Modern food microbiology 6th ed james m jay

Modern Food Microbiology
Sixth Edition

James M. Jay
Professor Emeritus
Wayne State University
Detroit, Michigan
Adjunct Professor
University of Nevada Las Vegas
Las Vegas, Nevada

AN ASPEN PUBLICATION®
Aspen Publishers, Inc.
Gaithersburg, Maryland
2000


The author has made every effort to ensure the accuracy of the information herein. However, appropriate information
sources should be consulted. The author, editors, and the publisher cannot be held responsible for any typographical or
other errors found in this book.

Library of Congress Cataloging-in-Publication Data

Jay, James M. (James Monroe), 1927—
Modern food microbiology / James M. Jay.—6th ed.
p. cm. — (Aspen food science text series)
Includes bibliographical references and index.
ISBN 0-8342-1671-X
1. Food—Microbiology. I. Title. II. Series.
QR115.J3 2000
664'001'579—dc21

99-054735

Copyright O 2000 by Aspen Publishers, Inc.
A Wolters Kluwer Company
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2 3 4 5


Preface

The sixth edition of Modern Food Microbiology, like the previous edition, focuses on the
general biology of the microorganisms that are
found in foods. Thus, the contents are suitable
for its use in a second or subsequent course in a
microbiology curriculum, or as a primary food
microbiology course in a food science or food
technology curriculum. Although organic chemistry is a desirable prerequisite, it is not necessary for one to get a good grasp of the topics
covered.
When used as a microbiology text, the following sequence has been found to be suitable.
A synopsis of the information in Chapter 1 will
provide students with a sense of the historical
developments that have shaped this discipline
and how it continues to evolve. Memorization
of the many dates and events is not recommended
since much of this information is presented again
in the respective chapters. The material in Chapter 2 is designed to provide a brief background
on microorganisms in nature with emphasis on
those that are important in foods. This material
can be combined with the intrinsic and extrinsic
parameters of growth in Chapter 3 as they exist
in food products and as they affect the common
foodborne organisms. Chapters 4 to 9 deal with
specific food products and they may be covered
to the extent desired with appropriate reviews of
the relevant topics in Chapter 3. Chapters 10 to

12 cover methods for culturing and identifying

foodborne organisms and/or their products, and
these topics may be dealt with in this sequence
or just before foodborne pathogens. The food
preservation methods in Chapters 13 to 19 include information that goes beyond the usual
scope of a second course. Chapters 14 and 19
are new to the sixth edition. Chapter 14 consolidates information from the previous edition that
was scattered throughout several chapters, and
it contains much new information on modified
atmosphere packaging. Chapter 19 covers high
pressure and pulsed electric field processing of
foods, and it contains two sections taken from
the chapter on high temperature processing in
the previous edition.
Chapters 20 and 21 deal with food sanitation,
indicator organisms, and the HACCP system, and
coverage of these topics is suggested before dealing with the pathogens. Chapters 22 to 31 deal
with the known (and some suspected) foodborne
pathogens including their biology and methods
of control. Chapter 22 is also new to this edition and it is intended to provide an overview of
the chapters that follow. The material in this chapter that deals with mechanisms of pathogenesis
is probably best dealt with when the specific
pathogens are covered in their respective chapters.
For most semester courses with a 3-credit lecture and accompanying 2 or 3 credit laboratory,
only about 70% of the material in this edition is


likely to be covered. The remainder is meant for
reference purposes. Citations for new and updated material can be found in the Reference lists

at the end of the chapters.
The following individuals assisted me by
critiquing various parts or sections of the sixth

edition, and I pay my special thanks to each:
P. Druggan, P. Feng, R.B. Gravani, D.R. Henning,
YJ. Lee, J.A. Seiter, L.A. Shelef, J.N. Sofos,
A.C.L. Wong, and A.E. Yousef. Those who assisted me with the previous five editions are acknowledged in the respective editions.


Contents

Preface ....................................................................................................

xv

Part I. Historical Background ..............................................................

1

1. History of Microorganisms in Food ..........................................................

3

Historical Developments ...................................................................

4

Part II. Habitats, Taxonomy, and Growth Parameters .......................

11

2. Taxonomy, Role, and Significance of Microorganisms in Foods ............

13

Bacterial Taxonomy ..........................................................................

13

Primary Sources of Microorganisms Found in Foods ........................

17

Synopsis of Common Foodborne Bacteria .......................................

19

Synopsis of Common Genera of Foodborne Molds ..........................

24

Synopsis of Common Genera of Foodborne Yeasts .........................

29

3. Intrinsic and Extrinsic Parameters of Foods That Affect Microbial
Growth .....................................................................................................

35

Intrinsic Parameters .........................................................................

35

Extrinsic Parameters ........................................................................

49

Combined Intrinsic and Extrinsic Parameters: The Hurdle
Concept ......................................................................................

53

Part III. Microorganisms in Foods ......................................................

57

4. Fresh Meats and Poultry .........................................................................

59

Biochemical Events That Lead to Rigor Mortis .................................

60

The Biota of Meats and Poultry ........................................................

