Honey note in all homebrew

That is a correct statement - the yeast in bottle conditioned beers are not dormant.

Best of luck there!!

Cheers!

 

Is there a white paper on this? I would like to see the details of the experimental method and the data.

 

I don't have any reason to think @pweis909's theory is wrong, but I would point out that Brettanomyces is thought to have some anti-oxidation effects because it "scavenges oxygen" months after primary fermentation is complete. Implicit in that concept is that Saccharomyces does not do the same thing, exactly. Saccharomyces may still do something important, but (if the traditional way of thinking is right) it is not doing what Brett. does.

Edited to add: Another way of putting my point is that if you have two beers, one fermented exclusively with Sacch. and one brewed with Sacch. and a little Brett., it is thought that the Brett. beer will suffer less from oxidation (though it may develop, you know, Brett. characteristics). This difference would be inexplicable if both yeasts were doing the same thing.

 

What Brett is primarily doing (my understanding) is breaking down complex carbs into simple sugars and metabolizing them. They’ll first use oxygen and then ferment. I believe sacch diastatica strains do the same. Now there may be more oxygen scavenging going on the just this. Regardless, whenever oxygen is in your beer, there are competing reactions taking place. It isn’t like the oxygen is all consumed by the yeast. Some of those reactions would contribute to staling and at some point human palates will begin to notice.

 

This is my main objection to the magical yeast theories. Even if they for some reason dedicate themselves to eating O2 when there is no sugar around (which I'll believe if I see data), they couldn't possibly use it all, even if they "wanted" it all.

 

Yeast are not absorbing o2 when there is no food source its a simple as that. They have certain cycles and they don't suddenly break said cycles because they sense they were put in a bottle.

The reason naturally carbonated beers (this is not limited to bottles, either) via, spunden, krausen, or simple sugar have more antioxidant properties is because they produce antioxidants. Fermentation generates sulfites. Both of them, the main and the second (at packaging).

For ales you have <=10ppm
Lagers <=50ppm - the colder the fermentation and the strain will be dependent on actual numbers- this is a reason why zee Germans ferment cold (there are others though of course). Colder the better, which is why I also promote cold with no ramps. Ramps lose them.

So to break down why these tests show naturally carbonated beers having the highest antioxidant power it's because they do.
But it's not because of continual oxygen consumption it's the sulfite production in the carbonating vessel and the oxygen consumption on the original transfer.

The bright beer transfer, is going to be the least protected because of what we outlined above. You have zero active consumption, and you are immediately digging into your first fermentation sulfites, with no second reserves. You probably expended most of them pushing the beer around to filter and whatnot.

When you transfer naturally carbonated beer, you are rousing the yeast and adding a very easily digestible food. That yeast grabs some oxygen after it stretches, grabs a quick meal then goes back to bed, at the bottom of the container. If he gets more food he will wake up, if not sleeping like a bear is he.

I think I wrote about fermentation generated sulfites years ago on the blog. The resource sections probably has some papers on this as well.


Brett works because it can do things the regular yeast can't. If that was the case every "normal" yeast beer would ferment out to zero and continually make carbonation. But it doesn't it stops when it can't eat any of the sugars.. and goes to sleep.

 

There are a number of activities occurring in bottle conditioned beer due to the presence of live yeast:

Amount of DO in the bottled beers

It has been measured that the DO levels of bottle conditioned beer decreases over the time periods of 2, 3, 4 and 5 months. The measured DO level is lower at month 5 than the values measured at month 2, 3, and 4.

In contrast for the control beer which was force carbonated and contained no live yeast to scavenge oxygen the DO levels for months 4, 5 and 6 were quite high and the increases from months 4 -> 5 -> quite high as well.

Sulfite (sulfur dioxide)

There are increased amounts of sulfite levels in bottle conditioned beers (in comparison to the control beer of forced carbonation). This is a result of the secondary fermentation which occurs in the bottle.

Antioxidant Capability

Bottle conditioned beers have higher levels of anti-oxidant capability vs. the control beer of force carbonation: “…bottle-conditioned beers and the artificially carbonated beers with live yeast added had a significantly elevated antioxidant capacity.”

Some ‘summary’ statements from the abstract:

“It is well known that bottle-conditioned beer has a longer shelf life than conventional beer in terms of flavor stability and freshness. This is likely due to a complex relationship between the yeasts inherent ability to scavenge oxygen species, produce SO2, chelate transition metals and employ other methods to defend against molecular oxygen.”

Yup, live yeast in bottle conditioned beer is active and through a combination of activities it yields improved beer stability over an extended period of time (e.g., 5-6 months).

Cheers!

 

Did you like just copy my post?

 

So...If bottle conditioned, low oxygen beers have a longer shelf-life, why are most bottled German import beers so terrible then? Are they pasteurized or filtered?

 

So my procedure, like many homebrewers (I suspect), is to simply keg upon completion of fermentation. Would there be any advantage to adding a bit of sugar (and if so, how much), when kegging in this fashion, or would the fairly fast drop in temperature negate any possible advantage. Cheers!

 

fwiw, I don't add sugar, but I do leave at room temp for 2 or 3 days after kegging/dryhopping.