Master Degree / Yüksek Lisans Tezleri
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Master Thesis Effect of Edible Film and Allicin on Shelf Life of Chicken Meat(01. Izmir Institute of Technology, 2024) Cancı, Şeyda; Baysal, Ayşe HandanTavuk eti besleyici değeri sebebiyle sağlıklı beslenme için önemli bir gıdadır ve büyüme çağındaki çocuklar ve yaşlılar gibi toplumun çoğu popülasyonu tarafından tüketilen bir gıdadır. Ancak tavuk eti kolay bozulabilen bir gıdadır ve bunun önüne geçmek için yenilebilir kaplamalardan ve biyoaktif bileşenlerden yararlanılmaktadır. Bu çalışmada, kitosanın antibakteriyel, antimikrobiyal, biyouyumlu ve biyolojik olarak parçalanabilir özellikleri ve allisinin antimikrobiyal, antifungal ve antioksidan özellikleri kullanılarak tavuk bagetlerdeki raf ömrüne etkisi incelenmiştir. Tavuk bagetlerin, farklı konsantrasyonlarda hazırlanan kitosan ve allisin çözeltileriyle K1A1(1% Kitosan + 10% Allisin), K1A2 (1% Kitosan + 20% Allisin), K2A1(2% Kitosan + 10% Allisin), K2A2(2% Kitosan + 20% Allisin) ve sadece kitosanın farklı konsantrasyonlarını içeren çözeltileriyle (%1 Kitosan, %2 Kitosan) kaplanması, mikrobiyolojik özellikleri, duyusal özellikleri, kimyasal parametleri, oksidatif bozulma parametreleri belirlenen raf ömrü boyunca 4 ⸰C'de saklanarak değerlendirilmiştir. Kitosan ve allisin ile kaplanan numunelerde ve kitosan çözeltisiyle kaplanmış numunelerde kontrol grubuna kıyasla toplam canlı, Enterobacteriaceae, Pseudomonas bakteri sayımlarında, bakteri sayısı önemli ölçüde azalmıştır. Toplam canlı gelişimini engellemede en etkili sonuç, tavuk bagetlerin raf ömrünü uzatan K2A1 örnek grubuyla elde edildi. Depolamanın 10. günündeki TBA sonuçlarında, %1 kitosanla kaplanmış tavuk bagetlerin 0.33 mg MDA/kg değeriyle lipid oksidasyonunu engellemede en başarılı grup olduğu bulunmuştur. Bu sonuçtan sonra en başarılı sonuç 0.55 mg MDA/kg değeriyle K1A2 örneği olmuştur. Anahtar Kelimeler: Allisin, Antimikrobiyal,Antioksidan, Kitosan, TBA, Toplam canlıMaster Thesis Development of Pectin-Wax Composite Edible Films With High Moisture Barrier Properties(01. Izmir Institute of Technology, 2024) Yemenicioğlu, Ahmet; Çakıtlı, Gamze; Yemenicioğlu, AhmetBu 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 Functionalization of a Vegan Snack With Antimicrobial Edible Coating(01. Izmir Institute of Technology, 2022) Atik, Hande; Harsa, Hayriye ŞebnemPomegranate peel is usually considered as a waste of fruit by many people, but it has quite high content of antioxidant, phenolic and antimicrobial compounds. The objective of this thesis is to observe the effect of edible film in vegan snack bar containing of dried fruits, nut and to functionalize the snack bar with enrichment of protein and antimicrobial content. The edible film was composed of 8% w/v of lentil protein extract, 15% w/w of pomegranate peel depends on protein content, 2% of pectin as a stabilizer and 0.5% of glycerol as a plasticizer. Application of coating was carried out by dipping method. Then, the coated vegan snack bar was dried at 40oC for 16 hours. The coated and uncoated bars were investigated in different conditions as 30% RH at 25 oC and 75% RH at 35 oC for 90 days. Optical properties, texture, total phenolic content, sensory, microbial and water activity analysis were determined to evaluate the impact of edible coating incorporation onto surface of the bar. The results showed that the coated bars have been preserved better than uncoated ones in terms of prevention of color change, microbial and textural properties, phenolic content and moisture loss in both conditions.Master Thesis Antimicrobial Properties of Silk Fibroin-Carrageenan Films Incorporating Grape Seed Extract(Izmir Institute of Technology, 2009) Arserim Uçar, Dilhun Keriman; Korel, FigenIn this study antimicrobial edible films were developed by incorporation of grape seed extract into silk fibroin-carrageenan films. Developed films were subjected to instrumental analysis such as scanning electron microscopy, atomic force microscopy, X-ray diffractometer, and Fourier transform infrared spectrometer for the characterization of the film. The antimicrobial activity of silk fibroin-carrageenan films on different bacteria including Listeria innocua, Staphylococcus aureus, Staphylococcus carnasus, Bacillus amyloliquefaciens, Escherichia coli, Pseudomonas fluorescens, Escherichia coli O157:H7, and Salmonella Typhimurium, on raw chicken breast meat and beef sausages were tested. Application of silk fibroin-carrageenan films incorporating grape seed extract and/or Na2EDTA on chicken breast meat and beef sausages demonstrated the efficacy of these films to enhance the microbial quality of the products. Increasing the concentration of grape seed extract in the films increased the antimicrobial activity of the films in food applications. It is found that silk fibroin-carrageenan films incorporating grape seed extract could be used to control the growth of S. aureus on beef sausages during 28 days of storage at 4 C. The use of these films on beef sausages had significant effect on moisture content of the sausages as well as the textural properties of the sausages. This study indicated the potential of using silk