60

Incidence/Prevalence of Microorganisms in Fresh Red Meats ..........

60

Microbial Spoilage of Fresh Red Meats ............................................

68

Spoilage of Fresh Livers ...................................................................

76

Incidence/Prevalence of Microorganisms in Fresh Poultry ................

77

Microbial Spoilage of Poultry ............................................................

78

Carcass Sanitizing/Washing .............................................................

81

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vi

Contents
5. Processed Meats .....................................................................................

87

Curing ..............................................................................................

87

Smoking ...........................................................................................

89

Sausage, Bacon, Bologna, and Related Products ............................

89

Bacon and Cured Hams ...................................................................

91

Fermented Meat Products ................................................................

93

6. Seafoods .................................................................................................. 101
Microbiological Quality of Various Fresh and Frozen Products ......... 101
Fermented Fish Products ................................................................. 104
Spoilage of Fish and Shellfish .......................................................... 105

7. Fermentation and Fermented Dairy Products ......................................... 113
Fermentation .................................................................................... 113
Dairy Products .................................................................................. 119
Apparent Health Benefits of Fermented Milks ................................... 124
Diseases Caused by Lactic Acid Bacteria ......................................... 128
8. Fruit and Vegetable Products: Whole, Fresh-Cut, and
Fermented ................................................................................................ 131
Fresh and Frozen Vegetables .......................................................... 131
Spoilage of Fruits ............................................................................. 141
Fresh-Cut Produce ........................................................................... 141
Fermented Products ......................................................................... 146
Miscellaneous Fermented Products .................................................. 154
9. Miscellaneous Food Products ................................................................. 163
Delicatessen and Related Foods ...................................................... 163
Eggs ................................................................................................. 164
Mayonnaise and Salad Dressing ...................................................... 167
Cereals, Flour, and Dough Products ................................................. 168
Bakery Products ............................................................................... 168
Frozen Meat Pies ............................................................................. 168
Sugar, Candies, and Spices ............................................................. 169
Nutmeats .......................................................................................... 169
Dehydrated Foods ............................................................................ 170
Enteral Nutrient Solutions (Medical Foods) ....................................... 171
Single-Cell Protein ............................................................................ 171
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Contents

vii

Part IV. Determining Microorganisms and/or Their Products in
Foods ........................................................................................ 177
10. Culture, Microscopic, and Sampling Methods ........................................ 179
Conventional Standard Plate Count .................................................. 179
Membrane Filters ............................................................................. 182
Microscope Colony Counts ............................................................... 184
Agar Droplets ................................................................................... 184
Dry Film and Related Methods ......................................................... 185
Most Probable Numbers ................................................................... 186
Dye Reduction .................................................................................. 186
Roll Tubes ........................................................................................ 187
Direct Microscopic Count .................................................................. 187
Microbiological Examination of Surfaces .......................................... 188
Metabolically Injured Organisms ....................................................... 190
Viable but Nonculturable Organisms ................................................ 194
11. Physical, Chemical, Molecular, and Immunological Methods ................ 201
Physical Methods ............................................................................. 201
Chemical Methods ............................................................................ 206
Methods for Characterizing and Fingerprinting Foodborne
Organisms .................................................................................. 214
Immunological Methods .................................................................... 221
12. Bioassay and Related Methods .............................................................. 237
Whole-Animal Assays ....................................................................... 237
Animal Models Requiring Surgical Procedures ................................. 242
Cell Culture Systems ........................................................................ 243

Part V. Food Preservation and Some Properties of
Psychrotrophs, Thermophiles, and Radiation-Resistant
Bacteria ..................................................................................... 251

13. Food Preservation with Chemicals .......................................................... 253
Benzoic Acid and the Parabens ........................................................ 253
Sorbic Acid ....................................................................................... 255
The Propionates ............................................................................... 257
Sulfur Dioxide and Sulfites ............................................................... 257

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Contents
Nitrites and Nitrates .......................................................................... 258
NaCl and Sugars .............................................................................. 264
Indirect Antimicrobials ...................................................................... 265
Acetic and Lactic Acids ..................................................................... 268
Antibiotics and Bacteriocins .............................................................. 268
Antifungal Agents for Fruits .............................................................. 274
Ethylene and Propylene Oxides ....................................................... 274
Miscellaneous Chemical Preservatives ............................................. 275
14. Food Preservation with Modified Atmospheres ...................................... 283
Definitions ........................................................................................ 283
Primary Effects of CO2 on Microorganisms ....................................... 286
Food Products .................................................................................. 288
The Safety of MAP Foods ................................................................. 290
Spoilage of MAP and Vacuum-Packaged Meats .............................. 293
15. Radiation Preservation of Foods and Nature of Microbial
Radiation Resistance ............................................................................... 301
Characteristics of Radiations of Interest in Food Preservation .......... 301
Principles Underlying the Destruction of Microorganisms by

