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Chandler', 'Oso Grande' and 'Sweet Charlie' strawberry cultivars were harvested at four stages of color development ranging from color break to full red and stored in the dark for 8 days at 1 • C. Changes in the physical and chemical characteristics of fruit during storage were compared with those occurring during development in the field. Strawberry fruit harvested at the three-quarters colored and full red stages continued their development and ripening during storage. However, fruit harvested at the color break and half-colored stages did not develop like those ripened in the field. Strawberries harvested at the three-quarters colored stage developed the same pH, acidity, soluble solids, ascorbic acid and total phenolics content during storage as the at-harvest levels present in strawberries harvested at the full red stage. In addition, three-quarters colored strawberries were as firm and red after storage as the full red stage fruit were at the time of harvest. Thus, strawberries harvested at the three-quarters colored stage can be stored for a longer period than strawberries harvested full red while retaining better color and firmness.

Postharvest Biology and Technology 6 (1995) 17-28. doi:10.1016/0925-5214(94)00048-W2016-03-04T18:48:28

Current temperature tracking systems lack the convenience and accuracy demanded by the real conditions of a fast-paced produce supply chain. In recent years RFID technology has been suggested to be an enhanced method for temperature tracking because of its many benefits, such as using little instrumentation, offering the quick readings necessary for real-time decision making, and allowing the capture of long-duration temperature profiles. However its limitation lies in that probeless systems fail to provide accurate temperature readings in some of the critical points of the pallet and the load. The objective of this work was to study the use of RFID in temperature monitoring by comparing the performance of RFID temperature tags versus conventional temperature tracking methods, as well as RFID temperature tags with probe versus RFID temperature tags without probes and their utilization along the supply chain. Therefore, the temperature mapping of a shipping trial comprising pallets of crownless pineapples instrumented using different RFID temperature dataloggers and traditional temperature dataloggers and packed in two kinds of packages (corrugated boxes and reusable plastic containers) inside a container was performed. The results showed that RFID temperature tags are analogous with regards to accuracy to the conventional methods, but have a superior performance because they allow quick instrumentation and data recovery, and the possibility of accessing the sensor program and data at any point of the supply chain without line of sight. In addition, the use of RFID tags with probe was justified by its role in determining the efficiency of the pre-cooling operations and low temperature abuse tracking during transportation and refrigerated storage; while the RFID tags without probe proved useful for high temperature abuse monitoring during transportation and refrigerated storage. The creation of a RFID sensor with a probe, able to record both ambient and pulp temperatures simultaneously is suggested.

: Fresh‘Oso Grande’strawberries wrapped in polyvinyl chloride stretch film lost 0.7% of their initial weight during storage for 8 d at 1 °C, whereas unwrapped fruit lost 11%. Greater water loss was associated with darker and less red fruit, lower concentrations of anthocyanins and other soluble phenolics, and higher polyphenol oxidase (PPO) activity. Anthocyanin degradation and oxidation of soluble phenolic compounds, caused possibly by increased PPO activity as a result of water loss, contributed to the development of strawberry surface browning during storage. Proper handling to reduce water loss during postharvest operations should be used to maintain acceptable color of strawberries during shipping and retailing.

Chandler', 'Oso Grande' and 'Sweet Charlie' strawberries were stored for 8 days at 1 or 10°C, or 4 days at 20°C, either unwrapped or wrapped in PVC film to retard water loss. Total ascorbic acid (AA) content was expressed on a dry weight basis to correct for water loss differences between treatments. Loss of AA was low and did not differ between wrapped treatments at 1 and 10°C, but was much greater at 20°C. Wrapping reduced AA loss by 5-fold at 1 and 10°C and by 2-fold at 20°C. The effect was not due to modification of O 2 and CO 2 levels in wrapped treatments, which was minimal. The results indicate that water loss had a greater effect on AA levels than temperature. Combining wrapping with storage at 1 or 10°C reduced AA loss by 7.5-fold compared to unwrapped strawberries stored at 20°C.