Modeling the effect of temperature on survival rate of Salmonella Enteritidis in yogurt

2017

GIDA

ÖzetYo¤urt düflük pH (4.2-4.5) içeri¤i ile mikrobiyolojik aç›dan genellikle güvenilir g›da olarak düflünülmektedir. Di¤er taraftan Salmonella spp. süt ürünleri tüketimi ile iliflkili hastal›klar›n en s›k nedeni olarak gösterilmektedir. Bu çal›flmada geleneksel yo¤urt kültürü kullan›larak yap›lan yo¤urtlarda, Salmonella Enteritidis'in süte fermantasyon öncesi farkl› inokülasyon düzeylerinde bulaflt›r›lmas› durumunda fermantasyon süresince canl› kalma durumu araflt›r›lm›flt›r. Say›m yap›lan her aflamada pH ölçümü yap›lm›flt›r. Fermantasyon sonunda S. Enteritidis say›s› yaklafl›k 3; 5 ve 7 log KOB/mL düzeylerinde bulaflma durumlar› için s›ras›yla 2.95; 4.93, 7.05 log KOB/g'dan 3.26; 5.55; 6.98 log KOB/g'a ulaflm›flt›r. Farkl› inokülasyon koflullar›nda örneklerin pH de¤erleri aras›nda fark görülmemifl (P>0.05), fermantasyon süresince pH de¤eri 6.3'ten 4.5'e düflmüfltür. Çal›flma düflünülenin aksine, Salmonella'n›n yo¤urt fermantasyonu süresince düflük inokülasyon düzeyinde dahi canl›l›¤›n› sürdürebilmesi bak›m›ndan önem tafl›maktad›r.Anahtar kelimeler: Yo¤urt, Salmonella, fermantasyon, canl› kalma INVESTIGATION OF SURVIVAL OF SALMONELLA ENTERITIDIS DURING YOGHURT FERMENTATION AT DIFFERENT INOCULATION LEVELS AbstractYoghurt has generally been considered microbiologically safe as a consequence of low pH (4.2-4.5). On the other hand, Salmonella spp. is reported the most common cause of diseases associated with consumption of dairy products. In this study, survival of Salmonella Enteritidis at different inoculation levels during fermentation of yoghurt prepared using traditional yoghurt cultures was investigated. The pH of the samples was monitored when the enumeration procedures were carried out. At the end of the fermentation process, the counts of S. Enteritidis reached from 2. 95; 4.93; 7.05 to 3.26; 5.55; 6.98 log CFU/g for the three initial inoculum levels (3; 5 and 7 log CFU/mL), respectively. The changes of pH values were similar for all experiments (P>0.05), and the pH dropped from 6.3 to 4.5 during the fermentation period. In contrast to common belief, the study showed that this pathogen can survive in milk fermentation process even at low contamination level.

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Section: Sonuç Ve Tartişmaunclassified

Section: Introductionunclassified

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Yoğurt Fermantasyonu Sirasinda Salmonella Enteritidis’i̇n Farkli İnokülasyon Koşullarinda Canli Kalma Durumunun Araştirilmasi

2017

GIDA

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“…Salmonella spp. have been reported as a major pathogen that constitutes a risk for public health throughout the world and are also the most common cause of diseases associated with consumption of dairy products (CDC, 2011; Scallan et al., 2011; Szczawińska and Szczawiński, 2011).…”

Section: Introductionmentioning

confidence: 99%

Modeling the survival ofSalmonellaEnteritidis andSalmonellaTyphimurium during the fermentation of yogurt

Pérez‐Rodríguez

Food sci. technol. int.

2017

The objective of this study was to evaluate the behavior of Salmonella Enteritidis and Salmonella Typhimurium, the two most important serovars of salmonellosis , during the fermentation of yogurt. The microorganisms were enumerated in milk throughout the fermentation process at three initial inoculum levels (3, 5 and 7 log CFU/mL). DMFit software was used in the fitting procedure of the data (IFR, Norwich, UK, Version 3.5). The data provided sigmoidal curves that were successfully displayed with the Baranyi model. The results showed that the initial inoculum level did not affect the growth for both pathogens; thus, the µ values (maximum specific growth rate) did not significantly differ across all the contamination levels, ranging from 0.26 to 0.38 for S. Enteritidis and from 0.50 to 0.56 log CFU/g/h for S. Typhimurium ( P > 0.05). However, the µ values significantly differed between the two serovars ( P < 0.05). The λ values (lag time) did not have a clear trend in either of the pathogens. The present study showed that Salmonella can survive the fermentation process of milk even at a low contamination level. In addition, the models presented in this study can be used in quantitative risk assessment studies to estimate the threat to consumers.

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Modelling survival of Salmonella Enteritidis during storage of yoghurt at different temperatures

Pérez‐Rodríguez

International Journal of Food Microbiology

2018