Irradiation ................................................................................... 303
Processing of Foods for Irradiation ................................................... 305
Application of Radiation .................................................................... 305
Radappertization, Radicidation, and Radurization of Foods ............. 306
Legal Status of Food Irradiation ........................................................ 312
Effect of Irradiation on Food Quality ................................................. 313
Storage Stability of Irradiated Foods ................................................. 315
Nature of Radiation Resistance of Microorganisms .......................... 315
16. Low-Temperature Food Preservation and Characteristics of
Psychrotrophic Microorganisms .............................................................. 323
Definitions ........................................................................................ 323
Temperature Growth Minima ............................................................ 324
Preparation of Foods for Freezing .................................................... 324
Freezing of Foods and Freezing Effects ........................................... 325
Storage Stability of Frozen Foods .................................................... 327

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Contents

ix

Effect of Freezing on Microorganisms .............................................. 327
Some Characteristics of Psychrotrophs and Psychrophiles .............. 331
The Effect of Low Temperatures on Microbial Physiologic
Mechanisms ............................................................................... 333
Nature of the Low Heat Resistance of Psychrotrophs ....................... 336
17. High-Temperature Food Preservation and Characteristics of
Thermophilic Microorganisms ................................................................. 341

Factors Affecting Heat Resistance in Microorganisms ...................... 342
Relative Heat Resistance of Microorganisms ................................... 346
Thermal Destruction of Microorganisms ........................................... 348
Some Characteristics of Thermophiles ............................................. 351
Other Aspects of Thermophilic Microorganisms ................................ 354
Canned Food Spoilage ..................................................................... 356
18. Preservation of Foods by Drying ............................................................. 363
Preparation and Drying of Low-Moisture Foods ................................ 363
Effect of Drying on Microorganisms .................................................. 364
Storage Stability of Dried Foods ....................................................... 366
Intermediate-Moisture Foods ............................................................ 367
19. Other Food Preservation Methods .......................................................... 375
High-Pressure Processing ................................................................ 375
Pulsed Electric Fields ....................................................................... 379
Aseptic Packaging ............................................................................ 380
Manothermosonication (Thermoultrasonication) ............................... 381

Part VI. Indicators of Food Safety and Quality, Principles of
Quality Control, and Microbial Criteria ................................... 385
20. Indicators of Food Microbial Quality and Safety ..................................... 387
Indicators of Product Quality ............................................................ 387
Indicators of Food Safety .................................................................. 388
The Possible Overuse of Fecal Indicator Organisms ........................ 401
Predictive Microbiology/Microbial Modeling ...................................... 402
21. The HACCP System and Food Safety .................................................... 407
Hazard Analysis Critical Control Point System ................................. 407
Microbiological Criteria ..................................................................... 415

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Contents

Part VII. Foodborne Diseases .............................................................. 423
22. Introduction to Foodborne Pathogens ..................................................... 425
Introduction ...................................................................................... 425
Host Invasion ................................................................................... 425
Pathogenesis .................................................................................... 428
Summary .......................................................................................... 434
23. Staphylococcal Gastroenteritis ................................................................ 441
Species of Concern in Foods ............................................................ 441
Habitat and Distribution .................................................................... 443
Incidence in Foods ........................................................................... 443
Nutritional Requirements for Growth ................................................. 444
Temperature Growth Range ............................................................. 444
Effect of Salts and Other Chemicals ................................................. 444
Effect of pH, Water Activity, and Other Parameters .......................... 444
Staphylococcal Enterotoxins: Types and Incidence .......................... 445
The Gastroenteritis Syndrome .......................................................... 453
Incidence and Vehicle Foods ............................................................ 454
Ecology of S. aureus Growth ............................................................ 455
Prevention of Staphylococcal and Other Food-Poisoning
Syndromes ................................................................................. 455
24. Food Poisoning Caused by Gram-Positive Sporeforming
Bacteria .................................................................................................... 461

Clostridium perfringens Food Poisoning ........................................... 461
Botulism ........................................................................................... 466

Bacillus Cereus Gastroenteritis ........................................................ 477
25. Foodborne Listeriosis .............................................................................. 485
Taxonomy of Listeria ........................................................................ 485
Growth .............................................................................................. 488
Distribution ....................................................................................... 492
Thermal Properties ........................................................................... 494
Virulence Properties ......................................................................... 497
Animal Models and Infectious Dose .................................................. 498
Incidence and Nature of the Listeriosis Syndromes .......................... 500
Resistance to Listeriosis ................................................................... 502
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xi

Persistence of L. monocytogenes in Foods ...................................... 503
Regulatory Status of L. monocytogenes in Foods ............................. 504
26. Foodborne Gastroenteritis Caused by Salmonella and Shigella ............ 511
Salmonellosis ................................................................................... 511
Shigellosis ........................................................................................ 525
27. Foodborne Gastroenteritis Caused by Escherichia coli .......................... 531
Serological Classification .................................................................. 531
The Recognized Virulence Groups ................................................... 531
Prevention ........................................................................................ 543
Travelers' Diarrhea ........................................................................... 543
28. Foodborne Gastroenteritis Caused by Vibrio, Yersinia, and
Campylobacter Species ........................................................................... 549

