17G-23 |
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T. S. MEIRON, Institute of Biochemistry, Food Science and Nutrition, Hebrew University, Faculty of Agricaltural, Food and Environmental Sciences., P.O. Box 12, Rehovot, 76100, Israel, A. Marmur, Department of Chemical Engineering, Technion – Israel Institute of Technology, Haifa, 32000, Israel, and I. S. Saguy, Institute of Biochemistry & Food Science, Hebrew Univ. of Jerusalem, Faculty of Agricultural, Food & Environmental Quality Sciences, PO Box 12, Rehovot, 76100, Israel. A large number of foods are coated mainly to enhance their perceived quality, improve their added-value and extend shelf-life. Therefore, adhesion between food and coating is an important quality aspect of these products. Although surface roughness is known to be an essential characteristic factor of most foods, the relationship between surface morphology and adhesion has not been fully established. A plethora of techniques exists for the measurements of mechanical adhesion between a food product and its coating, however their proper application and utilization for rough surfaces is cumbersome, mainly due to local imperfections caused by surface roughness and inadequate interpretation of the data. The overall objective was to develop an experimental system that allows studying the phenomena and quantifying the influence of surface roughness on mechanical adhesion. A model system simulating rough hydrophobic food surfaces and coatings was developed. The system consisted of rough low linear density polyethylene (LLDPE) film coated with paraffin wax. Mechanical adhesion was studied by employing a 180° peel strength test with an Instron. Film roughness parameters (i.e., Ra, l, roughness ratio) were measured on a contact profilometer. Surface roughness significantly affected the adhesion strength. The measured peel strength ranged from 1.7 to 27.5 N/m for surfaces characterized by Ra values of 1.5 – 61.5 mm and roughness ratio of 1.000 – 1.009, respectively. Since the chemical composition of the studied surfaces and coating was identical, the data illustrated that adhesive bonding was significantly enhanced by roughening the coated surface. Quantifying the effect of food and or package roughness on adhesion enables developing the necessary theoretical basis for studying a spectrum of related phenomena, such as breading, batter, biofilm forming, and interaction between food products and packaging. This methodology is also applicable for other research domains dealing with surface chemistry and coatings.
Session 17G, Food Engineering: Physical, chemical and electrical properties
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