Master Degree / Yüksek Lisans Tezleri

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  • Master Thesis
    Development of Pectin-Wax Composite Edible Films With High Moisture Barrier Properties
    (01. Izmir Institute of Technology, 2024) Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Bu tez çalışmasında literatürde ilk kez turunçgil pektininin aynı anda hem su buharı geçirgenliği (WVP) düşük, hem de antimikrobiyel etki gösteren çift fonksiyonlu filmlerinin üretilmesi amaçlanmıştır. Bu amaçla ulaşmak için pektinin mumlarla sıcak homojenizasyon yöntemiyle emülsifikasyon yöntemi kullanılarak karvakrol içeren kompozit filmleri üretilmiştir. Pektinin %15 gliserol ve %40 balmumu içeren kompozit filmleri CaCl2'le çapraz bağlandıktan sonra elde edilen en düşük WVP değeri 1.58 g.mm/m2.gün.kPa olarak belirlenmiştir (kontrol pektin filme göre %54 daha düşük WVP). Buna karşın pektinin %15 gliserol ve %30 karnauba mumu kullanılarak elde edilmiş filmleri çapraz bağlama uygulanmadan 0.16 g.mm/m2.gün.kPa gibi çok düşük bir WVP değeri göstermiştir (kontrol pektin filme göre %95.4 daha düşük WVP). Elde edilen bu sonuç karnauba mumu gibi erime noktası yüksek (e.n.=82-86 oC) mum kullanımının erime noktası düşük (e.n.= 62-66 oC) bal mumu kullanımına göre WVP değerini daha etkili düşürdüğünü göstermiştir. Dolayısıyla antimikrobiyal film üretimi amacıyla karnauba mumu içeren pektin film kompozitleri içerisine %1, 2 veya 3 oranında karvakrol ilave edilmiştir. Elde edilen karvakrol içeren tüm filmler Escherichia coli ve Listeria innocua üzerinde esansiyel yağ konsantrasyonuyla orantılı olarak antimikrobiyal etki göstermiştir. Ancak, filmlerin WVP değerleri de ilave edilen esansiyel yağ konsantrasyonu arttıkça artmıştır. Bu nedenle tezde elde edilmiş olan en düşük WVP (1.47 g.mm/m2.gün.kPa) gösteren antimikrobiyal film %1 oranında karvakrol içeren olmuştur (kontrol pektin filme göre %57 daha düşük WVP). Filmlere karnauba mumu ilavesi ışık geçirgenliklerini azaltırken mekaniki özelliklerini de kısmen zayıflatmaktadır. Bu tez çalışması gıdalarda daha az nem kaybına neden olabilecek antimikrobiyel pektin temelli film üretiminin mümkün olduğunu göstermiştir.
  • Master Thesis
    Developing the Mechanical Properties of Bio-Based Films Used in Food Packaging Industry
    (Izmir Institute of Technology, 2023) Irak, Ekrem Anıl; Toksoy, Muhammet Fati̇h; Tihminlioğlu, Funda; 01. Izmir Institute of Technology
    Canlı popülasyonun artmasıyla birlikte dünyamızda atık yönetimi günden günde daha önemli bir hale gelmektedir. Sürdürülebilirlik için ambalaj atığı yönetiminde de birçok yöntem gündeme gelmiştir. Bu popülaritesi artan yöntemlerden biri de biyobozunma ile atık bertaraf edilmesidir. Yapılan bu çalışmada da biyobazlı ve biyobozunur ambalaj üretimi üzerine çalışılmıştır. Markette en yaygın olan biyobazlı ve biyobozunur ambalaj filmi PLA granülünden üretilen filmlerdir. PLA filmi mekanik özellikleri bakımdan petrol bazlı granüllerden üretilen birçok filme göre daha rijit ve şekil verilmesi zordur. Bu da paketleme makinalarında ambalaj filmine form vererek torba haline getirilmesinde kopma ve şekil verilmesi verimliliği kaynaklı problemler çıkarmaktadır. Bu problemler üzerine odaklanılarak PLA filmin rijitliğini bir miktar azaltmak için alışveriş torbalarında kullanılan Mater-Bi granülü kullanılmıştır. Mater-Bi granülünden üretilen alışveriş torbaları petrol bazlı standart ambalaj filmlerine göre daha sünek bir yapıdadır. Mater-Bi granülü de PLA granülü gibi hem biyobazlı hem de biyobozunur yapıdadır. Hem PLA hem de Mater-Bi granülleri solvente çözülüp %100PLA, %80PLA-%20Mater-Bi, %70PLA-%30Mater-Bi, %60PLA-%40Mater-Bi ve %100 Mater-Bi olarak farklı oranlarda ambalaj filmi üretilmiştir. Bu oranlarda üretilen ambalaj filmindeki Mater-Bi oranının artışı ile ambalajın özelliklerindeki değişim incelenmiştir. Mekanik özellikler kapsamında kalınlık, birim ağırlık, verimlilik, çekme-gerdirme dayanımı, delinme direncine bakılmıştır. Form verilen filmlerin yapışma performansı da gıda güvenliği için önemli bir kriter olduğundan dolayı yapışma performansındaki değişim de test edilmiştir. Gıda güvenliği ve raf ömrü için kullanılan ambalaj filminin diğer bir amacı da pazarlamadır. Bu sebeple üretilen ambalaj filminin optik özelliklerindeki değişim de test sonuçlarında bulunmaktadır. PLA'nın transparan görünüşü ile Mater-Bi'nin sarımtırak görünüşü arası optik özellikte filmler üretilmiştir. Farklı oranlarda üretilen ambalaj filmlerinin analitik olarak inceleyerek FTIR analizleri yapılmıştır. Gıda güvenliği açısından regülasyonlara uygun olduğunu görmek için solvent kalıntısı tespit testi yapılmıştır. Formülasyonlar yapılan testlerin sonuçlarına göre değerlendirilmiştir.
