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ACS News Service Weekly PressPac: June 22, 2016

Protecting grapes from pests by boosting their natural immunity

“Daily Preharvest UV-C Light Maintains the High Stilbenoid Concentration in Grapes”
Journal of Agricultural and Food Chemistry

Wine enthusiasts concerned with potential environmental and health effects of synthetic pesticides prefer to buy “organic” pinots, chardonnays and other varietals. Now scientists are onto a new practice that could help meet that demand. They report that shining short-wavelength ultraviolet light (UV-C) on grapes right before harvest boosts levels of the fruits’ own disease-fighting compounds, which could reduce the need for pesticides. The study appears in ACS’ Journal of Agricultural and Food Chemistry.

As is true for any agricultural producer, vineyard owners need to prevent pathogens from harming their crops to stay in business. For many of them, this means applying synthetic pesticides. Out of concern for these substances’ potential effects on water, soil and human health, some winemakers have turned to more natural methods. One approach scientists are exploring involves the use of UV-C light, which studies have shown increases grapes’ production of stilbenoids. Some of these phenolic compounds have been associated with natural disease resistance. Raúl F. Guerrero from the Andalusian Institute of Agricultural and Fisheries Research and Training (IFAPA) and colleagues wanted to explore how daily doses of pre-harvest UV-C light would affect grapes’ stilbenoid content.

The researchers tested one set of grapes exposed to five minutes of UV-C light every day for three days before harvesting and compared them with another set of grapes that only received one five-minute dose. The latter technique had previously been optimized in grapes. The set that received multiple treatments showed an 86-fold increase in stilbenoid concentrations over the fruit that only got one application of UV-C. The three-day, pre-harvest treatment also affected texture, color and other characteristics, but the researchers say that the grapes were still of good quality.

The authors acknowledge funding from the European Social Fund of Andalusia and the National Institute for Agricultural and Food Research and Technology (INIA).

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Exposing grapes to ultraviolet-C light multiple times before harvest increased their disease-fighting compounds.
Credit: American Chemical Society
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