Nutritional, Quality and Chemical Characteristics in Citrus Sinensis (L.) Osbeck Sweet Oranges From Northern Italy (Piedmont)

In the North of Italy, Piedmont region (46° 1' 26.04" N; 8° 41' 13.92" E), there has been a historic tradition of citriculture since the XVII century, thanks to a favourable microclimate due to the presence of Maggiore Lake.  Fifteen accessions of Citrus sinensis were grouped into three morphological traits (IPGRI Descriptor for Citrus): pigmented, navel and common oranges. Fruit from 5 trees within each group were analyzed for health and eating quality during the 2009-2010 season:  titratable acidity (TA), pH, total soluble solids (TSS), total phenolic content (TPC), antioxidant activities, vitamin C, hesperidin and narirutin contents. Spectrophotometric (ferric reducing antioxidant power and Folin Ciocalteu methods) and HPLC techniques were used.  The antioxidant activity tested on orange juices ranged from 8.5 to 18.6 mmol Fe2+/kg FW; the TPC values ranged from 81.1 to 160.8 mg/100 g FW and the vitamin c content from 32.9 to 72 mg/100ml.  Hesperidin content ranged from 15.60 to 36.90 mg/100mL and narirutin from 14.67 mg/100mL to 35.20 mg/100mL.  Analyses of variance (ANOVA) for means comparison and HSD Tukey multiple range showed statistical differences between the three groups.  This is the first report of screening for quality characterization, quantification of polyphenols and antioxidant activity on orange fruit juice grown in an area far away the traditional area of cultivation. The results were compared with bibliographic data about commercial varieties of C. sinensis from mediterranean and subtropical areas and showed that oranges grown in the North of Italy have reasonable qualitative characteristics and good nutritional properties.