E-tongue testing: Scientists unlock tech that surpasses humans to sense white wine spoilage

06 May 2024 --- US-based scientists have found a way to speed up wine spoilage detection by using an “electronic tongue” with strand-like sensory probes that are said to outperform human senses when detecting contaminated wine. These findings could be helpful for the wine industry, where spoilage during storage threatens brand recognition and consumer brand loyalty.

Winemakers traditionally rely on two methods — sniffing the wine and petri-dish testing — to identify potential wine “faults” or spoilage.

The findings, detailed in the Journal of Food Science, indicate that e-tongue testing could complement the existing methods and allow winemakers to catch and mitigate problems sooner, says Carolyn Ross, food science professor and the study’s corresponding author at the Washington State University (WSU), which conducted the study.

“If you ran a sample using the electronic tongue, we could learn after one week if there’s contamination or a wine fault problem, versus waiting up to four weeks running just sensory testing.”

“It’s really helpful with understanding wine quality.”

“Tasting” the wine
To detect spoilage, the team purposely added four microbes to different bottles of Riesling wines (white wine) that contaminate the drink, causing spoilage and unpleasantness — Wickerhamomyces anomalus, Acetobacter aceti, Lactobacillus brevis and Pediococcus parvulus.

When immersed in a liquid, the e-tongue’s sensors can “taste” it by analyzing certain compounds’ presence. 

The team analyzed the samples every seven days with the e-tongue and a sensory panel of 13 trained volunteers for 42 days.

The e-tongue is housed at WSU's Sensory Science Center (Image credit: WSU).The human sensory panel only started to detect contamination in some samples after 35 days of storage, while the e-tongue could do it after only seven days, supporting the method’s speed. 

Lab to market
The scientists advocate the usage of the e-tongue alongside sensory testing as a potential tool for the early detection of microbial faults in white wines.

Meanwhile, Ross and her colleagues have also tested out the e-tongue with red wine in an earlier study and the team is currently working on the instrument building up a library to help inform its “tasting” abilities. 

In addition, the scientists developed and programmed the instrument to take a type of “fingerprint” of wine that can collect a variety of information that may interest winemakers, says the WSU.

“It gives good information about the holistic quality of the wines,” underscores Ross, although she noted that this type of analysis is best used to complement, not replace, other methods of judging wine quality.

The researchers are also looking for winery clients interested in the e-tongue capabilities to help assess the quality of their products.

The scientists are now looking for winery clients interested in using the e-tongue to test their product quality.The study received support from the Washington Wine and Grape Research Fund and the US Department of Agriculture. 

Understanding limitations
While the study’s findings indicate winemakers can use the e-tongue analysis if they suspect the development of a wine fault, the team also acknowledges the method’s limitations.

“The e-tongue cannot detect specific chemical changes during the development of wine faults,” flags the study. “If the winemaker suspects the development of a specific wine fault, other chemical analysis methods would be more appropriate.”

Additionally, the microorganisms used in the research were not prepared in a food-grade laboratory and thus, the sensory panel and e-tongue could only assess the aroma changes and not the basic tastes.

For better insights, the team also suggests a longer duration of storage study, preferably a year, to examine microbial growth in the wine further.

Edited by Insha Naureen