Article by By Matthew Swayne of PENN STATE
UNIVERSITY PARK, Pa. — An additive may help curb a chemical reaction that causes wine to look, smell and taste funky, according to food scientists.
The researchers added 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.”
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.
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.
Both types of chelators significantly inhibited the oxidation in the wine, said Kreitman, who worked with Ryan J. Elias, assistant professor of food science, Penn State; Annegret Cantu, director of research and development at VinPerfect; and Andrew Waterhouse, professor of enology, the University of California Davis.
“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.
The researchers analyzed the concentrations of iron and copper in white wine and also measured the amount of oxidation that occurred after the chelators were added to the wine samples. The wine was made from pinotgris, a variety of grape that is often used in white wines.