Light exclusion influence on grape anthocyanin

Authors: Lee, Jungmin

Submitted to: Heliyon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2017
Publication Date: 2/2/2017
Citation: Lee, J. 2017. Light exclusion influence on grape anthocyanin. Heliyon. 3:e00243. doi: 10.1016/j.heliyon.2017.e00243.

Interpretive Summary: Anthocyanins are important natural pigments that contribute to the appearance of red grapes, and their resulting wines. Though it is well known that anthocyanin development is linked to light and temperature, we still have no concrete understanding of how they result in anthocyanin accumulation and composition. This work demonstrated that completely eliminating sunlight during berry ripening (from onset of color to harvest) alters individual anthocyanin composition when compared to a control. The white polypropylene boxes that kept experimental grape clusters in complete darkness also affected berry temperature and humidity, and these environmental factors may have contributed to the changes in anthocyanin composition as well.

Technical Abstract: This study contrasted the anthocyanins of investigational grape clusters that developed without light incidence (light-excluded), to those of control clusters that were shaded naturally beneath the vine canopy (control-shaded). Treatment grape clusters were light-excluded during ripening by opaque white polypropylene enclosures; temperature, vapor pressure deficit, and light intensity were measured continually. All 15 ‘Merlot’ grape anthocyanins accrued in both groups, indicating no accumulations were terminated from light-exclusion during ripening. Light-excluded clusters had an overall lower anthocyanin concentration (98.1 mg/100g of berries) than that of control clusters (162.0 mg/100g of berries), but it was not significantly different. Light-excluded clusters showed altered concentrations of nine individual anthocyanins that were significantly higher in control-shaded clusters. Although the changes in anthocyanin composition could not be attributed solely to the elimination of light, as there were also deviations in berry temperature and vapor pressure deficit concurrent with preventing light from reaching the treatment clusters.