Food Engineering / Gıda Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/12

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End date: 2019Publisher: search.filters.publisher.American Chemical Society

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Now showing 1 - 4 of 4
  • Article
    Citation - WoS: 35
    Citation - Scopus: 43
    Controlled Release Properties of Zein-Fatty Acid Blend Films for Multiple Bioactive Compounds
    (American Chemical Society, 2014) Arcan, İskender; Yemenicioğlu, Ahmet
    To develop edible films having controlled release properties for multiple bioactive compounds, hydrophobicity and morphology of zein films were modified by blending zein with oleic (C18:1)Δ9, linoleic (C18:2)Δ9,12, or lauric (C12) acids in the presence of lecithin. The blend zein films showed 2-8.5- and 1.6-2.9-fold lower initial release rates for the model active compounds, lysozyme (LYS) and (+)-catechin (CAT), than the zein control films, respectively. The change of fatty acid chain length affected both CAT and LYS release rates while the change of fatty acid double bond number affected only the CAT release rate. The film morphologies suggested that the blend films owe their controlled release properties mainly to the microspheres formed within their matrix and encapsulation of active compounds. The blend films showed antilisterial activity and antioxidant activity up to 81 μmol Trolox/cm2. The controlled release of multiple bioactive compounds from a single film showed the possibility of combining application of active and bioactive packaging technologies and improving not only safety and quality but also health benefits of packed food.
  • Article
    Citation - WoS: 23
    Citation - Scopus: 22
    Modeling of Polystyrene Under Confinement: Exploring the Limits of Iterative Boltzmann Inversion
    (American Chemical Society, 2013) Bayramoğlu, Beste; Faller, Roland
    We explore the limits of a purely structure based coarse-graining technique, the iterative Boltzmann inversion (IBI), in the coarse-graining of a confined concentrated polystyrene solution. In the first place, some technical considerations and challenges encountered in the course of the optimization process are represented. The concepts of the choice of the initial potentials and the cross-dependency of the interactions as well as the order of optimization are discussed in detail. Furthermore, the transferability of a previously developed CG confined polystyrene solution model, the "parent CG confined model", to different degrees of confinement at constant concentration and temperature is examined. We investigate if a CG force field developed for a confined polymer solution by IBI is sensitive to changes in the degree of localization or arrangement of polymers near the surfaces although the concentration is kept constant. For this purpose, reference atomistic simulations on systems of different confinement levels have been performed. The differences in the structure and dynamics of the chains are addressed. Results are compared with those of an unconfined (bulk) system at the same concentration. The chain dimensions and orientations as a function of the distance from the surfaces are also reported. To the best of our knowledge, this is the first computational study that investigates the structural behavior of polymers in close proximity of the surfaces in a concentrated polymer solution rather than in a melt. Transferability of the parent CG confined model is tested by employing the parent force field in CG simulations of the reference systems. Results indicate that the degree of arrangement of monomers and solvent molecules near the surfaces is an important factor that needs to be paid attention to when considering the application of a CG force field developed by IBI to different degrees of confinement.
  • Article
    Citation - WoS: 76
    Citation - Scopus: 85
    Development of Flexible Antimicrobial Packaging Materials Against Campylobacter Jejuni by Incorporation of Gallic Acid Into Zein-Based Films
    (American Chemical Society, 2011) Alkan, Derya; Aydemir, Levent Yurdaer; Arcan, İskender; Yavuzdurmaz, Hatice; Atabay, Halil İbrahim; Ceylan, Çağatay; Yemencioğlu, Ahmet
    In this study, antimicrobial films were developed against Campylobacter jejuni by incorporation of gallic acid (GA) into zein-based films. The zein and zein-wax composite films containing GA between 2.5 and 10 mg/cm 2 were effective on different C. jejuni strains in a concentration-dependent manner. Zein and zein-wax composite films showed different release profiles in distilled water but quite similar release profiles at solid agar medium. Depending on incorporated GA concentration, 60-80% of GA released from the films, while the remaining GA was bound or trapped by film matrix. The GA at 2.5 and 5 mg/cm 2 caused a considerable increase in elongation (57-280%) of all zein films and eliminated their classical flexibility problems. The zein-wax composite films were less flexible than zein films, but the films showed similar tensile strengths and Young's modulus. Scanning electron microscopy indicated different morphologies of zein and zein-wax composite films. This study clearly showed the good potential of zein and GA to develop flexible antimicrobial films against C. jejuni.
  • Article
    Citation - WoS: 21
    Citation - Scopus: 24
    Consistency of Polyphenol Oxidase (ppo) Thermostability in Ripening Apricots (prunus Armeniaca L.): Evidence for the Presence of Thermostable Ppo Forming and Destabilizing Mechanisms in Apricots
    (American Chemical Society, 2003) Yemenicioğlu, Ahmet; Cemeroglu, Bekir
    Destabilization of thermostable polyphenol oxidase (TS-PPO) during the ripening of peaches has been previously shown (Yemenicioǧlu, A; Cemeroǧlu, B. Tr. J. Agric. For. 1998, 22, 261-265). This work studied the effect of ripening on thermal stability of apricot PPO for three different cultivars. Kabaaşi cultivar contained thermolabile PPO, whereas TS-PPO appeared in Hacihaliloǧlu and Çataloǧlu cultivars. The TS-PPO showed biphasic inactivation curves, and its D and z values between 60 and 90 °C varied in the ranges of 357-1.12 min and 11.9-12.7 °C, respectively. In Hacihaliloǧlu cultivar the TS-PPO was very consistent and existed at all stages of ripening, whereas in Çataloǧlu cultivar it appeared only at the half-ripe stage. The loss of consistent TS-PPO in Hacihaliloǧlu apricots after partial purification by acetone precipitation and DEAE-cellulose chromatography suggested the non-covalent nature of its stabilization. The main purified fractions (F1 and F2) showed monophasic inactivation curves with similar thermal inactivation parameters (ZF1 = 10.4 °C, ZF2 = 10.1 °C). However, their kinetic properties against catechol (KmF1 = 61 mM, KmF2 = 122.7 mM) and substrate specificities were considerably different. The results of this study showed the presence of TS-PPO forming and destabilizing mechanisms in apricots. Further studies are needed for the solution of these mechanisms and to develop some new strategies that may be utilized by molecular techniques for a planned production of apricot cultivars provided with heat labile but normal PPO activity.