Phd Degree / Doktora

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Department: search.filters.department.Thesis (Doctoral)--İzmir Institute of Technology, Food EngineeringSubject: search.filters.subject.Food packaging

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Now showing 1 - 5 of 5
  • Doctoral Thesis
    Innovative Food Applications of Novel Multifunctional Active Edible Gel Fillings and Coatings
    (01. Izmir Institute of Technology, 2022) Barış Kavur, Pelin; Yemenicioğlu, Ahmet
    This thesis organized as two chapters aimed to develop and test multifunctional novel gel filling and coating. In Chapter 1, the thesis focuses on developing antimicrobial and antibrowning gelatin based gel filling to produce safe caramel apples. For this purpose, water holding capacity and mechanical stability of gelatin (GEL) gels were improved by the incorporation of soy proteins (SP) and inulin (IN), respectively. The water activity (aw) of gels was also reduced to < 0.9 by the addition of sucrose (SUC). The apples were cored and the void cores were filled with GEL-SP-IN-SUC blend gel solution containing synergetic antimicrobials, nisin and lysozyme, and antibrowning agent ascorbic acid (each at 1% in gel). Candy sticks were then placed into gel-filled void cores, and apples were kept at 4oC for 20 h for gelation of filling before caramel dipcoating. The caramel apples with antimicrobial GEL-SP-IN-SUC filling showed 2.4 – 2.9 D lower Listeria count than traditional caramel apples during 7-day cold storage. The active blend gel-filling also prevented discoloration of apple core. In Chapter 2, the thesis focuses on controlling postharvest sprouting and microbial risks associated with shallot bulbs by active chitosan based coating loaded with eugenol (EUG). The sustained release of EUG was achieved by applying ultrasonic homogenization (US) to prepare a composite of chitosan (CHI) with chickpea proteins (CP) (CHI:CP ratio of films = 2). The CHI-CPEUG coating successfully reduced the sprouting and inhibited the inoculated E. coli and L. innocua in shallot bulbs by 2.3 log and 1.7 log, respectively.
  • Doctoral Thesis
    Development of Sensor Systems for Food Quality Monitoring
    (01. Izmir Institute of Technology, 2022) Büyüktaş, Duygu; Farris, Stefano; Korel, Figen
    The main objective of this thesis is to fabricate electrochemical sensors for the detection of 2,4-diaminotoluene (2,4 TDA), 2,6-diaminotoluene (2,6 TDA), and 4,4´-methylene diphenyl diamine (MDA), possibly carcinogenic primary aromatic amines (PAAs) that poses a serious health risk because they can transfer from multilayer food packages including adhesives based on aromatic polyurethane (PU) systems, to the food. The thesis is based on the following three chapters: (1) Development of a nano-modified glassy carbon electrode for the determination of 2,6-diaminotoluene (2) A screen-printed electrode modified with gold nanoparticles/cellulose nanocrystals for electrochemical detection of 4,4´-methylene diphenyl diamine (3) Development of a nano-modified screen-printed electrode for the determination of 2,4-diaminotoluene. In this work, full electrochemical characterization of the nano-modified electrodes was carried out, and the electrochemical properties were described. Migration tests were also conducted to modified sensors in order to investigate their potential application in real food systems. The results of this work clearly showed that modified electrochemical sensors allow reliable quantification of the most important primary aromatic amines migrating from packaging materials to food and can be used as an alternative to the commonly used conventional analytical techniques for the detection of these toxic compounds.
