45D-20 |
Oxygen-barrier performance of whey-protein-coated plastic films |
S. I. HONG, Korea Food Research Institute, San 46-1, Baekhyun-dong, Bundang-gu, Seongnam, 463-746, South Korea and J. M. Krochta, Dept. of Food Science & Technology, Univ. of California, Davis, 1 Shields Ave., 237 Cruess Hall, Davis, CA 95616. The oxidation of fats, oils, and other food components produces off-flavors, off-colors and nutrient loss. Thus, protection against oxygen is one of the most important requirements of food packaging. Common synthetic polyolefin films such as PE and PP are excellent moisture barriers, but they must be coated or laminated with synthetic polymers including EVOH copolymers and PVDC to provide an oxygen barrier. The resulting structures are expensive and non-recyclable. Replacing these synthetic oxygen-barrier layers with whey protein coatings could provide a new path for use of whey proteins and perhaps improve recyclability of the substrate film. Oxygen permeation properties of whey-protein-coated plastic films were examined to compare their oxygen barrier performance as affected by temperature, RH, substrate film, protein and plasticizer types. Corona discharge treatment was performed on the plastic (PE or PP) film surfaces by using a laboratory corona treater. Whey protein isolate (WPI) or concentrate (WPC) coating solutions (10% w/w, db) were applied on corona-discharge-treated substrate films and spread evenly using a Bird-type applicator. Coatings were then dried at room temperature for 18 h. Oxygen transmission rates were determined according to ASTM D3985 at various temperature (15-40oC) and relative humidity (30-85% RH) conditions. Smooth and transparent oxygen-barrier coatings based on whey protein could be formed on PE and PP plastic films, after treatment with corona discharge to modify their surfaces in order to achieve better adhesion of the whey protein coatings. Depending on plasticizer type, the resulting WPI- and WPC-coated films had excellent oxygen barrier properties at low to intermediate RH, comparable to synthetic oxygen barriers. Among plasticizers used, sucrose conferred the best oxygen barrier property to the whey-protein-coated films. Results suggest that whey protein coatings have great potential for replacing existing expensive synthetic oxygen barrier polymers.
Session 45D, Food Packaging: General
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