Understanding Oxidation

I was wondering if someone could shed some light on the principles of unwanted oxidation. What happens when your beer goes through oxidation after the initial wort is boiled and the yeast is pitched? When do you know that unwanted oxidation has occurred? How to you prevent oxidation when you move your beer to the secondary fermentor? When your beer has stopped fermenting in the primary, is it normal to see some activity when it is moved to the secondary? If there is activity in the secondary, does that mean oxidation has occurred?

If these questions are solved we should move on to fixing that whole world peace thing.

You'll notice oxidation after sloshing around a ton while transfering and a long time of being improperly stored. You have to try real hard to ruin your beer. Chances are the beer will be gone before it willo come even close.

Prevention: Make clean, non splashing transfers to secondary and bottling. Use a siphon hose instead of just pouring it out. When the primary is finished, there should not be any more visible activity, even in the secondary.

Action in the secondary does not mean oxidation has occoured. It means you a) transterred too early, b) added more fermentables or c) you may have an infection.. The most likely cause is option A. Leave the primary alone for at least a week and you should never have this problem.

keep in mind the difference between aeration and oxidation.

Aeration is dissolving air in the wort. This is what we do to cooled wort prior to pitching yeast and is a good thing. The yeast need the O2 to multiply.

Oxidation is when O2 chemically combines with something and is bad.

Walker-san said:

keep in mind the difference between aeration and oxidation.

Aeration is dissolving air in the wort. This is what we do to cooled wort prior to pitching yeast and is a good thing. The yeast need the O2 to multiply.

Oxidation is when O2 chemically combines with something and is bad.

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Thank you Walker-san. I was lumping the two together.

So, when does oxidation occur and how do you know it has/is happening?

(side note: I have a Blue Moon Clone in the secondary. The air lock has shown signs of activity and there is a "mini-krausen" - in other words a few bubbles - on the top. Could this have come from any of the ingredients I used, like the hops or corianders seeds, or did I move it over too early. I did wait ~10 days AND there had been no activity for 3-4 days prior to moving it to the secondary. Anyones thought are welcome.)

Not necessarily too early in your case, but you probably just aroused some yeast off the bottom...seeking out any remaining sugars.

It depends on your OG and FG also. If your yeast has 77% attenuation and your gravity has only gone down say 70% then there's still some sugars left to ferment.

Ninkasi...love the name. Won any awards lately?

homebrewer_99 said:

Not necessarily too early in your case, but you probably just aroused some yeast off the bottom...seeking out any remaining sugars.

It depends on your OG and FG also. If your yeast has 77% attenuation and your gravity has only gone down say 70% then there's still some sugars left to ferment.

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Thanks homebrew_99!

So...If I have not reached my FG "range," I am more likely to see some new activity in the secondary even though the primary appeared to have completed the fermentation process? Would that be a safe assumption?

If I have not reached the appropriate FG in the primary, should I attempt in some way to arouse the yeast to get the FG to where is should be BEFORE moving it to the secondary?