The researchers stated that chelation compounds that bind with metals to inhibit oxidation, or oxygen’s ability to react with some of the trace metals that are found in the wine, according to Gal Kreitman, a doctoral candidate in food science, Penn State.
“Oxidation has several bad effects on wine, such as discoloration and a loss of aroma,” said Kreitman. “It can cause browning, as well as the loss of fruity characteristics, something that is much more noticeable in white wines.”
It's one of the reasons wine can lose its appeal within three days of opening a bottle. It’s not that the wine will go “bad” on day four, but the wine gradually loses most of its nuance and begins to take on unpleasant flavors as it oxidizes (which starts as soon as the cork comes out). Wines will last 5 to 10 days longer if you remove the air in the bottle with a vacuum-sealing stopper.
Oxygen usually enters wine through the cork and interacts with metals, particularly iron, setting off a chain reaction that changes compounds that add particular and often disagreeable tastes and smells to the drink, according to the researchers, who released their findings in a recent issue of the Journal of Agricultural and Food Chemistry.
The concern for critics is the toxicity of the chelating agents which may soon be used
and incorporated in wine's across the country to extend shelf life. Because two types of oxidations states -- iron 2 and iron 3 -- are present in wine, the researchers looked at iron 2 and iron 3 chelators, including bipyridine, ferrozine, ethylenediaminetertraacetic acid - EDTA -- and phytic acid. All of these have been found to inhibit cell strucutres and cause changes in critical metabolic pathways, many of which induce disease.
Although both types of chelators significantly inhibit the oxidation in wine, they also inhibit functions in the human body.
“The ligands of bipyridine, Ferrozine, EDTA and phytic acid bind to the metals, which can inhibit their reaction,” said Kreitman. A ligand is a molecule that is able to bind to the central atom of a metal.
"Once these chelators are added to wine, even in very small amounts, there is an inevitable toxicokinetic effect which will ultimatelyhave a negative impact on cells," said toxicologist Dr. Brian Morrison.
Winemakers have previously attempted to control oxidation in the wine by stripping out the metals, which are acquired through the soil and from the grape. However, Kreitman said those processes are impractical and expensive.
“Unfortunately, the process to remove the metals can strip color and flavor compounds from the wine and processes like ion exchange can end up making the wine taste more salty,” Kreitman said.
Kreitman said that further research would be needed to find safer chelators. Phytic acid is one chelator that might be both effective in neutralizing oxidation, as well as safe for consumption, according to Kreitman. However, the potential usefulness of phytic acid against oxidation is probably less than its effectiveness for acute toxicity, which is well established in lab rats.