Document Detail

Formation of guaiacol in chocolate milk by the psychrotrophic bacterium Rahnella aquatilis.
MedLine Citation:
PMID:  11696092     Owner:  NLM     Status:  MEDLINE    
AIMS: The aim of this study was to identify the causative agent of a smoky/phenolic taint in refrigerated full cream chocolate milk. METHODS AND RESULTS: Microbiological examination of spoiled and unspoiled milk samples from the same processor showed high numbers of the psychrotrophic coliform Rahnella aquatilis in the spoiled samples only. Gas chromatography/mass spectrometry (GC/MS) was used to identify and quantify the taint compound as guaiacol (2-methoxyphenol) in the spoiled milk. Challenge studies in UHT chocolate and white milks inoculated with the isolate and incubated at 4-5 degrees C and 8-9 degrees C for 6 d showed the production of guaiacol in chocolate milk only, which was confirmed and quantified by GC/MS. CONCLUSIONS: The results indicate that if present in refrigerated chocolate milk, Rah. aquatilis can produce guaiacol within the expected shelf-life of the product, even without temperature abuse. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report that the coliform Rah. aquatilis can produce guaiacol in refrigerated chocolate milk products.
N Jensen; P Varelis; F B Whitfield
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Letters in applied microbiology     Volume:  33     ISSN:  0266-8254     ISO Abbreviation:  Lett. Appl. Microbiol.     Publication Date:  2001 Nov 
Date Detail:
Created Date:  2001-11-06     Completed Date:  2002-05-02     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8510094     Medline TA:  Lett Appl Microbiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  339-43     Citation Subset:  IM    
Food Science Australia, PO Box 52, North Ryde, NSW 1670, Australia.
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MeSH Terms
Cacao / microbiology*
Cold Temperature
Colony Count, Microbial
Food Microbiology
Food Preservation
Gas Chromatography-Mass Spectrometry
Guaiacol / chemistry,  metabolism*
Milk / microbiology*
Rahnella / growth & development,  metabolism*
Reg. No./Substance:
0/Benzaldehydes; 121-33-5/vanillin; 90-05-1/Guaiacol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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