As it turns out we humans are not as good as we think at discerning differences in wine. While some argue considerable expertise does exist around wine tasting, others have branded that expertise junk (or should that be drunk?) science.
To overcome the junk science aspect of wine tasting, artificial tongue technologies, sometimes referred to as electronic tongues, have been advanced over the years as an objective way to discern wines based on their taste, free from the human wine critic's personal prejudices.
To further the state-of-the-art in artificial tongue technologies, researchers at the Interdisciplinary Nanoscience Centre (iNANO), at Aarhus University, have developed a nanosensor that is capable of measuring the effect of astringency in your mouth when you drink wine.
In research published in the journal ACS Nano, the Danish researchers report having developed an optical sensor based on surface plasmon resonance, which is based on the collective oscillation of electrons that occurs on the surface between a metal and a dielectric when stimulated by light.
Surface plasmon resonance (SPR) is attractive to sensor designers because the resonance wavelength is very sensitive to conditions at the interface. Because of this sensitivity, SPR has been exploited, for example, to detect biomolecules (blood glucose, for example) clinging to the conductor surface.
The design of the SPR-based nanosensor in this case involves a small plate coated with gold nanoparticles. The researchers then put some of the proteins found in human saliva on the plate. When the wine comes in contact with the plate, the gold nanoparticles act like a lens that can focus a beam of light below the diffraction limit so that it becomes possible to measure down to 20 nanometers. This makes it possible to follow the salivary proteins and see how the interaction with the wine impacts them.
In effect, the SPR-based nanosensor is using salivary proteins to measure the sensation of astringency we have when we drink wine.
Joana Guerreiro, first author of the paper, explained in a news release:
“The sensor expands our understanding of the concept of astringency. The sensation arises because of the interaction between small organic molecules in the wine and proteins in your mouth. This interaction gets the proteins to change their structure and clump together. Until now, the focus has been on the clumping together that takes place fairly late in the process. With the sensor, we’ve developed a method that mimics the binding and change in the structure of the proteins, i.e. the early part of the process. It’s a more sensitive method, and it reproduces the effect of the astringency better.”
First applications for such a nanosensor would clearly be in the production of wine, allowing winemakers to control the development of astringency from the beginning of the process. However, the researchers point out that it could be used the development of targeted medicine as well as diagnostics.
“Understanding the effect is an important prerequisite for producing better and more targeted medicine. The sensor can be used for diagnostic purposes, so it could possibly be helpful for discovering and even preventing diseases,” added Duncan Sutherland, research director for the study, in the release.