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Abstract
Edible films and coatings based on polysaccharides, proteins and/or lipids were developed and tested for their effectiveness in controlling moisture loss and lipid oxidation of precooked ground beef patties. Factors affecting gas chromatographic analysis of lipid oxidation in precooked meat, such as sample preparation methods, equilibration times and sample phase fraction, were examined. They were controlled and used in the follow-up edible film application studies. Wheat gluten, soy protein, carrageenan and chitosan films and coatings had different effects on maintaining the quality of precooked patties after 3-day storage at 4°C. All coatings were as effective (P < 0.05) as polyvinyl chloride film in reducing patty moisture loss and more effective than films. Coating with wheat gluten, carrageenan or soy protein and wrapping with carrageenan films were effective (P < 0.05) in lowering patty thiobarbituric acid reactive substance values (TBARS) and hexanal values with wheat gluten coating being the most effective (P < 0.05), which resulted in about 28% and 48% reduction in TBARS and hexanal, respectively Incorporating fatty acids, especially 30–40% of palmitic acid and/or stearic acid, had a significant (P < 0.05) impact on water barrier properties and mechanical properties of soy protein films. Composite films of soy protein and propyleneglycol alginate showed improved (P < 0.05) moisture barrier properties and mechanical properties by adding propyleneglycol alginate up to 10% and 17.5%, respectively. The tortuous network structure observed in starch-alginate-fatty acid films using scanning electron microscopy may have contributed to the improved moisture barrier properties of these films, especially in films with 30% fatty acids. During 6-day storage at 4°C, starch-alginate-stearic acid based films were effective (P < 0.05) in limiting moisture loss from precooked patties. Tocopherol treated starch-alginate films and starch-alginate-stearic acid films were effective (P < 0.05) in inhibiting the lipid oxidation in patties by lowering TBARS and other oxidation products. All edible films, except for tocopherol-coated films, were generally not as effective (P > 0.05) as polyester vacuum bags in controlling moisture loss and lipid oxidation, and their effects were storage time dependable.
