Heat shock effects on the viability of Cronobacter sakazakii during the dehydration, fermentation, and storage of lactic cultured milk products

In the present study, the viability of heat-shocked and non-shocked cronobacter sakazakii, a foodborne pathogen, after drying and during the fermentation as well as storage of lactic cultured milk was evaluated It was found that heat shock increased the viability of C sakazakii The Pure Culture of C sakazakii. regardless of heat shock, grew rapidly in skim milk with a viable population of ca 8 59-8 70 log cfu/ml after ca 48 h of cultivation Thereafter, the viable population of C sakazakii remained stable. While in the mix culture with Streptococcus thermophilus or Lactobacillus bulgaricus, a marked reduction in the viable population of C sakazakii was noted after 24 h of cultivation in skim milk Nevertheless, at the end of fermentation, the heat-shocked C sakazakii had a Viable Population of 5 93-6 01 log cfu/ml, which is significantly higher (P < 0 05) than that of non-shocked cells of 4.96-4 99 log cfu/ml While the presence of C sakazakii did not affect the growth of lactic acid bacteria in skim milk Additionally, heat shock was found to enhance the survival of C sakazaku after freeze-drying or spray-drying and during the storage of the lactic fermented milk products (pH 4 3) at 5 degrees C for 48 h. (C) 2009 Published by Elsevier Ltd