STARS-XF: A Case Study

STARS^XF describes the process of both stabilizing and filtering wine, in one pass, often immediately prior to bottling or bulk tankering.

This process has been shown to be highly efficient in terms of time, energy consumption and both reduces the use of additives and reduces process losses over alternative methods.  This technology saves time and money!

Tartrate stability in the wine is guaranteed through the use of Oenodia^TM STARS Electrodialysis, while bottle-ready filtration is via crossflow filtration. Both processes occur end-to-end and in one-pass.

 

Download this Article
[148 kb PDF]

 

A Case Study

Winery:
The Hess Collection
Napa, California

Winemaker:
Alison Rodriguez

Objective:
To evaluate time/energy cost and quality of STARS-XF versus cold-stabilization followed by cross-flow microfiltration.

Summary:
First, stabilize and filter 3,000 to 6,000 gallons (11,356 litres – 22,712 litres) via traditional cold stabilization, followed by cross-flow filtration for the control, while simultaneously filtering and stabilizing the same amount via STARS-XF.

Minimum wine volume requirements for the trial:
Two pounds (0.907 Kg ) per 1,000 gallons (3,785 Kg) of KHT (Potassium Bitartrate) and four pounds (1.814 Kg) per 1,000 gallons of KHT; 3,000 to 6,000 gallons for STARS-XF.

The trial targets are:

• • XF: ~ 0.2 to 0.45 µm
  • Stability: Stability target of less than 3 percent change of conductivity via Davis Test (0° C, 30 min 15gr/L of KHT)
  • Four cases of before and after samples for both XF and traditional cold stabilization

Based on a previous trial, and pending results, this trial should show that STARS-XF significantly decreases stabilization time (microbial and tartrate stability) by approximately 80 to 95 percent, offers potential advantages by eliminating wine losses, multiple tank transfers, colour and phenolic loss, as well as the need for seeding and diatomaceous earth/pads/cartridges, and provides an overall faster processing speed.

Lot 1: Chardonnay, cold-stabilized, followed by racking and cross-flow filtration.
Lot 2: Chardonnay, single-pass cross-flow filtration and tartrate stabilization via STARS XF.

Conclusion:
Previous data show that overall processing time was reduced from six weeks to just 12.5 hours in the case of a Chardonnay and from 14 days to 12.5 hours in the case of a Pinot Noir. The main time savings were attributed to long cold stabilization time. STARS-XF showed some color improvement for a Pinot Noir sample and no change on a Chardonnay. It was noted that STARS allowed for greater adjustment of final pH level(s). STARS, combined with reverse osmosis, lowered water consumption by approximately 70 percent from 12 percent to 3 percent of total wine volume processed.

 

Winemaker’s Comments

What led to the creation of this trial?

Rodriguez: What really started it is our cross-flow that’s about 15 years old. We needed a new one and have been exploring our filtration options, and it just seemed like a natural progression to look at filtration plus cold stabilization. If you can achieve both of those in the same pass, that’s pretty efficient. What I did for the actual IQ trial was compare the STARS XF versus our regular cold stabilization and our regular cross-flow. I also tested out several other cross-flow iterations as well, which were not included in the trial.

I should probably say that it’s almost like a misnomer to call it cold stabilization. It’s actually tartrate stabilization because we never drop the temperature of the wine using STARS technology. So, to the best of my knowledge, this is the only set-up out there that can get your wine tartrate stable and basically bottle-ready in one pass.

How much fruit was ultimately involved?

Rodriguez: We stabilized two 25,000-gallon (94,635 litre) tanks of Chardonnay. This is fruit that is headed to our Monterey Chardonnay program, which comprises the largest fruit allocation in our portfolio.

Considering the size of the lots, isn’t that a large investment to risk on an experimental trial?

Rodriguez: I think both technologies involved and the STARS XF are well-adopted by our industry. Cross-flow, on its own, is a proven technology and has been for many years. And STARS is a proven standalone technology that has been adopted by the industry, I’d say for at least the past 10 or 15 years. So, I didn’t really feel like it was a big risk, considering both of those technologies are so normal. It was just really taking a look at what could we do. By combining the two technologies, would we really save in terms of time, in terms of energy, in terms of water, in terms of labor and in terms of wine? So, no, I didn’t really feel like it was a big risk with how proven the technologies are.

The Oenodia Stars-XF unit was a short-term loaner to The Hess Collection. Did the results of the trial convince you to purchase it? [The price quoted is in the mid- to high-six figures.]

Rodriguez: We are still evaluating our choices. I think the price is a little high.

Does the price of the STARS XF machine compensate for the reduced processing time and other possible long-term savings?

Rodriguez: I think that depends on what your cost of labor is, and it also depends on what your individual days to stabilization are. I’ve worked at other wineries in my past where it took two weeks and sometimes more to stabilize a tank using traditional cold stabilization. Here at The Hess Collection, we can stabilize usually inside of a week. But commonly, I would say the industry standard is more like two to three weeks. For those wineries, it makes a whole lot of sense. Trying to cold-stabilize in the middle of summer for three weeks, for instance, if you’re running cooling towers, you end up running a lot of water through your winery just to chill that wine down. There is that expense and the general environmental factors that one must weigh in before making a final purchasing decision.

From the results of this trial what have you learned, and how will you use this knowledge in future winemaking?

Rodriguez: I’ve learned that the STARS-XF technology saves a lot of wine, in addition to energy and water. But I’ve learned that the quality level is absolutely comparable and practically indistinguishable from your regular cold stabilization. While we only had the machine in our winery for a few days, I saw that it is not a labor-intense system. Aside from hooking up the machine to your tank and then hooking it up to your receiving tank, having someone in place to push out the small amount of lees that flow through the cross-flow, there’s not much to it, other than that—so, if you can run a regular cross-flow, you can easily run the STARS-XF machine.

Sometimes you have “lightbulb” moments in winemaking—and STARS is like that. I learned how fast and easy modern tartrate stabilization and filtration can be with STARS-XF, with no impact to wine quality, while saving time, energy, labour and water. Definitely a slam dunk from that perspective. This is technology I can easily imagine stabilizing our white wines in the $15+ price segment in the market. At the moment we are still evaluating the exact configuration of STARS unit for our winery.