Chitosan inactivates spoilage yeasts but enhances survival of Escherichia coli 0157:H7 in apple juice

Kiskó, G., Sharp, Richard and Roller, Sibel (2005) Chitosan inactivates spoilage yeasts but enhances survival of Escherichia coli 0157:H7 in apple juice. Journal of Applied Microbiology, 98 (4). pp. 872-880. ISSN 1365-2672

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Abstract

AIMS: 
To develop new measures for controlling both spoilage and pathogenic micro-organisms in unpasteurized apple juice using chitosan.

METHODS AND RESULTS: 
Micro-organisms were isolated and identified from apple juice treated or untreated with chitosan using enrichment, selective media, microscopy, substrate assimilation patterns and ribosomal DNA profiling. Chitosan (0·05–0·1%) delayed spoilage by yeasts at 25°C for up to 12 days but the effect was species specific: Kloeckera apiculata and Metschnikowia pulcherrima were inactivated but Saccharomyces cerevisiae and Pichia spp. multiplied slowly. In challenge experiments at 25°C, total yeast counts were 3–5 log CFU ml−1 lower in chitosan-treated juices than in the controls for 4 days but the survival of Escherichia coli O157:H7 was extended from 1 to 2 days; at 4°C, chitosan reduced the yeast counts by 2–3 log CFU ml−1 for up to 10 days but survival of the pathogen was prolonged from 3 to 5 days. The survival of Salmonella enterica serovar Typhimurium was unaffected by chitosan at either temperature.

CONCLUSIONS: 
The addition of chitosan to apple juice delayed spoilage by yeasts but enhanced the survival of E. coli O157:H7.

SIGNIFICANCE AND IMPACT OF THE STUDY: 
The results suggest that the use of chitosan in the treatment of fruit juices may potentially lead to an increased risk of food poisoning from E. coli O157:H7.

Item Type: Article
Uncontrolled Keywords: Apple juice; Chitosan; Escherichia coli O157:H7; Salmonella Typhimurium; Yeast
Subjects: Medicine and health > Microbiology
Depositing User: Rod Pow
Date Deposited: 04 Jul 2012 13:50
Last Modified: 01 Jun 2017 09:17
URI: http://repository.uwl.ac.uk/id/eprint/88

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