Survival of a five-strain cocktail of Escherichia coli O157: H7 during the 60-day aging period of Cheddar cheese made from unpasteurized milk

J. E. Schlesser, R. Gerdes, Sadhana Ravishankar, K. Madsen, J. Mowbray, A. Y L Teo

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

The U.S. Food and Drug Administration Standard of Identity for Cheddar cheeses requires pasteurization of the milk, or as an alternative treatment, a minimum 60-day aging at ≥2°C for cheeses made from unpasteurized milk, to reduce the number of viable pathogens that may be present to an acceptable risk. The objective of this study was to investigate the adequacy of the 60-day minimum aging to reduce the numbers of viable pathogens and evaluate milk subpasteurization heat treatment as a process to improve the safety of Cheddar cheeses made from unpasteurized milk. Cheddar cheese was made from unpasteurized milk inoculated with 101 to 105 CFU/ml of a five-strain cocktail of acid-tolerant Escherichia coli O157:H7. Samples were collected during the cheese manufacturing process. After pressing, the cheese blocks were packaged into plastic bags, vacuum sealed, and aged at 7°C. After 1 week, the cheese blocks were cut into smaller-size uniform pieces and then vacuum sealed in clear plastic pouches. Samples were plated and enumerated for E. coli O157:H7. Populations of E. coli O157:H7 increased during the cheese-making operations. Population of E. coli O157:H7 in cheese aged for 60 and 120 days at 7°C decreased less than 1 and 2 log, respectively. These studies confirm previous reports that show 60-day aging is inadequate to eliminate E. coli O157:H7 during cheese ripening. Subpasteurization heat-treatment runs were conducted at 148°F (64.4°C) for 17.5 s on milk inoculated with E. coli O157:H7 at 105 CFU/ml. These heat-treatment runs resulted in a 5-log E. coli O157:H7 reduction.

Original languageEnglish (US)
Pages (from-to)990-998
Number of pages9
JournalJournal of Food Protection
Volume69
Issue number5
StatePublished - May 2006
Externally publishedYes

Fingerprint

Cheddar cheese
Escherichia coli O157
Cheese
Milk
milk
cheeses
cheesemaking
heat treatment
standards of identity
Hot Temperature
acceptable risk
Vacuum
Plastics
plastic bags
cheese ripening
pathogens
pressing
pasteurization
pouches
Pasteurization

ASJC Scopus subject areas

  • Food Science
  • Applied Microbiology and Biotechnology
  • Biotechnology
  • Microbiology

Cite this

Survival of a five-strain cocktail of Escherichia coli O157 : H7 during the 60-day aging period of Cheddar cheese made from unpasteurized milk. / Schlesser, J. E.; Gerdes, R.; Ravishankar, Sadhana; Madsen, K.; Mowbray, J.; Teo, A. Y L.

In: Journal of Food Protection, Vol. 69, No. 5, 05.2006, p. 990-998.

Research output: Contribution to journalArticle

@article{0a48702aeef44099a5014bda44223d27,
title = "Survival of a five-strain cocktail of Escherichia coli O157: H7 during the 60-day aging period of Cheddar cheese made from unpasteurized milk",
abstract = "The U.S. Food and Drug Administration Standard of Identity for Cheddar cheeses requires pasteurization of the milk, or as an alternative treatment, a minimum 60-day aging at ≥2°C for cheeses made from unpasteurized milk, to reduce the number of viable pathogens that may be present to an acceptable risk. The objective of this study was to investigate the adequacy of the 60-day minimum aging to reduce the numbers of viable pathogens and evaluate milk subpasteurization heat treatment as a process to improve the safety of Cheddar cheeses made from unpasteurized milk. Cheddar cheese was made from unpasteurized milk inoculated with 101 to 105 CFU/ml of a five-strain cocktail of acid-tolerant Escherichia coli O157:H7. Samples were collected during the cheese manufacturing process. After pressing, the cheese blocks were packaged into plastic bags, vacuum sealed, and aged at 7°C. After 1 week, the cheese blocks were cut into smaller-size uniform pieces and then vacuum sealed in clear plastic pouches. Samples were plated and enumerated for E. coli O157:H7. Populations of E. coli O157:H7 increased during the cheese-making operations. Population of E. coli O157:H7 in cheese aged for 60 and 120 days at 7°C decreased less than 1 and 2 log, respectively. These studies confirm previous reports that show 60-day aging is inadequate to eliminate E. coli O157:H7 during cheese ripening. Subpasteurization heat-treatment runs were conducted at 148°F (64.4°C) for 17.5 s on milk inoculated with E. coli O157:H7 at 105 CFU/ml. These heat-treatment runs resulted in a 5-log E. coli O157:H7 reduction.",
author = "Schlesser, {J. E.} and R. Gerdes and Sadhana Ravishankar and K. Madsen and J. Mowbray and Teo, {A. Y L}",
year = "2006",
month = "5",
language = "English (US)",
volume = "69",
pages = "990--998",
journal = "Journal of Food Protection",
issn = "0362-028X",
publisher = "International Association for Food Protection",
number = "5",

