By: Cheryl Gray
Wine is a vulnerable product. From grape harvest to filtering the best from your fruit, the tools of the trade include filtration systems designed to tackle problems associated with mineral additions, oxygenation and other culprits that can threaten a wine’s flavor profile.
Experts in the winery filtration industry include Aftek Filtration Systems. The company, based in Rochester, New York, has been in business for nearly 40 years. Aftek works with multiple sectors in the food and beverage industry, including wine, beer, hard cider, distilled spirits and kombucha.
Jim Russell represents Aftek. He describes two common problems wineries must control and how Aftek can help.
“After selecting the correct media and proper processes to reduce or eliminate mineral addition or absorption, our next most common culprit seems to be oxygenation. It has been noted that with colors and flavors susceptible to oxygenation, this is something to minimize and eliminate.”
Russell also lists the problems that affect filtering wine.
“If we consider wine as a solution, certain additions may cause items in a solution to precipitate out as a solid. Adjusting brix levels and even the type of sugar (liquid vs. granulated) has seen drastic effects on filterability. Blending two different types of products may also cause a precipitate. Gum-arabic and certain ‘mouthfeel’ additives can be inherently difficult for membranes. Color-intensifier, especially crossflow-derived retentates, will not pass a membrane. Beta-glucans can also be problematic for membrane filtration and is hard to test for.”
Russell adds that looking at other areas, such as pad filtration and cartridges, while purging tanks and lines with gases, such as nitrogen, is a good idea.
“Cartridges are very good and neutral on absorption or minerality uptake, the limiting factor seems to be the volume to process for bulk solids. By selecting a pad (Eaton Becopad) that is water jet edges versus knife cut, we minimize leaking and not only have less loss but lower DO uptake. Going to the Becopad can achieve low to no drip loss and the lack of DE/perlite means no minerality uptake. These are also available in lenticular/modules. If you are looking for even higher processing in flow and volumes, consider the crossflow by Della Toffola. This equipment is going to give the highest quality with minimal effort.”
Russell cautions against cutting costs that may seem viable but could eventually cost more in the long run.
“Using fewer pads seems like you are saving money until you understand the mechanism being done in filtration. By reducing area, we increase flow per square meter, as the pads are designed to be about 0.5 bar or less on clean start-up.
This increase in flow causes soft materials to impact the matrix of the pads at high velocities, prematurely reducing the filtration area. It has been noted that in some cases, we have seen three flow times with double the area.
By targeting when you have multiple pad changes out per batch on certain varietals, it might be good to try to increase your area where possible. If this isn’t the case, it could be worth looking at using a slightly more open pad to reduce the loading.”
As for cartridges, Russell says it is important to protect the full life of your membrane filtration system.
“Premature clogging on membranes seems to be the biggest cause of not achieving full life on your membrane. Common factors include but aren’t limited to not pre-filtering tight enough, letting too much time pass from the last pre-filtering, improper enzymes for pectins or beta-glucans, improper cleaning, improper storage and unfilterable additions are a few of the most common.”
Aftek can also help with the selection of crossflow equipment. Russell says that because labor and materials costs have risen, crossflow for processing wines is an increasingly valuable weapon in a winery’s arsenal.
“Ceramic membranes are less impacted by pectin’s and can take more solid loading per area than their polymeric counterparts. The cleaning cycles done at higher pressure and the innate material strength lend to better regeneration. They also can take clay/bentonite fouling where the polymeric versions would be ruined. The selection of full-automatic systems also lends to less operator variability and better cleaning cycles.”
Filter Process & Supply is another company offering filtration products for wineries. Based in New Jersey, Filter Process & Supply works with its customers to help guide their processes of choosing the right filtration products. The company works with customers to deliver a timely shipment of filtration products and offers suggestions on ways to improve the filtration process. That includes working with clients to identify cost savings, increase throughput and provide technical support.
Peter Wojnarowicz, the company’s manager of applications, describes some other challenges in filtering wine.
“One of the biggest issues we see when reviewing existing applications is undersized filter equipment, causing you to have too much flow for too little surface area. This creates a flow velocity that can ultimately affect filter life. If you start with a high differential pressure, it could cause filter life to be cut short. There are exceptions, especially with viscosity-related products. The pore size of either synthetic or cellulose media can be affected by higher flows. If the pore size is below 1-micron, flow reduction is important for filter life. Impaction of the media at higher flows typically shortens the filter life.”
Wojnarowicz describes some of the solutions his company recommends and why those recommendations are important for wineries to consider.
“With wine, the maximum flow we tend to recommend is a 1/2 gallon per minute per square foot, but ideally, we would like to see a more conservative flow rate of a 1/4 to 1/3 gallon per square foot. So, for example, if we have a surface area on a 40cm X 40cm pad that is roughly 1.5 square feet, and we are using a 20-plate filter with same media throughout, the flow rate is seven to 10 gpm based on 30 square feet. With a divider plate using two-stage filtration, the flow would need to be lower.”
Next, Wojnarowicz describes multiple methods of filtering and clarifying wines.
“For smaller wineries, cartridge filtration and a small plate filter, typically a 20cm X 20cm, work well from 25 to 100 gallons, depending on how many plates are used. For larger volumes in the range of 200 to 1000 gallons, a 40cm X 40cm plate filter will work well, also based on the number of plates. Then, there are various-sized lenticular filters/stacked disc (same) filter systems. We have small, medium and large systems depending on the volume of beverage that will be filtered. We have been working with lenticular filtration and clarification in different industries for about 25 years.
For volumes from 500 to 1,000 gallons, a crossflow system is something that may be a good investment. Currently, we recommend cartridges, plate filters and lenticulars, and we will review the pros and cons of each in more detail with a customer.”
Choosing between stacked discs, plate fillers or lenticulars, Wojnarowicz explains, depends on the production needs.
“While both use the same media, plate filters have some drip loss, whereas stack disc systems are completely sealed. Higher pressures are attainable in stacked disc systems, which is good if the filtration run is nearing its end and a change-out can be avoided.
Typically, lenticular systems have a lower cost for the equipment but higher operating costs when compared to internally ported plate filters. To charge a lenticular, it could be up to four times the cost compared to charging a plate filter with the same square footage.”
Since lenticulars are closed systems, the wine, Wojnarowicz says, is subjected to higher pressures because it goes through finer pore sizes, which may lead to other problems.
“Potentially, higher pressures can strip out. We typically do not like to go above 20 psi when filtering. Pressures higher than that may be okay if the beverage run is near completion, but, if the process run is at a halfway point, it is probably better to change out and start with new media.”
Wojnarowicz adds that with proper training, minimizing drip loss in plate-filtered wine can be reduced to half a gallon or less.
The Vinter Vault, with two locations in California and a third in Texas, offers customers custom filtration setups, with the crossflow system being the largest. Company president Ryan Horn adds that The Vinter Vault also offers DE filtration, cartridge, plate and frame, as well as lenticular systems.
No matter what filtration system a winery installs, the goal is to produce wine with clarity and flavor that will maintain its integrity until it is uncorked and poured. Equally important is to perform filtration in a cost-effective manner by minimizing product loss through proper training and technique.
