By: Gerald Dlubala
Filtration of wines is absolutely a necessary and important step in winemaking,” says Massimiliano Buiani, Vice President Enological Sales for ATP Group. “But only if used and conducted in the proper way and manner, otherwise you will damage your wine.”
“Filtration is a very personal issue for winemakers because it is a process of endless possibilities,” says Buiani. “We filter wines for different reasons, including stability, aroma, clarity and overall aesthetics. There are different steps to take and different materials to use to filter wine to different levels. We can filter very aggressively or very fine. Some methods can tolerate mistakes better than others. We can filter at different speeds that will affect the process and subsequently the results. We can filter too tight at the wrong time, blocking membranes, damaging pads and cartridges, and ultimately adding cost to the production that wasn’t necessary. Filtering should be done step-by-step, slowly getting tighter and tighter as the process moves toward the winemaker’s goal. All of these variables affect the quality of the wine to some degree, and what works for a wine this year may not work next year because of all the variables that occur during the winegrowing season, both naturally and man-made.”
Filtration Methods Are An Ongoing Choice
“There are many types of materials to choose from for filtration, and they all serve purposes that the others may not,” says Buiani.
• Diatomaceous earth (DE) based systems are traditionally used for coarse filtration. The DE powder is added to the wine, clinging to the larger particles to make it easier to remove at a later time. It is a very forgiving way to filter wine, but it also absorbs a lot of product with it, too much in the opinion of many winemakers. There have also been recent health concerns raised over the handling of this powder so most wine producers are moving away from this method.
• The crossflow class of filtration is highly recommended by ATP Group and can be used with an endless type of membranes. Crossflow filtration is the latest and most popular technology, being completely automated, self-cleaning, internet-based and remotely accessible with the ability to run days on end without a stoppage. It was and is still considered the new frontier of wine filtration.
• Pad filtration systems are great for smaller wineries that can’t afford a high-end crossflow system. The pad filters are attached on vertical supports in a sandwich configuration. You have one system that can accept pads for different filtration settings from coarse to sterile. The downside is that these systems are more labor-intensive. They are non-automated, having to be manually cleaned, and the pads must be replaced after each use. They are also prone to leakage, translating to loss of product.
• Cartridge style filters are slid into housings, and able to be cleaned and used again, but that usefulness and ability to last longer are reflected in their increased cost over pad filters. Cartridge filtration is the best, most reliable option as a final safety check right before bottling, but it is also the most responsive, meaning small mistakes can turn into costly errors. It is in the winemaker’s best interest to take care and properly filter their product during all previous steps so that the final cartridge filtration catches very little, lengthening its lifespan.
• Centrifuges can be used in all wines, using G-forces of gravity to accelerate the process of separating the wine from the coarse particles. It provides in just fractions of seconds what we would have to wait months for gravity to do. And by the time gravity satisfactorily separated the liquid from the solid, the wine would be old and undrinkable. The downside of centrifuge use is their cost versus the limitations of the machine.
While all of these methods are valuable and useful in different situations, Buiani believes that a well-planned and implemented sterile filtration process is the formula for success. Just using one type or stage of filtration is not a proper solution. A combination of filtering processes is preferred, considering that choices of membrane, whether organic or ceramic, can affect the qualities of the wine. Buiani tells The Grapevine Magazine that experience matters.
“In today’s market, there is an abundance of over filtering and trying to get wine to market too soon, Over filtering turns into an extremely aggressive process, reacting negatively with aroma, flavor and color of the wine. The great winemakers recognize the correct process to get crystal clear, great tasting wine in the hands of the consumers while knowing that the methods proving successful this year may not be the answer next year. Each year’s harvest will vary, needing proper analysis to achieve great results.”
Mobile Filtration Helps Create Successful Wines
Along with selling filtration systems and accessories for every need in the winery, ATP Group provides a mobile filtration service that caters to those wineries that can’t or don’t want to invest in stationary filtration equipment. ATP Group uses its equipment and experienced operators on site to process volumes up to four thousand gallons within a ten-hour time frame.
