Effect of different levels of CO₂ on the antioxidant content and the polyphenol oxidase activity of ‘Rocha’ pears during cold storage

Abstract

Pears (Pyrus communis L. cv. 'Rocha') were exposed to air or controlled atmosphere (CA) containing various concentrations of CO 2 : 0, 0.5 and 5 kPa, all with 2 kPa O 2 . After 4 months of storage at 2 • C, the fruits were transferred to air at room temperature, and assessed in terms of soluble solids, titratable acidity, pH, incidence of brown heart and flesh browning, phenolic content, vitamin C content and polyphenol oxidase activity. By 4 months of storage, soluble solids and pH increased, and acidity decreased relative to harvest, but no differences were detected between pears stored under air or any of the CA tested. Higher contents of hydroxycinnamic derivatives and flavan-3-ols in the peel than in the flesh were recorded. However, the content of arbutin was higher in the flesh than in the peel, whereas flavonols were only detected in the peel. In general, hydroxycinnamic derivatives and flavonols were stable throughout storage, but flavan-3-ols decreased in concentration under air or CA. Arbutin was the only phenolic compound that increased in concentration as time elapsed. No clear relation was found between the storage conditions tested and the phenolic concentration in pears. Regarding ascorbic acid (AA) and dehydroascorbic acid (DHA), their concentrations were higher in the peel than in the flesh. Furthermore, AA and DHA were strongly affected by storage: the former decreased, whereas the latter increased in content. A decrease in PPO activity was apparent after harvest and during storage, particularly under higher levels of CO 2 . The combination 2 kPa O 2 + 5 kPa CO 2 increased the incidence of internal disorders (viz. brown heart and flesh browning) after storage.

Controlled and modified atmospheres influence chilling injury, fruit quality and antioxidative system of Japanese plums (Prunus salicina Lindell)

“…The experimental results indicated that GSH could be playing an important role in acquisition of chilling tolerance in Japanese plums leading to lower CI incidence and severity. This role could be quite similar to the one ascribed to AsA in pears (Veltman et al ., ; Larrigaudiére et al ., ; Galvis–Sánchez et al ., ). More research is required to elucidate the role of GSH in the development of various physiological disorders in fruits.…”

“…DHA concentrations increased significantly during ripening period after both storage intervals which is in agreement with Galvis–Sánchez et al . () who reported a similar increase in DHA during shelf life of ‘Rocha’ pears following 4 months of CA storage. The activities of enzymes involved in oxidation and recovery of AsA were determined to explain the dynamics of oxidised and reduced forms of AsA.…”

“…There is ample evidence in literature suggesting that AsA is very labile to losses in fruit during cold storage under normal air and CA conditions. The decrease in AsA concentration in 'Conference' and 'Rocha' pears under CA storage has been widely studied and correlated with the core browning disorder (Veltman et al, 1999;Galvis-Sa´nchez et al, 2006). Other reports also suggested that AsA concentration decreased during long-term cold storage of mangoes (Zhao et al, 2009) and pawpaws (Galli et al, 2009).…”

Application of Exogenous Ethylene Inhibits Postharvest Peel Browning of ‘Huangguan’ Pear

“…Browning disorder of pears is affected by both preharvest factors (such as picking date, maturity, fruit size and kind of fruit-bags) and postharvest factors (such as the duration of cooling period, the storage temperature and the CO 2 and O 2 concentrations; Lammertyn et al, 2000; Guan et al, 2005, 2008; Galvis-Sánchez et al, 2006; Wang and Wang, 2011). For example, pears with higher content of chlorogenic acid, a dominant phenolic acid in ‘Huangguan’ pears, are prone to browning (Franck et al, 2007; Kou et al, 2015).…”

“…Moreover, the occurrence of surface browning in ‘Huangguan’ pear was also reported to be related to the Ca 2+ deficiency and the cellular Ca 2+ distribution in skin tissues (Dong et al, 2015). In addition, heart browning and flesh browning of ‘Rocha’ pears are increased by the combination of 2 kPa O 2 + 5 kPa CO 2 (Galvis-Sánchez et al, 2006). …”