A wash can be infected and have the ethanol converted to vinegar by a bacteria (can't remember the strain off the top of my head).
The question is:
At what %abv does a wash have enough ethanol in it to prevent this infection?
Wash turning to Vinegar
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MyDBear
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The strain is most likely acetobacter. These bacteria are principally airborne, but are also carried by the so-called vinegar fly. Now to try and answer your question.
The only difference between the best wine that you have ever made and the best vinegar that you will ever make is the type of yeast that is used. Wine vinegar is a wonderful product that you may want to try to make. There are two steps involved in vinegar making. These are sugar to alcohol by yeast fermentation, and alcohol to acetic acid by bacterial oxidation. Any liquid with a sugar content of 5 to 20% can be made into vinegar if the right steps are taken.
The first step is turning the sugar to alcohol by the action of the yeast feeding on it. This is the same step as wine making, but not so critically controlled. There are natural yeasts in the air that usually inoculate the liquid to be fermented. A more exacting method would be to inoculate with yeast that is proven for wine making. Wild yeasts do not usually survive an alcohol content above about 12%, but select strains can survive up to 16 percent. At the end of the fermentation process the resulting amount of alcohol is approximately one half the original sugar percentage (actually 1 to 1.75). This is assuming that the yeast was able to survive till the sugar was all fermented. In other words higher sugar content makes stronger vinegar, up to a point.
The fermentation process is an anaerobic one, meaning “without oxygen”, so it must be excluded until fermentation is complete. The unfermented juice, known as “must” is allowed to have oxygen for a few hours prior to the fermenting. This gives the yeast a chance to multiply before going anaerobic. To accomplish anaerobic conditions, the must has to be contained in an airtight container but vented. The venting is to allow carbon dioxide (a byproduct of the fermentation) to escape. A water trap is used to create venting without allowing oxygen back into the vessel. It works by allowing the greater pressure carbon dioxide to bubble through the water column to the atmosphere.
A trap is available from wine making suppliers or you can make your own. I suggest clear vinyl tubing that can be tied into a large knot with the bottom part filled with water. A good container is a plastic 5-gallon food bucket with a tight lid. Another possibility for a small quantity would be to use a narrow-mouth jug covered with a piece of plastic wrap and a loose rubber band. This should allow any excess carbon dioxide pressure to escape without allowing the oxygen back in the jug. As the must ferments you can see bubbles passing through the water. For the first few days, a trap may not be necessary because the sheer volume of carbon dioxide emitted by the must will exclude any oxygen. Keep an eye on the water level of the trap for the first week, as heavy bubbling can often bump the water out or evaporate it all. The yeast is most active at temperatures between 70 and 90 degrees F., with little happening outside of this range. At these temperatures, fermentation should be complete in about 12 to 20 days. I have found temperatures of 55 to 65 degrees F. to be satisfactory and fermenting complete after about a month. You can tell fermentation is complete when the bubbling ends. Careful observation is required and the bubbling is very slow towards the end (one bubble every 15 minutes or less). This will be hard to see since about all that can be observed is a slow displacement of the water column in the water trap. When this point has been reached it is now time for the second step.
Step number two is converting the alcohol content to acetic acid by the acetobacter bacteria. The bacteria live on the alcohol they oxidize into acetic acid. This process is an aerobic one and as much oxygen as possible must be made available to the bacteria. The easiest way to do this is to fill a container such that a relatively large surface compared to the liquid volume is available to the air. For example, half-filled gallon jug, or even better, a half-full barrel on its side. Make sure to protect the container opening against insects such as fruit flies, sour beetles, flies, etc., with a piece of cloth or other air permeable material. To speed up the natural bacterial colonization process, vinegar “mother” from a previous vinegar making project can be added. “Mother of vinegar” is simply a massive colony of acetobacter. In commercial vinegar making, the alcoholic liquid is trickled down a tower of charcoal or wood chips, on which the bacteria colonize, while air is forced up the tower. By the time the liquid gets top the bottom it has been converted to vinegar.
The final strength of the vinegar will be dependent on the alcohol content of the feed-stock. The acetic acid content will be about the same as the original alcohol percentage. Thus vinegar of 12 % acetic acid would be possible from a "wine" of 12% alcohol content. Commercial vinegar is standardized at 5%, generally achieved by watering it down.
