Browsing by Subject "Food Microbiology"
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Item The effect of acid adaptation conditions on heat resistance of Escherichia coli O157: H7(2005) Tosun H.; Gönül Ş.A.The objective of this study was to determine the effect of acid adaptation conditions on heat resistance of E. coli O157: H7 932. E. coli O157: H7 was adapted to acid by exposing the cells to pH 4.5 (2h), pH 5.0 (1h), and pH 5.5 (1 h) in tryptic soy broth. D and z values of the acid adapted and control cultures at 54°C, 56°C, and 58°C were determined in E buffer. The heat resistance of E. coli O157: H7 increased significantly (p<0.05) after acid adaptation at pH 4.5 or pH 5.0. E. coli O157: H7 adapted to acid at pH 4.5 for 2 h had the highest D values at all temperatures tested (20.3-10.7-3.3 min) while D values of culture adapted to acid at pH 5.0 for 1 h were 18.2, 7.9, and 2.6 min at 54°C, 56°C and 58°C, respectively. Heat resistance of culture adapted to acid at pH 5.5 for 1 h and the control culture was not significantly different (P<0.05). Culture adapted to acid at pH 4.5 had the highest z value (5.10°C), whereas control culture had the lowest z value (4.33°C). This study showed that the magnitude of heat tolerance changed with the adaptation pH and at low adaptation pH, E. coli O157: H7 showed maximum heat resistance. Acid adaptation at pH 4.5 or 5.0 provides E. coli O157: H7 with cross-protection against heat treatments, and that this factor must be considered to estimate this pathogen's thermal tolerance accurately.Item Changes in quality attributes of intermediate-moisture raisins during storage(2009) Gülec H.; Kundakci A.; Ergönül B.The aim of this research was to determine the changes in chemical and microbiological qualities of ready-to-eat intermediate-moisture raisins during storage. Raisins were immersed into hot (98±1°C) glucose solutions (10% w/v and 20% w/v) containing 1% (w/v) potassium sorbate to inhibit mould and yeast growth. Raisins were kept in glucose solutions until the moisture content became 20%, 25% and 30%, respectively. The reconstituted raisins were then stored at ambient temperature (23±3°C) and 50-60% relative humidity for 8 months in polyethylene/polyamide (PE/PA) packaging material. The changes of moisture content, water activity, pH values, total titratable acidity, total sugar contents, Hunter L, a and b color values, total mesophylic aerobic bacteria counts, and mould and yeast counts were determined during storage at 2-month intervals. The results of chemical analysis showed that changes in the total titratable acidity, total mesophylic aerobic bacteria, and mould and yeast counts of the products were increased significantly (P<0.05). However, the pH values, total sugar contents, and Hunter L, a, and b color values were decreased during the storage period (P<0.05).Item Effects of a dry-ice process on surface and carcase decontamination in the poultry industry(Taylor and Francis Ltd., 2018) Uyarcan M.; Kayaardı S.1. The objective of this study was to evaluate the effects of dry-ice decontamination on equipment and carcase surfaces in a poultry slaughterhouse and to present an effective alternative method to the conventional decontamination processes. 2. Appreciable reductions occurred in total aerobic mesophilic bacterial counts of surface swab samples treated with dry ice (maximum difference 3.92 log cfu/100 cm2). 3. After dry-ice treatment, Listeria spp. were detected on surfaces of pluckers and chiller cylinders, whereas Salmonella spp. were totally inhibited. 4. A dry-ice spraying application was more effective than a dry-ice immersing application on total aerobic mesophilic bacteria and yeast and mould counts on poultry carcases. 5. Dry-ice treatment has advantages over conventional processes. Unlike other decontamination techniques, there are no residues, so no need to wash off chemical residues from surfaces as it removes contaminants effortlessly and is environmentally friendly. 6. Dry-ice blasting of production equipment can reduce the microbial load and has potential for use in the poultry industry. © 2017 British Poultry Science Ltd.Item Effect of non-thermal ultraviolet and ultrasound technologies on disinfection of meat preparation equipment in catering industry(SAGE Publications Inc., 2024) Kayaardı S.; Uyarcan M.; Atmaca I.; Yıldız D.; Benzer Gürel D.In recent years, ultraviolet and ultrasound treatments are gaining attraction as promising green decontamination technologies to ensure microbial safety in food industry. Decontamination by ultraviolet light is a physical process defined by the transfer of electromagnetic energy from a light source to an organism's cellular material and depended on the emission of radiation in the ultraviolet region (100–400 nm), specifically the UV-C region (200–280 nm) which has been demonstrated to be germicidal. Ultrasound technology is defined as sound waves with high and low frequency beyond the limit of human hearing and shows a decontamination effect that occurs as a consequence of cavitation at high power (low frequency) in general. In the present study, it was aimed to determine the effectiveness of ultraviolet light (254 nm, 10 min) and high frequency ultrasound techniques (40 kHz, 10 min) in reducing total aerobic mesophilic bacteria, yeast and mold, Esherichia coli/coliform and Salmonella spp. on the equipment surfaces used in the catering facility. For this purpose, the equipment (cutting knife, meat grinder knife, knife sharpener, cut-proof glove) used in the meat preparation department of catering facility were selected for the treatments. According to the results, appreciable reductions were achieved in total aerobic mesophilic bacterial counts of the ultraviolet treated samples (maximum difference 2.61 log cfu/cm2) and the ultrasound treated samples (maximum difference 4.07 log cfu/cm2). After ultraviolet treatment, Salmonella spp. were totally inhibited on the contaminated surfaces. Furthermore, Escherichia coli/coliform was not detected in the samples after both treatments whereas it was detected before the treatments. It has been concluded that the techniques are effective in reducing microbiological load and also ultraviolet treatment is effective on pathogenic microorganisms on food contact surfaces. As a result, the ultraviolet and ultrasound techniques are effective treatments for equipment disinfection in the catering sector and can be used industrially as it gives successful results. © The Author(s) 2023.