  • Doctoral Thesis
    Development of Novel Antimicrobial, Antioxidant and Bioactive Edible Gels Intended for Food Preservation and Promotion of Human Health
    (Izmir Institute of Technology, 2017) Boyacı, Derya; Yemenicioğlu, Ahmet
    The aim of this thesis was the development of edible gelatin (GEL) based composite gels with antimicrobial, antioxidant, and bioactive properties. For this purpose, composite gels of gelatin with rice starch (RS), candelilla wax (CW) and soy protein isolate (SPI) were incorporated with lysozyme (LYS) and green tea extract (GTE). LYS and GTE release profiles of GEL and its composites were tested in aqueous media and cold-smoked salmon selected as a model food. GEL, GEL/RS and GEL/CW gels did not show considerably different LYS and GTE release profiles in aqueous media, but their release profiles in the model food system were different. GEL/SPI gels bound LYS and prevented its release from the gels, but they released GTE. GEL showed the most rapid LYS delivery onto smoked salmon, while GEL/RS and GEL/CW caused sustained LYS delivery profiles. The total LYS delivered from GEL and GEL/RS gels onto smoked salmon were similar while GEL/CW gels caused almost 30% lower LYS delivery onto food samples. On the other hand, GEL/CW gels caused the highest amounts of GTE delivery onto model food. In broth media at 4°C, all LYS containing gels (with or without GTE) showed antimicrobial activity with a minimum 1.5 decimal reduction in L. innocua that was used as a target bacterium. In smoked salmon samples, the LYS containing gels inhibited the growth of L. innocua, but they did not cause a significant reduction in its counts. Antioxidant capacity, antihypertensive and antidiabetic activity, and cytotoxicity tests against human colon carcinoma cells (Caco-2) conducted with released GTE proved the bioactive potential of developed gels. The gels were also tested for their water binding capacity, and physical (textural properties) and morphological (SEM images) properties. This work clearly showed the possibility of using active gels as multifunctional delivery tools (as coating material, pad or pre-cast film) to prevent microbial and oxidative changes in food and to enhance their bioactive properties.
  • Doctoral Thesis
    Feasibility of Eugenol Encapsulated Poly (lactic Acid) (pla) Films Via Electrospinning as a Novel Delivery System for Volatile Compounds in Food Packaging Systems
    (Izmir Institute of Technology, 2017) Arserim Uçar, Dilhun Keriman; Korel, Figen; Korel, Figen; Yam, Kit L.
    Food safety and quality are important issues in food industry. The aim of this research was to evaluate the feasibility of delivering eugenol via poly(lactic) acid (PLA) emulsion fibers-grafted PLA films with bacterial cellulose into the package headspace. For this purpose, first, bacterial cellulose crystals as a natural carrier for eugenol were produced. The influence of hydrolysis temperature, time, and acid to cellulose ratio, acid concentration and type with the addition of the neutralization step on the structure, and the properties of bacterial cellulose crystals were studied. Nanocrystals, which had high thermal stability and high crystallinity bacterial cellulose, were produced. Bacterial cellulose stabilized oil-in-water Pickering emulsions were produced as carriers for eugenol. The emulsion formulations consisting of cellulose fibers and crystals, eugenol, and surfactants were characterized for food packaging applications. PLA films were produced with obtained eugenol emulsions and poly(lactic) acid which were obtained via the electrospinning method. The produced films revealed a significant antibacterial effect on L. innocua, and E. coli inoculated tomato stem scars as real food model. The fabricated films also had significant antifungal activity on B.cinerea inoculated table grapes. Developed novel biodegradable-PLA cellulose composite films had a great potential for delivering bioactive volatile compounds for intelligent food packaging applications. The findings of this research supports the technical feasibility of delivering eugenol for antimicrobial active packaging applications via electrospun fibers.
  • Doctoral Thesis
    Polysaccharide Based Packaging Film for Fresh Cut Produce
    (Izmir Institute of Technology, 2017) Şamlı, Merve; Harsa, Hayriye Şebnem; Büyükkileci, Ali Oğuz
    In this thesis, agro industrial wastes such as bracts and leaves of artichoke were used to develop biodegradable packaging materials for fresh-cut artichokes. As flim forming materials; cellulose, hemicellulose, lignin and wax fractions were extracted by using mild alkaline treatment applied to artichoke wastes. Carboxy methyl cellulose was chemically synthesized from extracted cellulose fiber. A mechanical process (Masuko Supermasscolloider, at-100 um grind size via 5 times feeding) with minimum environmental impact was selected to obtain cellulose micro fibrils with micro sized dimensions (50-200 um in length and 10-30 um in width).These fractions used as polysaccharide sources in film forming solutions. Different combinations of these polysaccharide based film materials were optimized using General Factorial Design and four film combinations were selected among the films produced.elected films were MFC and CMC based having good elasticity (16 % strain), tensile strength and low gas permeability properties (150mlO2/m2.day).Different concentrations of additives such as wax, stearic acid, chitosan were used with the glycerol addition of plasticizer. SEM analyses of selected films showed films showed films having smooth surface and dense structure by looking their cross sectional area. Thermal analyses proved sealabilitiy of films obtained by extracted fractions from artichoke at 200-250 oC temperature intervals. But, presence of MFC in films hindered the heat sealing ability. Therefore, MFC and CMC based films successfully showed optimal properties when they were combined with glycerol, stearic acid and wax.