Ethylene production and ACCoxidase activity in passion fruits (Passiflora edulis f. flavicarpa Deg.)

Passion fruit (Passiflora edulis f. flavicarpa Deg.) is one of the main cultivated species of Passiflora genus. Its fruits are rich in mineral salts and vitamins and to present agreeable aroma and flavour. The purpose of this work was to determine ethylene production and enzymatic activity of ACC oxidase (ACCO) in yellow passion fruit cropped in different maturation stages. The determination of maturation stage was effected with the help of a colorimeter that established the absolute value of fruit colour, using UV light, and classified the fruits into three groups (I, II, III). Ethylene production and ACC oxidase activity were measured by gaz chromatography. Fruits in group I, predominantly green, those in group II, as predominantly coloured, which means in an intermediary state of maturation, and those in group III, totally coloured, at the beginning of senescence. ACC oxidase activity was detected in predominantly green fruits, with values higher than those encountered in mature fruits. Higher ethylene production was also found in fruits of group I, with a mean value of 7,25 nL. g-1. h-1 , in relation to the maximum level established for species classified as poor producers of ethylene (0,5 nL. g-1. h-1). These results show that the ethylene production and ACC oxidase activity of passion fruits are related to their maturation stage. In comparison with other species, Passiflora edulis f. flavicarpa was considered as an intermediary producer of ethylene. The activity of ACC oxidase enzyme was higher in predominantly green fruits, but was limited and needs enzymatic co-factors for its maximum activity.

Passion fruit; ethylene; ACCO

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