title: Thermal inactivation of Bacillus cereus spores affected by the solutes used to control water activity of the heating medium.
abstract: The heat resistance of B. cereus spores (ATCC 7004, 4342 and 9818) over a wide temperature range (92-125 degrees C) in aqueous solutions of NaCl, LiCl, sucrose and glycerol at different water activities (1.00-0.71) was investigated. Sodium chloride in the heating medium tended to protect the spores of B. cereus against heat. The z-values increased significantly (P < 0.05) at and above a concentration of 4.0 M. The effects of LiCl were lower than those caused by the NaCl at the same a(w) values. An increase in z-values was observed. but the differences were only statistically significant (P<0.05) at the highest concentration tested (5.0 M). A concentration of sucrose 0.87 M caused in all cases a reduction in D-values, which was most pronounced for strains 4342 and 9818. With increasing concentration of sucrose ( > 0.87 M), the D-values showed an increase, although only those obtained for strain 4342 in sucrose solutions 2.22 M were higher than those found in pure water. The z-values were significantly higher (P < 0.05) when sucrose was added at concentrations above 1.42 M, except for strain 4342. When a(w) was lowered from 0.96 to 0.71 with glycerol, D-values obtained gradually increased, about 30, 50 and 60 fold for 4342, 7004 and 9818 strains, respectively. No significant effect on z-values were detected.
authors.affiliation: Departamento de Higiene y Tecnología de los Alimentos, Unversidad de León, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Mazas
authors.forename: S
authors.initials: S
authors.lastname: Martínez
authors.forename: M
authors.initials: M
authors.lastname: López
authors.forename: A B
authors.initials: AB
authors.lastname: Alvarez
authors.forename: R
authors.initials: R
authors.lastname: Martin
mesh_terms: D001409:Bacillus cereus; D005519:Food Preservation / Q000379:methods* / Q000592:standards; D005990:Glycerol; D006358:Hot Temperature; D018021:Lithium Chloride; D012965:Sodium Chloride; D012996:Solutions; D013171:Spores, Bacterial; D013395:Sucrose; D014867:Water
chemical_list: D012996:Solutions; D014867:Water; D012965:Sodium Chloride; D013395:Sucrose; D018021:Lithium Chloride; D005990:Glycerol