Immersion with oxygen injection method

This procedure is the most widely used all over the world today. It was developed thanks to progress made in scientific methods and knowledge of the production of penicillin, dating back to the second world war. The bacteria are dissolved in the fermenting must and constantly reproduce using the oxygen added by an aerator placed at the bottom of the fermenter (made from wood or stainless steel) which adds oxygen in the form of millions of micro-bubbles of air.

The must can be from wine, cider, beer, alcohol, malt or even whey (Swiss). The vat is only filled to a third of its capacity because the strong movement created by the oxygen produces a thick foam. The must is made up of 1% acetic acid for 5 to 13% of alcohol , then water is added to regulate the degree of alcohol. A nutritious substance is sometimes added, especially to distilled vinegar.

The temperature of around 30° is monitored regularly as overheating can kill the acetobacters, so can stopping the oxygen flow for more than ten seconds.

Because of this, a vat cooling system is used to circulate cold water and electricity generators are kept on stand-by in case of power cuts. The bacteria proliferate very rapidly thanks to oxygenation and the transformation from must to vinegar is greatly accelerated.

After the degree of residual alcohol is measured and found to be between 0.3° et 0.5°, racking of the vat can be carried out and a new filling operation can begin.
These delicate operations are now automated and managed with a high level of precision.

The vinegar obtained next needs to be filtered because it still contains bacteria and particles. The next stage is the process of fining which consists of clarifying the vinegar using a decanting agent, often bentonite, either in pure form or mixed with other substances to regulate impurities which have accumulated. Then comes the filtration stage, using different filters (diatomaceous earth, plates or membrances) to obtain a pure, clear vinegar. Then, if necessary, the degree of acidity is reduced by adding water.

Wine vinegar also goes through an extra stage of maturing, generally in oak casks in order to improve its flavour. This is the ageing process.
Lastly, after a final filtration stage, the vinegar can be bottled.

Acétateur FRINGS