help with an off-flavor....

[Brew Chef]

Out of the first generation of six beers we carry on draft in our new brewpub, and scaling up recipes 8X, we are very pleased with the results of the first "wave" of beer. There will be some adjustments to dial in the profiles we're looking for as usual.

One of the batches is an Irish Red, and there is a bizarre off-flavor that we can't identify. There is a similar subtle off flavor in some of the other beers but it is much more noticable in the Irish Red. Allow me to explain....

The first 4-6 ounces of Irish Red dispensed out of the draft tower faucet has a strange "almond/cardboard" flavor to it. As soon as this is dispensed, the rest of this beer tatstes normal. When the beer sits in the line for an extended amount of time (at least a few hours), that off-flavor comes back in the next 4-6 ounces.

There is literature on off flavors and an "almond/cardboard" flavor is sometimes described as a result of oxidation, however it did not say if it only shows up in the first few ounces of a pour from a faucet. Our draft lines and faucets are brand new. The only thing I can think of is this......

HSA (hot-side aeration) ? - I've never experienced this so I don't know it's effects or characteristics. Sounds unlikely if it's just in the first 4-6 ounces dispensed. Regular oxidation is also possible however good care was taken to keep air out of the kegging process.

"Dirty" co2 ? We force carbonate with standard co2 tanks filled and delivered from reputable welding supply outfits. Our kegs are purged with the same co2 at time of filling.

Draft line or faucet flavor? seems unlikely since they are both new.

PLease help!!

[GlacierBrewing]

The first 4-6 ounces of Irish Red dispensed out of the draft tower faucet has a strange "almond/cardboard" flavor to it. As soon as this is dispensed, the rest of this beer tatstes normal. When the beer sits in the line for an extended amount of time (at least a few hours), that off-flavor comes back in the next 4-6 ounces.

There is literature on off flavors and an "almond/cardboard" flavor is sometimes described as a result of oxidation, however it did not say if it only shows up in the first few ounces of a pour from a faucet. Our draft lines and faucets are brand new.

Boy, that is weird. I'd start at the simplest; Do you have a subtle "leak" in you line or faucet that is allowing atmospheric air into the line thereby oxidizing that beer that is sitting in the line? Or, are you certain you're pushing the beer with CO2 and not a tank of O2? I know, it sounds funny, but I've done some unbelievably dumb things that "I should have know better"!
Hope this helps ya'!

Prost!
Dave

[Brew Chef]

I don't think there are any leaks in the lines. I'd probably see them if there were and lose a lot of CO2. Our serving pressure is strong enough that beer would drip out and not just gas escape and air enter into the lines.

It's so strange!!!! It's just the first pour and then it's gone.

[Moonlight]

If it is just in the first few ounces, look no further than the the first few inches. First, switch the red onto a different line to see if the flavor follows the beer or faucet. I'm going to guess that it is the beer reaction to the faucets, as reds can do different flavor things than other beers. I would look to replace the faucets and perhaps shanks. Even though they are brand new, they may be a crappy metal or the gaskets may be an oxygen leaking material. At least try getting one or two new stainless sets and see if that changes anything. I know the flavor you speak of but don't know its source. I have found it in pitted brass faucets, especially worn-through chrome plated brass. Fat Tire is also very prone to this in an uncleaned faucet.

[Woolsocks]

I'd first eliminate the line/faucet. Get some professional line cleaning guys in who will circulate caustic and acid cleaners forward and backward (your local A/B distributor probably can help you there). Take apart the faucet, etc. If that's not it, then explore other things.

[jarviw]

almond/cardboard are textbook descriptors for oxidation stale. although Moonlight's insight in pitted brass faucets are certainly interesting!

I think I know the issue you are speaking of, how I hate to be the first customer to order a beer... for a long time I thought that's beer being warmed up/oxidized in the line... but it really shouldn't be the case with modern trunk line.

Actually, check the faucet! there's a pinhole that allows remaining beer inside the faucet to drain off once the tap is closed. I suspect that the faucet trapped too much beer inside, giving the first pour some bad oxidized taste. Watch how the beer drains off the faucet as you finish pouring.

Try blocking the faucet opening by pressing your thumb over (hard), open and then close the tap. the pressure build up inside the faucet should come out the pinhole as you close it, clears off the pinhole in doing so.

[Woolsocks]

If it happens in just a few hours if no one orders a beer, that's pretty fast for oxidation of cold beer isn't it?

[Moonlight]

Do recheck the connection from the hose to the shank. It may appear not to leak, but air is smaller molecules and far less viscous than beer. A hugely common way to pick up air in beer in the brewery is from hose connections that are not tight-either the hose not bound tight enough to the barb, or the triclover (etc) connections not completely snug. (Anything with rubber gaskets should not be smashed senselessly, just tight enough so that you can feel that the rubber is firm.) Ever notice how some triclover connections that you haven't touched in several months could use another quarter or half turn on the clamp? They could be sucking trace amounts of air.

I commonly find draft line connections that are loose enough to twist with your hands, a result of either initial poor banding or more often, the hose material deforming over time and often from cold. They will still not leak beer, but often will leak enough gas as to cause the beer to loose carbonation for lack of pressure, and have foaming/bubble problems.

If you have a CO2 leak checker, (like from Micromatic-which I would recommend everyone have,) you could pressurize your beer line with CO2 and check for CO2 leaks. If not, either just retighten your connections or try to tweak them with your hands to see how snug they are.

[jjs]

No way it's O2tion in that period of time. My guess would be a bug in the shank and or fucet. What kinds of line do you have? Poly or barrier? Brass anywhere? Remember, reds sometime can give off a faint diacetyl flavor from color malts in a softer beer when they are young. Bet it's a bug.

[Moonlight]

I doubt a bug would grow that fast in that temp. My take is that oxidation would affect flavor faster than bugs. Leave a glass of beer out for 24 hours and see what is the greater effect.

[beauxman]

I think the oxygen factor can happen fast, think about a glass of red wine and how fast that changes in just a few hours! Especially a small volume/large surface area. I'm not saying that's it but I would be hesitant to rule that out so fast.
-Beaux

[Woolsocks]

I bet the "bug" is leaving nasty flavors in the line, which are being picked up by the beer, rather than actually directly spoiling the beer.