Vibriosis (Vibrio parahaemolyticus) .................................................. 549
Other Vibrios .................................................................................... 552
Yersiniosis (Yersinia enterocolitica) .................................................. 556
Campylobacteriosis (Campylobacter jejuni) ...................................... 560
Prevention ........................................................................................ 563
29. Foodborne Animal Parasites ................................................................... 569
Protozoa ........................................................................................... 569
Flatworms ......................................................................................... 579
Roundworms .................................................................................... 584
30. Mycotoxins ............................................................................................... 595
Aflatoxins .......................................................................................... 595
Alternaria Toxins .............................................................................. 600
Citrinin .............................................................................................. 600
Ochratoxins ...................................................................................... 601
Patulin .............................................................................................. 601
Penicillic Acid .................................................................................... 602
Sterigmatocystin ............................................................................... 602
Fumonisins ....................................................................................... 602
Sambutoxin ...................................................................................... 606
Zearalenone ..................................................................................... 606
Control of Production ........................................................................ 606

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xii

Contents
31. Viruses and Some Other Proven and Suspected Foodborne
Biohazards ............................................................................................... 611

Viruses ............................................................................................. 611
Bacteria and Prions .......................................................................... 616
Toxigenic Phytoplanktons ................................................................. 622

Appendices ............................................................................................ 629
Appendix A: Relationships of Common Foodborne Genera of GramNegative Bacteria .................................................................................... 629
Appendix B: Relationship of Common Foodborne Genera of GramPositive Bacteria ...................................................................................... 631
Appendix C: Biofilms ...................................................................................... 633
Appendix D: Grouping of the Gram-Negative Asporogenous Rods,
Polar-Flagellate, Oxidase Positive, and Not Sensitive to 2.5 IU
Penicillin, on the Results of Four Other Tests ......................................... 635

Index ....................................................................................................... 637

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PART I

Historical Background

The material in this part provides a glimpse
of some of the early events that ultimately led to
the recognition of the significance and role of
microorganisms in foods. Food microbiology as
a defined subdiscipline does not have a precise
beginning. Some of the early findings and observations are noted, along with dates. The selective lists of events noted for food preservation, food spoilage, food poisoning, and food
legislation are meant to be guideposts in the con-

tinuing evolution and development of food microbiology.

An excellent and more detailed review of the
history of food microbiology has been presented
by Hartman.
Hartman, P.A. 1997. The evolution of food microbiology.
In Food Microbiology—Fundamentals and Frontiers,
eds. M.P Doyle, L.R. Beuchat, and TJ. Montville, 3-12.
Washington, D.C.: ASM Press.


CHAPTER

1

History of Microorganisms in Food

Although it is extremely difficult to pinpoint
the precise beginnings of human awareness of
the presence and role of microorganisms in
foods, the available evidence indicates that this
knowledge preceded the establishment of bacteriology or microbiology as a science. The era
prior to the establishment of bacteriology as a
science may be designated the prescientific era.
This era may be further divided into what has
been called the food-gathering period and the
food-producing period. The former covers the
time from human origin over 1 million years ago
up to 8,000 years ago. During this period, humans were presumably carnivorous, with plant
foods coming into their diet later in this period.
It is also during this period that foods were first
cooked.

The food-producing period dates from about
8,000 to 10,000 years ago and, of course, includes
the present time. It is presumed that the problems of spoilage and food poisoning were encountered early in this period. With the advent
of prepared foods, the problems of disease transmission by foods and of faster spoilage caused
by improper storage made their appearance.
Spoilage of prepared foods apparently dates from
around 6000 BC. The practice of making pottery
was brought to Western Europe about 5000 BC
from the Near East. The first boiler pots are
thought to have originated in the Near East about
8,000 years ago.11 The arts of cereal cookery,
brewing, and food storage were either started at

about this time or stimulated by this new development.10 The first evidence of beer manufacture has been traced to ancient Babylonia as far
back as 7000 BC.8 The Sumerians of about 3000
BC are believed to have been the first great livestock breeders and dairymen and were among
the first to make butter. Salted meats, fish, fat,
dried skins, wheat, and barley are also known to
have been associated with this culture. Milk,
butter, and cheese were used by the Egyptians as
early as 3000 BC. Between 3000 BC and 1200 BC,
the Jews used salt from the Dead Sea in the preservation of various foods.2 The Chinese and
Greeks used salted fish in their diet, and the
Greeks are credited with passing this practice on
to the Romans, whose diet included pickled
meats. Mummification and preservation of foods
were related technologies that seem to have influenced each other's development. Wines are
known to have been prepared by the Assyrians
by 3500 BC. Fermented sausages were prepared
and consumed by the ancient Babylonians

and the people of ancient China as far back as
1500 BC.8
Another method of food preservation that apparently arose during this time was the use of
oils such as olive and sesame. Jensen7 has pointed
out that the use of oils leads to high incidences
of staphylococcal food poisoning. The Romans
excelled in the preservation of meats other than
beef by around 1000 BC and are known to have
used snow to pack prawns and other perishables,


