July 2014 Issue of Wines & Vines

Technology That Allows Better Winemaking

Wine-processing tools can improve harvesting, sorting, settling and filtration

by Chik Brenneman
BevTec flotation unit
Solids are skimmed off the top of the GB BevTec flotation unit offered by American Tartaric Products.

Does technology make a better wine? This is a question I get asked a lot when I introduce visitors to our teaching and research winery at the University of California, Davis. At UC Davis, we have equipment in place that allows us to carry out “precision winemaking.” Precision winemaking is important in the research world, as it allows us to investigate the winemaking processes using strict control of experimental variables—notably temperature control, ability to clean and precise mixing regimens. Without this ability to control experimental variables, the results of research projects are put in question, leading to skepticism about their conclusions.


  • Author Chik Brenneman, who manages the winery and vineyard at the University of California, Davis, argues that technology itself does not improve wine quality; instead it allows the winemaker to do so.
  • New wine-processing technology singled out at the Unified Wine & Grape Symposium could help winemakers to better achieve their goals.
  • The criteria for selection included technology that allowed precision winemaking and technology common to multiple vendors.

Getting back to the question of whether or not technology makes better wine, I ask the judge to allow me to rephrase the question: How does this equipment allow us, as winemakers, to make a better wine? The answer is that technology in winemaking is a tool in itself, a tool that allows the winemaker to interpret a process and more efficiently make wine. The notion of making better wine is of a subjective nature. Winemaking has many variables that ultimately affect overall quality. Clearly a distinction must be made as to the overall outcome. We all want to make better wine, but technology can contribute to the production of both bad and good wines, it’s all in how you use the tool.

One of the first steps in understanding how to select and use various technological advancements is to identify your goals and prioritize them. Labor, energy and water have become very critical in recent years. Many industry vendors are focusing their development strategies around these resources. From a customer’s point of view, you are going to arrange these assets based on your goals. If your labor costs are high, or labor is in short supply, it comes in at No. 1. If your infrastructure costs are high, and you are looking to save on energy and water, labor savings might not be as important—but if it was a secondary benefit, that would be fine also.

There are many new products on the market for a range of applications. At the 2014 Unified Wine & Grape Symposium in January, reservation-only tours spotlighted some of the most innovative technological advances in winemaking (with specific focus on wine processing).

Harvesters that sort
Pellenc has a long history in viticulture and has developed a mechanical harvester that has fruit-sorting capabilities. Questions about quality and the notion that mechanical harvesting is used in lower tier wines are usually the main criticisms of this technology. Equipment manufacturers have responded to these concerns. Pellenc’s Selectiv’ system is not only a mechanical harvester, it also destems and removes material other than grapes. Waste items such as stems, leaves and petioles are left on the vineyard floor and do not have to be managed at the winery level, increasing the speed at which attention can be given to the fermentation. The bins coming into the winery should be ready for mixing, sampling and testing for pre-fermentation additions.

Sorting in the winery
In the absence of field sorting, the next option is sorting in the winery. Enter the Bucher Vaslin R1 and R2 grape sorters. The technology among pieces of grape-sorting equipment is relatively similar (cameras and computer memory), however Bucher Vaslin incorporates the sorting process into the other grape-processing equipment it manufactures.

Elevators feed the Delta series destemmer, and fruit drops onto vibrating sorting tables to give some separation to the berries as they are fed into the R1 or R2 grape sorters. What I found remarkable in my experience with the R1 was the relative speed at which sorting occurs: It is capable of up to 5 tons per hour, while the larger R2 can sort at a rate of at 10 tons per hour. Behind the berry sorting is a technology made possible by the relative low expense of memory in the computer world. Images of the fruit are taken as grapes pass in front of a camera; criteria to accept fruit have been preprogrammed in to the computer, and berries and other particles that fall outside the criteria for acceptance are rejected. Just seconds after each picture is analyzed, an air jet pushes rejected particles out of the main processing stream.

Programming is easy, but it takes some time, as you need to select berries that meet your acceptance criteria. What follows is a series of stops and starts while you examine the quality of the accepted stream versus the reject stream. Most systems allow some tweaking once the process has started. From a labor standpoint, an experienced operator should be monitoring both output streams and making adjustments as required.

While there is data to support differences in the chemical properties of the waste stream versus what went in to the tank and for fermentation, it is unknown whether these differences affect overall wine quality. Research conducted at the Teaching and Research winery at the University of California, Davis, in 2013 may shed light on this. UC Davis researchers (in conjunction with Pellenc, Bucher Vaslin, Plata Wine Partners and Silverado Winegrowers) undertook a study to try and answer this question. Results were to be released at the ASEV National Conference in Austin, Texas, in June; watch for updates from Wines & Vines.

