Spoilage characteristics of sous-vide beef caused by Clostridium estertheticum

The increasing popularity of sous-vide (SV) cooking necessitates research into the microbiological quality, sensory changes, and shelf life of SV products. Studies show that SV cooking significantly reduces the levels of meat microbiota and pathogens, positively affecting the shelf life and safety of SV products. However, the meat spoilage organism Clostridium estertheticum can survive SV cooking as it can produce heat-tolerant spores. Theses spores can germinate and multiply during storage at refrigerated temperatures, leading to spoilage of SV meat. Therefore, the aim of this study was to characterise the spoilage of SV beef caused by C. estertheticum compared to non-SV beef. In addition to the determination of spoilage characteristics, all beef samples were subjected to culture and qPCR analysis to determine the numbers of total bacteria, lactic acid bacteria, Enterobacteriaceae, yeasts, and C. estertheticum. Species identification of the colonies on the culture media was performed using MALDI-TOF MS. The tests were carried out at three different times (three repetitions). A total of 90 beef samples were analysed, of which 54 samples were artificially contaminated with three strains of C. estertheticum and vacuum-packed. Of these, 27 beef samples underwent SV cooking (55 °C, 70 min). After 28 days of storage at 4 °C, the SV beef samples exhibited significantly higher levels of gas and stronger spoilage odour compared to non-SV samples (p < 0.05). While drip loss and pH levels were also higher in SV beef, these were not considered specific spoilage characteristics caused by C. estertheticum. Microbiological and qPCR analyses revealed that all SV beef samples had very low bacterial and yeast counts but very high numbers of C. estertheticum, which strongly correlated with the sensory changes observed. We concluded that SV beef containing C. estertheticum has a shorter shelf life than contaminated non-SV beef. This is the first study to examine the spoilage of SV beef by C. estertheticum. The results may help raise awareness among meat producers and restaurants about the risk of meat losses due to spoilage caused by these bacteria.