Food Engineering / Gıda Mühendisliği

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

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  • Article
    Citation - WoS: 49
    Citation - Scopus: 55
    Effects 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 Technology
    Effects 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: 8
    Citation - Scopus: 8
    Differential Scanning Calorimetry as a Tool To Detect Antibiotic Residues in Ultra High Temperature Whole Milk
    (John Wiley and Sons Inc., 2009) Yıldız, Özge; Ünlütürk, Sevcan; Ünlütürk, Sevcan; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Detection of penicillin G, ampicillin and tetracycline in ultra high temperature whole milk was studied by differential scanning calorimetry (DSC). Thermal parameters including the heat of fusion, the evaporation temperature, the heat of evaporation and the melting temperature obtained from DSC analysis were used to characterise thermal behaviour of antibiotic free milk samples and milk samples fortified with Penicillin G, Ampicillin and Tetracycline. DSC curves of these antibiotics at selected concentrations (0, 2, 4, 8 ppb for Penicillin G and Ampicillin; 0, 100, 250, 500 ppb for Tetracycline) show big endothermic peaks in the temperature range of -30 °C and 200 °C. It was concluded that the antibiotic concentration had a significant effect on the thermal parameters at a 95% confidence level. The differences between the melting temperatures and the peak areas in heat flow curves provided a basis for detection of antibiotic residues in UHT whole milk.