The survival of Staphylococcus aureus during the fermentation and storage of yoghurt

Abstract

The effect of yoghurt culture Rx on the survival of Staphylococcus aureus CCM 5984 added to milk in various concentrations was observed during the fermentation and storage of yoghurt. The end of the fermentation process (3.5 h) was only accompanied by a slight reduction. During the storage of yoghurt at 4 degrees C a 1-2 log reduction was observed. No Staph. aureus was detected in yoghurt produced from milk contaminated by 10(3) Staph. aureus cells l-1 after 48 h of cold storage. When a concentration of 10(2) Staph. aureus cells was used for milk contamination, the pathogen was not recovered from yoghurt during the fermentation and storage. The fermentation and storage of yoghurt was accompanied by increases in lactic acid and titrimetric acidity, as well as by a decrease in pH value.

Prevalence and phylogenetic relationship among methicillin- and vancomycin-resistant Staphylococci isolated from hospital's dairy food, food handlers, and patients

“…Also, Carfora et al [39], Basanisi et al [40], Ektik et al [41], Papadopoulos et al [42], and Usman and Mustapha [43] could isolate CoPSA from dairy products samples, and MRCoPSA and VRCoPSA were among them. The lack of dairy food samples from CoPSA could be contributed to the low pH of the samples as a result of fermentation [44], in addition that food samples originated from large scale factories, while, the occurrence of CoNS in food may result primarily from its ability to withstand adverse environmental conditions throughout the manufacturing, storage and high adaptation capacity of those micro-organisms [45].…”

Microbiological shelf life at different temperatures and fate of Listeria monocytogenes and Escherichia coli inoculated in unflavored and strawberry yogurts

“…Previous studies showed that several potential pathogenic bacteria (Staphylococcus aureus, Campylobacter jejuni, Salmonella spp., Shigella spp., L. monocytogenes, and E. coli O157:H7) intentionally added to yogurt or fermented milk before or after fermentation, thus simulating cases of ineffective heat treatment or postcontamination, were hardly able to survive or otherwise multiply (Alm, 1983;Čuk et al, 1987;Zúñiga-Estrada et al, 1995;Pazakova et al, 1997;Issa and Ryser, 2000;Benkerroum et al, 2002;Belessi et al, 2008;Hsieh et al, 2010;Osaili et al, 2013).…”

Survival of E. coli O157:H7 Staphylococcus aureus, Shigella flexneri and Salmonella spp. in fermenting `Borde', a traditional Ethiopian beverage

“…Similar to our observation, elimination of S. aureus by LAB at low temperatures was also reported by Estrada, Mendonza, de la Garza, and Ferado (1999), where it survived the fermentation of milk by yogurt starter culture, but was inhibited as soon as the fermentation was followed by refrigeration at 4°C. Similarly, S. aureus, which survived fermentation of yogurt for 4 h, was eliminated after 48 h of cold storage (Pazakova, Turek, & Laciakova, 1997). In general, S. aureus with counts <10 5 cfu/ml may not be a point of concern, as enough toxins will not be elucidated to cause food-borne gastroenteritis.…”