73D-25 |
A simple method for determining the light transmittance of transparent polymer films used for packaging of foods |
K. N. TURHAN, Department of Food Engineering, University of Mersin, Ciftlikkoy, Mersin, 33342, Turkey and F. Sahbaz, Department of Food Engineering, Hacettepe University, Beytepe, Ankara, 06532, Turkey. Food components may undergo degradation under light and food-packaging materials can slow down the degradation by not transmitting a portion of the incident light. Understanding the transmittance of food-packaging materials is important in estimating shelf-life of foods. A simple method was proposed for determining the light transmittance of polymer films used for food packaging. The light transmittance of methylcellulose based films was measured using the proposed method. Experimental setup consisted of an illumination cell. A fluorescent lamp was used as the light source. Experiments were carried out in a dark room at 25±1°C. At the beginning of each run, 50 ml of 12x10-6M riboflavin solution was put into the cell. The cell was covered with the polymer film. At certain time intervals, sample was drawn from the cell. Same experiment was run without film for comparison. Concentration of riboflavin was spectrophotometrically measured at 445 nm. Methylcellulose films prepared using water and ethanol as the solvent and different molecular weigh PEGs as the plasticizer. The light transmittance of MC films ranged between 66 and 96% depending on the composition. Analysis of variance indicated that ethanol concentration in the film forming solution significantly affected the transparency of MC films. The addition of PEG400 to the polymer matrix did not have any significant effect. Moreover percent transmittance of films prepared with different molecular weight PEGs were not significantly different except for the one containing PEG1450 The films prepared with water, whether they contained PEG400 or not, had the highest transmittance. A new model and a simple procedure were suggested for measuring the light transmittance of polymer films used for food packaging. Although the experiments were done with riboflavin solutions and MC films only, this technique can be used for other polymers used for food packaging.
Session 73D, Food Packaging
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