Mobile lees and crossflow filtration are performed by the same units that the ATP Group sells. You’ll get all the benefits of a quality filtration system when you need it, saving you time and money by having the correct filtering units and experienced personnel come to your winery and perform all functions from setup through final filtration. Then, they’ll perform the cleanup and leave no trace that they were even there, except for that crystal clear, great tasting wine.
Koch Membrane Systems Deliver Crystal Clear Wines
“The amount of filtration needed during your wine production is a direct result of how your grapes are handled through harvest and crush,” says Nicholas Barretto, North American Wine Sales Manager for Koch Membrane Systems Inc. “Rough handling causes turbulence, which in turn causes more solids to be disrupted and in need of filtering. Although some high-end red wines are not filtered, sediment in the wine is just not very appealing to most consumers. Consumers want clarity, so filtration is necessary to remove the unwanted solids and deliver a crystal-clear end product. Equally important, filtration provides sterility, removing any remaining yeasts and bacteria that can cause secondary fermentation.”
Commonly used options include crossflow and pad filtration. Crossflow filtration uses a filter medium similar to what one may find within an HVAC system, but the orientation of the filter is different. In crossflow filtration, the filter medium will be situated perpendicular and on end to the flow of wine, allowing a lot of flow while being filtered.
Pad filtration is another option that allows different grades of pads, rated as coarse, medium and fine to be used during different stages of filtration to remove unwanted solids or polish a wine for clarity and color
“Think of wine like freshly squeezed orange juice with its pulpy, hazy appearance,” says Barretto. “It’s the same for the freshly squeezed wine. If you have months that you can just let your wine sit, it’ll eventually separate and filter itself just like that bottled orange juice in your refrigerator, with a clear separation between the solids on the bottom and the liquid above.”
To accelerate that settling, Barretto says that you can add Bentonite, a cleaning medium used for clarifying wines, liquor, beer, cider, vinegar and mead. When added to the wine, gravity makes it slowly descend while attracting other particles on the way to the bottom. It’s the same basic principle of gravity that is used in French Presses with coffee. The resulting crystal-clear wine is removed using a racking arm and sight glass for further processing.
Flotation filtration is another method of separating the solids that occur after crush when the juice is pumped into tanks. “It’s a little different process than the rest,” says Barretto.
We pump in nitrogen, taking advantage of its extremely small bubble properties to reverse gravity and send remaining solids to the top of the tank for removal.”
Most effective when your percentage of solids is between ten and twenty-five percent, centrifuges are also a valuable tool for separating solids and can be used on single decanters up through entire batches.
“And those solids left at the bottom of the tank still have value,” says Barretto. We can filter those down even further to get the remaining liquid out. Some winemakers consider this low-quality product and refuse to use it, but there is real value in the remaining liquids removed to be used in red blends.”
Improvements In Filtration An Ongoing Process
“We can be better,” says Barretto. “The best improvements have come from advancements in the filtering medium. They’re now reinforced with stronger mesh and coatings, providing a longer-lasting filter to start with. If we provide a way to control the pressure and concentration of the chemicals used to clean the membrane, we can save money by not having to replace as many membranes due to over fouling or damage.
Ceramic membranes are traditionally expensive and susceptible to damage, but the advantage is that they degrade very slowly, if at all. And technology has allowed the equipment operators to be hands-off, using self-guided touchscreens to control the systems. It decreases user error and also helps during times of employee turnover. Touchscreens provide much-needed simplicity in training to get new employees up to speed.
Koch Membrane Systems Offer Quality With Environmental Responsibility
Koch Membrane offers high-quality, internet and phone-enabled crossflow filtration systems that are self-cleaning and self-testing. Whether portable or in-house stationary units, they are designed to grow with your business, being expandable by 3 times the volume, cutting down on labor costs by potentially reducing the length of time it takes per filtration cycle or increasing the number of filtration cycles run per day.,
Completing the filtering cycle while staying environmentally friendly, Barretto tells The Grapevine Magazine that the final retained solids have shown to be valuable and compostable, even being able to be added back into the vineyards as soil additives.