Vinegar is a sour liquid used for seasoning and for preserving foods. The name vinegar comes from a French word meaning sour wine. But many kinds of vinegar are made from substances other than wine. Vinegar is produced by the action of yeast and bacteria on agricultural products, including fruits, grains, and such sugar solutions as honey and molasses. Different kinds of vinegar take their names from the material used. For example, wine vinegar comes from grapes, cider vinegar from apples, and malt vinegar from malted barley.
Making vinegar
involves several steps. First, the raw material is made liquid and its sugar content is adjusted to the level desired by the producer. Fruits are crushed. Grains are soaked in water in a process called malting, which releases their sugars. Water is added to honey or molasses to dilute (weaken) the sugar concentration.
In the second step, the sugars in the liquid are turned into alcohol. This process is called fermentation. The liquid undergoes fermentation in a barrel or tank that air cannot enter. Yeast added to the liquid begins the fermentation process, which lasts two or three days.
In the third step, the alcohol is converted to acetic acid and water in a process called acetification. Acetic acid gives vinegar its sour taste and its preservative quality. Bacteria of a variety called acetobacter in combination with air cause acetification to occur. The speed of the acetification process depends largely on the rate at which the alcohol is exposed to air. The method of acetification used today allows the alcohol rapid exposure to the air and usually requires only one or two days. In this method, the alcohol trickles through a bed of wood shavings, corncobs, or other coarse material that has been packed into a vessel called a generator. Air pumped up from the bottom of the generator comes into contact with the liquid as it trickles through the bed. The liquid may flow through the generator several times before all the alcohol has turned into acid. After acetification, the vinegar is filtered to remove impurities. It is then pasteurized and bottled for sale.
In the traditional method of acetification, the alcohol partly filled an open vessel such as a barrel. Only the liquid’s surface came into contact with the air. Acetification took weeks or months to complete by this method.
Uses of vinegar.
Vinegar is sold for use both at home and by commercial food processors. It is used mainly as a flavoring agent, especially in salad dressings and sauces and on vegetables and meats. Vinegar is also used to preserve fruits, vegetables, and other foods in a process called pickling (see Pickle ).
Kinds of vinegar.
Vinegar sold for use at home typically contains around 5 percent acetic acid. Most vinegar used in commercial food processing contains a higher concentration of acetic acid.
A kind of vinegar called distilled alcoholic vinegar or spirit vinegar is commonly used by commercial food processors. It is produced by boiling the fermented liquid and then condensing and collecting the vapor that forms. The distilled liquid can be shipped economically in a concentrated form to commercial users, who then acetify it. This kind of vinegar loses much of its flavor in the distilling process.
