Also, see our Making Your Own Vinegar poster
So you now have read Part I and both know what vinegar is made of as well as what it can be made from. “Doing is knowing” so the next step is to make vinegar on your own! In this part II, we will discuss the steps you will need to set up and prepare your vinegar fermentation. These will include: choosing the type of vinegar you want to make, cleaning procedures, how to inoculate your vinegar, and which type of storage vessels to use.
What should you make vinegar from?
The answer is anything you want! Vinegar can be made from any type of alcoholic beverage. However, this doesn’t limit you to beverages which are regularly alcoholic, but rather you can also use any sorts of juices that you can add yeast to in order to create an alcoholic beverage.
The instructions here are general but I will address special issues with wine, beer, etc. as well as your own concoctions such as hard cider or mead.
First thing: cleanliness and vessel materials
Before you start we need to discuss some cleanliness issues as cleanliness often makes the difference between a successful or failed fermentation. In addition, we need to discuss the appropriate fermentation vessel materials since vinegar has special requirements that are more stringent than even alcoholic liquids.
As Part I stated, vinegar is an acid and it will attack and corrode many materials. In short, there are certain materials which you can use and others which are completely prohibited due to the danger of vinegar attack.
In addition, if you have a larger setup, any fasteners (such as screws and bolts), valves/spigots, as well as washers, etc. should meet these same specifications to prevent corrosion and contamination by metal salts created by vinegar corrosion.
Permitted vessel materials
Stainless steel (typically 304 or 316 grade) – do not use the zinc plated or galvanized steel found in many hardware stores. These are easily attacked by vinegar.
Glass – always a good option and you rarely can go wrong with a glass vessel
Plastic – The best option is always food grade high density polyethylene (HDPE). The plastic type initials are usually shown on the bottom of the plastic vessel inside the recycle arrows. Make sure the HDPE is FDA compliant food grade since there are non-food grade HDPE buckets (e.g. for paint). If there is any question, you can order them directly from a company like Uline or buy them at your local homebrewing store.
Wood – wooden barrels are classic for vinegar making. The hoop material on the outside should not matter.
Silicone (gaskets,o-rings, etc.) – the best material for food grade applications are food grade silicone type o-rings and gaskets.
Iron, bronze, brass, aluminum – these metals are easily attacked and corroded by vinegar. The danger is not leaks but rather metal salts created in the reaction with the vinegar that are both foul tasting and sometimes toxic. None of these should be in contact with the vinegar at any time.
Many plastics – While vinegar in store bottles can be in PP or PET type plastic containers, for most plastic vessels you buy, it is best to stay with food grade HDPE to be safe. Vinegar can corrode some plastics. Polycarbonate should not be used as it is attacked by vinegar and also is known for its bisphenol A (BPA) content.
Vinyl and Nylon – this mainly applies to o-rings, gaskets, or pumps. Vinegar corrodes both of these over time and they should not be used. If you are handling vinegar with gloves, use latex or nitrile.
As a final note, make sure the opening of your vessel is as wide as possible so it is easily cleaned and allows a large surface area for the mother to form.
I must emphasize the importance of cleanliness, which is important at all steps of making vinegar, especially if you are starting with a sugar solution to go to alcohol and then vinegar. With the alcohol fermentation, it can be easy for spoilage microbes to infiltrate and ruin your batch.
There are two parts to cleaning: cleaning and sanitizing. Cleaning is the act of washing the vessel to remove any visible dirt and material, similar to washing dishes. Sanitizing is the act of using chemicals to kill any microbes that may spoil your fermentation.
First, you must clean the vessel. For simple cleaning of materials you can use dishwashing soap, though preferably without perfumes to affect the taste. Homebrew stores have other specialty chemicals like percarbonates, often sold in powdery form to add to water.
Sanitizing is the killing of microbes and must be done after cleaning. Chlorine bleach, diluted in a ratio of one tablespoon per gallon of water, does a great job if soaked for at least two minutes, though fifteen is preferable. Amongst homebrewers, a common standby is Iodophor, which is mixed in a ratio of one tablespoon per five gallons of water. This can be easily used on all materials for quick and comprehensive sanitation. Iodophor contains iodine, however, so it is best not to use it if you have iodine allergies. A good alternative chemical in this case is Star San, also available at most homebrew stores.
Making alcoholic beverages
I will not cover this in detail here since there are so many resources around the Internet which give the topic of homebrewing or winemaking its just depth. For fruit wines, the forum at winepress.us has several topics that can be excellent guides to making wines from all types of fruits.
In short, you will need to add yeast to the juice in order to make it into vinegar. For any quantity up to several gallons, one packet of yeast from a homebrew or winemaking store should suffice. Do not use baking yeast found in grocer stores as that is specially selected for baking and poor in providing fermentation for alcoholic beverages.
There are several key things you need to determine before trying to make juice into vinegar though. First, is the rough sugar content. Sugar content is measured either by Brix (that measures sugar in grams per 100 mL of water) or specific gravity (that measures the juice’s density relative to pure water).
Determining sugar content is important since sugar content directly determines the alcohol content from yeast and finally alcohol content determines vinegar acidity. Too low of a sugar content will generate a weak vinegar that may both taste bad and not prevent spoilage bacteria.
