- Legally means acetic acid product made from apples (like wine is from grapes)
- To be legal, vinegars in the US must contain a minimum of 4% acetic acid
Different countries- different starting materials
- Continental Europe- grape wines
- Great Britain- malt
- Hawaii and Far East- pineapple
- USA- apple
See Figure 1.
- In the late 1800s, chemists learned how to make acetic acid.
- Manufacturers added water to reduce the strength to 5%, colored it, and sold it as vinegar.
- Imitation vinegar is still manufactured and by law the label must state that it is diluted acetic acid.
Acetic Acid (Fermentation?)
- 2CH3CH2OH + O2 = 2CH3COOH + 2H20
- Ethanol 92 mg/mol
- Acetic acid 120 g/mol
- Theoretical yield (120/96) × 100 - 130%
- Practical yield ~ 120%
Acetic Acid Bacteria
- Obligatory aerobic
- Nitrogen-fixing bacteria
- Known for producing acid as a result of metabolic processes
- Acetobacter aceti (Figure 2).
- Made from good alcohol (wine, beer) that is fermented using acetic bacteria that convert alcohol to acetic acid.
- The process can be controlled by using great care in cleanliness and introducing chosen yeast (wine) and bacteria (vinegar) to obtain good quality every time.
Methods of Making Vinegar
- Home making
- Orleans process. ----> Better flavor of vinegar
- The generator system
- Submerged fermentation system (bubble method)
- Wine that usually contains 11-12% alcohol must be diluted to 5.5-7% alcohol before using it to make vinegar
- Vinegar should contain at least 5% acetic acid as required for preserving and pickling
Making Wine Vinegar
- Use glass, stainless steel, and enamel. Vinegar leaches molecules from iron and aluminum
- Sanitize utensils
- Everything that will touch vinegar should be sanitized. Soak everything for 20 minutes in a solution of 2 tablespoons chlorine laundry bleach to 1 gallon of water
- Dilute wine to 5.5-7% alcohol with water
- Fill sterilized containers about 2/3 full
- Add bacteria cultures
- Leaving wine exposed to air may sometimes start the process, but it is very risky because some other organisms may grow
- It is recommended to order pure cultures of bacteria sometimes called mother of vinegar
- They can be purchased in any store that supplies wine-making equipment. It usually comes as a clear liquid in a jar (Figure 3)
- Cover the container with a cloth to keep the insects out while allowing air to freely reach the stock (Figure 4 and Figure 5)
- Two factors require special attention when making vinegar at home:
- Oxygen Supply
- Between 80-85°F is ideal
- Low or fluctuating temperatures slow the process
- High temperatures will kill bacteria
- Formation of the Film
- Living bacteria are in the liquid
- They can be used to start the new batch of vinegar so it is not necessary to purchase new starter bacteria
- Full fermentation will take 3-4 weeks
- Filter vinegar through a layer of cheese cloth to remove formed film-mother of vinegar, before pasteurization
- Heat vinegar before pouring it into sterilized bottles
- Bottle and place in hot water bath
- In both cases, the temperature of the vinegar must reach at least 140°F and should not exceed 160°F and should be held at that temperature for at least 30 minutes
- Stored vinegar will stay in excellent condition almost indefinitely if it is pasteurized.
- Vinegar has a strong, sharp bite when it is just made
- It becomes mellow when aged
- It usually lasts 6 months or longer when stored at cool, steady temperature (50-60°F) (Figure 8)
- This undisturbed rest also allows suspended solids to fall, making the vinegar clear and bright
- Once vinegar is ready it should be kept away from oxygen because acetic acid could be converted into water and carbon dioxide
- Flavoring can be added to homemade vinegar just before bottling
- Some additives can include: garlic, ginger, or any combination of dried, fresh herbs
- Place flavoring material in a small cheesecloth bag and suspend in vinegar until the desired strength is reached
- It will take approximately 4 days, except for garlic, which takes only 1 day
- Wine or cider is fermented in wooden barrels or covered vats.
- There are screened air vents located in the top part of the container.
- Vents are screened to prevent Drosophila.
- A starter culture is put into the container, and the fermentation is continued until the certification is complete.
- About 3/4 of the vinegar will be drawn off and replaced with fresh wine or other fermentable liquid.
- The process will keep repeating itself as long as quality vinegar can still be produced.
- This process is very slow (several weeks) and is usually done in small batches (Figure 9, Figure 10, and Figure 11).
Rapid-generator Process (Schutzenbach)
- Fermentation is done in a container that consists of two chambers.
- The larger (upper) chamber is packed with solid materials almost to the top (wood shavings, corncobs, etc.) (bacteria attach to it).
- The upper chamber is separated from the lower chamber by a screen.
- Air is injected and blown upward through the screen and through the solid materials, and the air escapes through the top.
- The fermenting liquids are distributed evenly over the top of the material and allowed to percolate through the material.
- The resulting liquid is then pumped back to the top and recirculated until the alcohol content is reduced to 1/2 percent.
- The vinegar is drawn off and fresh alcoholic solution is added.
Frings Acetator or Generator
See Figure 12.
Submerged Culture Fermentation (Bubbling)
- First was developed during World War II for the production of penicillin
- Tiny bubbles of air are passed through the solution of ethanol
- Agitated by propellers, dispersing cells of acetic acid bacteria
Essentials for Vinegar Generator
- Must provide for the introduction of fresh substrate without disturbing the content of alcohol or the surface growth
- Must provide easy sampling for titatration
- Must protect system from contamination
- Must have means of temperature control
Rate of Acetic Acid Production
- The inherent capacity of Acetobacter aceti to convert alcohol to acetic acid
- The amount of ethyl alcohol (6-8% optimal, 12% tolerated)
- The temperature (80°F optimal, 68-96°F range)
- The amount of aeration of surface area of the growth material
Publication date: July 28, 2022
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This publication printed on: March 27, 2023