Potential occurrence of adhering livingBacillusspores in milk product processing lines

Abstract

C. FAILLE, F. FONTAINE AND T. BÉNÉZECH. 2001. Aims: The hygienic risk associated with microbial soil on surfaces of milk processing lines was evaluated, based on experimental results. Methods and Results: From a panel of Bacillus spores isolated from milk products, B. cereus CUETM 98/4, was found to be highly resistant to heat (D100=3·32 min in whole milk) and oxidant disinfectant (70% lethality of adherent spores with Ikalin 2%). From adhesion trials, up to 1·1 × 107 spores cm−2 were found to be adherent to solid surfaces when suspended in saline or in custard (105 and 107 cfu ml−1), and over 10% of these adherent spores would resist the cleaning procedure. Conclusions: A highly contaminated milk (105 cfu ml−1) subjected to a current sterilization process (8 log reduction) led to a residual contamination of less than 1 cfu in the representative processing line after a complete production run. Significance and Impact of the Study: This study highlighted the fact that under appropriate processing conditions (efficient sterilization and cleaning procedures), even disinfection would be sufficient to eliminate any contamination risk. Conversely, the disinfection procedure becomes an essential step under inappropriate processing conditions.

Diversity and biofilm-forming capability of bacteria recovered from stainless steel pipes of a milk-processing dairy plant

“…Staphylococci species have been frequently shown to harbour ica genes (Gutierrez et al 2012;Szweda et al 2012), which are involved in biofilm formation. However, surprisingly, and in contrast to previous reported results (Faille et al 2001), most B. cereus strains were found to be nonbiofilm producers, even though isolates of these species were a majority population in all samples. The abundance of potential nonbiofilm producers strains in all samples argues for attachment of these bacteria to the real biofilm producers forming mixed-species biofilms (Habimana et al 2010;Lourenco et al 2011;Simoes et al 2007) or for these bacteria being attached to inert milk constituents (fat, protein) precipitating on the stainless steel surfaces.…”

Detection of Some Virulence Factors of Bacillus Cereus in Heat-Treated Milk

“…may result from spores present in raw milk surviving the sterilization process. Postpasteurization contamination may occur as a result of adhering living Bacillus spores in milk product processing lines (Faille et al, 2001).…”

Calorimetric Evaluations of Bacillus subtilis Vegetative and Spore Cells Colonial Growth and Suppressive Effects of Sucrose Monopalmitate

“…have a potent heat resistance and cause the microbial spoilage of food products. Faille et al (2001) pointed out that paying attention to these bacteria is of importance in the milk industry where they can survive even after the heat treatment process. Bacillus species are, indeed, frequently isolated from various heat-treated milk products such as pasteurized milk, UHT-processed milk, milk powder, cheese and yoghurt (Helmy, 1984).…”