PubMed İndeksli Yayınlar Koleksiyonu / PubMed Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7645
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Article Citation - WoS: 9Citation - Scopus: 10Decontamination of Seeds Destined for Edible Sprout Production From Listeria by Using Chitosan Coating With Synergetic Lysozyme-Nisin Mixture(Elsevier, 2020) Sözbilen, Gözde Seval; Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThis study aimed at decontamination of seeds destined for edible sprout production from Listeria using chitosan (CS) coatings incorporated with synergetic lysozyme-nisin (LYS-NIS) mixtures. Low molecular weight (LMW) CS coating showed the highest potency against Listeria innocua, followed by medium molecular weight (MMW) and high molecular weight (HMW) CSs. The LMW CS film with LYS-NIS also caused almost 1.5-fold greater log reduction (similar to 5 log) in initial L. innocua load of broth culture than MMW and HMW CS films with LYS-NIS within 6 days. Moreover, LMW CS coating with LYS-NIS reduced the initial Listeria loads of inoculated mung beans, lentils, and wheats by 3.3, 3.4 and 4.1 log, respectively. Antimicrobial coating did not affect seed germination rates considerably. The LYS-NIS addition increased yellowness and opacity of films, and caused limited changes in their mechanical and morphological properties. LMW CS coating with LYS-NIS reduces risk of listeriosis from sprouted seeds.Article Citation - WoS: 49Citation - Scopus: 55Effects of Nisin and Lysozyme on Growth Inhibition and Biofilm Formation Capacity of Staphylococcus Aureus Strains Isolated From Raw Milk and Cheese Samples(International Association for Food Protection, 2012) Sudağıdan, Mert; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyEffects of nisin and lysozyme on growth inhibition and biofilm formation capacity of 25 Staphylococcus aureus strains isolated from raw milk (13 strains) and cheese (12 strains) were studied. Nisin was tested at concentrations between 0.5 and 25 μg/ ml; the growth of all strains was inhibited at 25 μg/ml, but the resistances of strains showed a great variation at lower nisin concentrations. In contrast, lysozyme tested at concentrations up to 5.0 mg/ml showed no inhibition on the growth of strains. Nisin used at the growth inhibitory concentration prevented the biofilm formation of strains, but strains continued biofilm formation at subinhibitory nisin concentrations. Lysozyme did not affect the biofilm formation of 19 of the strains, but it caused a considerable activation in the biofilm formation capacity of six strains. Twelve of the strains contained both biofilm-related protease genes (sspA, sspB, and aur) and active proteases; eight of these strains were nisin resistant. These results suggest a potential risk of S. aureus growth and biofilm formation when lysozyme is used in the biopreservation of dairy products. Nisin can be used to control growth and biofilm formation of foodborne S. aureus, unless resistance against this biopreservative develops. Copyright ©, International Association for Food Protection.Article Citation - WoS: 35Citation - Scopus: 43Controlled Release Properties of Zein-Fatty Acid Blend Films for Multiple Bioactive Compounds(American Chemical Society, 2014) Arcan, İskender; Yemenicioğlu, Ahmet; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyTo 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: 36Citation - Scopus: 38Antimicrobial Activity of Lactoperoxidase System Incorporated Into Cross-Linked Alginate Films(John Wiley and Sons Inc., 2009) Yener, Fatih Yalçın Güneş; Korel, Figen; Yemenicioğlu, Ahmet; Korel, Figen; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, the antimicrobial effect of lactoperoxidase (LPS) incorporated alginate films was investigated on Escherichia coli (NRRL B-3008), Listeria innocua (NRRL B-33314), and Pseudomonas fluorescens (NRRL B-253) in presence of different concentrations of H2O2 (0.2, 0.4, and 0.8 mM) and KSCN (1, 2, and 4 mM). The incorporation of 70 nmol ABTS/min/cm2 LPS into alginate films gave 0.66 to 0.85 nmol ABTS/min/cm2 enzyme activity at 0.2 to 0.8 mM H2O 2 concentration range. The antimicrobial activity of LPS system on target bacteria changed according to the concentrations of KSCN and H 2O2. The growth of all tested bacteria was prevented for a 6-h period by applying LPS system in presence of 0.4 or 0.8 mM H 2O2 and 4 mM KSCN. At 0.8 mM H2O2 and 4 mM KSCN, the LPS system also inhibited growth of L. innocua and P. fluorescens for a 24-h incubation period, whereas E. coli growth could not be inhibited for 24 h under these conditions. At 0.2 mM H2O2 and 1 to 4 mM KSCN, a considerable inhibitory effect was obtained only on P. fluorescens. The decreasing order of the resistance of studied bacteria to LPS system is as follows: E. coli, L. innocua, and P. fluorescens. The developed antimicrobial system has a good potential for use in meat, poultry, and seafood since alginate coatings are already used in these products. Further studies are needed to test the LPS incorporated edible films in real food systems.Article Citation - WoS: 21Citation - Scopus: 24Consistency 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; Yemenicioğlu, Ahmet; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyDestabilization 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.