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- Effect of different levels of CO2 on the antioxidant content and the polyphenol oxidase activity of ‘Rocha’ pears during cold storagePublication . Galvis-Sánchez, Andrea C.; Fonseca, Susana C.; Gil-Izquierdo, Ángel; Gil, María I.; Malcata, F. XavierAbstract: Pears (Pyrus communis L. cv. ‘Rocha’) were exposed to air or controlled atmosphere (CA) containing various concentrations of CO2: 0, 0.5 and 5 kPa, all with 2 kPa O2. After 4months 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 4months 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 CO2. The combination 2 kPa O2 + 5kPa CO2 increased the incidence of internal disorders (viz. brown heart and flesh browning) after storage.
- Maintaining optimal atmosphere conditions for fruits and vegetables throughout the postharvest handling chainPublication . Brech, J. K.; Chau, K. V.; Fonseca, S. C.; Oliveira, F. A. R.; Silva, F. M.; Nunes, M. C. N.; Bender, R. J.Optimal controlled and modified atmospheres (CA and MA) for fresh produce vary according to the specie, its maturity or ripeness stage, the temperature, and the duration of exposure. However, individual lots of produce are typically handled for different times and at different temperatures during storage, transportation, and retail display. In this paper, we review some of our previous work showing the potential for using different atmospheres for mangoes (Mangifera indica L.) and strawberries (Fragaria×ananassa Duchesne) depending on the anticipated storage length and temperature. Since it would be desirable, especially for produce transported over extended distances, as in marine transport, to maintain optimal atmosphere conditions throughout the postharvest handling chain, we also describe our procedure for designing a combination CA/MAP system that involves first designing the MAP for a particular commodity that will produce an optimal atmosphere for retail display conditions, then selecting a CA that will interact with the MAP to produce the optimal atmosphere within the packages during transportation at a lower temperature. An example of the design procedure is given from our work with fresh-cut kale (Brassica oleracea var. acephala DC.). Another example of this proposed MAP/CA system deals with its application to mixed load transportation of strawberries and snap beans (Phaseolus vulgaris L.).