title: Influence of controlled atmosphere on thermal inactivation of Escherichia coli ATCC 25922 in almond powder.
abstract: Heat controlled atmosphere (CA) treatments hold potential to pasteurize Salmonella enteritidis PT 30 in almonds. Nonpathogenic Escherichia coli ATCC 25922 was used as a surrogate species of pathogenic Salmonella for validation of thermal pasteurization to meet critical safety requirements. A controlled atmosphere/heating block system (CA-HBS) was used to rapidly determine thermal inactivation of E. coli ATCC 25922. D- and z-values of E. coli ATCC 25922 inoculated in almond powder were determined at four temperatures between 65 °C and 80 °C under different gas concentrations and heating rates. The results showed that D- and z-values of E. coli under CA treatment were significantly (P < 0.05) lower than those under regular atmosphere (RA) treatment at 4 given temperatures. Relatively higher CO2concentrations (20%) and lower O2concentrations (2%) were more effective to reduce thermal inactivation time. There were no significant differences in D-values of E. coli when heating rates were above 1 °C/min both in RA and CA treatments. But D-values significantly (P < 0.05) increased under RA treatment and decreased under CA treatment at lower heating rates. Combination of rapid heat and CA treatments could be a promising method for thermal inactivation of S. enteritidis PT 30 in almond powder.
authors.affiliation: College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, 712100, China.
authors.forename: Teng
authors.initials: T
authors.lastname: Cheng
authors.affiliation: College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, 712100, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Li
authors.affiliation: College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, 712100, China.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Kou
authors.affiliation: College of Mechanical and Electronic Engineering, Northwest A&F University, Yangling, 712100, China; Washington State University, Department of Biological Systems Engineering, Pullman, WA, 99164-6120, USA. Electronic address: shaojinwang@nwsuaf.edu.cn.
authors.forename: Shaojin
authors.initials: S
authors.lastname: Wang
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004926:Escherichia coli / Q000187:drug effects / Q000502:physiology*; D005511:Food Handling; D005516:Food Microbiology; D006358:Hot Temperature; D050296:Microbial Viability; D010100:Oxygen / Q000494:pharmacology; D061352:Pasteurization; D000068181:Prunus dulcis / Q000382:microbiology*; D012477:Salmonella enteritidis / Q000187:drug effects / Q000502:physiology; D000071436:Thermotolerance
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: Almond; CA-HBS; Gas concentration; Heating rate; S. enteritidis PT 30; Thermal inactivation