New Wine Filter Medium Is Safer

Winemakers switching from hazardous DE to recyclable cellulose alternatives

by Paul Franson
A study referenced in the German wine magazine Der Deutche Weinbau in Sept. 2003 concluded that red wine filtered with Vitacel tastes significantly better than diatomite-filtered red wine.
Napa Valley, Calif.—Increasing concern about the safety of crystalline silica found in the popular filtering aid diatomaceous earth (DE) is causing many wineries to switch from fossilized diatomites in favor of other methods of lees and wine filtration.

OSHA and insurance companies are backing the choice. When crystalline silica is inhaled, sharp particles remain stuck in the lungs. This can cause silicosis and even lung cancer. Every bag of DE posts this warning and recommends the use of OSHA-approved personal protection equipment.

The insurance industry has written riders stating that companies using crystalline silica will not be insured. In California, an insurance company was sued when it denied payment to a worker who died of exposure to crystalline silica. The insurer argued that it was not obligated to pay because the worker’s employer had exposed him to crystalline silica, a known danger. The California court ruled in the favor of the insurance company.

Supplies down, cost up
In addition, according to World Minerals magazine, the supply of DE is dwindling and new restrictions on its use have caused a 4% to 12% price increase.

Winemakers have looked at perlite as an alternative filter aid. Rather than using the pores in fossils like DE, it contains scoops like a broken glass Christmas tree light bulb that slow and trap particulates. It’s an alternative to DE because of the cost and similar use, but even though perlite lacks crystalline silica, its particulates still present a health concern.

In addition it lacks the ability to provide precise particulate retention. Most often it is mixed with cellulose to adjust the size of particulates that are retained.

Many winemakers would prefer a cross-flow filter and/or a centrifuge, but their costs preclude this at most wineries.

Winemakers like cellulose
Some wineries have switched to a cellulose filter aid like Vitacel made by J. Rettenmaier, a German company. Vitacel is a cellulose fiber produced in a sustainable way from hardwood. It is biodegradable, contains no crystalline silica and requires no OSHA protective equipment.

Jerome Jacobs, western regional sales manager for J. Rettenmaier USA, said that Napa’s 12 million-case Treasury Wine Estates has abandoned DE for Vitalcel, and other companies such as Mumm Napa and 45,000-case Honig Vineyard & Winery also use it to filter their wines.

Tamra Lotz, assistant winemaker at 275,000-case Mumm Napa, said, “The main reason for changing was health and safety concerns for employees. DE came up as a potential safety risk, and we decided to make the switch.”

She added, “As a bonus, cellulose is biodegradable.”

Lotz remarked that so far, things have gone well with the cellulose. “We had to do some trials at first to determine the usage amounts, but we have it dialed in pretty well now.” Like other wineries, the Rutherford vintner is looking at cross-flow filtration as an option and has done some trials.

Honig Vineyards, also in Rutherford, switched to Vitacel a few years ago. “We did it for environmental and health reasons,” said winemaker Kristin Belair. “We didn’t feel comfortable working with DE. Even with all the precautions, there was a lot of dust around.” She did find that she had to replace the filter cloths on the lees filter.

Belair has considered cross-flow filtering, but it’s expensive. She’d prefer to gain more experience first, anyway.

John Giannini is the winemaker at Fresno State University’s winery. He said that he had two main reasons for changing from DE to Vitacel: safety and environment. “I work with students all the time, and didn’t want to threaten their health.”

He also liked the fact that he can compost Vitacel. “We had to put the DE in the garbage.” He said it does as good a job and he’s detected no off flavors.

The operation has also looked at cross flow, however, “It’s very expensive and we don’t have the money to buy it,” he said of the winery, which is self-supporting and receives no state funds.

Giannini said that cross-flow filtering could cause the wine to rise in temperature as it’s recirculated, although he thinks the technology is improving.

He also likes the way he can choose different sizes of filter pores with Vitacel. “With cross flow, you’re limited to 0.2 micron. With Vitacel, you can go from a couple microns to very tight.”

Vitacel also soaks up less wine and comes in various pore sizes. It’s softer and less abrasive, for less wear to equipment and lower maintenance cost for pumps, valves and filter cloth.

It has one disadvantage, however: cost. Jacobs said that the largest wineries pay 18 cents per pound for DE, and about 58 cents per pound for Vitacel. The differential can be less if true filtration costs are calculated looking at flow rate, throughput, labor, energy, water, number of filtration runs to get the clarity needed for final filtration, and disposal cost, even without factoring in vital health and safety issues.

Fresno State’s Giannini said he uses less Vitacel than DE—about two-thirds as much—but it still costs a bit more. “It’s worth it,” he said.

Honig’s Belair admits that the Vitacel is a little more expensive than DE, even though she can use less of it, but said, “It’s a good trade-off. I like my crew.”

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