150 or so, but usually wind up at like 147ish. At first I was only getting about 55% efficiency, but my last brew I was at 75%.

When fermenting I place the bucket in a chest freezer and use a temperature controller. I put the probe dangling in the middle of the freezer, and set it to 68. I feel like this may be causing some issues. I know the yeasties will warm up a decent amount, so I have a feeling the interior temperature of the fermenting bucket is much higher. Would this produce off flavors?

I had a friend try some of my most recent batch, and he said it seems like it may be oxidized a little bit. I usually keep in primary for 3 weeks or so, then secondary for a week or 2, then keg. When I keg I put freezer at about 50 and set PSI to around 14 and let it go.

I understand it is hard to diagnose the problem without more details on the off flavors, but does anyone notice anything that could be causing it? It seems to be the same off taste in every beer I do. I use a hose manifold in mashing, although I bought copper pipe to create a copper manifold going forward.

 

[BrewScout]

Instead of racking to secondary, I suggest you try cold crashing. That will eliminate one possible cause of oxidation.

 

[AmandaK]

You'll probably have to be a tad more specific than "not a clean taste". Try and look here to see if you can't try and find a better descriptor.

As for what information was given, here's some suggestions:
1) Tape that temp probe to the fermenter! I tape it to my Better Bottles with painter's tape, then tape a small towel over the probe for insulation.
2) Oxidized? Hmm, most likely caused by splashing the wort/beer around. Don't splash when your wort is above 86* or after your fermentation has begun. After chilling and before fermenting is the only time it is okay to aerate your wort/beer. Does your beer taste papery/cardboardy? Your friend could be right.
3) When you mash at lower temps (e.g. 147*) you need to let the mash rest for 90 minutes instead of 60 to let all the sugars convert. That may help your efficiency issues.

Cheers!