Effect of cultivar and year on the quality of hazelnut fruits (Corylus avellana L.)

Several studies have shown that hazelnut consumption may play an important role in human health protection, based on the levels of antioxidant compounds contained in the fruit. Since cultivar and year are likely to influence nut composition, a study was designed to evaluate the effect of year (2001, 2002) and cultivar ('Ennis', 'Butler', 'Grossal', 'Segorbe', 'Merveille de Bollwiller' and 'Fertile de Coutard') on trees from an orchard located in Vila Real, in the northeast of Portugal. Nuts were evaluated for free cc-amino acids, protein, total lipid, starch and fiber. Fruit, kernel and shell weight, blank occurrence and yield were also determined. Free a-amino acids were quantified by HPLC. Crude protein (CP) and crude fat (CF) were determined according to the procedures of AOAC (1990), whilst for neutral detergent fiber (NDF) and starch the methods described by Van Soest et al. (1991) and Salomonsson et al. (1984), were followed respectively. Both cultivar and year induced significant differences in the content of the total amino acids and in most of the individual amino acids identified. Climatic conditions induced significant reduction of amino acids when the plant was submitted to stress. Cultivars also induced significant differences in CP, CF, starch and NDF whilst years had no influence. Fruit weight (kernel and shell) and blank fruit production was significantly affected by cultivar and year.