Tammy Balkwill, age 11, of Niagara Falls, Ontario, Canada, for her question:
WHERE DOES VINEGAR COME FROM?
Vinegar can be obtained in,a number of different odors, colors and flavors. Cider vinegar smells like apples and can be either yellow or brown. Distilled vinegar is water like in appearance and has no flavor other than acidity. A number of different types of vinegar are made with molasses and this color and flavor are reflected in the finished product.
Vinegar, the sour liquid used for seasoning salads and other .foods, is also an important product used in pickling and processing certain vegetables, fruits and meats. The name comes from the French word vinaigre, which means sour wine.
A chemical reaction known as fermentation is part of the secret of vinegar. A weak alcohol, often produced from the fermentation of fruit juices, is the raw material from which all vinegar is made.
In cider vinegar, juice of apples is used. Fermentation changes the fruit sugar into both alcohol and carbonic gas. The gas evaporates leaving esters, the alcohol and flavors from the fruit. Oxidation changes the cider into vinegar when oxygen in the air comes into contact with the alcohol in the cider. With the aid of vinegar bacteria, the alcohol changes into vinegar.
The slow, natural process is one way vinegar can be made. This can take between one and two years, depending on access to air and temperature. Fermented liquid is kept in oak barrels with holes to permit air circulation. It is four fifths full to allow ample air space. Since alcohol is lighter than the other parts of the liquid, it rises to the top and comes in contact with the air. Acetic acid is formed and as it increases in weight, it gradually sinks to the bottom of the barrel. This continues until all the alcohol becomes vinegar.
A quick method of making vinegar has the fermented cider continuously circulated through vats called generators. The generators are filled with porous material such as rattan shavings or corncobs. Lukewarm vinegar is circulated through the porous material for between 24 and 48 hours. The fermented cider then goes through a revolving spray where it is split into drops and brought into contact with currents of air. An efficient generator can convert between 1,000 and 2,000 gallons of cider into vinegar in between 48 and 72 hours. while the process of turning fermented fruit juices into vinegar is going on, especially in the case of making cider vinegar, a very slimy scum called mother of vinegar or bacteria xylinum is sometimes formed. Manufacturers make every effort to prevent this formation of vinegar mother since it slows down the circulation of air and temporarily disrupts the vinegar making process.