Ripening of ‘Golden’ papaya fruit: harvest time, ethylene action blockade and cold storage / Amadurecimento do mamão Golden : ponto de colheita, bloqueio da ação do etileno e armazenamento refrigerado

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The present work had as objective the study of how the harvest time, ethylene action blockade and cold storage influence the ripening and the quality of ‘Golden’ papaya fruit. In the first experiment ‘Golden’ papayas were harvested at 4 maturity stages (Stage 0: totally green; Stage 1: up to 15% of yellow skin; Stage 2: 16-25% of yellow skin; Stage 3: 26-50% of yellow skin) and analyzed during ripening at 23ºC in relation to physical and chemical (skin color, pulp firmness, soluble solids, titratable acidity and ascorbic acid), physiological (respiration and ethylene production) and sensorial (flavor, odor, firmness and appearance) characteristics. From the 2nd day of storage at 23ºC, fruits presented stable respiratory activity around 31 mL CO2 kg-1 h-1 for stages 0, 1 e 2 and 37 mL CO2 kg-1 h-1 for stage 3. It was not observed typical climacteric behavior in any maturity stage. Only fruits harvested in stage 0 and 1 showed ethylene production peak of 2.1 µL C2H4 kg-1 h-1 at the 7th day and 1.3 µL C2H4 kg-1 h-1 at the 6th day of storage at 23ºC, respectively. Fruits harvested at stages 2 and 3 had superior scores in sensorial evaluation, mainly for flavor and appearance. Sensorial characteristics of fruits from all maturity stages were scored as regular or superior. Harvest at different maturity stages altered the fruit postharvest physiology and when effectuated at early stages reduced the fruit quality but did not make the fruit consume impossible. In the second experiment papayas harvested at maturity stage 1 were evaluated. Half of the fruit treated and non-treated with 100 nL L-1 of 1-methylcyclopropene (1- MCP) were exposed to 23ºC, while the other half was stored at 11ºC for 20 days, prior to transference to 23ºC. During the ripening, fruits were analyzed for the same physical, chemical and physiological characteristics as done in the first experiment, besides the activity of the pectinmethylesterase (PME) enzyme. Fruits that received 1-MCP, and were not refrigerated, presented reduction in respiratory activity, ethylene production, skin color development and PME activity, maintaining high pulp firmness during the storage at 23ºC. Even with gradual increase in ethylene production at 23ºC, fruits treated with 1-MCP maintained high firmness, but presented loss of green skin color. The cold storage harmed the ethylene production in non-treated and 1- MCP-treated fruits when they were transferred to 23ºC. Even so, the firmness in those fruits decreased, being this decrease always lower in 1-MCP treated fruits. The results suggest that pulp softening is more dependent on ethylene when compared to skin color development and that there are processes responsible for firmness loss that are independent on ethylene. It is also possible to assume that prolonged ethylene inhibition or the inhibition of receptor sites in fruits that were harvested at early maturity stages, reflects in slow recovery capacity of ethylene action and production, suggesting that the use of ethylene action blockers in these fruits must be done with caution.

ASSUNTO(S)

mamão papaya plantl respiration respiração vegetal fisiologia pós-colheita plant hormone maturação vegetal plant maturity postharvest physiology hormônio vegetal

ACESSO AO ARTIGO

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