Browsing by Author "Dikici A."

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    Determination of the changes in the gastric fluid endurance of O157 and non-O157 Shiga toxin-producing Escherichia coli during storage of experimentally produced beef frankfurter
    (Springer, 2021) Bozatli S.B.; Dikici A.; Ergönül B.
    Resistance of Shiga toxin-producing Escherichia coli (STEC) O157:H7 and serogroups O103, O26 and O145 to synthetic gastric fluid (SGF, pH 1.5) were investigated during frankfurter storage. Pathogens were inoculated (5 ± 1 log10cfu g−1) on frankfurters and frankfurters were stored at 4 °C for 75 days in vacuum packages. Population changes of the competitive flora and STEC, changes in the pH of the frankfurters and resistance of STEC to SGF were monitored on days 0, 15, 30, 45, 60 and 75 of frankfurter storage. Direct synthetic gastric fluid (DSGF) challenges were also conducted to assess pathogen resistance without being effected by frankfurters, by inoculating pathogen cultures directly into SGF. Results showed that acid resistance of O145 and O26 was stronger than that of O103 and O157 during frankfurter storage. Resistance of O103 to SGF was better than that of O157 during frankfurter storage but, was similar to that of O157 during DSGF challenges. Results indicate that acid resistance of some strains of STEC pathogens might differentiate during storage of frankfurters. Different resistance capabilities to SGF were observed in the STEC strains when inoculated and stored on frankfurters than directly inoculated in the SGF. © 2020, Association of Food Scientists & Technologists (India).
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    Survival of Escherichia coli 0157:H7 and non 0157 strains in synthetic gastric fluid inoculated on commercially available frankfurters
    (Parlar Scientific Publications, 2021) Betul Bozatli S.; Dikici A.; Ergonul B.
    In this study acid resistance of STEC 0157:H7 and non-0157 STEC serogroups of 026, O103 and 0145 were investigated during storage of commercially available frankfurters. Pathogens were surface inoculated on frankfurters ca. 5±1 log cfu/g and the inoculated frankfurters were stored at 4°C for 75 days. Microbiological analysis and pH measurements were conducted at days 0, 15, 30, 45, 60 and 75 of cold storage. In the first part of the study, different brands of commercially available frankfurters produced from cattle meat (Brand A, B, C, D, E) were investigated in order to evaluate which brand aided pathogen survival in acidic environment. Pathogen resistance to synthetic gastric fluid (SGF) was very weak in brands A, B, C, and D samples, and survivor counts were undetectable during SGF experiments after "Day 0" of the storage. These preliminary experiments showed that pathogens had stronger acid resistance on one brand of frankfurters, therefore in the second part of the study triplicate trials were conducted with this brand (Brand E). On brand E frankfurters, the pathogens were still detectable at the 45th day of storage after SGF exposure except for 0157:H7. The gradual decrease in the pH of this brand of frankfurters might have aided acid resistance of the pathogens. Results show that in every brand of samples tested, the non-0157 serogroups had higher survivor counts than 0157:H7, during storage and SGF experiments of frankfurters. © 2021 Parlar Scientific Publications. All rights reserved.
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    Investigating the effect of decontaminants on microbiological and chemical properties of rainbow trouts
    (TUBITAK, 2021) Dikici A.; Özpolat E.; Bozatli S.B.; Koluman A.; Patir B.; Çalicioğlu M.
    This study was designed to determine the effect of decontamination on the shelf life of whole rainbow trouts. For this purpose 0.5% cetylpyridinium chloride (CPC), 10% trisodium phosphate (TSP), 2.5% acetic acid (AA), 2.5% lactic acid (LA), 1200 ppm acidified sodium chloride (ASC) and control (tap water) were used as decontaminants. After the decontamination process, the samples were stored in cold storage and subjected to microbiological and chemical analyzes on days 0, 3, 6, 9, 12 and 15. Mesophilic bacteria, psychrophilic bacteria, lactic acid bacteria, Pseudomonas spp., Enterobacteriaceae and coliform bacteria were enumerated for the evaluation of microbiological quality, whereas pH, total volatile alkaline nitrogen (TVB-N), thiobarbituric acid (TBA) were determined for the evaluation of the chemical quality of fish samples. The study was repeated 3 times and 6 fish were used in each group corresponding to 108 fish in total. Microbiological samples were evaluated with a modification in USDA/FSIS chicken carcass method. The data of microbiological analysis showed that decontamination provided a significant improvement on the microbiological quality and the decontaminants used in this study extended the microbiological shelf life of rainbow trout. However, acidic decontaminants and TSP caused some changes in the physical properties of rainbow trouts. On the other hand, the use of CPC extended the shelf life of rainbow trouts without adversely affecting the texture. The microbiological sampling protocol used in this study was proved to be easier to apply and gave coherent results. © TÜBİTAK
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    Hybrid artificial neural network based on a metaheuristic optimization algorithm for the prediction of reservoir temperature using hydrogeochemical data of different geothermal areas in Anatolia (Turkey)
    (Elsevier Ltd, 2022) Varol Altay E.; Gurgenc E.; Altay O.; Dikici A.
    Due to the increase in the changes in global climate in recent years and the depletion of fossil fuels, the interest in renewable energy sources in many developed countries is increasing day by day. Among the renewable energy sources, geothermal energy has an important place because it can be used both in electricity production and directly as heat energy. Before using geothermal fluids, it is necessary to determine their properties by making detailed geological studies and thus to determine the most suitable drilling location. These processes are very costly, time-consuming, and require special equipment. Such disadvantages can be eliminated by using machine learning methods. In this study, the machine learning methods developed for the classification approach were used to predict the purpose of the geothermal waters with the help of the geothermal data set obtained from different regions. In this study, naïve Bayes classifier, K-nearest neighbor, linear discrimination analysis, binary decision tree, support vector machine, and artificial neural network, which are widely used in the literature, were used. In addition, promising results were obtained by designing a hybrid metaheuristic artificial neural network model. While an accuracy in traditional machine learning methods between 71% and 82% was obtained, a 91.84% accuracy was obtained in the model proposed. © 2022 Elsevier Ltd
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    Investigation of efficient thermal inactivation parameters of Escherichia coli O157:H7 in meatballs by grilling
    (Springer, 2023) Tosuncuk Ö.; Bozatli S.B.; Dikici A.
    The aim of the study was to investigate the safe cooking parameters to eliminate E.coli O157:H7 in commonly consumed meatball types, by simulating the meatball formula and the cooking practices of restaurants. Ground meat was inoculated around 7 ± 1 log cfu/g with a cocktail of 5 strains of E.coli O157:H7. The meatballs were prepared with different ingredients and seasonings depending on the type (kasap or İnegöl). The cooking experiments were conducted on a grill, at two different temperatures, 170 and 180 °C. Results show that, in order to achieve ≥ 5 log destruction of E.coli O157:H7 in Kasap and İnegöl meatballs cooked at 170 °C, the internal temperature should reach to 85 °C. On the other hand, when the meatballs were grilled at 180 °C, 5 log reductions were achieved by cooking the meatballs to an internal temperature of 80 °C for Kasap meatballs and 85 °C for İnegöl meatballs. Differences in the meatball formulation and shape affected the thermal destruction of E.coli O157:H7. Measuring of the grill temperature and core temperature of meatballs during cooking and reaching the target temperatures for each type of meatball would help prevent Shiga toxin-producing E.coli (STEC) infections in public eating establishments. © 2023, Association of Food Scientists & Technologists (India).