Sürdürülebilir Kalkınma Amaçları

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• MakaleAçık Erişim2025/r/gumushane/14119
  Effect of heating rate on thermal inactivation kinetics of Escherichia coli O157:H7 in ground beef

  Ozturk, Samet; Huang, Lihan; Hwang, Cheng-An; Sheen, Shiowshuh

  The objective of this study was to investigate the effect of heating rate on thermal inactivation kinetics of microorganisms in food, testing the survival of Escherichia coli O157:H7 in ground beef during isothermal and dynamic heating. A 4-strain cocktail of E. coli O157:H7 was inoculated to irradiation-sterilized ground beef (10 % fat) and then subjected to isothermal heating (55–63 °C) and dynamic heating (20–63 °C). One-step analysis was used to determine the kinetic parameters. Different degrees of increased thermal resistance were observed in E. coli O157:H7 during dynamic heating. In comparison to isothermal heating, slight increase in the thermal resistance was found during fast heating (1.2–1.8 °C/min). However, slow heating (0.3–0.9 °C/min) led to significantly increased thermal resistance due to heat adaption at temperatures below 61.3 °C, but E. coli O157:H7 became more sensitive to heat above this temperature, suggesting that the increased resistance may diminish after reaching a critical temperature. To account for the increased heat resistance during dynamic heating, a unified kinetic model was developed and validated by applying one-step dynamic analysis, resulting in more accurate kinetic parameters to describe the survival curves of all heating rates. This study demonstrated that the kinetic parameters derived from isothermal conditions may not be applicable to dynamic conditions. It is necessary to consider the effect of heating rate and to determine the thermal inactivation kinetic parameters under dynamic conditions. It also demonstrated the advantage of using one-step dynamic analysis for evaluating thermal processes. The results of this study may be particularly useful for designing slow-heating processes to ensure proper cooking of products.

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• MakaleYalnız künye2012/r/gumushane/10538
  Combination of culture-dependent and culture-independent molecular methods for the determination of lactic microbiota in sucuk

  Kesmen, Z.; Yetiman, A. E.; Gulluce, A.; Kacmaz, N.; Sagdic, O.; Cetin, B.; Adiguzel, A.; Sahin, F.; Yetim, H.

  In this study, the culture-dependent and culture-independent molecular methods were used for the identification of lactic acid bacteria (LAB) in sucuk a Turkish fermented dry sausage. On the one hand, the PCR-DGGE method targetting the V1 and V3 regions of 16S DNA was applied to DNA that was directly extracted from sucuk samples. On the other hand, rep-PCR fingerprinting was performed for the primary differentiation and grouping of the isolates, and the results were confirmed by sequencing of the 165 rDNA and 16S-23S rDNA intergenic spacer region. As a result of the PCR-DGGE analysis of all the samples, total 8 different lactic acid bacteria were identified, and Lactobacillus sakei, Lactobacillus curvatus and Weissella viridescens were the dominant microbiota among these bacteria. The culture-dependent approach indicated that the majority of the strains belonged to the Lactobacillus genera including Lb. sakei, Lactobacillus plantarum, Lb. curvatus, Lactobacillus brevis, Lactobacillus farciminis and Lactobacillus alimentarius. However, Leuconostoc and Weisella were also detected as minor genera. Again, Lactococcus piscium, Weissella halotolerans, Staphylococcus succinus and the comigrated Staphylococcus piscifermentans/Staphylococcus condimenti/Staphylococcus camosus group were detected only with the culture-independent method while Lb. plantarum, Leuconostoc mesenteroides and Leuconostoc citreum were identified only by using the culture-dependent method. In the results, it was concluded that the combination of culture-dependent and culture-independent methods was necessary for reliable and detailed investigation of LAB communities in fermented food products. (C) 2011 Elsevier B.V. All rights reserved.

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