title: Plasticizer types and coating methods affect quality and shelf life of eggs coated with chitosan.
abstract: Effects of different plasticizer types (glycerol, propylene glycol, and sorbitol) and coating methods (brushing, dipping, and spraying) on the internal quality and shelf life of chitosan-coated eggs were evaluated during 5 wk of storage at 25 degrees C. The Haugh unit and yolk index values suggested that chitosan coating, irrespective of the plasticizer types, extended the shelf life of eggs by almost 3 wk at 25 degrees C compared with noncoated eggs. After 5 wk of storage, plasticizer types did not significantly affect the quality (weight loss, Haugh unit, and yolk index) of chitosan-coated eggs. However, there was an observable trend indicating that use of sorbitol rather than propylene glycol and glycerol as a plasticizer was better in reducing weight loss (whole egg) of chitosan-coated eggs during a 5-wk storage. After a 5-wk storage, there were no significant differences in weight loss and weight of albumen and yolk among chitosan-coated eggs, regardless of the coating methods. However, both brushing and dipping methods yielded chitosan-coated eggs with better yolk (higher yolk index values) and albumen (lower pH) qualities than did the spraying method. During 3 to 5 wk of storage, the Haugh unit values of chitosan-coated eggs by the brushing method were higher than or comparable to those by dipping or spraying. Therefore, coating of eggs with chitosan using sorbitol as a plasticizer and by the brushing method may offer a protective barrier in preserving the internal quality and thus extending shelf life of eggs.
authors.affiliation: Department of Food Science and Technology, Catholic University of Daegu, Hayang 712-702, South Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: H K
authors.initials: HK
authors.lastname: No
authors.forename: W
authors.initials: W
authors.lastname: Prinyawiwatkul
mesh_terms: D048271:Chitosan / Q000494:pharmacology; D003257:Consumer Product Safety; D004531:Eggs / Q000382:microbiology* / Q000592:standards*; D005506:Food Contamination / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D005990:Glycerol / Q000494:pharmacology; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D019946:Propylene Glycol / Q000494:pharmacology; D013012:Sorbitol / Q000494:pharmacology; D013997:Time Factors
chemical_list: D013012:Sorbitol; D019946:Propylene Glycol; D048271:Chitosan; D005990:Glycerol