ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578
II. Foodborne Illness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 578
A. Sequelae of Foodborne Diseases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581
B. Factors Causing Foodborne Disease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 581
C. Trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583
D. Economic Burden of Foodborne Illness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 583
III. Microbiological Considerations of Frozen Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584
A. Safety of Frozen Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584
B. Freezing and Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 585
C. Surviving the Freezing Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
1. Freeze Injury . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 586
2. Microbial Survival . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 587
3. Pathogen Survival in Frozen Food Systems . . . . . . . . . . . . . . . . . . . . . . . 588
D. Microbiological Spoilage of Frozen Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . 588
IV. Microbiological Examination of Frozen Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 588
A. Microbiological Sampling Plans and Guidelines . . . . . . . . . . . . . . . . . . . . . . . 588
B. Practicalities of Microbiological Analysis of Frozen Food . . . . . . . . . . . . . . . 590
1. Sample Preparation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 590
2. Determination of Microbiological Quality . . . . . . . . . . . . . . . . . . . . . . . . . 591
a. Aerobic Colony Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 591
b. Total Psychrophilic Aerobes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 592
c. Yeasts and molds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 592
3. Indicator Bacteria: Enterobacteriaceae and E. coli . . . . . . . . . . . . . . . . . . 592
4. Pathogen Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593
a. Salmonella sp. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 593
b. Staphylococcus aureus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
c. Listeria monocytogenes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
5. Rapid Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594
V. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596
In spite of increasingly rigorous food hygiene and food safety regulations, foodborne illness con-
tinues to increase costing the global economy billions of dollars annually [1]. Pathogenic microbes
are responsible for approximately 30% of all outbreaks, which make understanding the epidemiol-
ogy of microbial foodborne illness and the methodology of pathogen detection vital to its control. In
2000, approximately 84% of all microbiological tests performed by the U.S. Food Industry were
done to enumerate aerobic colony counts (ACC), yeast and molds (MYC), and coliforms and
Escherichia coli, leaving only 16% of tests assessing pathogenic microbes [2]. This chapter
reviews recent epidemiological data on foodborne illness worldwide and discusses the contribution
of frozen foods to illness outbreaks and the factors that affect microbial survival in frozen foods.
Finally, standard microbiological methods to enumerate ACC, MYC, Enterobacteriaceae, and
food pathogens Salmonella, Listeria monocytogenes, and Staphylococcus aureus are described.
