Calcium Tartrate is often confused with calcium chloride. Calcium Tartrate is actually a by-product of the wine's industry, made from crushed white wine fermenting cherries. It's the calcium salt of L - tartaric acid, a naturally occurring acid usually found in grapes. Tartrates (or "calcium carbonate") are a common component of wine, particularly white wine, rose wines, port and sherry. They are often removed during the secondary fermentation process in order to preserve the higher alcohol content of these wines.
The calcium ions in wine are separated from the higher concentration of ferricyanide ions by a layer of tartaric acid. In older varieties of red wines, this layer tends to be thicker and is known as the Limanol layer. Limanol is formed by a process called chelation. Wine makers believe that the thickness of this Limanol layer, which can be almost two millimeters thick, contributes to its longer shelf life.
When these two layers come into contact, they become rough and slivery and, over time, can precipitate out of a wine's aging process and into the bottle. Because of this, some wineries remove the calcium tartrate and powder before packaging. Others leave it in the mixture during the winery's fermentation process. Whatever the circumstances, once this powder and or layer of tartaric acid becomes precipitated it will begin to lose its carbon dioxide molecules and begin to slowly release its volume.
Problem solved by using calcium sulfate
Winemakers have been aware of this relationship between the calcium tartrate market and vintages for centuries. It was recognized some time ago that certain types of white wines were more prone to having calcium l-tartrates precipitated out of their wines. This problem was solved by manufacturers by adding trace amounts of calcium sulfate to their products, thus reducing the amount of calcium tartrate needed to make their wine distinctly acidic. This product became a market favorite and soon manufacturers were able to mass produce low priced sparkling wines that still contained large amounts of calcium l-tartrate.
It's possible that the calcium ions in wine are not the only elements affecting the flavor and aroma of the finished product. During the fermentation process, microorganisms cause other changes in the wine, producing additional organic compounds called tannins. As the microorganisms increase during the fermentation process, they convert sugars into alcohol, CO2 and other gasses. This process produces additional tannins which enhance the taste of the wine. It has been suggested that the concentration of these calcium ions is responsible for this effect. However, no definitive proof has been established.
In modern times, wine fermentation is carried out in stainless steel barrels where temperature and pressure are less important factors in determining the flavor and aroma of the final product. The concentration of calcium ions in the barrels used in the modern day wine industry remains the same as in years past. The concentration of calcium in the wine depends on factors such as the type of grape variety used and the type of maturation process used, including the length of time the grapes spend in the barrels. During the long months spent in the barrels, calcium tartrate crystals can form. These crystallized calcium ions impart a sharp and bitter taste to the final wine.
The Food and Drug Administration has acknowledged the existence of the calcium tartrate preservative, despite the fact that its use has been widely debated in the past. In fact, the FDA did not ban the use of this chemical until it was certain that there was enough evidence to justify its use as a food preservative. At the time of this writing, the FDA is still uncertain about the extent of the potential health hazards associated with the use of calcium tartrate and the overall contents of the substance in the vast majority of the beverages industry. In an effort to combat the fears generated by the reports and studies cited above, the FDA is currently testing regulated dietary supplements containing calcium tartrate. At this point, the results of this study cannot be said to be conclusive, but it is hoped that over the next several years the knowledge surrounding the dangers of the substance will have grown sufficiently to convince the FDA that the use of a preservative in these products is justified.
In summary, calcium tartrate is an inexpensive and safe food preservative. It has proven particularly useful in the food and beverage industry because it inhibits the growth of both yeast and bacteria. It can be added to many styles of wine, especially those produced in white wine barrels. The wine industry is certainly not the only one that uses this substance. Many different types of beers, breads, desserts and many other food products make use of a calcium salt mixture to inhibit bacterial growth. Because this compound is not considered to be toxic in small amounts, the use of this substance as a food preservative is not prohibited by law.