Ageing wine in oak barrels turns a great wine into an exceptional wine, with complexity and textures not possible with other methods. However, if not managed properly, oak barrels can also undo a lot of hard work in the vineyard and on the crush pad. Without adequate protection, microbial activity and oxidation can degrade the wine’s quality.

One of the most common ways to protect barrel-ageing wine is to maintain sufficient molecular sulfur dioxide (SO₂) levels. Yet, since every barrel is a hand-crafted, unique vessel, differences arise in how the SO2 protection holds up. This, in turn, affects the quality of wine in individual barrels.

This article outlines a premium estate winery’s experience working with BarrelWise to track and manage Free SO₂ (and thus protect the wine’s quality) on a barrel-by barrel level, and how this has become their new standard for barrel management.

“Working with BarrelWise to help protect our wines is a great investment. Not only protecting our asset but also ensuring that we are making the highest quality of handcrafted wines possible.” - Paul Gardner, Proprietor
BarrelWise vehicle overlooking Pentâge vineyards atop Lake Okanagan.
BarrelWise team spent significant time at beautiful Pentâge Winery helping the winemaking team implement precision management of ageing barrels.

Pentâge Winery’s Experience

Pentâge is a boutique winery located near Penticton in BC’s Okanagan valley. The winery features world class wines, a beautiful 5,000 square foot natural rock cellar, and incredible views of Skaha Lake. The proprietors, Paul Gardner and Julie Rennie, have planted several rare varietals and produce fantastic small lots of Tempranillo, Roussanne/Marsanne, GSM, Cab Franc, among several others. The winery is also renowned for its Pentâge and Hiatus red blends. The Pentâge team ages much of their wine in barrels, utilizing both French and American oak from a variety of coopers. The barrels are serviced in place rather than forklifted from the stacks.

Traditionally, and as is typical in the winemaking industry, the winemaker would track sulfites by taking samples of select barrels using a wine thief and blend them together to form a composite sample. The winemaker would then use an aeration-oxidation (AO) apparatus to measure the concentration of Free SO₂ in this sample. The result is used to make sulfite addition decisions across all barrels. This method is imperfect – it relies on averages from a sub-set of barrels and obscures the variances that develops within barrel groups, as well as individual outliers that require customized additions. However, it is the only viable approach for most wineries, since the AO analysis takes 15 minutes per sample, making it impossible to sample all barrels individually. So, just like the other wineries, Pentâge was forced to work with limited information when managing the health of its barreled wines.

The BarrelWise solution: barrel-by-barrel Free SO₂ adjustments

As a former marine engineer, Paul has always been both knowledgeable and enthusiastic about new technology. In July 2020, while researching ways to further improve the winemaking practices at Pentâge, he came across the BarrelWise Barrel Management System (BMS), which enables efficient wine barrel sampling, topping and sulfite addition. Shortly after, BarrelWise bungs were installed on Pentâge’s barrels and the BarrelWise team was hired to visit the winery every month to assist with managing the winery’s barrel program.

BarrelWise crew and their system in Pentage winery's natural rock barrel cellar.
The BarrelWise team in Pentâge’s natural rock barrel cellar

A key part of BarrelWise’s product offering is its proprietary rapid Free SO₂ sensor that is designed for measuring sulfites in individual barrels quickly, easily, and accurately. This sensor was brought to Pentâge and used to analyze samples of wine from every barrel for Free SO₂.

Because of the operational challenges of analyzing and treating every individual barrel in a winery cellar, Free SO₂ levels inevitably vary from barrel to barrel. This phenomenon has been observed by BarrelWise in every winery the company works with. Pentâge was no exception –the analysis identified several barrels that required the winemaker’s attention to correct the imbalances. Sulfites levels in wine must be balanced: persistently low levels of Free SO₂ can expose wine to an increased risk of oxidation and microbial spoilage; at the same time, too much SO₂ will eventually affect the wine’s taste.

The data, collected by BarrelWise and presented in an interactive report, enabled Pentâge to carry out targeted sulfite additions, and provide optimal protection for its barrel-ageing wines, while keeping its sulfites use as low as possible.

