Effect of grape bunch sunlight exposure and UV radiation on phenolics and volatile composition of Vitis vinifera L. cv. Pinot noir wine Jianqiang Song a,b , Richard Smart c , Hua Wang b , Bob Dambergs d , Angela Sparrow e , Michael C. Qian a,⇑ a Department of Food Science & Technology, Oregon State University, Corvallis, OR 97331, USA b College of Enology, Northwest A&F University, Yangling, Shaanxi 712100, China c Smart Viticulture, 31 North Corner, Newlyn, Cornwall TR185JG, UK d Australian Wine Research Institute and Tasmanian Institute of Agriculture, PO Box 98, Hobart, Tasmania 7001, Australia e Tasmanian Institute of Agriculture, Perennial Horticulture Centre, PO Box 46, Kings Meadows, 7249 Tasmania, Australia article info Article history: Received 11 April 2014 Received in revised form 24 September 2014 Accepted 26 September 2014 Available online 7 October 2014 Keywords: Sunlight exposure Ultraviolet (UV) radiation Pinot noir wine Wine phenolics Terpene alcohols C 13 -norisoprenoids abstract The effect of canopy leaf removal and ultraviolet (UV) on Pinot noir grape and wine composition was investigated in this study. Limited basal leaf removal in the fruit zone was conducted, compared to shaded bunches. The UV exposure was controlled using polycarbonate screens to block UV radiation, and acrylic screens to pass the UV. The results showed that bunch sunlight and UV exposure significantly increased the Brix and pH in the grape juice, and increased substantially wine colour density, anthocya- nins, total pigment, total phenolics and tannin content. Bunch sunlight and UV exposure affected terpene alcohols, C 13 -norisprenoids and other volatile composition of the wine differently. Sunlight exposure and UV resulted in increase of nerol, geraniol and citronellol but not linalool. Sunlight exposure slightly increased the concentration of b-ionone, but the increase was not statistically significant for UV treat- ment. Neither sunlight nor UV treatment showed any impact on the concentration of b-damascenone. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Canopy manipulation practices can change canopy microcli- mate of grapevines to affect plant temperature, photosynthesis, metabolic activity, and disease resistance (Smart, Dick, Gravett, & Fisher, 1990). Canopy management of grapevines such as trellis system, vigour control, shoot trimming and leaf removal have been used to increase light penetration to the fruiting zone. It has been well demonstrated that cluster sun exposure modifies grape ripen- ing which results sometimes in increased sugar, and typically decreased titratable acidity, especially malic acid in the fruit (Smart et al., 1990). Canopy management by improving sun expo- sure promotes the formation of varietal aroma compounds like monoterpenes and C 13 -norisoprenoids, and increased phenol com- position such as flavonoids and pigments in grape berries and wines in some varieties (Lee et al., 2007; Spayd, Tarara, Mee, & Ferguson, 2002). Thus, sunlight exposure, when not excessive in hot climates, appears to be associated with modified flavour and potential wine quality (Sun, Sacks, Lerch, & Vanden Heuvel, 2011). However, sunlight exposure inevitably elevates UV radiation. Although UV radiation, including UV-A (315–400 nm) and UV-B (280–315 nm), comprises only a minor component of sunlight energy, it could have major effect on grapevine physiology, since UV radiation, especially UV-B, has potential damaging effect on grapevine leaves and berries (Kolb, Kopecky, Riederer, & Pfündel, 2003).The increased levels of UV radiation reaching the surface of the earth in recent decades due to depletion of the stratospheric ozone layer sparked the interest of research to better understand the effect of UV radiation on agriculture including grape and wine (Keller & Torres-Martinez, 2002). Natural intensity of UV radiation has been shown to alter grape- vine physiology (Nunez-Olivera, Martinez-Abaigar, Tomas, Otero, & Arroniz-Crespo, 2006), and change grape production and compo- sition (Berli, Fanzone, Piccoli, & Bottini, 2011; Kolb et al., 2003; Spayd et al., 2002). Grape maturation has been reported to be accelerated due to the increase of UV radiation (Berli et al., 2011). As a protective response against UV radiation stress, the synthesis of secondary metabolites mainly UV absorbing phenols such as flavonoids were stimulated in grape berries (Kolb et al., 2003; Spayd et al., 2002). It was assumed that UV radiation could result in the changes of volatile compounds in the finished wines because the volatile precursors including carotenoids, amino acids, http://dx.doi.org/10.1016/j.foodchem.2014.09.150 0308-8146/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: 100 Wiegand Hall, Corvallis, OR 97331, USA. Tel.: +1 (541) 737 9114; fax: +1 (541) 737 1877. E-mail address: Michael.qian@oregonstate.edu (M.C. Qian). Food Chemistry 173 (2015) 424–431 Contents lists available at ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem