Physiological and Compositional Changes in Orange Fruit in Relation to Modification of their Susceptibility to Penicillium italicum by Ethylene Treatments

Abstract

Abstract Exposure of orange fruit to 1000 μl/liter C 2 H 4 at 20°C for 2 to 6 days before inoculation with Penicillium italicum Wehmer reduced fungal growth as indicated by lesion diameter and glucosamine content. Respiration rates were stimulated by C 2 H 4 treatments and fungal inoculation, which also increased C 2 H 4 production rate. Ethylene treatments with or without inoculation did not influence soluble solids, pH, titratable acidity, or total phenolics content of fruit juice. Total phenolics of the rind increased in uninoculated fruit, but not in inoculated fruit, in response to C 2 H 4 treatment. No polyphenol oxidase activity was detected. Phenylalanine ammonia-lyase activity exhibited a significant increase in rind of uninoculated fruit, but not in inoculated fruit which were subjected to C 2 H 4 for 6 days followed by 6 days in air at 20°C.