Researchers working on sulfite-free wine

Sulfites are a common ingredient in wine, whether it is naturally occurring during the winemaking process or purposefully added by producers to preserve freshness or enhance the flavour in a vintage wine. They are a class of compounds including sulfur dioxide and sulfite salts and, although they act as antioxidants and antibacterial compounds, they may also cause negative health effects for those who are intolerant to them.

The US Department of Agriculture suggested that symptoms may include chest tightness, hives, stomach cramps, diarrhoea and breathing problems, but the reason for intolerances has not been wholly understood.

“For some individuals, though, the sensitivity to sulfites may be an allergic type of response. People with asthma appear to be at an increased risk of having asthma symptoms following exposure to sulfites,” the Department noted.

To prevent these symptoms from occurring, any wine containing over 10 parts per million (10 ppm) of sulfites that is sold in the US must have a label that states ‘contains sulfites’.

But researchers from the University of Kansas (KU) School of Engineering are hoping to stop people with intolerances from being restricted to buying and consuming certain wines. They are working on developing a low-cost, easy-to-use device that attaches to the bottle and can filter up to 99% of sulfites from any wine as it is being poured.

“Our idea is that you’d have a device like an aerator,” explained Professor Mark Shiflett, leader of the investigation. “And it would be inexpensive. When you’re at the cash register you’d have these devices for sale. They’d be a dollar or less. You’d buy a handful. With every one sold, KU would get a fee back.”

Shiflett suggested that while there are other commercially available products which claim to remove sulfites, they are not always effective and are expensive to buy. According to Maddie Lyda, an undergraduate senior in chemical engineering, tests on samples on the market have revealed they only remove only about half of sulfites.

Currently, possible processes to remove sulfites involve putting drops of a chemical in the glass of wine, pouring wine through a filter on top of the glass or stirring a filter through the wine.

“We’re doing a chemical separation — where the wine passes through a material that acts like a magnet for the sulfites,” said William Gilbert, a postdoctoral researcher in Shiflett’s lab. “These are materials that if you were to look at the atomic scale you would find chemical sites that specifically bind sulfites so they don’t pass into the wine glass.”

But Shiflett specified that it would selectively bind to the sulfite alone, leaving other components of the wine, like the sugars and the tannins, unaffected. This should ensure the quality of the wine is maintained and, when attached to the bottle, make it an easier method of sulfite removal that would appeal to consumers.

The aim is to develop a product that has a strong business model; it should spark an ‘entrepreneurial spirit’ in the KU researchers and enable them to invent something that could market and sell, but it should also be inexpensive for consumers.

“You need it at a price point where it will sell and it will be really effective,” said Shiflett. “We want something that takes out 99% of sulfites and doesn’t put anything into the wine. A year from now, maybe we could go onto Shark Tank or go to a big wine producer like E & J Gallo Winery and say, ‘Look — a box of wine could come with one of these sulfites filters on the end of it.’”

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