}

TY - JOUR

T1 - Survival of a five-strain cocktail of Escherichia coli O157

T2 - H7 during the 60-day aging period of Cheddar cheese made from unpasteurized milk

AU - Schlesser, J. E.

AU - Gerdes, R.

AU - Ravishankar, Sadhana

AU - Madsen, K.

AU - Mowbray, J.

AU - Teo, A. Y L

PY - 2006/5

Y1 - 2006/5

N2 - The U.S. Food and Drug Administration Standard of Identity for Cheddar cheeses requires pasteurization of the milk, or as an alternative treatment, a minimum 60-day aging at ≥2°C for cheeses made from unpasteurized milk, to reduce the number of viable pathogens that may be present to an acceptable risk. The objective of this study was to investigate the adequacy of the 60-day minimum aging to reduce the numbers of viable pathogens and evaluate milk subpasteurization heat treatment as a process to improve the safety of Cheddar cheeses made from unpasteurized milk. Cheddar cheese was made from unpasteurized milk inoculated with 101 to 105 CFU/ml of a five-strain cocktail of acid-tolerant Escherichia coli O157:H7. Samples were collected during the cheese manufacturing process. After pressing, the cheese blocks were packaged into plastic bags, vacuum sealed, and aged at 7°C. After 1 week, the cheese blocks were cut into smaller-size uniform pieces and then vacuum sealed in clear plastic pouches. Samples were plated and enumerated for E. coli O157:H7. Populations of E. coli O157:H7 increased during the cheese-making operations. Population of E. coli O157:H7 in cheese aged for 60 and 120 days at 7°C decreased less than 1 and 2 log, respectively. These studies confirm previous reports that show 60-day aging is inadequate to eliminate E. coli O157:H7 during cheese ripening. Subpasteurization heat-treatment runs were conducted at 148°F (64.4°C) for 17.5 s on milk inoculated with E. coli O157:H7 at 105 CFU/ml. These heat-treatment runs resulted in a 5-log E. coli O157:H7 reduction.

AB - The U.S. Food and Drug Administration Standard of Identity for Cheddar cheeses requires pasteurization of the milk, or as an alternative treatment, a minimum 60-day aging at ≥2°C for cheeses made from unpasteurized milk, to reduce the number of viable pathogens that may be present to an acceptable risk. The objective of this study was to investigate the adequacy of the 60-day minimum aging to reduce the numbers of viable pathogens and evaluate milk subpasteurization heat treatment as a process to improve the safety of Cheddar cheeses made from unpasteurized milk. Cheddar cheese was made from unpasteurized milk inoculated with 101 to 105 CFU/ml of a five-strain cocktail of acid-tolerant Escherichia coli O157:H7. Samples were collected during the cheese manufacturing process. After pressing, the cheese blocks were packaged into plastic bags, vacuum sealed, and aged at 7°C. After 1 week, the cheese blocks were cut into smaller-size uniform pieces and then vacuum sealed in clear plastic pouches. Samples were plated and enumerated for E. coli O157:H7. Populations of E. coli O157:H7 increased during the cheese-making operations. Population of E. coli O157:H7 in cheese aged for 60 and 120 days at 7°C decreased less than 1 and 2 log, respectively. These studies confirm previous reports that show 60-day aging is inadequate to eliminate E. coli O157:H7 during cheese ripening. Subpasteurization heat-treatment runs were conducted at 148°F (64.4°C) for 17.5 s on milk inoculated with E. coli O157:H7 at 105 CFU/ml. These heat-treatment runs resulted in a 5-log E. coli O157:H7 reduction.

UR - http://www.scopus.com/inward/record.url?scp=33646473824&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33646473824&partnerID=8YFLogxK

M3 - Article

C2 - 16715794

AN - SCOPUS:33646473824

VL - 69

SP - 990

EP - 998

JO - Journal of Food Protection

JF - Journal of Food Protection

SN - 0362-028X

IS - 5

ER -