Geisenheim University Study Reveals: Petainer Kegs Maintain Wine Freshness Comparable to Bag-in-Keg Solutions

Wine on draught offers many benefits to the wine producer, and the team in the bar. From cheaper exporting & cheaper packaging materials on the production side, to fast, efficient and consistent service in the bar. As always, ensuring that the product poured is what the producer intended is the most important aspect of product packaging.

Our latest 'real world experience' test evaluates Petainer Kegs and Bag-in-Keg solutions when coupled for extended periods; 4 weeks for still wine, and 2 weeks for sparkling. This test would show whether contact with the dispense gas impacts the quality of wine during this extended coupled period.

We worked with Geisenheim University, a German research and teaching university. With 150 years of experience, they preform tests from vine to glass. They advised that they would look for key chemical and sensory changes week on week. Firstly, they would measure dissolved and free sulphur in the wine. Sulphur is a preservative added to most wines that protects against oxidation. Oxidation can affect both the colour and the flavour of wine, eventually transforming the wine in to vinegar. Secondly they would measure the colour of the wine. Again, this is a sign of oxidation, with wine losing its vibrancy. Lastly, CO2 content would be measured. This would be a key marker in the ability to keep sparkling wines at the correct carbonation, and would show any impact of the dispense gas interacting with still wines. All samples were tasted by trained experts to ascertain the freshness of the wines.

Method

The test was constructed with two white wines, a still Riesling and a carbonated Riesling. Wine was dispensed with a 70% Nitrogen, 30% CO2 mix for Petainer Kegs and compressed air for the Bag-in-Keg solution. Wine was taken weekly to be evaluated against the chemical and sensory tests.

Results: Still Wine

The results of this latest research shows conclusively that Petainer Kegs will preserve flavour of wine over 4 weeks when coupled to dispense gas. The testers at Geisenheim found:

1. No difference in the colour values & intensity between Petainer Keg and Bag-in-Keg.
2. No difference in the SO2 content between both keg types, plus very little difference week 0 vs week 4.
3. Sensory tests showed no difference in quality over 4 weeks and vs Bag-in-Keg. Wine remained Fresh with a Clean Taste.
4. No impact of the dispense gas on the wine - 70-30 dispense gas is appropriate even at long timeframes.

Results: Sparkling Wine

The results for sparkling wine show that Petainer Kegs will preserve the flavour of wine over 2 weeks when coupled to dispense gas. The testers at Geisenheim found:

1. No difference in the colour values & intensity between Petainer Kegs and Bag-in-Keg.
2. No difference in the SO2 content between both keg types, plus very little difference week 0 vs week 2.
3. Sensory tests showed no difference in quality over 2 weeks and vs Bag-in-Keg. Wine remained Fresh with a Clean Taste.

Wine, whether sparkling or still was indistinguishable from both the start of the test and between Petainer and a Bag-in-Keg solution. This means that there is no additional benefit conferred by having the bag. In Petainer Kegs, oxidation is prevented by oxygen scavengers in the Keg wall, and as is evidenced, any oxygen that is able to pass through the fitting is neutralised by the free sulphur present in the wine. Further, nitrogen gas will protect the wine, creating a barrier that sits on the wine. As nitrogen will not dissolve in to the wine, it serves as further protection to the wine. When it comes to carbonation, a Petainer Keg offers a benefit not present in Bag-in-Keg; carbonation can be adjusted in the bar.

So what would this mean to a brewer looking to explore a one-way kegs? Firstly, it should suggest that a Bag-in-Keg or a bag-less keg are both sufficient to protect your product. Going for a bag-less Petainer Keg provides a few advantages.

When it comes to preparation, a Petainer Keg can be filled immediately as it is pre purged, and can be filled upright or inverted, meaning they can be used straight from the pallet.

With Petainer’s being a transparent product, fillers can keep an eye on foaming, and adjust pressure to maintain the fastest fill possible. Without needing to pre purge, invert and fill slower to avoid foaming, Petainer’s will save operational hours and costs during the filling process.

Petainer’s also offer flexibility when filling, with options for manual, semi manual and automatic filling.

Full study available on request.