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Vinegar

Article index
 Production of vinegar
 Forming of acetic acid
 Wooden barrel
 Filled oak barrel
 Acetifier
 Organic vinegar
 Filtration
 Distilling
 Pasteurising
Vinegar is a solution containing 4 to 15% acetic acid and flavourings. Acetic acid is an organic acid with a typical, strong smell.

Vinegar is used for the preparation of several sauces, like mayonnaise and mustard, and to preserve vegetables. In the products where it is applied, vinegar softenes the fibrous structures and breaks down the fat, making the product easier to digest.
The pH of vinegar lies between 2 and 3,5, depending on the concentration of the acetic acid. This makes vinegar suitable for preserving products.

There are many types of vinegar, for actually all products that contain sugars can be used as basis. These vinegar types contain, apart from acetic acid, also elements of the raw material. Some well known examples are:
  • Apple or cider vinegar
  • Wine vinegar (red or white)
  • balsamic vinegar: concentrated wine vinegar( ripening time of at least several years in wooden barrels)
  • rice vinegar: (red, black or white)
  • herb vinegar
  • malt vinegar: first starch converted into maltose.
There is also organic vinegar, which is made of sugars and water, and therefore has a neutral taste and contains no minerals. When this vinegar is kept at a dark place, its shelf life is up to 2 years.

Production of vinegar

In fact all products that contain sugars can be used as basis for vinegar. These sugars are first converted into alcohol by using yeast. Then the alcohol can be converted in several ways to acetic acid by the acetic acid bacteria Acetobacter in the presence of oxygen. This conversion takes place in two steps. During the first step, the ethanol is converted into ethanal, which in the second step is converted into acetic acid.

Forming of acetic acid

The forming of acetic acid by different methods is given below.

Wooden barrel

The alcoholic product is placed in a wooden barrel that has several air holes. Screens are placed over the air holes to keep bugs out. The barrel still contains 15% of the vinegar produced in the previous cycle, which serves as bacteria culture. The acetic acid bacterium is also by nature present in the air. The fluid is kept at a temperature of 29°C for several months, until the desired acetic acid level has been reached.

Filled oak barrel

A tall oak barrel is filled with beech shavings, charcoal of grape pulp. The alcoholic product is poured into the vessel at the top and then slowly seeps through the filling. An air compressor is used to blow sufficient air towards the product through the perforated bottom and the holes in the side. After a few days or weeks the vinegar reaches the bottom of the vessel with such a high acetic acid level that the vinegar must be diluted to an acetic acid level of 5 to 6%. The so formed vinegar is transported to a storage tank.

Acetifier

The bottom of a big generator vat, also called acetifier, is a grid with beech shavings on top of it, which contain acetic acid bacteria by nature. This generator vat is filled with an alcoholic product. Air bubbles are pumped into the liquid by centrifugal pumps in the bottom. This supplies enough oxygen for the acetic acid bacteria and circulates the product over the wood shaving until all alcohol is converted into acetic acid. This process takes place at a constant temperature of 30°C. The formed vinegar is transported to large synthetic barrels to rest and ripe.

Organic vinegar

An acetifier is also used for the production of organic vinegar. In this case, concentrated alcohol (96%) is mixed with an amount of unpurified vinegar of a previous production and water. In this manner an alcohol solution of 40% is formed, which is then diluted to a solution of 12% in a nutritional tank. Furthermore a nutrient for the acetic acid bacteria is added.
The mixture is pumped to the acetifier. Like before the acetic acid bacteria get sufficient oxygen by air supply, which keeps the content moving as well. The temperature is kept at 28°C. Eventually approximately 12% acetic acid is produced, forming a non-transparent, brown pulp, a concentrated vinegar. A part of this vinegar is re-used in the mix tank.

Filtration

The produced vinegar is filtrated. Stainless steel plates are used to press the vinegar through paper filters and remove sediment, usually 3% of the product.

To produce organic vinegar, a clarification tank is used. The sedimentation process is accelerated by adding a flocculant, like bentonite. Next the liquid on top is drained leaving appr. 30 cm above the bottom, after which the last insoluble particles are removed by means of ultrafiltration. The so produced bulk vinegar is either sold as bulk or diluted to an acetic acid level of 4%.

Distilling

It is also possible to distil the vinegar. Therefore the vinegar is heated to boiling temperature. The produced vapour is brought in a condenser, after which the condensate can be filled.

Pasteurising

The filtered product is generally pasteurised. Then the vinegar is packed in glass or synthetic bottles. The product can be kept outside the refrigerator.
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acetic acid

Vinegar is a solution containing 4 to 15% acetic acid and flavourings. Acetic acid is an organic acid with a typical, strong smell. Vinegar is used for the preparation of several sauces, like mayonnaise and mustard, and to preserve... read full description