What happens when a fermentation or acetification gets stuck (fails to reach the desired end point)? Take the case of cider vinegar. The fresh cider begins to turn hard or alcoholic, but at the same time an acetobacter contamination begins to feed on the resulting alcohol. The yeast cannot tolerate the acid generated and stops working before converting all the sugar to alcohol. When the bacteria runs out of alcohol, the mixture stagnates as a partly sweet, partly sour slop. No amount of aging ever improves it.
The addition of fresh cider will do nothing as the acid again stops the yeast and the end result is more of the same. I read recently that this can be remedied by the addition of sulfur dioxide to kill the bacteria and re-inoculating with yeast (see a book on wine making for more about bacteria and re-inoculating with yeast). It is much easier to maintain a degree of cleanliness beforehand than trying to fix the bad result. After many years of making vinegars with much variability and with about a 20% failure rate, I've learned the necessity of first fermenting and then oxidizing. Since then, I've had very high quality vinegar. One cautionary note: Do not use a barrel that has been used previously to make vinegar for the fermentation step. Otherwise, you risk contamination of the yeast mixture with acetobacter. This barrel is excellent for the acidifying process as it is already inoculated. Another thing that may happen is a stuck fermentation due to the cider not being at the correct temperature. Changing the environmental conditions should get it going again. If not, the addition of fresh cider and or new yeast may be necessary. I have never had a problem with acetification, but if conditions happened to be so sterile that bacteria didn't get in to the fermented cider, or someone forgot to remove the water trap to let oxygen in after the fermentation was finished, the liquid could remain a wine until conditions were changed.
Making other fruit flavored vinegars can be done two ways. One by juicing and fermenting the fruit as with apples or grapes,or by combining the flavoring fruit or juice with apple cider or grape juice and fermenting it. The other way, and the more commonly mentioned method, is to use a finished vinegar and infuse a mashed flavoring fruit such as raspberries in the vinegar for about a month or so in a tight container, then decant it. This method is also used for herb-flavored vinegars.
I once heard a story about a person making 2 barrels of cider vinegar. One barrel turned out fine while the other never turned to vinegar. What they didn't know was that during the winter somebody else had gotten into the one barrel and drank or siphoned off all the unfrozen liquid. This liquid, known as applejack, is nearly pure ethanol or ethyl alcohol. The poor person never did know where all the "good" stuff went. Barring such unforeseen events, making vinegar should be a pretty straight-forward operation using the previous guidelines.
This might not be exactly what you were looking for but it will tell you how vinegar is made and you can take the steps nessessary to avoid making it.
The only difference between the best wine that you have ever made and the best vinegar that you will ever make is the type of yeast that is used. Wine vinegar is a wonderful product that you may want to try to make. There are two steps involved in vinegar making. These are sugar to alcohol by yeast fermentation, and alcohol to acetic acid by bacterial oxidation. Any liquid with a sugar content of 5 to 20% can be made into vinegar if the right steps are taken.
The first step is turning the sugar to alcohol by the action of the yeast feeding on it. This is the same step as wine making, but not so critically controlled. There are natural yeasts in the air that usually inoculate the liquid to be fermented. A more exacting method would be to inoculate with yeast that is proven for wine making. Wild yeasts do not usually survive an alcohol content above about 12%, but select strains can survive up to 16 percent. At the end of the fermentation process the resulting amount of alcohol is approximately one half the original sugar percentage (actually 1 to 1.75). This is assuming that the yeast was able to survive till the sugar was all fermented. In other words higher sugar content makes stronger vinegar, up to a point.
The fermentation process is an anaerobic one, meaning “without oxygen”, so it must be excluded until fermentation is complete. The unfermented juice, known as “must” is allowed to have oxygen for a few hours prior to the fermenting. This gives the yeast a chance to multiply before going anaerobic. To accomplish anaerobic conditions, the must has to be contained in an airtight container but vented. The venting is to allow carbon dioxide (a byproduct of the fermentation) to escape. A water trap is used to create venting without allowing oxygen back into the vessel. It works by allowing the greater pressure carbon dioxide to bubble through the water column to the atmosphere.
