Acetic acid and cider production

What keeps the fermented sugars (alcohol) from being converted into acetic acid (vinegar) when making a hard cider.

Background: My friend brought four gallons of fresh pressed apple cider home from NY and so I figured I would do some experimentation. All of the jugs had begun to ferment and thus I was "burping" them relatively regularly by just slightly twisting the cap. Anyway they had a nice flavour to them when I tested them and so I did / am doing the following:

1. Heated cider to 140 for 10 minutes and added 1 cup of brown sugar + a little water and then pitched the yeast (champagne yeast which I rehydrated that morning) and airlocked it. It's fermenting nicely.

2. Did not heat the cider and just let the wild yeast live and pitched some fresh yeast on top of it (champagne yeast which I rehydrated that morning). It's also fermenting nicely.

3. Same as #1 but want to try another type of yeast (probably an ale yeast as I've heard one can have nice results)

4. Apple cider vinegar. I realize that the process for making cider vinegar is similar to the fermentation however you are supposed to open the lid every day and give it a stir.

I suppose my question is then...is this what introduces or promotes the bacteria that turn alcohol into acetic acid?

How does one keep their cider from turning into vinegar once bottling? Or does it simply not turn to vinegar because it is not exposed to the air and has a protective layer of CO2 at (most) all times. I would like to thank whoever will respond to this post in advance.

Its all about the bacteria that make vinegar. If the cider is sterol prior to adding the yeast and then you use sterol equipment and an air lock there should not be any bacteria to make the vinegar. If using wild yeast it is a bot more of a luck thing. if the yeast can establish them selves than you create an environment that is not very effective for making vinegar. thats why making wild yeast brews don't always work out because some times a bad yeast or a bad bacteria take hold before the good yeast.

It's all about oxygen. The reaction converting ethanol to acetic acid requires oxygen, if you keep your cider well sealed and fully topped up there is no o2 available and no chance of vinegar. Since this is a requirement of good cider anyway you don't don't need to worry.

It's not actually possible to keep your fermentation sterile and not a requirement of a good cider. A good fermentation will stop any spoilage organisms getting established. Did you know that winegrapes are never washed before crushing? and definitely not heated.

gregbathurst said:

It's all about oxygen. The reaction converting ethanol to acetic acid requires oxygen, if you keep your cider well sealed and fully topped up there is no o2 available and no chance of vinegar. Since this is a requirement of good cider anyway you don't don't need to worry.

Click to expand...

So when I was pouring the cider from the plastic into the glass jugs (and this cider had already started to ferment via the natural wild yeasts) there is a risk that I could end up with vinegar due to the fact that it was invigorated with oxygen during the transfer?

Yes.... There is that possibility.

My own experience with wild fermentation of fresh pressed cider is that you have a pretty good chance of ending up with vinegar if you let it sit long enough.... It's usually best to drink it reasonably quickly before it gets vinegary....

That's why I went to using Sulphite and then proper beer or wine yeast... It really reduces the chances of ending up with vinegar (I have about 4 gallons of home made vinegar sitting in the basement from hard cider batches gone awry)

Thanks