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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCEMENT OF THE QUALITY AND MICROBIAL STABILITY OF FRESH FRUITS AND VEGETABLES WITH EDIBLE COATINGS AND OTHER SURFACE TREATMENTS

Location:

2009 Annual Report


1a.Objectives (from AD-416)
Improve technology that preserves quality, edibility and storability of whole fresh and fresh-cut produce, with emphasis on chemical-free and organic-compatible treatments. Model how fruit coatings influence concentrations of internal gases and, thus, affect quality.


1b.Approach (from AD-416)
Assess potential incidence of disease preharvest to anticipate problems under postharvest conditions. Test antagonistic microorganisms as a decay-control treatment as well as antimicrobial essential oils and natural phytoalexins. Coating formulations will be developed from new or traditional ingredients and analyzed for their ability to block pores in the fruit peel, and reduce microbial populations for intact and fresh-cut produce. Intact fruit will undergo treatments that reduce wound-ethylene in the fresh-cut product. In all cases, affect of treatments on quality will be evaluated.


3.Progress Report
This project aims to extend shelf life, quality and microbial stability of intact and fresh-cut fruit. Allowable sanitizers and commercial fruit coatings were tested for their effect on eliminating the canker bacteria that causes blemishes on citrus fruit rendering them unmarketable and subject to quarantine (in that they are banned from shipment to other citrus growing areas) and a reduction of the pathogen was observed, but not eliminated. Antimicrobial compounds were screened for efficacy against the canker bacteria, and several food grade candidates were found and tested in coatings. Modified atmosphere (low oxygen and high carbon dioxide) was applied to canker-infected citrus at different temperatures to reduce viable canker bacteria. Work was continued on laser labeling of fruit, its effect on decay and water loss, and minimizing water loss with an edible wax. Treatment of fruit with a high alkaline wash was shown to alter the fruit waxy cuticle and reduce decay organisms. Reduction of decay organisms translated to less microbial populations on the subsequent fresh-cut product for papaya and carambola. Treating fruit that had been subjected to the alkaline wash with wax coatings resulted in synergistic control of water loss compared to either treatment alone. Fresh-cut carambola shelf life and quality was extended due to treatment with calcium ascorbate (calcium and vitamin C) while further reducing microbial populations in addition to the high alkaline wash treatment of the whole fruit prior to cutting. Spraying of citrus in the field with wax formulations is being tested for reduction of canker bacteria prior to harvest, such that less bacterium enters the packinghouse. A new clamshell was designed to reduce water loss of small and fresh-cut fruits. The new clamshell plus an edible coating maintained the red color of rambutan and lychee fruit, which normally turn brown after harvest, rendering the fruit unmarketable. A fresh juice project was initiated to produce a safe and nutritious fresh squeezed juice. This project is due to term within the first two month of the new fiscal year and will be replaced by a bridging project due to a pending national review.


4.Accomplishments
1. A Fruit Sanitizer, Controlled Atmosphere and an Antimicrobial Oil Were Found to be Effective Against Citrus Canker: Citrus canker, caused by a bacterium, reduces marketability of citrus fruit due to blemishes, and subjects the fruit to quarantine in that Florida citrus cannot be shipped to other citrus-growing areas. The most effective sanitizer, essential oil, coating and storage atmosphere will be combined to create a systems approach that is lethal to the canker bacteria, but that does not impair fruit quality so that the quarantine can be rescinded. The first step in this process was demonstrated for the sanitizer, peroxyacetic acid, which eliminated citrus canker on fruit surfaces and packing lines. Canker bacteria still survived in wound sites on fruit, however. A controlled atmosphere of low oxygen and high carbon dioxide combined with mild heat significantly reduced canker bacteria on fruit, including in wound sites. This was followed by the successful testing of an antimicrobial oil, found to be effective against the canker bacteria in a Petri plate, to also be effective in commercial application to whole fruit. Complete elimination of the canker bacteria on citrus fruit leaving the packinghouse would result in allowed shipment of citrus fruit to other citrus growing areas, both domestically and abroad.


5.Significant Activities that Support Special Target Populations
Work on citrus canker elimination from citrus fruit benefits the small citrus fresh fruit grower in rural Florida by lifting the quarantine on their fruit that prevents shipment to other citrus-growing areas.

Work on tropical fruits benefits the small rural and often woman or minority-owned farms in south Florida.


6.Technology Transfer

Number of New Patent Applications Filed1

Review Publications
Bai, J., Wu, P., Manthey, J., Goodner, K., Baldwin, E. 2009. Effect of harvest maturity on quality of fresh-cut pear salad. Postharvest Biology and Technology. 51:250-256.

Narciso, J.A. 2009. A simple method for screening antimicrobial compounds with application to plant disease and fruit quality. Letters in Applied Microbiology. 48:548-553.

Sood, P., Ference, C., Narciso, J., Exteberria, E. 2009. Laser etching: A novel technology to label Florida grapefruit. HortTechnology. 19(3):504-510.

Yin, X., Bai, J., Seavert, C.F. 2009. Pear responses to split fertigation and band placement of nitrogen and phosphorus. HortTechnology. 19(3):586-592.

Last Modified: 7/23/2014
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