The effects of hot air (HA) pretreatment on quality, phenolic accumulation and antioxidant activity of fresh-cut pitaya fruit were investigated. It was found that 42 °C HA pretreatment for 3 h ...effectively alleviated the browning of fresh-cut pitaya fruit stored at both 4 °C for 14 d and 20 °C for 48 h. To better understand the physiological mechanisms of HA on browning alleviation, higher storage temperature at 20 °C was used to accelerate and amplify the wounding responses. The results demonstrated that HA pretreatment delayed the wound induced biosynthesis of phenolic compounds of fresh-cut pitaya fruit during earlier storage period but enhanced their contents and maintained higher antioxidant activity during the later stage of storage. It retarded but enhanced the activation of key enzymes (PAL, 4CL and C4H) and their relative gene expressions involved in the phenylpropanoid pathway. Moreover, HA pretreatment suppressed the activities of enzymes associated with oxidative browning of phenolics (PPO and POD), activated ascorbate-glutathione (AsA-GSH) cycle and inhibited the wound induced proliferation of ROS production which could cause oxidative damage of fresh-cut pitaya fruit. These findings suggested that pretreatment with HA could be an efficient and feasible approach for the browning alleviation and quality retention of fresh-cut pitaya fruit, and the phenylpropanoid metabolism and AsA-GSH cycle played crucial roles in this process.
•Hot air (HA) pretreatment alleviated browning of fresh-cut pitaya fruit.•HA pretreatment delayed but enhanced the wound-induced phenolic accumulation.•HA pretreatment reduced PPO and POD activities.•HA pretreatment enhanced antioxidant system and reduced ROS level.
Many fruits are harvested at the early ripening stage and left to attain an edible stage during the post-ripening process or by ethylene treatment. However, the post-ripening quality of fruit is ...generally inferior to the quality of fruit that ripened naturally. Sugar metabolism plays critical roles in regulating fruit flavor and stress responses. Methyl Jasmonate (MeJA) treatment modulates sugar accumulations and postharvest fruit quality. However, the regulation mechanism of MeJA on sugar metabolism and its relationship with fruit post-ripening quality are unclear. The results indicated that MeJA-treated fruit possessed higher total antioxidant, lycopene and soluble solids content and lower electrical conductivity and malondialdehyde content. Besides, the post-ripening quality of fruit was strongly related to the starch and sucrose content. Compared to the control and ethephon treatments, MeJA treatment increased the activities and transcript levels of amylase, sucrose phosphate synthase (SPS) and sucrose synthase (SUS), but decreased the activities and transcript levels of acid invertase and neutral invertase. Further analysis suggested that the sucrose content had a strongly positive correlation with the activities and transcript levels of SUS and SPS, except
SlSPS2
. Thus, MeJA treatment improved fruit post-ripening quality by regulating sugar metabolism.
The treatment of CO2→1-MCP significantly accelerate the decrease of soluble tannin and maintained quality of persimmon fruit.
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•CO2 treatment induced deastringency and quality ...deterioration of persimmon fruit.•CO2 followed by 1-MCP before cold storage (CO2→1-MCP) made up the shortage of CO2.•CO2→1-MCP promoted the decrease of soluble tannin of persimmon fruit.•CO2→1-MCP significantly maintained fruit quality and prolonged the storage time.•CO2→1-MCP induced antioxidant enzyme activities and inhibited LOX activity.
The different sequential combined effect of carbon dioxide (CO2, 90%) and 1-methylcyclopropene (1-MCP, 0.5μLL−1) on storage quality of persimmon fruit was investigated. In this study, the application of CO2 could induce the decrease of soluble tannin. But, the CO2-treated persimmon fruit soften rapidly, reducing their shelf life. Compared with CO2 treatment before cold storage, the treatment with CO2 deastringency after cold storage (air→CO2), CO2 deastringency followed by 1-MCP treatment before cold storage (CO2→1-MCP), and 1-MCP treatment followed cold storage before CO2 deastringency (1-MCP→CO2) were more effective in prolonging the storage time of persimmon fruit, especially the application of CO2→1-MCP, as indicated by higher firmness and soluble solids content, and the lower electrical conductivity and MDA content during most of the storage periods. Moreover, the treatment with CO2→1-MCP could induce the enhancement of antioxidant enzyme activities including superoxide dismutase, peroxidase and catalase. Meanwhile, the treatment with CO2→1-MCP could also maintain the lower lipoxygenase activity. These results suggest that the treatment of CO2→1-MCP may be an useful technique to decrease the soluble tannin content, maintain quality and prolong the storage time in postharvest persimmon fruit during storage.