  • Master Thesis
    Surface Modified Halloysite Nanotubes Incorporated Polyl-Lactide Nanocomposites for Food Packaging Applications
    (Izmir Institute of Technology, 2019) Tüzün, Ece Zeynep; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Biodegradable Poly (L-lactide) (PLA) can replace petroleum based packaging materials to solve environmental problems. PLA lacks of ductility and have moderate barrier properties. In this study, halloysite nanotubes (HNTs) possessing unique surface chemistry and tubular structure were incorporated into PLA matrix to overcome drawbacks of PLA. Firstly, HNT surface was modified with aminopropyltriethoxysilane (APTES) to enhance interfacial adhesion between HNTs and PLA matrix by decreasing the hydrophilicity of HNTs. Modified HNTs (m-HNTs) were characterized by SEM, FTIR, TGA, N2 adsorption-desorption analysis, XRD and XPS. FTIR, XRD and XPS results revealed that APTES was successfully grafted onto HNTs. The optimum pH and APTES concentration for the silanization of HNTs were determined as 3.50 and 1%, respectively. HNT/PLA and m-HNT/PLA nanocomposite films with different wt% of nanofiller loadings were prepared by solution casting. The films were characterized by FTIR, XRD, tensile test, water vapor permeation, DSC, TGA, contact angle and SEM analysis and color measurements. Better dispersion and consequently better mechanical properties were obtained with m-HNT addition compared to unmodified ones. Tensile strength at break of PLA was increased by 4.7% and 16.6% with 2 wt% HNT and m-HNT addition, respectively. m-HNT/PLA nanocomposites had better water vapor barrier properties than unmodified HNT/PLA nanocomposites while both of them improved the barrier property. Best mechanical and water vapor barrier properties were achieved with 2% modified HNT (1% APTES) containing PLA nanocomposites. Therefore, nanocomposite films produced in this study with high transparency and good barrier property can be a suitable candidate for fresh food packaging.
  • 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 Technology
    In 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
    Development of Bio-Based Coatings as Flexible Food Packaging Applications
    (Izmir Institute of Technology, 2018) Adalı, Merve Betül; Korel, Figen; Korel, Figen; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The sustainable packaging solutions require the development of materials based on renewable resources and efficient production methods, which are important nowadays. In this study, a multilayer coated flexible polyethylene terephthalate (PET) sheets were produced by Layer-by-Layer (LbL) assembly using chitosan and pectin bio-based materials incorporated with galls extract (GE) as an active agent. These fabricated films were firstly characterized and results of increasing the depositing of chitosan and pectin from 0 to 60 layers indicated that the deposition of biopolymers successfully improve the performance of flexible films. The optimization of the deposition different number of layer on PET (20 – 40 and 60 layers) was carried out by the study of the surface characterization and the shelf-life tests in order to find out surface modification. The coated LbL films were applied on fresh-cut ‘Abate Fetel’ pears and color, microbial, sensory assays were carried out during 7 days of storage at 4 ºC. At the end of storage, in terms of all tests, the LbL treated samples were presented better preserved compared to the control samples (treated base film). In addition, the release of active agents from multilayer films was evaluated using LbL films in contact with food and gradual reduction was observed. This research demonstrates the feasibility of LbL coating, which acts as a carrier of active substances to enhance the quality of fresh-cut products as an active packaging system.
