705 Influence of Temperature on Berry Quality of ‘Glen Ample’ Red Raspberry S.F. Remberg 1 , A. Sønsteby 1,3 , A.-B. Wold 1 and O.M. Heide 2 1 Norwegian University of Life Sciences, Department of Plant and Environmental Sciences, Ås, Norway 2 Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, Ås, Norway 3 Norwegian Institute for Agricultural and Environmental Research, Bioforsk, Kapp, Norway Keywords: Rubus idaeus, temperature, fruit quality, vitamin C, antioxidant activity, berry weight Abstract The influence of post-flowering temperature (12, 18, and 24°C) on berry quality of the red raspberry ‘Glen Ample’ was studied under controlled environment conditions. Berry weight decreased throughout the harvesting period at all temperatures, but the decrease was markedly faster at high temperatures. Fruit maturation and harvest were advanced in the order of increasing temperature. The yield levelled off at about 1.6 kg per plant, due to lack of pollinating insects in the phytotron compartments. Because the moisture content increased in parallel with the berry weight, the concentration of a range of bioactive compounds decreased with decreasing temperature and progress of the harvest season when expressed on a fresh weight basis. L-ascorbic acid (vitamin C) increased with decreasing temperature, despite the dilution effect of large berries. Berry antioxidant activity was closely correlated (r=0.958) with total phenolic concentration, predominantly anthocyanins and ellagitannins. INTRODUCTION Due to introduction of new cultivars and new diversified production methods, red raspberry (Rubus idaeus L.) production has expanded significantly in Norway, as well as in the rest of Europe, and has become an economically important crop. Red raspberry is rich in antioxidants and other phytochemicals with potential health benefits (deAncos et al., 2000; Rao and Snyder, 2010). The most abundant antioxidants in red raspberries are the phenolic compounds in the forms of anthocyanins and ellagic acid derivatives (Määttä-Riihinen et al., 2004; Beekwilder et al., 2005). Vitamin C, which is also a contributor to the antioxidant activity, accounts for 6% of the total antioxidant activity in red raspberries (Kalt et al., 1999). An important development in raspberry production has been the use of plastic tunnels for out-of-season production and protection of the crop. The biennial-fruiting cultivar ‘Glen Ample’ has become very popular for this use, and is presently the main raspberry cultivar grown in Norway (Sønsteby et al., 2009). These new developments have greatly extended the harvesting and marketing season and improved the profitability of the crop. Most research in the area of screening the antioxidant activity in dietary plants have mainly been focused on variation among species and cultivars (Kalt et al., 1999; Halvorsen et al., 2002; Määttä-Riihinen et al., 2004) and effects of postharvest handling and storage (Kalt et al., 1999). However, change to protected cultivation has also emphasized the need for further understanding of the environmental responses of the crop. This involves changes in the climatic environment which might influence the chemical composition of the fruits. Therefore, we have studied the effect of temperature under controlled conditions on berry quality of the red raspberry ‘Glen Ample’ (Remberg et al., 2010). Proc. XXVIII th IHC – International Berry Symposium Eds.: B. Mezzetti and P. Brás de Oliveira Acta Hort. 926, ISHS 2012