Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Structure and Gas Transmission Properties of Surface Modified Food Packaging Materials by Layer-By Assembly(Izmir Institute of Technology, 2019) Koca, Nazan; Bayramoğlu, Beste; Bayramoğlu, Beste; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, two different LbL coatings of chicken egg white lysozyme (LZ) (0.2 % w/v)-gum arabic (GA) (0.2 % w/v) and lysozyme (LZ) (0.2 % w/v)-iota carrageenan (IC) (0.2 % w/v) were investigated as a potential agent in the fabricaton of surfacemodified food packaging materials with improved gas barrier properties. The effects of solution pH, adsorption time, number of layers, and inclusion of drying step in between deposition steps on multilayer formation were explored for both LbL coatings seperately. Film growth was monitored up to 10 layers by UV-Vis spectrometry and Surface Plasmon Resonance (SPR), which allows for in situ observation of the multilayer formation. The LbL coatings were characterized by AFM (Atomic Force Microscopy) and SEM (Scanning Electron Microscopy). The oxygen and water vapor transmission rates of the coatings (assembled on corona treated polypropylene (PP) films) were also measured. The most successful LbL assembly was obtained at pH 7-7 combination, with 20 minutes adsorption time and with intermediate drying steps for both (LZ-GA and LZ-IC) LbL coatings. For both LbL coating, both the UV-Vis and SPR measurements showed the similar zig-zag trend; i.e. desorption of some of the pre-adsorbed LZ from the interface with the deposition of GA (or IC) on it, probably due to formation of soluble complexes between them. The importance of intermediate drying steps was established by UV-Vis, AFM and gas transmission rate measurements. The absence of intermediate drying caused a reduction in total mass deposited and the gas barrier properties of the coatings.Master Thesis Comparison of Dipping and Spraying Methods in Layer-By Deposition of Chitosan and Sodium Caseinate(Izmir Institute of Technology, 2016) Üney, Sinem; Bayramoğlu, Beste; Bayramoğlu, Beste; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this thesis; it is aimed to develop a novel, ultra thin, homogeneous edible coating with adequate gas barrier properties by layered deposition of chitosan and sodium caseinate with dipping and spraying methods and compare the coating structures. The parameters considered in this study are pH, adsorption times, number of layers and the types of the top layer. To determine the appropriate conditions, zeta potential and hydrodynamic diameter measurements of chitosan and sodium caseinate were done. After determining the appropriate concentrations and pH values, layer deposition has been initiated. Following the formation of multilayer coating by UV-Vis spectrophotometer, the most suitable combination was determined for the formation of multilayer coating. Multilayered coating characterization was done by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Surface Plasmon Resonance which allows to observe coating formation in-situ. Moreover antimicrobial activity, water vapor permeability and oxygen permeability were also investigated. It has been observed that the multilayer coating structures obtained by dipping and spraying methods have some differences. The formation of multilayer coating has been followed successfully with UV-Vis spectrophotometer; besides information about surface topography and coating thickness is obtained by Atomic Force Microscopy (AFM). The multilayered coatings have no significant effects on oxygen permeability and water vapor permeability; however it has contact antimicrobial effect.