Make your own Cider Vinegar
Making Cider Vinegar Adam Rubinstein
Making cider vinegar is easy. In the same way that apple juice, left to its own devices, will start to ferment into cider using the natural yeasts present on apples, there is another natural process that will turn the resulting alcohol into acetic acid to make vinegar.
Apple juice > Cider > Cider vinegar
Just as we manage the process to ensure a successful fermentation, we need to manage the step to make vinegar, but it is even easier as the process requires oxygen, so you don’t need sealed vessels.
After fermentation has finished, all the sugars in the apple juice have been converted into alcohol. The next process makes use of Acetobacter, another natural microbe, to convert the alcohol into acetic acid. However, Acetobacter is lethal to good cider-making, so make sure you keep the two processes and equipment separate.
If you put your finished cider into a wide mouthed vessel and cover it with muslin, it will turn to vinegar with the natural Acetobacter in the air. This can take between a couple of months and a couple of years, depending on
temperature (ideally 30ºC, same as cider) and air circulation, but you can speed it up with a little bit of management.
Make sure you put your muslin covered vessel where there is plenty of air movement. I’ve been keeping mine in old glass sweet jars at the corner of the stairs where the air circulates several times a day as we pass by. If you put it somewhere out of the way, under the stairs for example, there is very little air circulation so it will be very slow.
You can add the Acetobacter yourself. Vinegar mother is a white layer that appears on top of your vinegar during the process. You don¹t need much so it can be propagated from someone who already makes vinegar and once you have it, it is easy to keep alive. You can also sometimes buy ‘live’ cider vinegar (ie with the mother) to add, from some health-food shops. Once you have your vinegar mother you can also use any left over half-bottles of wine to make wine vinegar although, with all that cider, you probably don’t drink much wine!
Commercial systems bubble air through the cider to speed up the process and it would be fairly easy to do with fish-tank apparatus but I don’t bother. Instead, when the white ‘mother’ forms on the surface, I give it a little swirl as I imagine this layer of cellulose reduces the oxygen reaching the cider. I haven’t read that you need to do this but I think it makes sense. The mother sinks when it is disturbed giving a new liquid surface in direct contact with the air.
The resulting delicious vinegar is ideal for salad dressings and drinking for your health, and it will keep indefinitely in sealed bottles, often forming a layer of ‘mother’ at the top. However, as there is a direct link between the alcohol content of the cider (normally about 5-6%) and the acid content of your vinegar, I find that it isn’t strong enough for making pickles and chutneys. But with a minor additional process, you can make vinegar as strong as you like.
You just need to make your cider stronger BEFORE you start the vinegar process. There are two easy ways you can do this. The easiest is to add sugar to your cider while it is fermenting. The disadvantage of this method is it is not easy to calculate how much sugar to add to get the alcohol (and therefore acidity) you want to end up with. The advantage is that you will end up with much greater quantities of strong vinegar so this is how it is done commercially.
I prefer to wait until cider fermentation has finished and then freeze-distill it. To do this, leave a tupperware container of finished cider in the freezer overnight. As the freezing point of alcohol is -114ºC, only the water in the cider will freeze and you can just pour it through a sieve to remove the water (make sure you collect the liquid in a container under the sieve, that’s the bit you want). For making chutneys, I aim to roughly halve the volume of liquid so the alcohol content (and final acidity of the vinegar) will be doubled at around 10%. This is achieved with just one freeze but by freezing and removing the ice several times you could make it much stronger.
The traditional set-up for vinegar-making is known as the Orleans or barrel process and consists of a barrel laid on its side, three-quarters full of liquid and with just a muslin cover. The alcohol converts to vinegar at about 1% per week so cider with an alcohol of 6% can give a vinegar of 6% acetic acid within a couple of months depending on conditions. Two-thirds of the vinegar is then drawn off, fresh cider is added, and the cycle is repeated. My apparatus for this uses an 8 litre glass Kilner jar with a tap at the bottom so the sediment doesn’t get stirred up when drawing off the finished vinegar.
I can let anyone have vinegar mother and I highly recommend having a try as the end product is really good and you can’t really go wrong.
Update - One of my batches (a strong one that I had added sugar to) grew a different, yeasty-like, flora floating on top. It seemed like the vinegar process was continuing though. After a couple of months I decided to pasturise and re-inoculate it with a new vinegar mother just to be on the safe side. This involved heating it in a stainless steel pan gently up to 75C and keeping it there for 15 minutes before allowing it to cool. Pasturisation happens at 75C and alcohol evaporates at 80C so the temperature is crucial.