Antioxidant Properties and Fruit Quality During Long‐term Storage of “Rocha” Pear: Effects of Maturity and Storage Conditions

Abstract

Free radical scavenging activity and the content of ascorbic acid and glutathione were investigated during long‐term storage of the pear (Pyrus communis L. ‘Rocha’) fruit harvested at different maturity stages, stored in air or under controlled atmosphere and subjected to postharvest treatments with diphenylamine (DPA) and 1‐methylcyclopropene (1‐MCP). Harvest maturity had a significant effect on storage disorders, fruit firmness, soluble solids content and acidity. Differences in ascorbate content and free radical scavenging activity at harvest did not persist during storage. Controlled atmosphere and DPA strongly reduced the incidence and severity of browning disorders and superficial scald, whereas 1‐MCP provided the most effective control. Neither DPA nor 1‐MCP affected the free radical scavenging activity or the levels of ascorbate and glutathione in the pear. These results suggest that the benefits of 1‐MCP on internal breakdown are not directly related with its effects on the antioxidant levels and that, under good storage conditions, the antioxidant properties of the “Rocha” pear can be maintained for up to 8 months. PRACTICAL APPLICATIONS The importance of fruit antioxidant metabolites as beneficial phytochemicals has been widely recognized. Interestingly, the same metabolites are also essential for the health of the fruit itself. Thus, maintaining high levels of antioxidants in fruits throughout the supply chain is of utmost importance to maintain fruit quality and to deliver to consumers the health benefits of fruit consumption. Many studies have addressed fruit antioxidants, but these studies either report comparisons among fruit types analyzed at a single (often uncharacterized) stage of development or they study changes during short storage periods. European consumers have pears available all year round and the typical storage duration of European pears extends up to 8 months. Moreover, different storage regimes and several postharvest treatments that may impact fruit antioxidants are used in commercial practice. It is thus relevant to characterize pear antioxidants during long‐term storage and the effect of storage conditions and common postharvest treatments on fruit antioxidants. Harvest data are known to have a large effect on post‐storage fruit quality, but its effect on antioxidants during storage is unknown. This information is useful to nutritionists and consumers who have to choose fruit and to all involved in the fruit supply chain in order to provide fruit with better quality.

Efficacy of 1-methylcyclopropene on the mitigation of storage disorders of “Rocha” pear under normal refrigerated and controlled atmospheres

“…Silva et al (2010) reported no effect of 1-MCP at 500 nl l À1 on acidity of ''Rocha'' pear stored at 0 C for up to eight months in relation to untreated controls, but fruit treated with 500 or 1000 nl l À1 of 1-MCP had higher acidity after a four-month storage period than fruit treated with 100 nl l À1 of 1-MCP or Food Science and Technology International 0(0) untreated controls (Isidoro and Almeida, 2006). The effect of 1-MCP on titratable acidity may be dependent on the maturity of the fruit at harvest, as suggested by the results reported by Alpalha˜o et al (2008) in two consecutive years: higher titratable in 1-MCP-treated fruit in relation to untreated controls during storage and shelf life were registered in one year, but no differences were observed in another year.…”

“…The ethylene action inhibitor 1-methylcyclopropene (1-MCP) reduces or prevents superficial scald in pear cultivars (Argenta et al, 2003;Chiriboga et al, 2013;Ekman et al, 2004;Isidoro and Almeida, 2006;Silva et al, 2010;Trinchero et al, 2004;Villalobos-Acun˜a et al, 2011;Xie et al, 2014). A few studies have been conducted to evaluate 1-MCP effects on ''Rocha'' pear at the laboratory scale and in packinghouse settings (Alpalha˜o et al, 2008;Almeida, 2006, 2008;Silva et al, 2008Silva et al, , 2010.…”

An insight into the role of fruit maturity at harvest on superficial scald development in ‘Beurré D’Anjou’ pear

“…Thus, the balance between the content of oxidative species and antioxidants within the fruit skin has an important role in the development and progression of superficial scald in both apples and pears (Ju et al, 1996;Rao et al, 1998;Diamantidis et al, 2002;Zubini et al, 2007;Whitaker et al, 2009;Silva et al, 2010). Low temperature storage weakens the antioxidant mechanisms of plant tissues (Mir et al, 1999) including pears (Chiriboga et al, 2013) hence making the fruit more prone to develop this physiological disorder.…”

Biochemical markers to predict internal browning disorders in ‘Rocha’ pear during storage under high CO2

“…‘Rocha’ pear can be stored for up to 10 months under controlled atmosphere (CA) (2.5–3 kPa O 2 + 0.5–0.7 kPa CO 2 ) . However, during long‐term storage under CA, similarly to other pear cultivars, it develops two major physiological disorders: internal browning and superficial scald . Internal browning disorders (IBD) affect the inner part of the fruit and in the most severe cases the damage can be extended up to the peel…”

“…1 However, during long-term storage under CA, similarly to other pear cultivars, it develops two major physiological disorders: internal browning and superficial scald. 2 Internal browning disorders (IBD) affect the inner part of the fruit and in the most severe cases the damage can be extended up to the peel. 3 IBD results from the reaction of polyphenoloxidase (PPO) with its phenolic substrates, leading to the formation of o-quinones which spontaneously polymerize to form melanins, the browning compounds.…”