Fluorescence-based assay system discerns different types of white wine

June 17, 2016, Wiley
Credit: Wiley

Swirl, sniff, sip, and swallow: Discrimination of different wines has always been a matter of tongue and taste. Is objective and reliable discrimination of the thousands of wine varieties possible by means of a simple chemical analytics kit? Scientists in Heidelberg, Germany, say yes, and in the journal Angewandte Chemie they present two polyelectrolyte semiconductors that in combination form a simple fluorescence-based analytical technique to discern at least thirteen white wines.

Chemical wine analytics traditionally aims to identify illegally added substances or to quantify certain ingredients. Besides, there is a broad sensory science for wine that distinguishes the wines just by sight, smell, taste, touch, and hearing, but the decisions are, after all, subjective. Seeking a more objective basis, Uwe Bunz and his team employed sensors to chemically fingerprint the wines. Such a fingerprint reflects the composition of the wine including alcohols, sugars, acids, vitamins, nutrients, and the plethora of secondary plant products like flavonoids, tannins, etc. However, as the latter in particular number in the thousands, conducting an exhaustive chemical analysis is difficult.

Therefore, Bunz and his team turned to a simple colorimetric assay based on the fluorescence response of a certain type of colored polyelectrolytes called PPEs. These soluble and charged polymers respond to the typical wine ingredients such as colorants, sugars, and acids. "The fluorescence response of the sensor elements to the wines is primarily due to the wine colorant," the authors explain. As white wines contain colorants, the scientists obtained strong but varied fluorescence quenching, and its modulation was mainly caused by the sugars and acids present in the wine.

The scientists remark that a small set of two PPEs and their complex was sufficient to obtain a simplified but reliable fluorescence response pattern as a specific fingerprint. All of the 13 tested were discerned by their specific fingerprint. "Only one of 52 unknown wines was misclassified, representing an accuracy or 98%," the authors wrote. However, only for the Riesling wines an assignment of the grape from which the wine was produced by the wine fingerprint was possible. The authors presume that the different strains of yeasts used to make the wines have an additional large influence on the chemical composition of the products, more so than the grape type. It appears that identifying the grape will indeed remain a matter of taste.

Explore further: New 'smart' bottle helps uncorked wine keep longer

More information: Jinsong Han et al. Identification of White Wines by using Two Oppositely Charged Poly(-phenyleneethynylene)s Individually and in Complex, Angewandte Chemie International Edition (2016). DOI: 10.1002/anie.201602385

Related Stories

Wine-making shortcut gives bubbly a fruitier aroma

June 17, 2015

The best sparkling wines take months to ferment to perfection. In recent years, many winemakers have turned to commercial yeast products to give this process a boost. How they ultimately affect bubbly has been an open question, ...

Expensive and inexpensive wines taste the same, research shows

April 15, 2011

(PhysOrg.com) -- Psychologist Prof Richard Wiseman (University of Hertfordshire) today revealed the results of The Taste Test - a large-scale experiment to discover whether expensive wines are good value for money. The experiment ...

Study: Pesticides found in wine

April 4, 2008

A European environmental group said pesticides used on grapes were found in 35 of the 40 bottles of wine they tested.

Recommended for you

Biologists' new peptide could fight many cancers

January 16, 2018

MIT biologists have designed a new peptide that can disrupt a key protein that many types of cancers, including some forms of lymphoma, leukemia, and breast cancer, need to survive.

Insulating bricks with microscopic bubbles

January 16, 2018

The better a building is insulated, the less heat is lost in winter—and the less energy is needed to achieve a comfortable room temperature. The Swiss Federal Office of Energy (SFOE) regularly raises the requirements for ...

Fast-moving electrons create current in organic solar cells

January 12, 2018

Researchers at Purdue University have identified the mechanism that allows organic solar cells to create a charge, solving a longstanding puzzle in physics, according to a paper published Friday (Jan. 12) in the journal Science ...

Super-adsorbent MOF captures twice its weight in water

January 11, 2018

Material chemists in the Kingdom of Saudi Arabia have developed a superporous solid made up of a patchwork of metal ions and organic linkers (a metal-organic framework, or MOF) that can suck up to 200% of its own weight in ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.