A sample of interactive BarrelWise report which the Pentâge team uses to manage sulfites precisely for each barrel.
A sample of interactive BarrelWise report which the Pentâge team uses to manage sulfites precisely for each barrel.

Custom sulphite additions reduce variability

The variability of the Free SO₂ levels between individual barrels was not a surprise to Paul. Now that he had the barrel-by-barrel data, the Pentâge team were able to make custom sulphite additions and maintain Free SO₂ levels close to desired set point for each barrel with no winery laboratory time required. The custom additions targeted barrels that were low in Free SO₂, while leaving barrels that were high to naturally fall towards the desired set point. An example of three barrel groups at Pentâge winery, each with their own desired set point, is shown below before and after custom targeted additions were made with the data from the BarrelWise sensor.

Comparison of free SO2 distribution across barrels in 3 different groups before and after custom sulfite additions.
Comparison of Free SO₂ distribution across barrels in 3 different groups before and after custom sulfite additions. The outcome is a meaningful reduction in variance and elimination of outliers.

This precision gave the winemaker and owners a much greater confidence that their wine is properly protected, and that they are producing the best wine possible with the fruit from their fantastic vineyard. As a result, Pentâge was happy to sign on for ongoing monthly service. In the owners’ words, “With the value of the product in our red wine barrel program this is a no brainer”.

The bigger picture

To date, the variance in free sulfites across individual barrels which was uncovered, and is now being carefully managed at Pentâge, has been a commonplace problem in the winemaking industry. After analyzing over 1,000 barrels across many barrel groups, at multiple wineries, BarrelWise found that ~15% of barrels end up more than 10 ppm away from the group average Free SO₂ reading during the ageing process. Results of a composite sample, or samples from a random sub-set of barrels, as commonly done in the industry, obscure this variance. The fixed sulfite additions, made to all barrels in a group based on these average readings then exacerbate the problem by chronically underdosing barrels that are low (and at risk of spoilage), and overdosing the barrels that are high (sulfites may start to affect the taste).

Barrel-by-barrel Free SO₂ analysis data for 5 barrel groups from 2 wineries suggests that significant variance is commonplace.  

Wine quality management impacts profitability

Barrels that have sulfite levels outside of optimal are at higher risk of quality issues. They may affect the quality of the overall blend, leading to lower wine ratings and customer satisfaction. This outcome may damage the winery’s brand. To avoid this, the lower quality barrels may be downgraded to lower tiers, targeting less sophisticated consumers and lower price points. But then the revenue potential is also reduced.

 Every time a winery spends money on growing or purchasing premium fruit, premium oak, perhaps amore resource intensive barrel work regime (e.g. more frequent racking, or ageing on lees), yet in the end has to settle for a lower price point due to quality issues, it suffers as a business.

 BarrelWise solution enables wineries to minimize this risk. Keeping track of barrel-by-barrel data can help to avoid expensive downgrades by catching and addressing any problems early, and maximizing the revenue potential of every barrel.

Summary: precision winemaking improves ROI

BarrelWise team touring Pentâge estate vineyard after a day of work in the cellar
BarrelWise team touring Pentâge estate vineyard after a day of work in the cellar

Free SO₂ variance between barrels is widespread in the industry. Wineries typically use barrels of varying ages, oak types, toasts, and sizes, all of which contribute to this variation. Wines from the same fruit and same fermentation, aging indifferent barrels can have drastically different characteristics. But this variance also creates opportunities for quality losses through over-oxidation or unnoticed microbial activity. New technologies like the BarrelWise system are allowing winemakers to easily and efficiently collect barrel-by-barrel data so that these potential issues can be corrected. This helps to reduce the frequency of barrel downgrades and the profit losses that that come with it.

Paul sees a lot of value in leveraging modern tools to better safeguard the quality of his wines: “Working with BarrelWise to help protect our wines is a great investment. Not only protecting our asset but also ensuring that we are making the highest quality of handcrafted wines possible.”

Lola, the Pentâge guard dog, sleeping in an ATV whilst on the job.
Lola, the Pentâge guard dog, napping on the job.


If you would like more info about what BarrelWise can do for your winery, please Contact Us - we would love to hear from you!