Diphenylamine Residues in Apples (<i>Malus domestica</i> Borkh.), Cider, and Pomace following Commercial Controlled Atmosphere Storage

Abstract

Diphenylamine (DPA) is used for scald suppression on apples held in commercial controlled atmosphere (CA) storage. The whole fruit tolerance in the United States for DPA is 10 ppm. This study was conducted to quantify terminal DPA residues in Red Delicious and Granny Smith apples and processed products including cider and wet and dried pomace following DPA treatments at maximum labeled use rates. Samples were analyzed at several intervals during an approximately 9-month CA storage period. Initial DPA residues in whole apples were <10 ppm and progressively declined under commercial CA storage. Only traces of DPA occurred in cider; however, DPA concentrated in both wet and dried pomace. Residues were less in dried pomace than in wet pomace, presumably due to loss by volatility during the drying process. DPA residues in cider and pomace also dissipated with time in CA storage. Keywords: Diphenylamine; apples; Malus domestica; controlled atmosphere storage; concentration factors