Despite the best practice of modern winemaking methods, microbial contamination often occurs during wine production. Spoilage microbes are capable of survival and growth in the wine, potentially producing off-flavors, off-aromas, and turbidity. Microbiological contamination is often undetected until related problems in the wine become noticeable by sensory evaluation.
ETS offers Scorpions™ assays, based on specific genetic markers, to detect wine and juice spoilage organisms. This genetic analysis method detects microbial populations directly in wine or juice. Results are routinely reported within two business days, giving winemakers the ability to address problems before wine defects occur. Targeting Specific Spoilage Microorganisms
ETS has developed a series of Scorpions™ assays to provide winemakers a tool for rapid identification and quantitation of spoilage microbes in their wines. The assays utilize a combination of gene amplification and hybridization to accurately quantify the total number of viable cells in a sample.
Wine and Juice Bacteria Spoilage Panels screen for a range of bacteria in juice and wine, including Acetobacter, Gluconobacter, Gluconacetobacter, and selected Pediococcus and Lactobacillus species. The Wine Yeast Spoilage Panel screens for selected Brettanomyces and Zygosaccharomyces species. The Juice Yeast Spoilage Panel detects selected Hanseniaspora (Kloeckera), Pichia, Brettanomyces, and Zygosaccharomyces species. Additional Scorpions™ assays are available for detection of Saccharomyces and Oenococcus.
Targeted genetic probes give the winemaker the ability to monitor only those specific spoilage organisms that have the potential to adversely impact wine quality.
Used separately, or in combination, ETS Scorpions™ Panels enable the winemaker to specifically monitor those organisms that pose a threat to the quality of their individual wines.
Brettanomyces is a widely distributed yeast in winery environments. They can produce high concentrations of volatile acids, esters, and the volatile phenols 4-ethylphenol (4EP) and 4-ethylguaiacol (4EG). These volatile phenols are largely responsible for off-flavors or taint associated with Brettanomyces.
Zygosaccharomyces is a spoilage yeast that is tolerant of high sugar concentrations and is resistant to sorbate. It is commonly found throughout the winery environment and is often associated with grape juice concentrates that are used to adjust color and sugar in final wine blends. The yeast can cause turbidity and CO2 gas in bottled wines. Pichia is a wild yeast that is often present at high levels on incoming fruit. Pichia can initiate fermentation, resulting in production of high levels of volatile acids, including acetic acid and ethyl acetate. These yeast have been associated with films formed in barrels and tanks during storage.
Hanseniaspora (Kloeckera) is a wild apiculate yeast that is often present at high levels on incoming fruit. Hanseniaspora can initiate fermentation in the must and produce high levels of volatile acids, including acetic acid and ethyl acetate. It has been associated with acid rot in grapes infected by Botrytis cinerea. Population levels usually decline as alcohol concentration increases.
Pediococcus is one of the common lactic acid bacteria found in wine. They may produce polysaccharides that cause undesirable texture defects. Pediococcus can produce biogenic amines, such as histamine, putrescine and cadaverine. Although biogenic amines are not currently regulated in the United States, legislation in the European Union, Australia and Switzerland is a forewarning of future export hurdles.
Lactobacillus is another lactic acid bacteria commonly found in wine. They may produce high concentrations of diacetyl often causing undesired buttery flavors. Lactobacillus is also notorious for producing acetic acid in a short period of time - often in a matter of a few days. This can occur readily during sluggish or stuck fermentations. These bacteria have also been implicated in the production of mousy flavor.
Acetic acid bacteria are commonly associated with grapes and the winery environment. The three groups of commonly detected acetic acid bacteria are Gluconobacter, Gluconacetobacter and Acetobacter. These bacteria can generate acetic acid in the absence of SO2 and in the presence of oxygen. These organisms can cause elevated volatile acidity in wines exposed to air. Advantages of Gene Specific Analysis
There are several advantages of genetic analysis as compared to traditional plating methods.
- Detects Viable but Non-culturable (VNC) organisms - Most wine spoilage microbes can survive in a VNC state under the combined environment stress of SO2, pH, and alcohol.
- Specific identification - Scorpions™ technology is highly specific to the target organism, requiring three exact DNA sequences, aligned and properly spaced, to detect the target organism. This specificity ensures accurate species identification for all of the wine spoilage microbes.
- Time to results - Standard turn around time for Scorpions™ is two working days.
Proactive use of Scorpions™ technology enables early detection of wine spoilage microbes. Early detection enables the winemaker to intervene, preventing spoilage and preserving quality.