Enterococcus faecium as a Salmonella surrogate in the thermal processing of wheat flour: Influence of water activity at high temperatures.
Food Microbiol
; 74: 92-99, 2018 Sep.
Article
em En
| MEDLINE
| ID: mdl-29706342
ABSTRACT
This study investigated the influence of temperature-dependent water activity (aw) on thermal resistances of Enterococcus faecium NRRL B-2354 (E. faecium) and Salmonella Enteritidis PT 30 (S. Enteritidis) in wheat flour. The aw for wheat flour samples at 20, 40, and 60⯰C was determined by a vapor sorption analyzer and at 75, 80 and 85⯰C using custom-built thermal cells with high temperature humidity sensors. Full-factorial isothermal inactivation studies of both strains in sealed aluminum-test-cells included three temperatures (75, 80, and 85⯰C) and three aw,25°C levels (0.30, 0.45 and 0.60 within ±0.02 range, prior to the thermal treatments). Isotherm results of wheat flour demonstrate a significant increase (Pâ¯<â¯0.05) of aw as temperature rises (e.g. aw,25°Câ¯=â¯0.45⯱â¯0.02 became aw,80°Câ¯=â¯0.71⯱â¯0.02 in a closed system). Inactivation kinetics of both microorganisms fitted a log-linear model, the yielded D-values varied from 2.7⯱â¯0.2â¯min (D85°C of S. Enteritidis at aw,25°C 0.60⯱â¯0.02) to 65.8⯱â¯2.5â¯min (D75°C of E. faecium at aw,25°C 0.30⯱â¯0.02). The zT of E. faecium and S. Enteritidis decreased from 16.4 and 16.9⯰C, respectively, to 10.2⯰C with increased moisture content (dry basis) from 10 to 14%. Under all tested conditions, E. faecium exhibited equal or higher (1.0-3.1 times) D- and zT-values than those of Salmonella. Overall, E. faecium should be a conservative surrogate for Salmonella in thermal processing of wheat flour for control of Salmonella over a moisture content of 10-14% and treatment temperatures between 75 and 85⯰C.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Salmonella
/
Triticum
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Água
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Enterococcus faecium
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Farinha
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Microbiologia de Alimentos
/
Temperatura Alta
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Food Microbiol
Assunto da revista:
CIENCIAS DA NUTRICAO
/
MICROBIOLOGIA
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Estados Unidos
País de publicação:
ENGLAND
/
ESCOCIA
/
GB
/
GREAT BRITAIN
/
INGLATERRA
/
REINO UNIDO
/
SCOTLAND
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UK
/
UNITED KINGDOM