9 Nov 2015

Does ultraviolet radiation improve wine quality?

3:05 pm on 9 November 2015

New Zealand has a reputation of being one of the worst places in the world to get sunburnt, but the ultraviolet radiation that causes it is not all bad news, according to Lincoln University UV expert Brian Jordan.

red wine

Photo: Quinn Dombrowski / CC BY-SA 2.0

Ultraviolet radiation levels vary across the earth's surface, with some sites in the southern hemisphere receiving almost 40 percent more than comparable latitudes in the northern hemisphere.

Professor Jordan said until now UV had only been considered as a damaging radiation, but it was now thought to have a more positive role in plant growth and development.

He said researchers were now looking at whether UV radiation improved the red grape colour and taste of Pinot Noir wine.

"One of the processes that takes place in the vineyard is to remove the leaves. It's a very common practice and the idea behind that is the removal of the leaves reduces the humidity in the vines and that reduction in humidity is perceived to reduce the disease prevalence. When the leaves are actually removed it actually then leads to higher light and higher UVB reaching the berries, so what we've been looking at is to see that effect that extra UVB can have on the berries by chemical composition.

"We've found very strong correlation between the high UVB and the higher UVB after leaf removal and compounds called flavonoids and these flavonoids are produced by the plant to protect itself against the UVB, so it basically absorbs the UVB, but they are also very strong anti oxidants, so they're actually adding some clear benefit to the berry and indeed to the wine making process."

"We really want to predict what the bio chemical composition will be of the grapes at the harvest time so the industry and the wine maker can actually make the best quality wine."