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Reduction of Bacillus cereus spores in sikhye, a traditional Korean rice beverage, by modified tyndallization processes with and without carbon dioxide injection
Author(s) -
Kim H.,
Kim H.,
Bang J.,
Kim Y.,
Beuchat L.R.,
Ryu J.H.
Publication year - 2012
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2012.03278.x
Subject(s) - spore , bacillus cereus , carbon dioxide , bacillales , food science , endospore , biology , bacillaceae , botany , chemistry , microbiology and biotechnology , bacteria , ecology , bacillus subtilis , genetics
Aims: The objective of this study was to inactivate Bacillus cereus spores in sikhye using a modified tyndallization process involving injection with carbon dioxide (CO 2 ). Methods and Results: Heat tolerance of B. cereus spores in tryptic soy broth and sikhye was evaluated. The D 95°C values of the B. cereus spores were 2·8–4·9 min, dependent of type of heating medium or inoculum level. The lethality of conventional heat treatment and modified tyndallization with or without CO 2 injection against B. cereus spores in sikhye was determined. The order of effectiveness was modified tyndallization with CO 2 > modified tyndallization without CO 2 > conventional heat treatment. Modified tyndallization with CO 2 reduced the number of B. cereus spores in sikhye by 5·8 log CFU ml −1 . The increased CO 2 concentration and decreased pH of sikhye resulting from CO 2 injection rapidly reverted to near‐normal values after heat treatment. Conclusions: Modified tyndallization with CO 2 was more effective than conventional heat treatment or modified tyndallization without CO 2 in reducing B. cereus spores in sikhye. Significance and Impact of the Study: Results of this study will be useful when developing strategies to control B. cereus spores in sikhye and may have application to other beverages.