Aroma Source Help?

I sampled a HB from a customer of the Local Brew/Pub. I am trying to smell it to get a feel for what it will taste like, and I couldn't immediately tell, so I was smelling it and waiting, a few times. Brewmaster is sitting beside me, and another employee who also HBs is on the other side of me. We're all trying to get a handle on the aroma when the Brewmaster says 'Green Apples'. Pow, that was it. It was a stout I think, (I may be wrong I'd had MANY, MANY pints and 'tastes' of stuff by then), but the green apple flavor was subtle, but actually quite appealing. It was a neat light contrast to the rich flavor of the dark grains. It was felt that the aroma was an off flavor, not intentional, an aldehyde? or something, he wasn't sure of the chemical description, but said that this flavor would change and become something that was NOT desirable.

Can anybody tell me what this might have been and how it could come about?

Man, I would like to be able to do this INTENTIONALLY with a STABLE flavor source, it was awesome! Could you ADD green apples off the tree to the boil just before flame out, to kill of bacteria/natural yest and still gain the green apple flavor, without killing the flavor?

Found it and damm if he wasn't right!

http://www.howtobrew.com/section1/chapter8-3.html

The conditioning process is a function of the yeast. The vigorous, primary stage is over, the majority of the wort sugars have been converted to alcohol, and a lot of the yeast are going dormant; but there is still yeast activity. During the earlier phases, many different compounds were produced by the yeast in addition to ethanol and CO2, e.g., acetaldehyde, esters, amino acids, ketones- diacetyl, pentanedione, dimethyl sulfide, etc. Once the easy food is gone, the yeast start re-processing these by-products. Diacetyl and pentanedione are two ketones that have buttery and honey-like flavors. These compounds are considered flaws when present in large amounts and can cause flavor stability problems during storage. Acetaldehyde is an aldehyde that has a pronounced green apple smell and taste. It is an intermediate compound in the production of ethanol. The yeast reduce these compounds during the later stages of fermentation.

http://brewingtechniques.com/library/backissues/issue1.4/miller.html#aeration
See Hot Side Aeration.

"The phrase "hot-side aeration" refers to the hot side of the process, which is wort production. Your understanding is basically correct. Wort contains melanoidins and tannins that are readily oxidized at high temperatures. If air is introduced during wort production--in other words, on the hot side --these substances will be oxidized and later, in the finished beer, they can turn around and give up their oxygen to alcohols that were created during fermentation. An oxidized alcohol is an aldehyde, and aldehydes are the bad guys that are responsible for all the stale, old-beer flavors we have all encountered in far too many imported brews."

I took an off-flavor seminar last year. It was really great. They put various chemicals in Coors lite (since it has no flavor or aroma) and we sniffed our way through 30 of them. We also tried to set four mixes at 10, 20, 30 & 40 IBU in order: one person got all four right.

They finished up with four badly treated beers (I believe it was Red Hook), so we could compare oxidation, high storage temps, etc.

We also got a tour of the fermentation lab at Oregon State. An all stainless, steam heated, chilling jacketed homebrewer's wet dream.

david_42 said:

I took an off-flavor seminar last year. It was really great. They put various chemicals in Coors lite (since it has no flavor or aroma) and we sniffed our way through 30 of them. We also tried to set four mixes at 10, 20, 30 & 40 IBU in order: one person got all four right.

They finished up with four badly treated beers (I believe it was Red Hook), so we could compare oxidation, high storage temps, etc.

We also got a tour of the fermentation lab at Oregon State. An all stainless, steam heated, chilling jacketed homebrewer's wet dream.

Click to expand...

That sounds like a fantastic seminar. I would love to sample the off flavors and aromas in a controlled manner like that.

david_42 said:

I took an off-flavor seminar last year. It was really great. They put various chemicals in Coors lite (since it has no flavor or aroma) and we sniffed our way through 30 of them. We also tried to set four mixes at 10, 20, 30 & 40 IBU in order: one person got all four right.

They finished up with four badly treated beers (I believe it was Red Hook), so we could compare oxidation, high storage temps, etc.

We also got a tour of the fermentation lab at Oregon State. An all stainless, steam heated, chilling jacketed homebrewer's wet dream.

Click to expand...

That sounds awesome.

hmmmmmmm.............

http://kotmf.com/articles/flavors.php

Acetaldehyde
A flavor of green apples or freshly cut pumpkin; it is an intermediate compound in the formation of alcohol. Some yeast strains produce more than others do, but generally its presence indicates that the beer is too young and needs more time to condition.