A trap is available from wine making suppliers or you can make your own. I suggest clear vinyl tubing that can be tied into a large knot with the bottom part filled with water. A good container is a plastic 5-gallon food bucket with a tight lid. Another possibility for a small quantity would be to use a narrow-mouth jug covered with a piece of plastic wrap and a loose rubber band. This should allow any excess carbon dioxide pressure to escape without allowing the oxygen back in the jug. As the must ferments you can see bubbles passing through the water. For the first few days, a trap may not be necessary because the sheer volume of carbon dioxide emitted by the must will exclude any oxygen. Keep an eye on the water level of the trap for the first week, as heavy bubbling can often bump the water out or evaporate it all. The yeast is most active at temperatures between 70 and 90 degrees F., with little happening outside of this range. At these temperatures, fermentation should be complete in about 12 to 20 days. I have found temperatures of 55 to 65 degrees F. to be satisfactory and fermenting complete after about a month. You can tell fermentation is complete when the bubbling ends. Careful observation is required and the bubbling is very slow towards the end (one bubble every 15 minutes or less). This will be hard to see since about all that can be observed is a slow displacement of the water column in the water trap. When this point has been reached it is now time for the second step.
Step number two is converting the alcohol content to acetic acid by the acetobacter bacteria. The bacteria live on the alcohol they oxidize into acetic acid. This process is an aerobic one and as much oxygen as possible must be made available to the bacteria. The easiest way to do this is to fill a container such that a relatively large surface compared to the liquid volume is available to the air. For example, half-filled gallon jug, or even better, a half-full barrel on its side. Make sure to protect the container opening against insects such as fruit flies, sour beetles, flies, etc., with a piece of cloth or other air permeable material. To speed up the natural bacterial colonization process, vinegar “mother” from a previous vinegar making project can be added. “Mother of vinegar” is simply a massive colony of acetobacter. In commercial vinegar making, the alcoholic liquid is trickled down a tower of charcoal or wood chips, on which the bacteria colonize, while air is forced up the tower. By the time the liquid gets top the bottom it has been converted to vinegar.
The final strength of the vinegar will be dependent on the alcohol content of the feed-stock. The acetic acid content will be about the same as the original alcohol percentage. Thus vinegar of 12 % acetic acid would be possible from a "wine" of 12% alcohol content. Commercial vinegar is standardized at 5%, generally achieved by watering it down.
What happens when a fermentation or acetification gets stuck (fails to reach the desired end point)? Take the case of cider vinegar. The fresh cider begins to turn hard or alcoholic, but at the same time an acetobacter contamination begins to feed on the resulting alcohol. The yeast cannot tolerate the acid generated and stops working before converting all the sugar to alcohol. When the bacteria runs out of alcohol, the mixture stagnates as a partly sweet, partly sour slop. No amount of aging ever improves it.
The addition of fresh cider will do nothing as the acid again stops the yeast and the end result is more of the same. I read recently that this can be remedied by the addition of sulfur dioxide to kill the bacteria and re-inoculating with yeast (see a book on wine making for more about bacteria and re-inoculating with yeast). It is much easier to maintain a degree of cleanliness beforehand than trying to fix the bad result. After many years of making vinegars with much variability and with about a 20% failure rate, I've learned the necessity of first fermenting and then oxidizing. Since then, I've had very high quality vinegar. One cautionary note: Do not use a barrel that has been used previously to make vinegar for the fermentation step. Otherwise, you risk contamination of the yeast mixture with acetobacter. This barrel is excellent for the acidifying process as it is already inoculated. Another thing that may happen is a stuck fermentation due to the cider not being at the correct temperature. Changing the environmental conditions should get it going again. If not, the addition of fresh cider and or new yeast may be necessary. I have never had a problem with acetification, but if conditions happened to be so sterile that bacteria didn't get in to the fermented cider, or someone forgot to remove the water trap to let oxygen in after the fermentation was finished, the liquid could remain a wine until conditions were changed.
Making other fruit flavored vinegars can be done two ways. One by juicing and fermenting the fruit as with apples or grapes,or by combining the flavoring fruit or juice with apple cider or grape juice and fermenting it. The other way, and the more commonly mentioned method, is to use a finished vinegar and infuse a mashed flavoring fruit such as raspberries in the vinegar for about a month or so in a tight container, then decant it. This method is also used for herb-flavored vinegars.
I once heard a story about a person making 2 barrels of cider vinegar. One barrel turned out fine while the other never turned to vinegar. What they didn't know was that during the winter somebody else had gotten into the one barrel and drank or siphoned off all the unfrozen liquid. This liquid, known as applejack, is nearly pure ethanol or ethyl alcohol. The poor person never did know where all the "good" stuff went. Barring such unforeseen events, making vinegar should be a pretty straight-forward operation using the previous guidelines.
This might not be exactly what you were looking for but it will tell you how vinegar is made and you can take the steps nessessary to avoid making it.
Be Patient God aint finished with me yet
