Effects of package atmosphere and temperature on phenolics, total antioxidant capacity and colour in kernels of 'Franquette' walnuts during 8-month storage
M.V. Christopoulos, E. Tsantili, V. Papageorgiou, M. Komaitis and D. Rouskas
ISHS Acta Horticulturae 858:75-81. 2010.
2010
บทคัดย่อ
The effects of package atmosphere and temperature on phenolic compounds, total antioxidant capacity and colour were investigated in kernels of 'Franquette' walnuts stored for up to 8 months. Dried walnuts were sealed under air or 100% N2 and stored at 1°C or 20°C. The highest total phenolics concentration (25.41 mg gallic acid equivalents g-1) and total antioxidant capacity (185.6 μmol trolox equivalents g-1, and 174.2 μmol trolox equivalents g-1 according to FRAP and DPPH method, respectively) were observed in samples before storage. The above parameters decreased progressively during storage. Low temperature and N2-atmosphere inhibited decline while their combination provided best preservation of nutritional value. Additive effects of low temperature and N2-atmosphere were also observed in retention of L* and hue angle colour parameters while Chroma was affected only by temperature. Major phenolic compounds were ellagic, protocatechuic, vanillic, and syringic acids and found at concentrations of 822.4 μg g-1, 581.8 μg g-1, 581.6 μg g-1, and 310.2 μg g-1, respectively. At the end of storage all phenolic compounds decreased and the decrease was most pronounced in air at 20°C (54% of all compounds, in average) and less in N2-atmosphere at 1°C (18% of all compounds, in average).