Influence of controlled atmosphere on thermal inactivation of Escherichia coli ATCC 25922 in almond powder. (June 2017)

• Record Type: Journal Article
• Authors: Cheng, Teng; Li, Rui; Kou, Xiaoxi; Wang, Shaojin
• Is Part Of: Food microbiology. Volume 64(2017:Jun.)
• Page Start: 186
• Page End: 194
• Publication Date: 2017-06
• Subjects: Almond -- CA-HBS -- S. enteritidis PT 30 -- Heating rate -- Gas concentration -- Thermal inactivation; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2017.01.007
• Languages: English
• ISSNs: 0740-0020

Abstract

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 CO2 concentrations (20%) and lower O2 concentrations (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. Highlights: Thermotolerance of E. coli was determined using a CA-HBS. D- and z- values of E. coli under CA were significantly lower than those under RA. 20% CO2 /2% O2 were effective to reduce thermal inactivation time. Heating at 0.1 °C/min achieved highest inactivation in CA but lowest in RA treatments.