  • Master Thesis
    Development of Whey Protein Isolate Based Nanocomposite Food Packaging Film Incorporated With Chitosan and Zein Nanoparticles
    (Izmir Institute of Technology, 2014) Oymacı, Pelin; Demir, Mustafa Muammer; Alsoy Altınkaya, Sacide; Alsoy Altınkaya, Sacide; Demir, Mustafa Muammer; 03.02. Department of Chemical Engineering; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The purpose of this study was to investigate the effect of chitosan and zein nanoparticles addition on the barrier and mechanical properties of whey protein isolate (WPI) films as an alternative to conventional synthetic packaging materials. Chitosan nanoparticles (CSNP) were produced via ionic gelation method using sodium tripolyphosphate (TPP) and deacetylated chitosan. Zein nanoparticles (ZNP) were synthesized based on antisolvent procedure in the presence of sodium caseinate (SC) to enable dispersion in water. Both plain and nanoparticle added WPI films were prepared by solution casting method. Water vapor barrier and mechanical properties of films were measured and the improvements in these properties with nanoparticle addition was further investigated through surface wetting, morphological, viscoelastic and thermal properties of the films. Both nanoparticles significantly decreased the water vapor permeability (WVP) and improved the mechanical properties of the WPI film. The highest enhancement in barrier and mechanical properties of the WPI films were recorded with 20% (w/w of WPI) CSNP and 120% (w/w of WPI) ZNP addition which corresponded to the maximum nanoparticle loading levels. At these loadings, the average WVP of pure WPI films loaded with ZNP and CSNP decreased by 84% and 57%, and the average tensile strength increased by 304% and 161%, respectively. On the other hand, the nanoparticles did not change the elongation at break significantly. ZNP was found more effective than CSNP in improving barrier and mechanical properties of the WPI films due to its hydrophobic nature and better dispersion in the protein matrix which allowed much higher loadings compared with the maximum loading levels achieved with CSNP. CSNP addition imparted antibacterial activity to the WPI films.
  • Master Thesis
    Preparation and Characterization of Corn Zein Nanocomposite Coated Polypropylene Films for Food Packaging Applications
    (Izmir Institute of Technology, 2010) Özçalık, Onur; Tıhmınlıoğlu, Funda; Tıhmınlıoğlu, Funda; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Feasibility of prepared novel corn zein nanocomposite (CZNC) coated polypropylene (PP) film (CZNC-PP) structures for food packaging applications was investigated. Excellent barrier properties of corn zein nanocomposites were successfully combined with mechanically strong PP as an eco-friendly promising alternative to conventional barrier packaging systems. In this study, the effect of nano-sized layered silicate amount, type and processing of CZNC layer on the barrier, mechanical, optical and surface properties of the CZNC-PP films were investigated. Incorporation of organomodified montmorillonite (OMMT) by solution intercalation into zein coating matrix improved barrier and mechanical properties of PP films. The properties of single CZNC layers and interactions between layered silicates and zein matrix were also investigated. Fine delamination of OMMT in zein coating was found to be responsible for the improvements in oxygen and water vapor barrier of single corn zein layers due to more tortuous path formed for permeation of oxygen and water vapor. Prepared CZNC-PP films achieved nearly 4 times reduced oxygen permeability while WVP of the films were reduced by 30% with 5 wt% OMMT content in 5.9 m corn zein coating. Meanwhile, improvements were less significant for unmodified nanoclay loadings due to the incompatibility between unmodified MMT and corn zein. Hydrophobicity of CZNC surface increased with increasing OMMT loading in accordance with WVP results. Permeation data was fitted to various phenomenological models predicting the permeability of polymer nanocomposites as a function of clay concentration and aspect ratio of nanoplatelets. While significant improvements in mechanical properties including doubled elastic modulus and 75% higher yield strength of PP films were obtained, incorporation of OMMT in CZNC layer did not change the color of CZNC-PP films significantly.