according to Seneca. The practice of smoking
meats as a form of preservation is presumed to
have emerged sometime during this period, as
did the making of cheese and wines. It is doubtful whether people at this time understood the
nature of these newly found preservation techniques. It is also doubtful whether the role of
foods in the transmission of disease or the danger of eating meat from infected animals was
recognized.
Few advances were apparently made toward
understanding the nature of food poisoning and
food spoilage between the time of the birth of
Christ and AD 1100. Ergot poisoning (caused by
Claviceps purpurea, a fungus that grows on rye
and other grains) caused many deaths during the
Middle Ages. Over 40,000 deaths due to ergot
poisoning were recorded in France alone in AD
943, but it was not known that the toxin of this
disease was produced by a fungus.12 Meat butchers are mentioned for the first time in 1156, and
by 1248 the Swiss were concerned with marketable and nonmarketable meats. In 1276, a compulsory slaughter and inspection order was issued for public abattoirs in Augsburg. Although
people were aware of quality attributes in meats

by the thirteenth century, it is doubtful that there
was any knowledge of the causal relationship
between meat quality and microorganisms.
Perhaps the first person to suggest the role of
microorganisms in spoiling foods was A. Kircher,
a monk, who as early as 1658 examined decaying bodies, meat, milk, and other substances and
saw what he referred to as "worms" invisible to
the naked eye. Kircher's descriptions lacked precision, however, and his observations did not receive wide acceptance. In 1765, L. Spallanzani
showed that beef broth that had been boiled for
an hour and sealed remained sterile and did not
spoil. Spallanzani performed this experiment to
disprove the doctrine of the spontaneous generation of life. However, he did not convince the
proponents of the theory because they believed
that his treatment excluded oxygen, which they
felt was vital to spontaneous generation. In 1837,
Schwann showed that heated infusions remained

sterile in the presence of air, which he supplied
by passing it through heated coils into the infusion.9 Although both of these men demonstrated
the idea of the heat preservation of foods, neither took advantage of his findings with respect
to application. The same may be said of D. Papin
and G. Leibniz, who hinted at the heat preservation of foods at the turn of the eighteenth century.
The event that led to the discovery of canning
had its beginnings in 1795, when the French
government offered a prize of 12,000 francs for
the discovery of a practical method of food preservation. In 1809, a Parisian confectioner,
Frangois (Nicholas) Appert, succeeded in preserving meats in glass bottles that had been kept
in boiling water for varying periods of time. This
discovery was made public in 1810, when Appert
was issued a patent for his process.6 Not being a

scientist, Appert was probably unaware of the
long-range significance of his discovery or why
it worked. This, of course, was the beginning of
canning as it is known and practiced today.5 This
event occurred some 50 years before L. Pasteur
demonstrated the role of microorganisms in the
spoilage of French wines, a development that
gave rise to the rediscovery of bacteria. A.
Leeuwenhoek in the Netherlands had examined
bacteria through a microscope and described
them in 1683, but it is unlikely that Appert was
aware of this development, as he was not a scientist and Leeuwenhoek's report was not available in French.
The first person to appreciate and understand
the presence and role of microorganisms in food
was Pasteur. In 1837, he showed that the souring
of milk was caused by microorganisms, and in
about 1860 he used heat for the first time to destroy undesirable organisms in wine and beer.
This process is now known as pasteurization.

HISTORICAL DEVELOPMENTS
Some of the more significant dates and events
in the history of food preservation, food spoil-


age, food poisoning, and food legislation are
listed below.
Food Preservation
1782— Canning of vinegar was introduced by a
Swedish chemist.
1810—Preservation of food by canning was

patented by Appert in France.
— Peter Durand was issued a British patent
to preserve food in "glass, pottery, tin
or other metals or fit materials." The
patent was later acquired by Hall,
Gamble, and Donkin, possibly from
Appert.14
1813—Donkin, Hall, and Gamble introduced
the practice of postprocessing incubation
of canned foods.
— Use of SO2 as a meat preservative is
thought to have originated around this
time.
1825—T. Kensett and E. Daggett were granted
a U.S. patent for preserving food in tin
cans.
1835—A patent was granted to Newton in England for making condensed milk.
1837—Winslow was the first to can corn from
the cob.
1839—Tin cans came into wide use in the
United States.3
— L.A. Fastier was given a French patent
for the use of brine bath to raise the boiling temperature of water.
1840— Fish and fruit were first canned.
1841—S. Goldner and J. Wertheimer were issued British patents for brine baths based
on Fastier's method.
1842—A patent was issued to H. Benjamin in
England for freezing foods by immersion in an ice and salt brine.
1843—Sterilization by steam was first attempted by I. Winslow in Maine.
1845— S. Elliott introduced canning to Australia.

1853—R. Chevallier-Appert obtained a patent
for sterilization of food by autoclaving.

