Adding a Coat

January 14/Food & Farm Week -- Research from Washington State University has provided new data on food processing and preservation.

"Green asparagus was treated with different coatings (chitosan-beeswax, sodium caseinate-beeswax and Semperfresh) and evaluated for changes in fresh weight, sensory attributes, tiprot disorder and texture after a storage period of 14 days at 4C. Chitosan-beeswax significantly reduced fresh weight loss of asparagus compared to untreated spears," researchers in the U.S. report.

"Semperfresh and sodium caseinate coatings resulted in the smallest loss of desirable green color in spears. Coatings did not significantly delay the development of tiprot disorder compared to untreated spears; however, chitosan coatings markedly reduced the foul odor in spears affected with tiprot, suggesting antimicrobial activity by chitosan. Coatings did not significantly delay undesirable changes to spear texture. Chitosan and sodium caseinate coatings caused spears to become abnormally stiff or inflexible, and chitosan coatings were responsible for spear yellowing and an astringent taste. The suitability of these coatings for use on asparagus will depend on improvements in formulations and the application technique. Current recommendations to extend the quality and shelflife of green asparagus rely on storage temperatures between 2-4C and modified atmosphere packaging (MAP). The practice of storing fresh green asparagus in MAP, however, has not gained wide acceptance by the fresh pack industry. This is likely because of several reasons, including the increasing cost of petroleum-based packaging material, and the fact that end users of packaging products are becoming more interested in packaging material that does not end up in landfills. Edible coatings are used extensively as a postharvest treatment to preserve the quality of many fruits and vegetables, but less is known about their effects on quality attributes of fresh green asparagus," wrote S.J. Fuchs and colleagues, Washington State University.

The researchers concluded, "An edible coating comparable to MAP in terms of extending the quality and shelflife of asparagus would be beneficial to the fresh asparagus industry as well as the retail market and consumer."

Fuchs and colleagues published their study in the Journal of Food Processing and Preservation ("EFFECT OF EDIBLE COATINGS ON POSTHARVEST QUALITY OF FRESH GREEN ASPARAGUS." Journal of Food Processing and Preservation, 2008;32(6):951-971).

For additional information, contact S.J. Fuchs, Washington State University, Dept. of Horticulture & Landscape Architecture, Pullman, WA 99164, USA.

From the January 19, 2009, Prepared Foods E-dition