For store bought juices, your job can be pretty easy. Look at the Nutrition Facts label and find the grams of sugar. Make sure you only use the grams of sugar and not the total carbohydrate grams. Next, divide this by the stated serving size in mL and multiply by 100. So for example, a typical orange juice has 23 g of sugar for a 240 mL serving size. This means the Brix is 23 / 240 x 100 = 9.6 Brix.
If you have homemade juice you will need a tool called a hydrometer
You drop the hydrometer in a graduated cylinder filled with the juice and it rises and floats relative to the sugar content. The reading on the hydrometer at the surface of the juice will tell you your Brix/specific gravity.
From this, you can use a table like the one here to determine the potential alcohol your yeast can produce. For vinegar production, you want a minimum of 4.5% potential alcohol and a maximum of about 8% so you need a Brix/specific gravity roughly between 9/1.035 to 14/1.055. Note this maximum alcohol is much lower than your typical wine.
If the Brix is high, unlikely unless you are starting with a syrup like maple or honey, you can add water to dilute it to the correct level. The equation for the water to add given your desired Brix is:
Volume of water = Volume of Juice or Syrup x (Current Brix – Target Brix) / Target Brix
Make sure that the volume of water and juice are in the same units when you calculate.
If the Brix reading is low, you have two options. One is to add sugar to increase the Brix. Regular refined or raw sugar will do. The amount of sugar you need to add for a desired Brix is:
For every 1 Brix increase: 1.5 oz. Sugar x Volume of Liquid / 1 Gallon
The second option is to boil the juice down. This means placing the juice in a pot on the stove and boiling the juice until the liquid level is reduced. Since the water boils away but the sugar remains, the Brix increases as the liquid volume decreases. Given the starting and ending volume of your juice, you need to reduce the volume per the next equation:
Final juice volume = Starting juice volume x Staring Brix / Final Brix
Now that you have adjusted the sugar to the correct level, you are ready to add brewing yeast to the batch to produce alcohol.
Using alcoholic beverages
If you are starting with wine, cider, mead, beer, etc. your job is much easier. In the case of beer, you don’t need to do anything. Just remember that beer is typically lower alcohol so you want to use a beer of at least 4.5% ABV to get an appropriately acidic vinegar.
For wine, with ABV between 12-14%, you will have to first remove sulfites and then dilute it down. Sulfites are added to wine specifically to prevent the reactions that allow the formation of vinegar. They are easy to remove though. Stirring for about thirty minutes is the oldest way to help the sulfites escape as a gas. A quicker and safe way is to add a small amount of standard 3% hydrogen peroxide. For one 750mL bottle of wine, ½ teaspoon is enough. Add the hydrogen peroxide, stir for a few seconds and the sulfites are removed.
Next, is dilution. Vinegar making bacteria are not effective above 10% ABV and most wine vinegars are 7-8% acidity max. So you need to dilute your wine with water (and mother of vinegar as will be described later) to an appropriate alcohol level. To dilute the wine to the desired ABV with water and mother of vinegar:
Combined volume of water + mother of vinegar to add =
Wine volume x (Starting ABV – Final ABV)/Final ABV
So to get 7% ABV from 14% ABV wine, the combined water+mother should be equal to the wine volume. To go from 12% to 5%, the volume should be 1.4 times the volume of wine.
Please note the vinegar conversion is not 100% efficient so usually the final acidity is around 90% of the starting ABV. So your target ABV should be your target vinegar acidity divided by 0.9.
Starting your vinegar
Now the alcoholic mash is prepared, you are ready to start your vinegar. In order to start your vinegar you must add the mother of vinegar. This is available in several forms. First, there are commercial mothers of vinegar such as those sold by us through Amazon or homebrew outlets. These are grown to produce especially vital cultures and are filtered to remove harmful spores that may cause mold etc. There are also the raw vinegars you can find at the grocery store such as the common raw apple cider vinegars.
The advantage of mothers designed for vinegar making is the amount of solid mother is larger and the vinegar is fermented in a specialized industrial process that maximizes the amount of bacteria for fermentation. Store bought raw vinegars can be fine though (honestly) they can be less consistent partially due to the manufacturing process (submerged process) that is biased towards cultivating bacteria that need a rapid and ready supply of injected oxygen. Many of these can survive but it is not consistent since the health benefits of the vinegar do not vary with the vitality of the mother bacteria. They may also require more time and bias your vinegar towards an apple cider flavor.
They can also take a bit longer to get started in fermentation and building a mother. This was a fact I have found when the vinegar bacteria from different sources and manufacturing processes are cultured on petri dishes media for RNA analysis (another topic for another time).
However, you choose, adding the liquid mother (with solids) should be done as follows:
1. For wine or alcohols with ABV between 6-15%, the dilution should be done as per the previous section adding water and mother in equal proportions to set the volume needed to dilute the wine to the desired ABV.
2. For alcohols between 4.5-8%, if you want an acidity near to the ABV, you do not have to add water but just add mother in a proportion 1:1 between the mother and alcohol.
Add the mixture to your fermentation vessel and then cover it with something such as cheesecloth or a thin towel. You need the cover to be air permeable as the vinegar fermentation requires oxygen, however, you want it to be snug, tied with a string, so no pests such as fruit flies can get in and begin to breed.
Then sit it in a warm place and wait for your mother to form. The initial lag can be as quick as 2 weeks or as long as six weeks depending on factors such as the bacteria type, temperature, and the amount of nutrients in your alcoholic mash.
Update February 2018: Want to make vinegar even faster? Please see our new post on the semi-quick (Boerhaave) process.