Food Engineering / Gıda Mühendisliği

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

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Author: search.filters.author.Göksungur, Mehmet Yekta

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  • Article
    Citation - WoS: 39
    Citation - Scopus: 49
    Production of Antimicrobial Films by Incorporation of Partially Purified Lysozyme Into Biodegradable Films of Crude Exopolysaccharides Obtained From Aureobasidium Pullulans Fermentation
    (University of Zagreb, 2005) Kandemir, Nilay; Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; Elmacı, Zehra Seda; Arslanoğlu, Alper; Arslanoğlu, Alper; Baysal, Taner; 04.03. Department of Molecular Biology and Genetics; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Antimicrobial films were produced by incorporating partially purified lysozyme into films of crude exopolysaccharides (59% pullulan) obtained from Aureobasidium pullulans fermentation. After film making, the films containing lysozyme at 100, 260, 520 and 780 μg/cm2 showed 23 to 70% of their expected enzyme activities. The highest recovery of enzyme activity (65-70%) after the film making was obtained in films prepared by incorporating lysozyme at 260 μg/cm2 (1409 U/cm2). The incorporation of disodium EDTA·2H2O and sucrose did not affect the initial lysozyme activity of the films significantly. With or without the presence of disodium EDTA·2H2O at 52 or 520 μg/cm2, lysozyme activity showed sufficient stability in the films during 21 days of cold storage. However, the presence of sucrose at 10 mg/cm2 in the films caused the destabilization of part of enzyme activity (almost 35%) at the end of storage. The combinational incorporation of lysozyme at 780 μg/cm 2 (4227 U/cm2) and disodium EDTA·2H2O at 520 μg/cm2 gave antimicrobial films effective on Escherichia coli. However, in the studied lysozyme concentration range the films did not show any antimicrobial activity against Lactobacillus plantarum. This study clearly showed that the partially purified lysozyme and crude exopolysaccharides from Aureobasidium pullulans may be used to obtain antimicrobial films to increase the safety of foods.
  • Article
    Citation - WoS: 29
    Citation - Scopus: 32
    Optimization of Lactic Acid Production From Whey by L Casei Nrrl B-441 Immobilized in Chitosan Stabilized Ca-Alginate Beads
    (John Wiley and Sons Inc., 2005) Göksungur, Mehmet Yekta; Gündüz, Meltem; Harsa, Hayriye Şebnem; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The production of lactic acid from whey by Lactobacillus casei NRRL B-441 immobilized in chitosan-stabilized Ca-alginate beads was investigated. Higher lactic acid production and lower cell leakage were observed with alginate-chitosan beads compared with Ca-alginate beads. The highest lactic acid concentration (131.2 g dm-3) was obtained with cells entrapped in 1.3-1.7 mm alginate-chitosan beads prepared from 2% (w/v) Na-alginate. The gel beads produced lactic acid for five consecutive batch fermentations without marked activity loss and deformation. Response surface methodology was used to investigate the effects of three fermentation parameters (initial sugar, yeast extract and calcium carbonate concentrations) on the concentration of lactic acid. Results of the statistical analysis showed that the fit of the model was good in all cases. Initial sugar, yeast extract and calcium carbonate concentrations had a strong linear effect on lactic acid production. The maximum lactic acid concentration of 136.3 g dm-3 was obtained at the optimum concentrations of process variables (initial sugar 147.35 g dm-3, yeast extract 28.81 g dm-3, CaCO3 97.55 g dm-3). These values were obtained by fitting of the experimental data to the model equation. The response surface methodology was found to be useful in optimizing and determining the interactions among process variables in lactic acid production using alginate-chitosan-immobilized cells.