Assessing the growth of Escherichia coli O157:H7 and Salmonella in spinach, lettuce, parsley and chard extracts at different storage temperatures

Aims The objective of this work was to study the growth potential of Escherichia coli O157:H7 and Salmonella spp. in leafy vegetable extracts at different temperature conditions. Methods and Results Cocktails of five strains of E. coli O157:H7 and of Salmonella enterica were used. Inoculated aqueous...

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Bibliographic Details
Published in:	Journal of applied microbiology Vol. 120; no. 6; pp. 1701 - 1710
Main Authors:	Posada‐Izquierdo, G., Del Rosal, S., Valero, A., Zurera, G., Sant'Ana, A.S., Alvarenga, V.O., Pérez‐Rodríguez, F.
Format:	Journal Article
Language:	English
Published:	England Oxford University Press 01-06-2016
Subjects:	absorbance Beta vulgaris - microbiology Colony Count, Microbial E coli Escherichia coli Escherichia coli O157 - growth & development Escherichia coli O157 - isolation & purification Food contamination & poisoning Food Contamination - analysis Food Storage foodborne pathogens growth rate Lactuca - microbiology leafy vegetables Lettuce Microbiology modelling Petroselinum - microbiology Plant Leaves - microbiology predictive microbiology Salmonella Salmonella - growth & development Salmonella enterica Spinacia oleracea Spinacia oleracea - microbiology Temperature Vegetables - microbiology absorbance leafy vegetables growth rate predictive microbiology foodborne pathogens modelling
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Summary:	Aims The objective of this work was to study the growth potential of Escherichia coli O157:H7 and Salmonella spp. in leafy vegetable extracts at different temperature conditions. Methods and Results Cocktails of five strains of E. coli O157:H7 and of Salmonella enterica were used. Inoculated aqueous vegetable extracts were incubated at 8, 10, 16 and 20°C during 21 days. Microbial growth was monitored using Bioscreen C®. In spinach extract, results showed that for E. coli O157:H7 and Salmonella significant differences (P < 0·05) for μabs (maximum absorbance rate) were obtained. For both pathogens, growth in chard was slightly lower. In contrast, iceberg lettuce and parsley showed the lowest values of μabs, below 0·008 h−1. The coefficients of variance (CoV) calculated for the different replicates evidenced that at low temperature (8°C) a more variable behaviour of both pathogens is expected (CoV > 180%). Conclusions This study provides evidence that aqueous extracts from vegetable tissues can result in distinct growth niche producing different response in various types of vegetables. Significance and Impact of the Study Finally, these results can be used as basis to establish risk rankings of pathogens and leafy vegetable matrices with relation to their potential growth.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	1364-5072 1365-2672
DOI:	10.1111/jam.13122