The effects of freezing and thawing on the survival of Escherichia coli O157:H7 in apple juice.
Int J Food Microbiol
; 67(1-2): 89-96, 2001 Jul 20.
Article
en En
| MEDLINE
| ID: mdl-11482573
ABSTRACT
Unpasteurized apple juice, adjusted to pH 3.6 to 7.0 was inoculated (10(7) CFU/ml) with single strains of E. coli O157H7 to evaluate the effect of frozen storage on the viability of this organism. Samples were stored under frozen conditions (-20+/-2 degrees C) for up to 16 days. Cell populations were determined at regular intervals by plating onto tryptic soy agar with added pyruvate (TSAP) or onto sorbitol MacConkey agar (SMA). Populations in the neutralized juice remained unchanged during frozen storage. Populations in non-neutralized juice decreased by 1-3 log10 CFU/ml depending on the strain tested and the pH of the juice. The greatest population decrease was observed with the first freeze/thaw cycle of frozen storage (24 h) and a slow decline in survival occurred thereafter. Injury was observed after 2 weeks of storage when juice pH was at or below pH 4.2. When samples were subjected to multiple freeze/thaw cycles, loss of viability and injury increased with each freeze/thaw cycle.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Bebidas
/
Escherichia coli O157
/
Rosales
/
Conservación de Alimentos
/
Congelación
Idioma:
En
Revista:
Int J Food Microbiol
Asunto de la revista:
CIENCIAS DA NUTRICAO
/
MICROBIOLOGIA
Año:
2001
Tipo del documento:
Article
País de afiliación:
Estados Unidos