fibroin-carrageenan films incorporating grape seed extract to be used as an antimicrobial edible food packaging.Master Thesis Development of Lysozy Incorporated Antimicrobial Zein Films and Evaluation of Their Effectson Quality of Cold Stored Burgers(Izmir Institute of Technology, 2008) Uysal, İlke; Korel, FigenIn this study antimicrobial edible food packaging films were obtained by incorporation of hydrophilic partially purified lysozyme into hydrophobic zein films.The antimicrobial enzyme was incorporated into films by homogenization or stirring methods to increase its distribution in the films and to modify the film structure. The soluble and bound lysozyme activities of different zein films, as well as antimicrobial activity of films on different bacteria including Bacillus amyloliqufaciens, Listeria innocua, Eschericia coli, Pseudomanas fluorescens, Escherichia coli O157:H7, Salmonella typhimurium and Staphylococcus aureus and on cold stored burgers were tested. The lysozyme was combined with disodium EDTA to increase sensitivity of G(-) bacteria to enzymatic action. The films obtained by incorporation of 175 to 700 .g/cm2 lysozyme with stirring or homogenization methods showed good antimicrobial activity on most of the tested bacteria, except S. aureus. In general, due to their higher free soluble lysozyme content, the zein films incorporated with lysozyme by the stirring method gave higher antimicrobial activity on tested bacteria than films obtained by the homogenization method. However, the homogenization method caused better distribution of resulting antimicrobial activity in films than the stirring method. The films incorporated with 700 .g/cm2 lysozyme and 300 .g/cm2 disodium EDTA and prepared by stirring or homogenization method successfully suppressed the total viable counts and total coliform counts of cold stored turkey and beef burgers. The films also effectively reduced the oxidative changes in beef burgers during cold storage, but they showed no beneficial effects on beef color and sensory properties.Master Thesis Development of Antimicrobial Protective Food Coating Materials From Edible Alginate Films(Izmir Institute of Technology, 2007) Yener, Fatih Yalçın Güneş; Korel, FigenConsumer interests in high quality, healthy, convenient and safe food continue to increase, presenting food processors with new challenges to which functional edible coating and film concepts offer potential solutions. The interest in the research of edible film which has many advantages and applications has increased during last decade.There is a particular interest in the use of antimicrobial biopreservatives in edible films and to increase food safety without application of chemical preservatives. In this study,we have developed antimicrobial or protective edible films by incorporation of antimicrobial enzyme lactoperoxidase or protective cultures (Lactobacillus delbrueckii subsp. lactis and Lactobacillus plantarum) into alginate films, respectively. The main objective of this research was to increase food safety by using lactoperoxidase or lactic acid bacteria incorporated into alginate films. The results obtained in the study showed that in reaction mixtures, the lactoperoxidase system has antimicrobial activity against E. coli, L. innocua, and P. fluorescens. The developed lactoperoxidase incorporated antimicrobial films also reduced the total microbial load of a selected seafood during cold storage. The lactic acid bacteria, used in edible films for the first time, also successfully incorporated into alginate films. The bacteria showed sufficient stability in alginate films and at surface of red meat during cold storage. The results of this study clearly showed the good potential of using lactoperoxidase and lactic acid bacteria incorporated alginate films in food packaging. The developed films can be used in antimicrobial packaging or protective packaging. However, further studies are needed to show the beneficial effects of developed films on different food systems.Master Thesis Preparation and Characterization of Corn Zein Nanocomposite Coated Polypropylene Films for Food Packaging Applications(Izmir Institute of Technology, 2010) Özçalık, Onur; Tıhmınlıoğlu, FundaFeasibility 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.Master Thesis Effect of Organo-Modified Clay Addition on Properties of Polyhydroxy Buttrate Homo and Copolymers Nanocomposite Films(Izmir Institute of Technology, 2012) Akın, Okan; Tıhmınlıoğlu, FundaAs an alternative to conventional non-degradable food packaging plastics, bionanocomposites, based on bacterial biodegradable thermoplastic polyesters, poly(hydroxybuthyrate) (PHB) and poly(hydroxybutyrate-covalerate) (PHBHV) polymers incorporated with commercial organomodified monmorillonite (OMMT) were prepared by solution intercalation and melt-mixing techniques. The enhancements in barrier, mechanical, thermal, surface and optical properties of resulting nanocomposite films were evaluated as effected by OMMT concentration and preparation method. The degree of dispersion of layered silicates into polymer matrix was evaluated by X-Ray diffraction (XRD) analyses. The best level of dispersion was obtained in nanocomposites that