ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
II. Effects of Freezing on Microbial
Environments and Microbes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
A. Changes in the Microbial Environment during Freezing of Foods . . . . . . . . . . 86
B. Growth of Microorganisms in Frozen Foods . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
C. Injury of Microorganisms during Freezing, Thawing, and Frozen Storage . . . 87
III. Cryoprotectants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
IV. Effects of Freezing on Microorganisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
A. Viruses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
B. Bacteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
C. Fungi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
D. Protozoa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
E. Multicellular Parasites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
V. Freezing of Foods in Relation to HACCP Systems . . . . . . . . . . . . . . . . . . . . . . . . . . 94
VI. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Microorganisms that can be present in foods for human consumption may be viruses, bacteria,
yeasts, moulds, protozoa, or multicellular parasites. Some foodborne microorganisms in each of
these groups can cause disease in humans. Some bacteria, yeasts, and molds can grow in foods
to cause spoilage by the production of offensive odors and flavors or by causing undesirable
changes in the appearance or texture of a food. Microorganisms that are neither pathogenic nor
involved in spoilage processes may also be present in foods, but such organisms generally have
been of little interest to food microbiologists.
