Resumo

CRUZ, Javier De la; VELA, Gilber; DORANTES, Lidia  e  GARCIA, Hugo S.. Ethylene effect on ACC content and ACC oxidase during ripening of 'maradol' papaya. Rev. fitotec. mex [online]. 2010, vol.33, n.2, pp.133-140. ISSN 0187-7380.

'Maradol' papaya (Carica papaya L.) fruits were subjected to atmospheres containing certified mixtures of synthetic air and ethylene (0, 100, 300 and 500 µL L^-1) in fiberglass containers for different periods (8, 16 and 24 h). After exposure, fruits were transferred to ambient conditions (25 °C) for ripening. The analyses performed on each treatment were: firmness, soluble solids content, reducing sugars content, titratable acidity, peel and flesh color (Hue), ethylene production rate (EPR), 1-aminocyclopropane-1-carboxylic acid (ACC) content and ethylene-forming enzyme (ACC oxidadese) activity. Results showed that the first noticeable change in fruits was the yellow and red color turning in peel and flesh respectively, both typical of a fully ripe and ready-to-eat-papaya fruit. Fruits exposed to 500 µL L^-1 of ethylene for 16 and 24 h showed a climacteric peak one day after treatment, while fruits exposed for only 8 h displayed their climacteric peak 2 d after ethy-lene exposure. Papayas treated for 16 and 24 h developed very low Hue values in a shorter time then the control, and their ACC content increased to 2.7 nmol g^-1 h^-1. ACC oxidase activity also increased to 3 nL g^-1 h^-1, and EPR reached 24 nL g^-1 h^-1. This set of conditions allowed fruits to reach firmness values of 5.2 kgf cm^-2 and 12 % of soluble solids after 6 d at 25 °C. Reducing sugars content and percent age of titratable acidity were not different (P > 0.05) between treatments. Similar values were found in control fruits after 8 d at normal ripening conditions. Results suggest that it is possible to shorten ripening of 'Maradol' papaya fruit from 8 to 3 d after application of exogenous ethylene.

Palavras-chave : Carica papaya; ACC; ACC oxidase; ethylene.

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