1854— Pasteur began wine investigations. Heating to remove undesirable organisms
was introduced commercially in 18671868.
1855—Grim wade in England was the first to
produce powdered milk.
1856— A patent for the manufacture of unsweetened condensed milk was granted to Gail
Borden in the United States,
1861 — I. Solomon introduced the use of brine
baths to the United States.
1865—The artificial freezing offish on a commercial scale was begun in the United
States. Eggs followed in 1889.
1874—The first extensive use of ice in transporting meat at sea was begun.
— Steam pressure cookers or retorts were
introduced.
1878— The first successful cargo of frozen meat
went from Australia to England. The first
from New Zealand to England was sent
in 1882.
1880— The pasteurization of milk was begun in
Germany.
1882—Krukowitsch was the first to note the
destructive effects of ozone on spoilage
bacteria.
1886—A mechanical process of drying fruits
and vegetables was carried out by an
American, A.F. Spawn.
1890—The commercial pasteurization of milk
was begun in the United States.

— Mechanical refrigeration for fruit storage was begun in Chicago.
1893—The Certified Milk movement was begun by H.L. Coit in New Jersey.
1895—The first bacteriological study of canning was made by Russell.
1907—E. Metchnikoff and co-workers isolated
and named one of the yogurt bacteria,
Lactobacillus bulgaricus.
— The role of acetic acid bacteria in cider
production was noted by B.TP. Barker.
1908—Sodium benzoate was given official
sanction by the United States as a preservative in certain foods.


1916—The quick freezing of foods was
achieved in Germany by R. Plank, E.
Ehrenbaum, and K. Reuter.
1917—Clarence Birdseye in the United States
began work on the freezing of foods for
the retail trade.
— Franks was issued a patent for preserving fruits and vegetables under CO2.
1920—Bigelow and Esty published the first
systematic study of spore heat resistance
above 212°F. The "general method" for
calculating thermal processes was published by Bigelow, Bohart, Richardson,
and Ball; the method was simplified by
CO. Ball in 1923.
1922— Esty and Meyer establishedz = 18°F for
Clostridium botulinum spores in phosphate buffer.
1928—The first commercial use of controlledatmosphere storage of apples was made
in Europe (first used in New York in
1940).

1929—A patent issued in France proposed the
use of high-energy radiation for the processing of foods.
— Birdseye frozen foods were placed in
retail markets.
1943— B.E. Proctor in the United States was the
first to employ the use of ionizing radiation to preserve hamburger meat.
1950—The D value concept came into general
use.
1954— The antibiotic nisin was patented in England for use in certain processed
cheeses to control clostridial defects,
1955—Sorbic acid was approved for use as a
food preservative.
— The antibiotic chlortetracycline was approved for use in fresh poultry (oxytetracycline followed a year later). Approval was rescinded in 1966.
1967—The first commercial facility designed
to irradiate foods was planned and
designed in the United States. The second became operational in 1992 in
Florida.

1988—Nisin accorded GRAS (generally regarded as safe) status in the United
States.
1990—Irradiation of poultry approved in the
United States.
1997—The irradiation of fresh beef up to a
maximum level of 4.5 kGy and frozen
beef up to 7.0 kGy was approved in the
United States.
1997—Ozone was declared GRAS by the U.S.
Food and Drug Administration for food
use.

Food Spoilage
1659— Kircher demonstrated the occurrence of
bacteria in milk; Bondeau did the same
in 1847.
1680—Leeuwenhoek was the first to observe
yeast cells.
1780— Scheele identified lactic acid as the principal acid in sour milk.
1836—Latour discovered the existence of
yeasts.
1839—Kircher examined slimy beet juice and
found organisms that formed slime when
grown in sucrose solutions.
1857— Pasteur showed that the souring of milk
was caused by the growth of organisms
in it.
1866— L. Pasteur's Etude sur Ie Vin was published.
1867—Martin advanced the theory that cheese
ripening was similar to alcoholic, lactic,
and butyric fermentations.
1873—The first reported study on the microbial deterioration of eggs was carried out
by Gayon.
— Lister was first to isolate Lactococcus
lactis in pure culture.
1876— Tyndall observed that bacteria in decomposing substances were always traceable
to air, substances, or containers.
1878—Cienkowski reported the first microbiological study of sugar slimes and


isolated Leuconostoc mesenteroides
from them.

1887—Forster was the first to demonstrate the
ability of pure cultures of bacteria to
grow at 00C.
1888—Miquel was the first to study thermophilic bacteria.
1895—The first records on the determination
of numbers of bacteria in milk were
those of Von Geuns in Amsterdam.
— S.C. Prescott and W. Underwood traced
the spoilage of canned corn to improper
heat processing for the first time.
1902— The termpsychrophile was first used by
Schmidt-Nielsen for microorganisms
that grow at 00C.
1912—The term osmophilic was coined by
Richter to describe yeasts that grow well
in an environment of high osmotic pressure.
1915—Bacillus coagulans was first isolated
from coagulated milk by B. W. Hammer.
1917—Bacillus stearothermophilus was first
isolated from cream-style corn by RJ.
Donk.
1933—Oliver and Smith in England observed
spoilage by Byssochlamys fulva; first
described in the United States in 1964
by D. Maunder.

Food Poisoning
1820—The German poet Justinus Kerner described "sausage poisoning" (which in
all probability was botulism) and its high
fatality rate.

