Anthocyanins not only give wine its colour, they also change its taste. This is what Italian researcher Maria Alessandra Paissoni from the University of Turin found out as part of her doctorate.
To prove this, she first extracted all anthocyanins from a Barbera and a Nebbiolo that were pressed in 2015, Paissoni explained at the "Enoforum" internet conference organised by the OIV. She then divided the compounds into three fractions and brought them into contact with salivary proteins. "The higher the degree of acetylation, the stronger the anthocyanins precipitated," she said. Paissoni then organised sensory analyses with trained students from the University of Bordeaux. They tasted solutions with 12 per cent alcohol, a pH of 3.5 and 4 g/l of tartaric acid to which either 1 g/l of anthocyanins from the skins or 1 g/l of anthocyanins from the seeds, 300 mg/l of a total fraction of anthocyanins or 400 mg/l of the glucoside fraction had been added. "Bitterness", "aggressiveness", "saltiness" and "heat" were the most common descriptions they used.
"When I asked the students to rate the intensity of these flavours, the strongest astringency was described in the solution with the anthocyanins from the skin," Paissoni explained. In contrast, when she added the entire anthocyanin or glucoside fraction to the solution, the students' perception of astringency decreased. "But I got opposite results when I used the anthocyanins from the seeds," she rued.
(uka)