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The role of heat exchangers in the contamination of milk with Bacillus cereus in dairy processing plants
Author(s) -
Giffel M C Te,
Beumer R R,
Langeveld L P M,
Rombouts F M
Publication year - 1997
Publication title -
international journal of dairy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.061
H-Index - 53
eISSN - 1471-0307
pISSN - 1364-727X
DOI - 10.1111/j.1471-0307.1997.tb01734.x
Subject(s) - bacillus cereus , cereus , contamination , heat exchanger , spore , food science , sodium hydroxide , biology , microbiology and biotechnology , chemistry , bacteria , ecology , genetics , physics , thermodynamics
In the dairy industry microbiological contamination may arise from equipment used for handling or processing. In this study it was demonstrated that Bacillus cereus spores could adhere stainless steel, germinate and/or multiply in a tube heat exchanger. The levels of B cereus detect in the tubes, after 24 h at 20°C, varied from less than 1 to 2600 cm ‐2 . Adhering cells and/or spores were more resistant to cleaning with K500 and sodium hydroxide, determined by laboratory suspension tests and surface tests on stainless steel. This was confirmed in a field trial with a tube heat exchanger after cleaning B cereus could still be isolated from all tubes determined by swab samples of individual tubes. The identity of the isolates was checked by polymerase chain reaction/randomly amplified polymorphic DNA typing to confirm that the organisms found on the surfaces were the same as the bacteria in the ingoing milk.