Cuticular phenolics and scald development in 'Delicious' apples

Abstract

Influences of fruit maturity, AVG and ethephon preharvest treatments, and storage conditions on cuticular phenolic concentration, α-farnesene accumulation and oxidation, and scald development of 'Delicious' apples [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] were studied. Advanced maturity and ethephon treatment increased free phenolics in fruit cuticle at harvest, while AVG treatment caused a reduction. Free cuticular phenolics increased during early storage in ethephon-treated and nontreated fruit but not in AVG-treated apples. Advanced maturity and ethephon did not alter α-farnesene accumulation overall, but reduced conjugated triene (CT281) formation and scald development. When stored in a low-ethylene room (<1 μL·L-1), AVG-treated fruit accumulated very low levels of α-farnesene and CT281 and did not develop scald after 6 months at 0 °C. When stored in a commercial room (ambient ethylene >5 μL·L-1), the AVG-treated and control fruit accumulated similar amounts of α-farnesene and CT281 and developed similar percentages of scald. In general, free phenolic concentrations in fruit cuticle were negatively correlated with CT281 formation and scald development of apples. Chemical names used: aminoethoxyvinylglycine (AVG); 2-chloroethylphosphonic acid (ethephon).