Filtration in the Winery
Every year, after harvest and punch downs, winemakers have to make an important decision – to filter or not to filter. Located within the lees is often a high percentage of recoverable product that many would like to use to boost their bottom line. For some vintners, as much as 10 percent of their winery’s volume comes from that sediment, an amount they’d prefer didn’t go to waste.
However, if you ask twenty different winemakers their opinions on wine filtration, you’ll get twenty-one different answers. Some prefer no filtration. Some prefer moderate filtration. Some prefer instead to fine their wines. The goal for all winemakers is the same – spectacular tasting, clear wines with no impurities. Their decision will be based on the wine that they are making. Early drinking wines should be filtered to avoid deposits settling in the bottle. For full-bodied reds, you may want to let time be the judge. Having sediments in a bottle of red wine is generally accepted, however, with proper fining, you can still get clear red wine.
No matter what method a vintner uses, it will require specialized equipment. Fining requires an absorptive clay like Bentonite, or, in some cases, egg whites. Filtering requires a filtration system that can handle the winery’s production levels. For those who choose this route, proper research and a list of priorities will assist in selecting the right system for their winery.
Small Scale Production
Smaller wineries with less capital to invest in filtration may use a plate and frame filter press. This filter consists of many plates and frames put together back-to-front and then front-to-back. A centrifuge pump ensures the solids don’t settle in the press. Its main function is to separate out the hard solids. There are a variety of sizes of filters for differently sized wineries: 20 plate filter with 12 or 20 plates; 40 plate filter with 30 or 40 plates; 60 plate filter with 60 plates; or 80 plate filter with 80 plates.
Smaller wineries with less capital to invest in filtration may use a plate and frame filter press. This filter consists of many plates and frames put together back-to-front and then front-to-back. A centrifugal pump ensures the solids don’t settle in the press. Its primary function is to separate the hard solids. A variety of filters are made depending on the needs of the winery, ranging in size from 20, 40, 60 or 80 plate filters.
“I currently use a plate and frame filter for my initial filtering and then a cartridge filter for finishing,” said Micole Moore, co-owner and winemaker at Ramona Ranch Winery in Ramona, California. “The pros for plate and frame is that you have a lot of filter plates so you can filter more wine, and the cons are it takes a while to hydrate the plates and while you filter, wine tends to leak out the bottom. [However], it was affordable and serves my purpose.”
The plate and frame filter is somewhat labor intensive. Before getting started, plates need moistening, and someone has to change them as they fill with filter cake particles. The machine must be monitored by staff for this purpose, and afterward, cleaned manually.
“Just be careful because filter pads clog and will require changing. If you don’t monitor them, you may be in for a long night of filtering,” Moore said.
A definite advantage to plate and frame filtration is that it can be done on a small scale, reclaiming wine or juice from 50 to 100 gallons of lees. For a small operation, that might be enough to stretch to another barrel. There is also less risk of oxidation than the rotary drum vacuum systems.
Medium Scale Production
For vintners ready to graduate to a larger and more effective system, Ken Kosmicki, Project Manager and Equipment Sales for Della Toffola Group, recommends an MTW crossflow filter. “These machines are able to filter for a variety of needs. They’re very effective for filtering high solids such as lees. Crossflow filters are the most popular machines nowadays.”
Ideal for filtering wine, must and vinegar, cross-flow filters rely on ceramic membranes to ensure an effective micro-filtering process. The hollow fiber membranes are either polypropylene or polyethersulfone, depending on the application. Both are resistant to a wide range of chemical agents, heat action and mechanical stress, thus requiring less filter change-out and repairs.
“We are able to filter out more difficult to filter particles,” Kosmicki said. “We can filter up to 30-35 percent of solids into the machine and give back 85-90 percent concentration.”
MTW crossflow filters are made with AISI 304-316L stainless steel with Viton silicone seals. They come in various sizes containing between two and 36 modules and can be customized to suit the winery’s needs. Also, unlike the plate and frame filter, the MTW crossflow filter is fully automated and does not need in-person monitoring.
“Our machines are fully automatic; they can be fully monitored via the internet with your Android cell phone or a tablet remotely. You set the volume of flow, press play and continue on with your day,” Kosmicki said. “Yes, the capital outlay is significant, but when you are doing a cost analysis, you have to keep in mind that you’re not paying someone to sit and monitor the machine for hours on end. Other systems are very labor intensive.”
The ability to monitor the machine from anywhere also has benefits when repairs are needed. “I’ve had many winemakers call me, and I’m able to analyze their system right from my cell phone. I can tell them what to do immediately. This saves the expense and time delay of waiting for a repair person to arrive,” said Kosmicki.
Automation also extends to maintenance as well. “Our machines are also auto-cleaning,” Kosmicki said. “You don’t need to have anyone around the winery to monitor the machine. It even runs a permeability test to show the operator how clean it is.
With proper care, the MTW will last for decades, according to Kosmicki. “We guarantee the membranes for ten years. I have some clients who have had their machines for twenty years, and they’re still running like a pro.”
Large Scale Production
Rotary drum vacuum technology is standard for large wineries as well as mobile services, but are appropriate for any size winery. These filters feature a stainless steel drum with a screen on the outside and a partial vacuum on the inside. The drum, coated with diatomaceous earth, provides the filter medium and is positioned in a trough through which the wine flows and traps any solids.
A drum vacuum system has a rate of production as fast as 1,000 gallons of lees per hour. The rotary vacuum can handle very sludgy lees without clogging, thanks to the automatic scraper blade that eliminates the waste substances with every turn of the drum.
A single electric control panel manages all inspections and adjustments for the drum vacuum. Winemakers can inspect the drum to ensure cleanliness and proper sterilization. Its aneuverability makes it easy to store when not in use.
A potential con to the drum vacuum system is that the diatomaceous earth can have a subtle but noticeable effect on the wine flavor, which may require further work by the winemaker. Also, some exposure to air is inevitable, risking oxidation.
Purchase Versus Rental
For those wineries who cannot afford larger machines, various companies throughout wine regions will bring their services to you. Winesecrets in Sebastopol, California is one such company, offering a variety of services, including testing. If you suspect something is wrong with your wine, but aren’t sure what, send a small lot to the Winesecrets Test Track to find out.
After conducting bench trials on multiple parameters, (often completed in one business day) they can ultrafilter the wine to intensify color, or, add or remove alcohol to perfect the wine’s structure. With their many different systems, they will come to your winery and help you handle your winemaking needs.