Settling by flotation
Technology also allows us to re-evaluate traditional winemaking practices. Take the process of cold settling juice to remove grape solids, for instance. While it is the winemaker’s choice to ferment with high solids (there is some benefit to the yeast and malolactic bacteria), these solids contain enzymes (generally referred to as esterases) that decrease the overall fruitiness of the wine by degrading the ester compounds formed during alcoholic fermentation. In the simplest sense, the juice is pressed off the skins and placed in tank at a low temperature (50° F) and settled until the solids content is less than 1%. The juice is then racked to another tank, warmed slightly, and fermentation is initiated. This process requires two tanks that have to be cleaned, resulting in twice the amount of water used. Technology carried over from the wastewater treatment field is a modification of a system referred to as the Jameson Cell. The cell is very simple in that after the juice is pressed, it is conveyed to a holding tank, in which small bubbles of inert gas are introduced through the bottom. As the bubbles rise, they carry along with them the solids, which are skimmed off the top of the tank. The clear juice on the bottom of the tank is then conveyed to the primary fermentor. The process saves a minimum of 24 hours in tank space availability as well as the water required to clean the settling tank and the energy required to cool the juice during the settling period. American Tartaric Products offers a modified approach to the Jameson Cell with its GB BevTec unit that operates as a closed system. The principles of flotation are the same, and modifications to the system are possible for a system capacity of up to 8,000 gallons per hour.

Removing solids with cross flow
Some manufacturers have chosen to modify existing technology (notably cross-flow filtration systems) to accommodate the removal of solids from juice. Cross-flow filtration has been a viable industry-accepted filtration technology for more than a decade. A small tube acts as the filtration medium. The juice/wine is passed parallel to the membrane pores, and the high pressure of the inlet side forces the wine/juice through the pores to the lower pressure filtrate side. The sweeping forward motion across the membrane surface keeps the membrane pores from fouling where the unfiltered product (or retentate) is returned to the feed tank to make another round across the filter. The retentate progressively becomes more concentrated and eventually cannot be filtered. (My experience is that this fraction is less than 0.5% of the total volume filtered.) The benefits here are similar to that of the aforementioned juice clarification techniques: to clarify a juice without the aid of natural settling is a more efficient process with respect to labor, energy and available winery resources.

Sensors that save money
Sensors are probably one of the biggest advances in wine technology. It is hard to say whether any one sensor is better than another; it is all dependent on what your goals are in applying sensor technology and the sensor’s ability to capture the data point you are seeking.

I recall a personal experience where sensors would have been extremely beneficial in resolving a filtration issue. The timing and technology advances were not current, and our team struggled with trying to determine why wine that appeared to be bottle-ready was fouling the membrane filters to the point of shutting down our bottling operations every day. If we had been able to incorporate pressure sensors that read up-to-the-minute measurements and were viewable to a cellar supervisor via tablet or the Internet, we would have saved thousands of dollars in lost revenue. Advances in sensors and the ability for them to report real-time data is now a standard of sensor technology. Our research fermentors, developed by Cypress Semiconductor, currently are able to transmit tank jacket temperature, must temperature, juice temperature, Brix, pump status (on/off/mode) and system set points. A recent project will focus on the values of sensors in practical industry applications. Our new set of research fermentors, developed by Placer Process Systems, will incorporate fluid flow, differential tank product pressure and temperature in real time to an operator interface. In addition, with the incorporation of automated valves, the entire system status can be displayed in real time for a user to activate both manual and automated processes.

The reality of sensor technology is that it provides a real-time tool for wine processes. Incorporation into any winery’s daily process monitoring and controls systems provides the winemaker or system managers tools to view real-time transmissions and provide support for operations that need attention. For any of the technologies presented here, there is opportunity to apply sensor technology. You as a customer should query the vendor and provide them with the goals of your program (perhaps relating back to the labor, energy and water issue).

To circle back to whether a technology makes a better wine or not: Who knows? Your ability to interpret the information and mobilize resources to react to that information is tantamount. If your goals are set, and you understand the expectations and possible outcomes, then it is up to you to determine if the differences translate to a better wine.

Chik Brenneman is the University of California, Davis, Department of Viticulture and Enology winemaker and facilities manager responsible for oversight of the campus winery and vineyards.

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