title: Inactivation and sublethal injury kinetics of Staphylococcus aureus in broth at low temperature storage.
abstract: Low temperatures are widely used to ensure food quality and safety. However, sublethally injured Staphylococcus aureus is an important microbiological safety concern in low temperature food. The objective of this study was to develop predictive inactivation kinetic models for the inactivation and sublethal injury of S. aureus in broth at different temperatures (4 to -18°C) and time points. S. aureus was diluted in tryptic soy broth plus 0.6% (wt/vol) yeast extract (TSBYE) to obtain approximately 10(8) CFU/ml and was stored separately at 4, -3, -11, and -18°C. After specific time points within 96 days, survival of S. aureus was determined on TSBYE and TSBYE agar plus 10% NaCl for enumeration of the total viable and noninjured cell numbers, respectively. Linear, Weibull, and modified Gompertz models were applied to determine survival curve regression. The combination of low temperature and time resulted in S. aureus inactivation, although the cells were able to survive in this sublethal state. Storage temperature was the critical parameter in survival of S. aureus. The modified Weibull model successfully described a second model of noninjured S. aureus cell survival at different low temperatures, whereas only the linear model was able to fit the total viable cells. The predictive model may be used to estimate the level of S. aureus contamination in food at low storage temperatures and times, and it provides new insight into the sublethally injured survival state of S. aureus in low temperature food.
authors.affiliation: College of Food Science and Technology, Henan Agricultural University, 63 Nongye Road, Zhengzhou 450002, People's Republic of China; Henan Key Laboratory Cultivation Base of Quick-Frozen Flour-Rice Food and Prepared Food, Henan Agricultural University, 63 Nongye Road, Zhengzhou 450002, People's Republic of China.
authors.forename: Biao
authors.initials: B
authors.lastname: Suo
authors.affiliation: College of Food Science and Technology, Henan Agricultural University, 63 Nongye Road, Zhengzhou 450002, People's Republic of China.
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Food Science and Technology, Henan Agricultural University, 63 Nongye Road, Zhengzhou 450002, People's Republic of China.
authors.forename: Zhili
authors.initials: Z
authors.lastname: Pan
authors.affiliation: Henan Key Laboratory Cultivation Base of Quick-Frozen Flour-Rice Food and Prepared Food, Henan Agricultural University, 63 Nongye Road, Zhengzhou 450002, People's Republic of China.
authors.forename: Na
authors.initials: N
authors.lastname: Wang
authors.affiliation: College of Food Science and Technology, Henan Agricultural University, 63 Nongye Road, Zhengzhou 450002, People's Republic of China; Henan Key Laboratory Cultivation Base of Quick-Frozen Flour-Rice Food and Prepared Food, Henan Agricultural University, 63 Nongye Road, Zhengzhou 450002, People's Republic of China. zhila@163.com.
authors.forename: Zhilu
authors.initials: Z
authors.lastname: Ai
authors.affiliation: Faculty of Resource and Environmental Engineering, Jiangxi University of Science and Technology, No. 86, Hongqi Avenue, Ganzhou, Jiangxi, 341000, People's Republic of China.
authors.forename: Shuijing
authors.initials: S
authors.lastname: Yu
authors.affiliation: U.S. Food and Drug Administration, Institute for Food Safety and Health, 6502 South Archer Road, Bedford Park, Illinois 60501, USA.
authors.forename: Joelle K
authors.initials: JK
authors.lastname: Salazar
mesh_terms: D002364:Caseins / Q000737:chemistry; D003080:Cold Temperature; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology / Q000379:methods*; D061353:Food Storage / Q000379:methods*; D007700:Kinetics; D016014:Linear Models; D011492:Protein Hydrolysates / Q000737:chemistry; D012044:Regression Analysis; D012965:Sodium Chloride; D013211:Staphylococcus aureus / Q000502:physiology*; D013696:Temperature; D013997:Time Factors
chemical_list: D002364:Caseins; D011492:Protein Hydrolysates; C026375:trypticase-soy broth; D012965:Sodium Chloride