100B-32 |
Tensile properties of fruit and vegetable edible films |
T. H. MCHUGH and C. W. Olsen. Processed Foods Research, USDA, Agricultural Research Service, Western Regional Research Center, 800 Buchanan Street, Albany, CA 94710 Value added edible films increase utilization of fruits and vegetables by opening new markets for these materials. Fruit and vegetable-based films may be used in, on or around food products, improving their nutritional value, visual appeal and flavor. Edible films can also act as barriers to improve preservation of foods. They are also environmentally friendly. The objective was to test the tensile properties of 100% apple, peach, carrot and broccoli films at three different relative humidities. Effects of additional pectin on film tensile properties were also investigated. Films were prepared from apple, peach, carrot and broccoli purees. Varying percentages of pectin (1% to 5%) were added to the film forming solutions. After degassing, mixtures were cast on Teflon plates and dried at 25°C and 55% relative humidity. Films were cut using a dog bone shaped die with a gauge length of 100 mm to form samples. Samples were preequilibrated to varying relative humidities for 48 hours at 25°C using saturated salt solutions. Tensile tests were run on the Instron universal testing machine at 7.5 mm/min. Maximum and breaking strength, elastic modulus and percentage elongation were determined. The maximum strength values averaged 15 MPa for carrot films and 10 MPa for broccoli films. Elastic modulus values averaged 700 MPa for both carrot and broccoli films. The strength of peach films averaged 2 MPa and the elastic modulus 10 MPa. The elongation for fruit films ranged from 27 to 38%, while the elongation for vegetable films ranged from 2 to 7%. Increases in relative humidity resulted in decreased strength and increased elongation values. Pectin addition resulted in increased film strength. This study provides technical information regarding the tensile properties of fruit and vegetable edible films. Such information is useful for the application of these films as food products and packages.
Session 100B, Food Packaging
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