1857—Milk was incriminated as a transmitter
of typhoid fever by W. Taylor of Penrith,
England.
1870— Francesco Selmi advanced his theory of
ptomaine poisoning to explain illness
contracted by eating certain foods.
1888— Gaertner first isolated Salmonella enteritidis from meat that had caused 57 cases
of food poisoning.

1894—T. Denys was the first to associate
staphylococci with food poisoning.
1896—Van Ermengem first discovered
Clostridium botulinum.
1904—Type A strain of C. botulinum was identified by G. Landman.
1906— Bacillus cereus food poisoning was recognized. The first case of diphyllobothriasis was recognized.
1926— The first report of food poisoning by
streptococci was made by Linden,
Turner, and Thorn.
1937—Type E strain of C. botulinum was identified by L. Bier and E. Hazen.
1937— Paralytic shellfish poisoning was recognized.
1938—Outbreaks of Campylobacter enteritis
were traced to milk in Illinois.
1939—Gastroenteritis caused by Yersinia
enterocolitica was first recognized by
Schleifstein and Coleman.
1945— McClung was the first to prove the etiologic status of Clostridium perfringens
(welchii) in food poisoning.
1951— Vibrio parahaemolyticus was shown to
be an agent of food poisoning by T.
Fujino of Japan.

1955—Similarities between cholera and Escherichia coli gastroenteritis in infants
were noted by S. Thompson.
— Scombroid (histamine-associated) poisoning was recognized.
— The first documented case of anisakiasis
occurred in the United States.
1960—Type F strain of C. botulinum identified
by Moller and Scheibel.
— The production of aflatoxins by Aspergillus flavus was first reported.
1965—Foodborne giardiasis was recognized.
1969— C. perfringens enterotoxin was demonstrated by CL. Duncan and D.H. Strong.
— C. botulinum type G was first isolated
in Argentina by Gimenez and Ciccarelli.
1971 — First U.S. foodborne outbreak of Vibrio
par ahaemolyticus gastroenteritis occurred in Maryland.


— First documented outbreak of E. coli
foodborne gastroenteritis occurred in the
United States.
1975—Salmonella enterotoxin was demonstrated by L.R. Koupal and R.H. Deibel.
1976— First U.S. foodborne outbreak of Yersinia
enterocolitica gastroenteritis occurred in
New York.
— Infant botulism was first recognized in
California.
1977—The first documented outbreak of
cyclosporiasis occurred in Papua, New
Guinea; first in United States in 1990.
1978— Documented foodborne outbreak of gastroenteritis caused by the Norwalk virus
occurred in Australia.

1979—Foodborne gastroenteritis caused by
non-01 Vibrio cholerae occurred in Florida. Earlier outbreaks occurred in Czechoslovakia (1965) and Australia (1973).
1981 — Foodborne listeriosis outbreak was recognized in the United States.
1982—The first outbreaks of foodborne hemorrhagic colitis occurred in the United
States.
1983—Campylobacter jejuni enterotoxin was
described by Ruiz-Palacios et al.
1985— The irradiation of pork to 0.3 to 1.0 kGy
to control Trichinella spiralis was approved in the United States.
1986—Bovine spongiform encephalopathy
(BSE) was first diagnosed in cattle in
the United Kingdom.
Food Legislation
1890—The first national meat inspection law
was enacted. It required the inspection
of meats for export only.

1895—The previous meat inspection act
was amended to strengthen its provisions.
1906— The U.S. Federal Food and Drug Act was
passed by Congress.
1910—The New York City Board of Health issued an order requiring the pasteurization of milk.
1939— The new Food, Drug, and Cosmetic Act
became law.
1954— The Miller Pesticide Chemicals Amendment to the Food, Drug, and Cosmetic
Act was passed by Congress.
1957— The U.S. Compulsory Poultry and Poultry Products law was enacted.
1958—The Food Additives Amendment to the
Food Drug, and Cosmetics Act was
passed.

1962—The Talmadge-Aiken Act (allowing for
federal meat inspection by states) was
enacted into law.
1963— The U.S. Food and Drug Administration
approved the use of irradiation for the
preservation of bacon.
1967—The U.S. Wholesome Meat Act was
passed by Congress and enacted into law
on December 15.
1968— The Food and Drug Administration withdrew its 1963 approval of irradiated bacon.
— The Poultry Inspection Bill was signed
into law.
1969—The U.S. Food and Drug Administration established an allowable level of
20 ppb of aflatoxin for edible grains and
nuts.
1973—The state of Oregon adopted microbial
standards for fresh and processed retail
meat. They were repealed in 1977.

REFERENCES
1. Bishop, RW. 1978. Who introduced the tin can? Nicolas
Appert? Peter Durand? Bryan Donkin? Food Technol
32(4):60-67.
2. Brandly, RJ., G. Migaki, and K.E. Taylor, 1966. Meat
Hygiene. 3d ed., Chap. 1. Philadelphia: Lea & Febiger.

