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Home HortScience Clamshells Best for Retaining Tropical Fruit Quality
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HILO, HI—Longans, a subtropical fruit rich in vitamin C, minerals, and bioactive polyphenols, have traditionally been grown in Southern China, Thailand, and Taiwan. The exotic fruit is fast becoming recognized as a cash crop in Hawaii, where the number of longan trees planted grew from just 2300 in 2001 to 11,800 in 2008. Longans are gaining popularity with Hawaii's consumers and show promise as an export crop to U.S. mainland markets. Building consumer acceptance for the emerging fruit requires that longans arrive in markets in excellent condition, but defects such as fruit skin darkening and postharvest diseases can limit longan shelf life and export potential.

Marisa M. Wall from the U.S. Department of Agriculture, Agricultural Research Service, (USDS–ARS) and author of a new research study of longans, said that the tropical fruit must survive many steps before it is ready for consumers. According to Wall, Hawaii-grown longans are harvested, sorted, and packed in fruit fly-free fiberboard boxes lined with polyethylene or micro-perforated film. The fruit is then irradiated to meet quarantine regulations and air-shipped to mainland U.S. distributors. These steps in the supply chain often take place without refrigeration. Wholesalers may then store fruit at 10 °C until retail marketing, when the surrounding temperature may rise again. "These temperature changes during the postharvest chain make it difficult to maintain optimum atmospheres when using modified atmosphere packaging," Wall said.

Wall and colleagues Kate Nishijima, Lisa Keith, and Mike Nagao designed a research study to establish optimum storage temperatures and packaging systems to retain fruit quality of 'Biew Kiew' longans. The results of their research appeared in HortScience.

"We found that clamshell, Peakfresh® film, and micro-perforated film are all suitable packages for longans stored under optimal temperatures," the researchers said. "However, for longans stored under simulated shipping conditions (with fluctuating temperatures), sensory quality was highest when packaged in clamshell containers."

The scientists said that, although the use of Peakfresh® film and micro-perforated packaging retained longan quality under constant 10 °C, fruit packed in clamshell containers tended to have firmer arils, lower disease incidence, and slightly higher flavor scores under fluctuating postharvest temperatures. They observed some seasonal differences in fruit quality, disease incidence, shelf life, and response to packaging, which they said could be attributed to variations in preharvest conditions and maturity at harvest. "When we considered multiple seasons and the two temperature regimes, we found that shelf life and quality were consistently maintained when longans were stored in clamshell packages," Wall said.

The study noted that clamshell packages may also have additional benefits of reducing fruit injury, restricting disease spread, and promoting brand identification for longans.

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The complete study and abstract are available on the ASHS HortScience electronic journal web site:

Founded in 1903, the American Society for Horticultural Science (ASHS) is the largest organization dedicated to advancing all facets of horticultural research, education, and application. More information at


Original Article:

Influence of Packaging on Quality Retention of Longans (Dimocarpus longan) Under Constant and Fluctuating Postharvest Temperatures
Marisa M. Wall, Kate A. Nishijima, Lisa M. Keith, and Mike A. Nagao
HortScience 46:917–923. [Abstract][Full Text][PDF]

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