contain 1%w/w of OMMT. However, intercalated structure was observed at higher amount of clay loaded composites. The fine delamination of OMMT in PHB and PHBHV matrix was found to be responsible for the improvements in water vapor barrier performance since more tortuous path formed for permeation of water vapor. Moreover, enhancement in mechanical and thermal properties was highly depending on the dispersion level of layered silicates which is in good accordance with structural analyses. Addition of 2%w/w of OMMT reduced the WVP of virgin films by 41.1%. Meanwhile, improvements were less significant at higher amount of clay loaded samples due to weak interaction between polymer and layered silicates. Moreover, significant improvements in mechanical properties including doubled tensile strength and 69% increase in strain at break were obtained for 2%w/w of OMMT incorporated PHB composites. In addition, significant enhancement in thermal stability, which is the major drawback of PHB films, was obtained in nanocomposites, decomposition temperature increased by 10 oC compared to pristine polymers. Moreover, addition of layered silicates into polymer matrix at low content resulted in increase in erosion rate which makes nanocomposites more eco-friendly promising alternative to conventional barrier packaging systems.Master Thesis Water vapour permeable edible membranes(Izmir Institute of Technology, 2005) Alyanak, Didem; Balköse, DevrimIn this study, polysaccharide based edible films were prepared and characterized. Also water vapour sorption, diffusion and permeability characteristics of these films were studied. For these purposes cellulose ethers such as sodium salt of carboxymethyl cellulose (NaCMC) and hydroxypropylcellulose (HPC) were used as a film forming materials. Distilled water and glycerin were used as solvent and plasticizer respectively. To determine the effect of polymer concentration of the film forming solution on the film properties, NaCMC and HPC films were prepared from three different concentrations (3, 4, 5g polymer/100ml distilled water) of film forming solutions. During the characterization studies of the films, to determine the elements and structural composition of the films, energy dispersive X-Ray and scanning electron microscopy analyze were applied to NaCMC and HPC based edible films. Also, X-Ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry analysis were applied to determine the form of elements, functional groups and glass transition temperature.Water vapour sorption capacities of NaCMC and HPC based films were measured nearly 70%w and 25%w respectively. GAB and Halsey models were found to give the best fit for the water vapour sorption data of both NaCMC and HPC films. Diffusion coefficient of water vapour in vacuum microbalance test was higher than that determined using the humidity chamber, this case could be result of the structural changes of films such as formation of porous structure in microbalance tests due to the fast drying of films by high vacuum. NaCMC based edible films showed higher diffusion coefficient values than HPC based films, due to the heterogeneous structure and bigger pore dimensions of the NaCMC films that was observed in the scanning electron micrographs. Water vapour permeability (WVP) of both films increased with increasing thickness and increasing film forming solution concentration and WVP values of NaCMC based films were higher than the WVP values of HPC films. In mechanical properties, while NaCMC films have brittle, stronger and stiffer structure, HPC films show elastic and ductile property.Master Thesis Production of Functional Packaging Materials by Use of Biopreservatives(Izmir Institute of Technology, 2005) Mecitoğlu Güçbilmez, Çiğdem; Yemenicioğlu, AhmetIn this study, partially purified lyophilized lysozyme (LSZ) and lactoperoxidase (LPS) from chicken egg white and bovine whey were incorporated into zein and alginate films, respectively. The LSZ showed very low affinity to zein films. Thus, when zein films incorporated with 63-455 .g/cm2 (187-1318 U/ cm2) LSZ was exposed to release tests in distilled water, the enzyme released rapidly from the films with release rates of 9 to 29 U/cm2/min. The ethanol used in film making caused significant activation of the LSZ. Therefore, the released LSZ activity from zein films was mostly 130-300 % higher than the activity incorporated into films. On the other hand, the LPS incorporated into alginate films showed a very high affinity to these films and immobilized.The incorporation of 0.53 or 1.06 mg/cm2 proteins such as crude thermally processed chick-pea proteins (TP-CP) and sericine in combination with LSZ and LPS into zein or alginate films increased the antioxidant activity of edible films significantly.In zein films, the incorporation of antioxidant proteins reduced the total activity of LSZ released from the films between 50 % and 75 %, but increased the immobilized enzyme activity 3.5-15 fold. On the other hand, incorporation of antioxidant proteins into alginate films enhanced LPS activity slightly to moderately. The results of this study clearly showed the good potential of edible films and natural biopreservatives in active packaging.