Hazy Wine Due to Contamination

09 March 2023

In 2020, two wineries based in Canada reported cloudiness in their wine following the bottling process performed by a mobile bottling company. The wine is bottled in self-contained trucks at the wine maker’s facilities, where empty bottles are provided by the winemaker and then fed into the truck’s system for the filling process.

Envista Forensics was retained, and we sent a specialty wine expert from our Expert Alliance to perform the investigation.  Our expert reviewed documentation from the wine bottling company, interviewed company personnel, and analyzed samples, as necessary, to determine the cause of the haziness of the wines.

Haze and Sediment Found and Tested

The first winery noticed sediment in their Pinot Gris and Rosé.  However, during our investigation, we determined that there weren’t many hazy Pinot Gris bottles, and they did not show any microbial growth. The hazy Rosé bottles were intermittent.

Both hazy and clear bottles were sent to an independent wine lab for microbial study.  The hazy wine showed significant growth of a new native Saccharomyces yeast (a sugar fungus) and the clear bottles showed no microbial growth at all.

The haze and sediment from bottles at the second winery were also found to have high levels of a native Saccharomyces yeast in them, while the clear bottles from the same bottling process, showed none.

Matching DNA Determines Contaminated Truck

After further investigation, Envista’s specialty wine expert was able to confirm that the same bottling truck was used at both wineries that experienced microbial contamination.  Subsequent microbial analyses by the lab showed that the DNA fingerprint of the organisms in all the hazy bottles was the same.

Envista’s expert then interviewed the bottling company to discuss the lab results. We provided our determination of what had occurred and discussed what steps should be taken to prevent it from recurring. The contamination came from 1 of 12 filler nozzles on the bottling truck in question.  It was discovered that through a fault in the sterilization of the line on-site at the wineries, one filler head had yeast growth that was not eliminated through the bottler’s typical sanitation process.  

The truck had been brought back to the shop for a deeper cleaning and no further problems have been reported since.

The Final Assessment

The conclusion of identical DNA from the affected bottles from two different wineries would indicate that the contamination was coming from the truck and not the wineries. Our quick resolution got the wineries back into production fast, during one of their busiest times of the year.

These sorts of issues certainly come up in the mobile bottling business fairly regularly, especially when all the wineries in a region need the service.  The trucks work very hard and for long spurts of time, and don’t always get the maintenance that might be desired during busy times.  

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