YOĞURT FERMANTASYONU SIRASINDA SALMONELLA ENTERİTİDİS’İN FARKLI İNOKÜLASYON KOŞULLARINDA CANLI KALMA DURUMUNUN ARAŞTIRILMASI

Yoğurt düşük pH (pH 4.2-4.5) içeriği ile mikrobiyolojik açıdan genellikle güvenilir gıda olarak düşünülmektedir. Diğer taraftan Salmonella spp. süt ürünleri tüketimi ile ilişkili hastalıkların en sık nedeni olarak gösterilmektedir. Bu çalışmada geleneksel yoğurt kültürü kullanılarak yapılan yoğurtlarda, Salmonella Enteritidis’in süte fermantasyon öncesi farklı inokülasyon düzeylerinde bulaştırılması durumunda fermantasyon süresince canlı kalma durumu araştırılmıştır. Sayım yapılan her aşamada pH ölçümü yapılmıştır. Fermantasyon sonunda S. Enteritidis sayısı yaklaşık 3; 5 ve 7 log KOB/mL düzeylerinde bulaşma durumları için sırasıyla 2.95; 4.93, 7.05 log KOB/g’dan 3.26; 5.55; 6.98 log KOB/g’a ulaşmıştır. Farklı inokülasyon koşullarında örneklerin pH değerleri arasında fark görülmemiş (P>0.05), fermantasyon süresince pH değeri 6.3’ten 4.5’e düşmüştür. Çalışma düşünülenin aksine, Salmonella’nın yoğurt fermantasyonu süresince düşük inokülasyon düzeyinde dahi canlılığını sürdürebilmesi bakımından önem taşımaktadır.

Anahtar Kelimeler:

Yoğurt, Salmonella, fermantasyon, canlı kalma

INVESTIGATION of SURVIVAL of SALMONELLA ENTERITIDIS DURING YOGHURT FERMENTATION at DIFFERENT INOCULATION LEVELS

Yoghurt has generally been considered microbiologically safe as a consequence of low pH (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.

Keywords:

Yoghurt, Salmonella, fermentation, survival,

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