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Effect of different storage conditions on E. coli O157:H7 and the indigenous bacterial microflora on lamb meat.
Int J Food Microbiol. 2007 Apr 10; 115(2):244-51.IJ

Abstract

Lamb chops inoculated with 2.23-2.83 log cfu/g of E. coli O157:H7 strain NCTC 12900 were packed in air (AP), vacuum (VP), and two modified atmospheres (MAP) consisting of 100% CO2 and a commercial mixture of 35% CO2/35% O2/30% N2. All samples (initial total counts <3.5 log cfu/g) were stored in a commercial cold storage facility set at 4 degrees C and one AP trial also at 12+/-1 degrees C in a temperature controlled incubator. Pathogen and indigenous flora evolution, physicochemical and sensory changes, surface packages temperature and MAP gas composition were monitored throughout the lamb meat shelf life. Temperature monitoring revealed that during chilled storage packed chops exceeded 7 degrees C about 3% of the time for periods of 10-20 min at 6 h intervals corresponding to defrosting cycles. In AP samples under these conditions, the E. coli O157:H7 strain had an overall increase of 0.48 log cfu/g by day 12. This increase, which may be regarded as an artefact of the sampling procedure, might also be a response to fluctuating temperatures. Regardless of rapid proliferation of the background microflora on AP lamb meat kept at 12+/-1 degrees C, the pathogen significantly increased by 2.35 log cfu/g after nine days. There was a slight decrease (0.20 log cfu/g) of the pathogen numbers after four weeks cold storage in VP despite a significant increase in lactic acid bacteria (LAB). With a relatively small outgrowth of LAB, chilled storage in 100% and 35% CO2 resulted in significant differences compared to similar conditions in air (decrease from initial numbers of 0.80 and 0.45 log cfu/g, respectively). Our data confirm the importance of effective temperature control to prevent pathogen growth on raw meat and also that contaminated meat remains hazardous regardless of refrigeration and protective packaging. Further studies are needed to determine the behaviour of E. coli O157:H7 at temperatures that fluctuate around the minimum for growth.

Authors+Show Affiliations

Barrera O
Department of Food Hygiene and Food Technology, University of León, 24071-León, Spain.
Rodríguez-Calleja JM
No affiliation info available
Santos JA
No affiliation info available
Otero A
No affiliation info available
García-López ML
No affiliation info available

MeSH

AirAnimalsColony Count, MicrobialConsumer Product SafetyEscherichia coli O157Food ContaminationFood MicrobiologyFood PackagingFood PreservationHumansMeatSheepTemperatureTime FactorsVacuum

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17292989

Citation

Barrera, Oriol, et al. "Effect of Different Storage Conditions On E. Coli O157:H7 and the Indigenous Bacterial Microflora On Lamb Meat." International Journal of Food Microbiology, vol. 115, no. 2, 2007, pp. 244-51.
Barrera O, Rodríguez-Calleja JM, Santos JA, et al. Effect of different storage conditions on E. coli O157:H7 and the indigenous bacterial microflora on lamb meat. Int J Food Microbiol. 2007;115(2):244-51.
Barrera, O., Rodríguez-Calleja, J. M., Santos, J. A., Otero, A., & García-López, M. L. (2007). Effect of different storage conditions on E. coli O157:H7 and the indigenous bacterial microflora on lamb meat. International Journal of Food Microbiology, 115(2), 244-51.
Barrera O, et al. Effect of Different Storage Conditions On E. Coli O157:H7 and the Indigenous Bacterial Microflora On Lamb Meat. Int J Food Microbiol. 2007 Apr 10;115(2):244-51. PubMed PMID: 17292989.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of different storage conditions on E. coli O157:H7 and the indigenous bacterial microflora on lamb meat. AU - Barrera,Oriol, AU - Rodríguez-Calleja,Jose M, AU - Santos,Jesús A, AU - Otero,Andrés, AU - García-López,María-Luisa, Y1 - 2007/01/20/ PY - 2006/08/04/received PY - 2006/10/25/revised PY - 2006/10/26/accepted PY - 2007/2/13/pubmed PY - 2007/5/15/medline PY - 2007/2/13/entrez SP - 244 EP - 51 JF - International journal of food microbiology JO - Int J Food Microbiol VL - 115 IS - 2 N2 - Lamb chops inoculated with 2.23-2.83 log cfu/g of E. coli O157:H7 strain NCTC 12900 were packed in air (AP), vacuum (VP), and two modified atmospheres (MAP) consisting of 100% CO2 and a commercial mixture of 35% CO2/35% O2/30% N2. All samples (initial total counts <3.5 log cfu/g) were stored in a commercial cold storage facility set at 4 degrees C and one AP trial also at 12+/-1 degrees C in a temperature controlled incubator. Pathogen and indigenous flora evolution, physicochemical and sensory changes, surface packages temperature and MAP gas composition were monitored throughout the lamb meat shelf life. Temperature monitoring revealed that during chilled storage packed chops exceeded 7 degrees C about 3% of the time for periods of 10-20 min at 6 h intervals corresponding to defrosting cycles. In AP samples under these conditions, the E. coli O157:H7 strain had an overall increase of 0.48 log cfu/g by day 12. This increase, which may be regarded as an artefact of the sampling procedure, might also be a response to fluctuating temperatures. Regardless of rapid proliferation of the background microflora on AP lamb meat kept at 12+/-1 degrees C, the pathogen significantly increased by 2.35 log cfu/g after nine days. There was a slight decrease (0.20 log cfu/g) of the pathogen numbers after four weeks cold storage in VP despite a significant increase in lactic acid bacteria (LAB). With a relatively small outgrowth of LAB, chilled storage in 100% and 35% CO2 resulted in significant differences compared to similar conditions in air (decrease from initial numbers of 0.80 and 0.45 log cfu/g, respectively). Our data confirm the importance of effective temperature control to prevent pathogen growth on raw meat and also that contaminated meat remains hazardous regardless of refrigeration and protective packaging. Further studies are needed to determine the behaviour of E. coli O157:H7 at temperatures that fluctuate around the minimum for growth. SN - 0168-1605 UR - https://www.unboundmedicine.com/medline/citation/17292989/Effect_of_different_storage_conditions_on_E__coli_O157:H7_and_the_indigenous_bacterial_microflora_on_lamb_meat_ DB - PRIME DP - Unbound Medicine ER -