Relationships of antioxidants in apple peel to changes in α-farnesene and conjugated trienes during storage, and to superficial scald development after storage

Abstract

Three experiments were conducted: (1) ‘Cortland’ and ‘Delicious’ apples were harvested at four weekly intervals; (2) ‘Cortland’ apples were induced to ripen prematurely with ethephon sprays; (3) ‘Cortland’ apples were enclosed in brown bags for six weeks before harvest. At harvest and after intervals of storage at 0°C, concentrations of α-farnesene and conjugated trienes, estimates of total lipid-soluble and total water-soluble antioxidant activity, and concentrations of α-tocopherol, carotenes, ascorbic acid, glutathione, anthocyanins and flavonols in fruit peel were measured. The objective was to determine if differences in antioxidants at harvest persisted through storage, and if changes in antioxidants corresponded to accumulations of conjugated trienes and development of scald. Treatments resulted in significant differences in antioxidant and pigment concentrations at harvest. Water-soluble antioxidants and anthocyanins declined during storage, but lipid-soluble antioxidants generally increased. In general, antioxidant concentrations at harvest were inversely related to maximum conjugated triene concentrations at the end of storage, and to scald development. However, no individual antioxidant was associated consistently with conjugated triene accumulation or scald development, and as conjugated triene concentrations increased, total lipid-soluble antioxidant activity also increased. Water-soluble antioxidants generally decreased during storage. Possible involvements of antioxidants with scald development is discussed.