Fermentation is the metabolic process by which organic molecules are converted into acids, gases or alcohol in the absence of oxygen.
Types of Fermentation
- Lactic acid fermentation.
- Alcoholic fermentation.
Vinegar is an aqueous solution of acetic acid and trace chemicals that may include flavoring. The residual ethanol content must be less than 0.5 % in wine vinegar and less than 1% in other vinegar.
- The word “vinegar” is derived from French ‘vinaigre’ a word that simply means “sour wine”.
- Although acetic acid is the primary constituent of vinegar aside from water, acetic acid is not vinegar.
- Vinegar contains many vitamins and other compounds not found in acetic acids such as riboflavin, vitamin B-1 and mineral salts from the starting material that impart vinegar with its distinct flavor.
- Wine (white, red, sherry wine),
- Apple cider
- Malted barley
Microorganisms used in Fermentation of Vinegar
- Species of Acetobacter and Gluconobacter.
- Acetobacter oxidizes vinegar to CO2 and H2O, hence differs from Gluconobacter.
- But Acetobacters are better acid producers.
Types of Vinegar
The main types of vinegar are as follows:
It is prepared from grain-based ethanol or laboratory-produced acetic acid and then diluted with water. It is used for pickling and household cleaning.
Apple Cider Vinegar:
It is prepared from apple cider. It has a golden brown color. Apple cider vinegar is best for salads, dressings, marinades, condiments, and most general vinegar needs.0.03% ethanol.
It is prepared from Trebbiano. It has a dark brown appearance. Balsamic’s flavor is so intricate that it brings out the best in salty foods such as goat cheese, astringent foods such as spinach, and sweet foods such as strawberries.
It is prepared from sugar cane juice. It is dark yellow to golden brown color.
prepared from coconut water. It is cloudy white in appearance with a sharp, acidic, slightly yeasty taste. It is used in South Asian cooking and is essentially important to Thai and Indian dishes.0.42% ethanol.
Clear or very pale yellow, rice vinegar originated in Japan, where it is essential to sushi preparation, popular in Asian cooking and is great sprinkled on salads and stir-fry dishes.0.68%
prepared from dates.
prepared by fermentation of distilled alcohol.
made from fruit wines.
- It is mature under the full heat of the sun in wooden barrels and has a nutty sweet taste.
Other are potato vinegar, malt vinegar, molasses vinegar, honey vinegar, special vinegar, etc.
Image Source: doi: 10.20944/preprints201612.0007.v1
Methods of Vinegar Fermentation
Vinegar is a product of two-stage fermentation. In the first stage, yeast converts sugars into ethanol anaerobically. In the second ethanol is oxidized to acetic acid aerobically by bacteria of genera Acetobacter and Gluconobacter.
There are three methods of vinegar fermentation.
- Orleans Method
- Generator Method
- Submerged Method
1. Orleans Method
One of the earlier and slower methods of creating high-quality vinegar. This method involves the fermentation of vinegar inside a container/barrel.
- Wooden barrels are laid on their sides and bungholes are drilled into the top side and ends of barrels. The topside is plugged with a stopper.
- The alcohol poured into the barrel via long-necked funnels inserted into holes. The mother of vinegar is added at this point.
- The mother of vinegar is a gooey film that appears on the surface of the alcohol products as it is converted to vinegar. It contains the highest concentration of Acetobacters. It skimmed off the top and added to subsequent barrels of alcohol to spread the formation of vinegar.
- The barrel is filled to a level just below holes on ends.
- Nettings or screens are placed over holes to prevent insects from getting into barrels.
- The barrels are allowed to sit for several months. The room temperature is kept at approximately 85 F (29 C).
- Specimen are collected occasionally by placing an outlet into the side holes and drawing liquid off.
- When alcohol has converted to vinegar, it is drawn off through spigot. About 15% of the liquid is left to blend with the next batch.
2. The Generator Method
Distilled and industrial vinegar are often produced via the generator method.
- Tall oak vats are filled with vinegar-moistened bench wood shavings, charcoal or grape pulp.
- Alcohol product is poured into the top of the vat and slowly drips down through the fillings.
- Oxygen is allowed into the vats in two ways
- one through bungholes that have been punched into sides of vats
- second through perforated bottoms of vats
- An air compressor blows air through the holes.
- When alcohol product reaches the bottom of the vat, usually within a span of several days to several weeks, it has converted to vinegar.
- It is poured off from the bottom of the vat into storage tanks.
- The vinegar delivered in this strategy has extremely high acidic corrosive substance, frequently as high as 14% and must be weakened with water to carry its acidic corrosive substance to orchestrate of 5-6%.
- To produce distilled vinegar, the diluted liquid is poured into the boiler and brought to its boiling point.
- Vapour rises from liquid and is collected in the condenser
- It then cools and becomes liquid again
- The liquid is then jarred as distilled vinegar.
3. The Submerged Method
This method is newer, faster, and more efficient methods of producing vinegar. It is mainly used in industrial business where needed equipment is present.
- Production plants are filled with large stainless steel tanks called acetators. The alimentator are filled with centrifugal pumps in the bottom that pump air bubbles into the tank, in much same way that on aquarium pump does.
- As pump stirs alcohol, Acetozyme nutrients are piped into the tank. The nutrients spur the growth of Acetobacters on oxygen bubbles. A heater in the tank keeps the temperature between 80- 100 F (26-38 C).
- Within a matter of hours, the alcohol product has been converted into vinegar.
- The vinegar is piped from acetators to plate and frame filtering machine.
- The stainless steel plates press alcohol through a pipe filter to remove any sediment, usually about 3% of the total product.
- The sediment is flushed into a drain while filtered vinegar moves to the dilution station.
- It is primarily used to flavor and preserve foods and also used as an ingredient in salad dressings and marinades.
- Vinegar lowers the blood sugar level and fights diabetes.
- It helps to lose weight and reduce belly fat.
- Lowers Cholesterol level.
- Used in cooking.
- It is used as a treatment for different ailments.
- Also used in skin care treatment and dandruff treatment as well.
- Slow digestion (gastroparesis)
- Leg cramps and pain
- Unsettled stomach
- Sore throats
- Sinus Problems
- High blood pressure
- Damages teeth enamel
- Allergic reactions due to vinegar may occur including symptoms like swelling, hives, and difficulty in breathing