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W. Y. CHOI¹, K. M. KIM, and H. J. PARK. (1) Graduate School of Biotechnology, Korea University, 5 Ka Anam-Dong, Sungbuk-Ku, Seoul, 136-701, South Korea

JUSTIFICATION : Edible coatings for fresh produce can provide an alternative way to control and extend quality and shelf life during storage. Edible coatings can give the same effect as modified atmosphere storage in respect to modifying internal gas composition. In previous works, wettabilities of the edibe coatings on fruit skins has not studied extensively. In this studies, several edible coating emulsions were prepared for fresh produces and were tested for wettabilities and barrier properties. OBJECTIVE : Our objectives are to develop edible coating emulsions based on wettabilties on fruit skins, and to find the coating effects on storage life such as respiration and weight loss of the fruits. METHOD : A 1.5% Chitosan coatings dissolved in 2% lactic acid solution is prepared with or without adding emulsifier (tween80, 0.2%). In the respiration, closed system was employed. Apples were stored in the 4.5§¤sealed jar at 20°É for 24hr. Then, respiration rates of the apples were measured by TCD in GC. Weight loss of the apples with or without coatings was measured during storage time. RESULTS : Low pH of the organic solvents in chitosan coating solution can break the wax layer on fruit skins, which resulted in increasing weight loss and decreasing respiration rate of the coated fresh produces. For examples, respiration rate of the apples coated with chitosan coatings was 20.12 mg CO2/hr¤ýkg in pH 2.7 and became higher (13.29 mg CO2/hr¤ýkg) in pH 5.5 during storage. Also, the weight loss of the coated apples in pH 2.7 was higher than that of the coated apples in pH 5.5. The coating thickness of the chitosan coatings increased as the molecualar weight of the chitosan increased. The respiration rate of the apples contained 10cp chitosan without emulsifier was 15.3 mg CO2/hr¤ýKg and increased to 18.7 CO2/hr¤ýKg when the coatings contained emulsifier. SIGNIFICANCE : Our results are the preset for developing mathematical models to predict optimal coating condition of chitosan coatings with dynamic contact angle measuring of the coatings.