A "Laiyang" pear is a climacteric fruit with a special taste and nutritional value but is prone to a post-harvest aroma compound loss and a loss in fruit quality. In this study, pears were pretreated ...with 0.5 μl L-1 1-methylcyclopropene (1-MCP) at 20°C for 12 h and then stored at 0 ± 1°C for 150 days to evaluate the influence of 1-MCP on fruit quality and the changes in components of volatile aromas. In addition, pears were further treated with 2 mmol L-1 ethephon. The effects of ethephon on the recovery of aroma production were investigated during the 150 day storage at 0 ± 1°C and the subsequent 7 day shelf life at 20 ± 1°C. Treatment with 1-MCP inhibited firmness loss, increased electrical conductivity, reduced respiration and ethylene production rates as well as the contents of soluble solids, and maintained the storage quality of the fruits. However, 1-MCP treatment inhibited the emission of volatile aromas in pear fruits by decreasing the activities of various enzymes, such as lipoxygenase (LOX), hydroperoxide lyase (HPL), alcohol dehydrogenase (ADH), pyruvate carboxylase (PDC), and alcohol acetyltransferase (AAT). During the shelf-life, activities of the above mentioned enzymes were significantly enhanced, and a higher content of volatile aromas were found in fruits treated with 1-MCP + ethephon, while other qualities were not compromised. These results showed that 1-MCP treatment could effectively maintain the quality of the "Laiyang" pear during cold storage, and the additional application of ethephon on fruits during shelf-life may be a promising way to restore volatile aromas in pear fruits after long-term storage.
•The main cuticular wax components of apple fruit are acids, 1-alcohols and n-alkanes.•Ethephon stimulated the changes in total wax, alcohol, olefin, alkane and acid.•n-tetradecanal was induced by ...ethephon while disappeared in 1-MCP and Control.•Ethephon accelerated the conversion of wax components > C18 to those of ≤C18.
To investigate ethylene effects on fruit cuticular wax during cold storage, apple fruit (Malus domestica Borkh. c.v. Starkrimson) were treated with 500mgL−1 ethephon and 1μLL−1 1-methylcyclopropene (1-MCP), and the composition and contents of the cuticular wax were analyzed at 20 d intervals during cold storage. The results showed that the prevailing cuticular wax components were acids, 1-alcohols and n-alkanes. Ethephon accelerated fruit senescence, positively regulated total wax quantity and its alcohol, olefin, alkane, and acid constituents during cold storage, especially 1-pentacosanol, 1-octacosanol, α-farnesane, n-octacosanoic acid, stearyl acid butyl ester, stearic acid hexyl ester and n-tetradecanal, while 1-MCP inhibited these processes. It can be concluded that ethylene altered the fruit cuticular wax contents and constituents, which may alter the subsequent postharvest qualities of the fruit and the susceptibility of the fruit to disorders during cold storage.
•Four apple wax synthesis key genes, MdCER4, MdCER6, MdWSD1 and MdMAH1 were identified.•Ethylene increased MdCER6 expression level, a key gene in VLCFA synthesis.•Ethylene regulated the ...alcohol-forming pathway by stimulating MdCER4 and MdWSD1.•Ethylene altered wax composition and structure via MdCER6 and alcohol-forming pathway.•Ethephon increased and 1-MCP reduced wax density during cold storage, respectively.
To investigate the impact of ethylene in regulating wax synthesis-related gene expression and the consequent fruit quality changes during cold storage, four key apple wax synthesis genes from ‘Starkrimson’ apple, MdCER4, MdCER6, MdWSD1 and MdMAH1, were identified, and their expression levels in response to treatments with ethephon and 1-methylcyclopropene (1-MCP) during cold storage were studied. The fruit quality changes in these two treatments were also determined during cold storage. The results showed that ethephon increased cuticular wax density, accelerated wax crystal melting and fruit senescence during cold storage of ‘Starkrimson’ apple, while 1-MCP delayed these processes. The results also showed that ethephon increased the expression levels of MdCER6 (a key gene in very long chain fatty acids synthesis), MdCER4 and MdWSD1 (two key genes in the alcohol-forming pathway of wax synthesis), while 1-MCP decreased their expression. In addition, neither ethephon nor 1-MCP regularly regulated the expression of MdMAH1, a key gene in the final step of the alkane-forming pathway of wax synthesis. Therefore, it was concluded that ethylene altered fruit cuticular wax composition and crystal morphology via MdCER6 and the subsequent alcohol-forming pathway, thus affecting the fruit quality to some extent during ‘Starkrimson’ apple fruit cold storage.
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