The adultery referred to is the adulteration of red wine. SpectroscopyNOW.com have reported that researchers in Italy can reveal whether red wine has been adulterated with anthocyanins to artificially improve its red colour.
E. Ferrari and his fellow researchers of the Università di Modena e Reggio Emilia, working with M. Vignali of Vinicola San Nazaro in Italy point out that the red colour in red wines are commonly and legitimately corrected by blending with Rossissimo, a wine rich in anthocyanins. The process is a natural part of the Italian oenological industry.
However in Asia it’s a different story.
Knowing that deeper reds are often more desirable and so attract a higher price there are some parts of the wine market, particularly in Asia, where anthocyanins extracted from Black Rice and other sources are added to improve wine colour.
This practice does not produce negative effects on health, however, in many countries, it is considered as a food adulteration. For those markets where artificially boosting the reds is either illegal or simply frowned upon, there is a requirement for a simple and quick approach to testing red wine for such adulteration.
Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue according to pH. They belong to a parent class of molecules called flavonoids. Plants rich in anthocyanins are blueberries, blackberries, raspberries, cranberries, blackcurrants, black cherries, red cabbage, violets, black rice and muscadine grapes.
Anthocyanins are often responsible for the blue to red colours found in flowers, fruits and leaves. In grapes, they develop during the stage of veraison when the skin of red wine grapes changes colour from green to red to black.
In most red wine grapes anthocyanins are found only in the outer cell layers of the skin, leaving the grape juice inside virtually colourless. The colour of the wine in this case depends on the skins of the grapes being crushed with the colourless juice in fermentation.
The exception to this is the small class of grapes known as Teinturiers, such as Alicante Bouschet, which have a small amount of anthocyanins in the pulp. This means that when the grape skins and pulp are crushed together the juice is much darker.
Examples of Teinturier grapes are Royalty, Rubired and the rare Pontac grape – of which a small amount survives in South Africa. Most Teinturier grapes have some connection to Alicante Bouschet.
Accounts from the early 1800s record that that wines from Bénicarlo in Valencia, north east Spain were added to the Bordeaux blend to give the wines extra colour and power in a poor Bordeaux vintage. One source from 1824 (Henry Christmas, George Augustus Frederick) states that each hogshead of Bordeaux had 3 or 4 gallons of Alicante Bouschet or Bénicarlo added to it.
This was called tracait a la anglaise (the English treatment). Cyrus Redding (1833) says that Claret was a mix of Bordeaux and Bénicarlo. Although the Bénicarlo grape seems to have disappeared from history it could be the Spanish grape Bobal which is native to the Utiel-Requena region in Valencia as Bénicarlo is one of Bobal’s synonyms.
If you’d like to learn more on this topic check out my Blog Bordeaux From Valencia).
However adding Black Rice extract to a wine is a very different story to the adding of darker grape juice. The Italian researchers found that by analysing the NMR data they were able to get an efficiency validation of greater than 95 percent.
NMR stands for Nuclear Magnetic Resonance and NMR spectroscopy is a research technique that exploits the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained.
Given the scandal over the wineries that had to be shut down in China for making adulterated wines in December last year this research could prove to be very valuable for detecting what’s really in our wine.