Antioxidant Activity in ‘Cortland’ Apple Peel and Susceptibility to Superficial Scald after Storage

Abstract

Abstract ‘Cortland’ apples (Malus domestica Borkh.) from both exterior and interior of large trees were harvested over a 25-day period, and samples were stored for 0 to 5.5 months in air at 0°C. Antioxidant activity of peel at harvest was assayed. Hexane extracts of whole fruit were used to estimate α-farnesene and conjugated trienes after 1 to 4 months of storage; these values were correlated with scald development after 3 to 5.5 months of storage, α-Famesene increased during the first 2 months of storage and then decreased, while conjugated trienes increased progressively with storage time. α-Famesene was not affected by harvest date, but conjugated trienes were decreased by later harvest. Conjugated trienes were positively correlated more strongly with scald than was α-farnesene. Antioxidant activity increased with later harvest in both exterior and interior fruit, even though exterior fruit ripened during this time, while interior fruit did not. Antioxidant activity at harvest was negatively correlated more strongly with scald development than was either α-farnesene or conjugated trienes, with r values as high as −0.83. A large optical density (OD) peak at ≈200 nm was detected in the hexane extracts of apples, and it was correlated with antioxidant activity (r = +0.63). OD200 values for harvest extracts were as strongly correlated with scald development after storage as were antioxidant assays. A large number of compounds absorbed at 200 nm, including many with antioxidant activity. We propose that OD200 of hexane extracts is an estimate of antioxidant activity at harvest and may represent a convenient and effective chemical index of scald susceptibility of apples after harvest.