Developing objective wine tasting tongues

Get ready to move aside Jancis Robinson, James Halliday, Michael Broadbent et al. Artificial tongues are being developed apace that promise to bring some objectivity into that arcane art of wine tasting.
The latest contribution to the science of taste comes from researchers at Aarhus University in Denmark. Their study published in ACS Nano describes an artificial tongue that detects the effects of tannins, the molecules that give wines their astringency, in the mouth. To do that, the machine uses proteins found in human saliva.

The abstract of the article is almost as incomprehensible to me as most wine tasting notes but here it is for more scientifically literate readers:

We report an optical sensor based on localized surface plasmon resonance (LSPR) to study small-molecule protein interaction combining high sensitivity refractive index sensing for quantitative binding information and subsequent conformation-sensitive plasmon-activated circular dichroism spectroscopy. The interaction of α-amylase and a small-size molecule (PGG, pentagalloyl glucose) was log concentration-dependent from 0.5 to 154 μM. In situtests were additionally successfully applied to the analysis of real wine samples. These studies demonstrate that LSPR sensors to monitor small molecule–protein interactions in real time andin situ, which is a great advance within technological platforms for drug discovery.

The IEEE Spectrum website helps with an explanation

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 in the development of targeted medicine as well as diagnostics.