Enzyme reactions leading to avocado fruit mesocarp discoloration

After storage at 5.5°C for 31 days avocado fruit turned black round the seed in response to being placed in sealed containers for short periods, waxing the skin or wrapping in cellophane. All the treatments increased the shelf-life but at the expense of flesh discoloration except in the case of cellophane wrapping. Discoloration was associated with increased activities of both polyphenol oxidase and peroxidase but total phenol concentrations and phenylalanine ammonia-lyase activities were not affected. The results suggest that low temperature storage predisposes mesocarp blackening and this is brought about by further anearobic conditions.