Sodium Bisulfite is a very valuable and versatile product that plays several key roles throughout the wine making process. It is used, almost without exception, in all commercially made wines.
What is Sodium Bisulfite Used For?
Among its many uses are: purifying fresh juices before the fermentation begins; using it in heavier doses with water for sanitizing bottles and equipment as needed; and, adding it to your wine at bottling time to reduce some of the negative effects of storage such as oxidation and deterioration of flavor.
What Is Sodium Bisulfite?
For the sake of keeping this article in layman terms, Sodium Bisulfite is essentially very fine crystallized sodium granules that release sulfur gas when it is dissolved in a liquid. This sulfur gas permeates the liquid it was added to and then eventually dissipates into the air over the coarse of several hours.
The sulfur gases that are released from the Sodium Bisulfite act as a sanitizer, killing wild molds, bacteria, germs and other unwanted little nasties. The sulfur gases also help to preserve the wine by displacing any air that may be saturated in the wine. The sulfur gas is not so strong as to smell up the whole house, but its odor is noticeable when standing next to a liquid that has been treated.
It is important to note here that Sodium Bisulfite is also the active ingredient found in Campden Tablets. Each Campden Tablet equals 1/16 of a teaspoon of Sodium Bisulfite, or to put it another way, it takes 16 Campden Tablets to equal one teaspoon of Sodium Bisulfite. So, when we talk about Sodium Bisulfite you can think of it as being interchangeable with Campden Tablets.
Sodium Bisulfite is also interchangeable with Potassium Bisulfite. It comes in the same crystallized form as Sodium Bisulfite, and the dosage is measured the same. The main difference is the active sulfur is stabilized in potassium instead of sodium.
Sanitizing Fresh Juices With Sodium Bisulfite
You can add Sodium Bisulfite in lighter doses directly to any fresh wine making juices before fermentation to sanitize them. These fresh squeezed juices can contain a whole host of contaminating organisms, along with the natural yeast. These micro-organisms, if allowed to grow, pose a threat to your wine by way of spoilage.
Normally, the yeast that comes naturally in the juice is able to handle the situation on its own by overtaking the juice and destroying any possibility of having a contaminating growth. But, this does not always happen.
If the yeast is not put in a healthy situation for what ever reason, or the amount of yeast being naturally provided is not enough, then it can not take over the juice as normal. This in turn gives opportunity to any micro-organisms that may exist to multiply and eventually spoil the juice.
By adding a light dose of Sodium Bisulfite in the very beginning --1/16 teaspoon per gallon--you are then essentially destroying all of the organisms in the fresh juice, including the natural yeast. You are starting with a clean slate--so to speak. Over a 24 hour period the sulfur gases dissipate into the air after which time you can add a fresh package of domesticated wine yeast of your choice.
IT IS IMPORTANT that you wait 24 hours before adding the yeast. And, that during the 24 hour period you leave the juice open to air so that the sulfur gases do not remain trapped in the juice, but rather, dissipate into the air. If this is not done the sulfur gas in the juice will destroy the newly added yeast.
As a side note, if you are making wine with packaged juices then a Sodium Bisulfite treatment is not required. It is only fresh juices that require this treatment for a sound fermentation.
Sanitizing Equipment With Sodium Bisulfite
Sodium Bisulfite is also useful in stronger doses with water for sanitizing your equipment. The recommended dose is 1 teaspoon of Sodium Bisulfite per gallon of water.
It is also recommended that either Citric Acid, Tartaric Acid or Acid Blend be added to the solution at the rate of 1/2 teaspoon per gallon. This is not necessary, but if used these acids will increase the potency of the Sodium Bisulfite solution by causing the sulfur gases to release more rapidly.
When using this solution to sanitize items such as fermentation vessels or wine bottles it is not necessary to fill the container completely full. This is because the fumes off of the solution are what do the sterilizing.
For example, only 1 or 2 inches of the solution is required in the bottom of each wine bottle. And, in a typical 5 gallon glass carboy 3 or 4 inches is sufficient.
If you have other pieces of home wine making equipment to sanitize such as stirring spoons or siphoning hoses, you can throw them into a wine fermenter that is being sanitized and seal it up with the lid for 20 minutes or better.
When sanitizing wine bottles just put one or two inches in each bottle right before bottling and let stand for 20 minutes. When you are ready to fill the bottles with your wine, just dump the solution out and let drain for a minute or two--rinsing is not required.
You can safely store any remaining sulfite solution in an air-tight container for several weeks between uses. However, this is not recommended if an acid has been added to the solution as described earlier. This is because the acid will cause the solution to loose its potency at a very rapid pace.
Preserving Your Wine With Sodium Bisulfite
Sodium Bisulfite is also very helpful for preserving a wine during storage. Excessive oxygen is wine's major enemy during this time between fermentation and consumption. Too much oxygen can cause a wine to turn brown or slightly orange. And, it can also bring about a flavor in a wine similar to raisins or in more extreme cases old fashion cough syrup.
Adding Sodium Bisulfite to a wine right before bottling will help to eliminate these oxidative effects. And, will help to preserve the wine's overall character.
It does so by driving out any excessive oxygen that may be saturated into the wine. The sulfur gases from the Sodium Bisulfite displaces the oxygen and later permeates the air space in the wine bottle as well.
The recommended dose of Sodium Bisulfite is 1/16 teaspoon per gallon of wine added to the wine right before bottling.
Using Sodium Bisulfite During Racking
Some sources recommend adding Sodium Bisulfite to your wine each time it is racked (siphoned). This is done to the wine to displace any oxygen that may have been absorbed during the siphoning process.
I would strongly recommend against adding Sodium Bisulfite during rackings. But, if you do decide to do so, you should verify with a wine hydrometer that the wine has completed its fermentation.
And even then, I would still suggest that you only add approximately half the dose that is typically recommended. Instead of using five 16th teaspoons for five gallons, reduce the dose to two or three 16th teaspoons for every 5 gallons. And, never would I recommend adding Sodium Bisulfite to a wine that is still fermenting under any circumstances.
The real problem with adding Sodium Bisulfite during racking is you run the risk of killing the yeast in a must that has not yet completed fermentation. That is why checking the wine with a hydrometer first to verify that the fermentation is complete is essential.