1) Department of Food Engineering, Faculty of Engineering, Sivas Cumhuriyet University, Sivas, Turkey; 2) Department of Chemistry, Faculty of Science, Sivas Cumhuriyet University, Sivas, Turkey; 3) Department of Chemical Engineering, Faculty of Engineering, Sivas Cumhuriyet University, Sivas, Turkey; 4) Agricultural and Biological Engineering, The Pennsylvania State University, University Park, PA 16802, USA
Nene Meltem Keklik1), Adil Elik2), Uğur Salgin3), Ali Demirci4), Gamze Koçer1)
Surface contamination of cheese varieties with pathogenic microorganisms is a potential risk in dairy industry. Pulsed UV (PUV) light is a method, which provides rapid inactivation of a wide range of microorganisms on foods. In this study, white cheese inoculated on top surface with Staphylococcus aureus or Escherichia coli O157:H7 was exposed to PUV light. Treatment parameters were time (5, 15, 30, 45, 60 s) and distance from the quartz window of xenon lamp (5, 8, 13 cm). The 60 s-8 cm treatment (91.22 J/cm2) resulted in the highest inactivation level without visually altering the appearance of white cheese. After this treatment, approximately 1.31 and 2.20 log10 reductions (cfu/cm2) were obtained for S. aureus and E. coli O157:H7, respectively. Lipid oxidation, pH, and moisture content, except the color parameters, remained unchanged (p>0.05) after the 60 s-8 cm treatment. Only 1.75 % of the PUV light reached to a depth of 0.5 cm in white cheese after treatment at 5 cm. These findings indicate that although PUV light is able to reduce pathogen counts of white cheese, this technology can only be utilized for surface decontamination.
Keywords: Escherichia coli O157:H7, Staphylococcus aureus, microbial inactivation, pulsed UV light, white cheese
Arch Lebensmittelhyg 71,
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