3. Cowell, N.D. 1995. Who introduced the tin can?—A
new candidate. Food Technol 49(12):61-64.
4. Farrer, K.T.H. 1979. Who invented the brine
bath?—The Isaac Solomon myth. Food Technol. 33(2):

75-77.


5. Goldblith, S. A. 1971. A condensed history of the science and technology of thermal processing. Food
Technol. 25(12): 44-50.
6. Goldblith, S.A., M.A. Joslyn, and J.T.R. Nickerson.
Introduction to Thermal Processing of Foods, vol. 1.
Westport, CT: AVI.
7. Jensen, L.B. 1953. Man's Foods, chaps. 1, 4, 12.
Champaign, IL: Garrard Press.
8. Pederson, C S . 1971. Microbiology of Food Fermentations. Westport, CT: AVI.

9. Schormiiller, J. 1966. Die Erhaltung der Lebensmittel.
Stuttgart: Ferdinand Enke Verlag.
10. Stewart, G.F., and M.A. Amerine. 1973. Introduction
to Food Science and Technology, chap. 1. New York:
Academic Press.
11. Tanner, F. W. 1944. The Microbiology of Foods, 2d ed.
Champaign, IL: Garrard Press.
12. Tanner, F.W., and L.P. Tanner. 1953. Food-Borne Infections and Intoxications. 2d ed. Champaign, IL:
Garrard Press.


PART II

Habitats, Taxonomy, and
Growth Parameters

Many changes in the taxonomy of foodborne organisms have been made during the past decade,
and they are reflected in Chapter 2 along with

the primary habitats of some organisms of concern in foods. The factors/parameters that affect
the growth of microorganisms are treated in Chapter 3. See the following for more information:
Deak,T., and L.R. Beuchat. 1996. Handbook of Food Spoilage Yeasts. Boca Raton, FL: CRC Press. Detection, enumeration, and identification of foodborne yeasts.

Doyle, M.P., L.R. Beuchat, TJ. Montville, eds. 1997. Food
Microbiology—Fundamentals and Frontiers. Washington, D C : ASM Press. Food spoilage as well as foodborne
pathogens are covered in this 768-page work along with
general growth parameters.
International Commission on Microbiological Specification of Foods (ICMSF). 1996. Microorganisms in Foods.
5th ed. Gaithersburg, MD: Aspen Publishers, Inc. All
of the foodborne pathogens are covered in this 512page work with details on growth parameters. Well referenced.


CHAPTER 2

Taxonomy, Role, and Significance
of Microorganisms in Foods

Because human food sources are of plant and
animal origin, it is important to understand the
biological principles of the microbial biota associated with plants and animals in their natural
habitats and respective roles. Although it sometimes appears that microorganisms are trying to
ruin our food sources by infecting and destroying plants and animals, including humans, this
is by no means their primary role in nature. In
our present view of life on this planet, the primary function of microorganisms in nature is
self-perpetuation. During this process, the heterotrophs carry out the following general reaction:
All organic matter
(carbohydrates, proteins, lipids, etc.)

i

Energy + Inorganic compounds
(nitrates, sulfates, etc.)
This, of course, is essentially nothing more than
the operation of the nitrogen cycle and the cycle
of other elements (Figure 2-1). The microbial
spoilage of foods may be viewed simply as an
attempt by the food biota to carry out what appears to be their primary role in nature. This
should not be taken in the teleological sense. In
spite of their simplicity when compared to higher
forms, microorganisms are capable of carrying
out many complex chemical reactions essential
to their perpetuation. To do this, they must ob-

tain nutrients from organic matter, some of which
constitutes our food supply.
If one considers the types of microorganisms
associated with plant and animal foods in their
natural states, one can then predict the general
types of microorganisms to be expected on this
particular food product at some later stage in its
history. Results from many laboratories show that
untreated foods may be expected to contain varying numbers of bacteria, molds, or yeasts, and
the question often arises as to the safety of a given
food product based on total microbial numbers.
The question should be twofold: What is the total number of microorganisms present per gram
or milliliter and what types of organisms are represented in this number? It is necessary to know
which organisms are associated with a particular food in its natural state and which of the organisms present are not normal for that particular food. It is, therefore, of value to know the
general distribution of bacteria in nature and the
general types of organisms normally present
under given conditions where foods are grown

and handled.
BACTERIAL TAXONOMY
Many changes have taken place in the classification or taxonomy of bacteria in the past decade. Many of the new taxa have been created as
a result of the employment of molecular genetic


Nitrogen
(Atmospheric)

Nitrogen fixation

Denitrification

Atmospheric nitrogen fixed by
many microorganisms, e.g..
Rhizobium. Ctostridium, Azotobacter
etc.

Reduction of nitrates to gaseous
nitrogen by bacteria, e.g..
pseudomonads

Nitrate formation
(Nitrification)
Nitrite oxidized to nitrate by
nitrobacter

Organic nitrogen formation
Nitrate serves as plant
food

"Fixed" nitrogen utilized by
plants—converted to plant protein;
plants consumed by animals.
animal proteins, etc.. formed

Many heterotropic
species reduce
nitrates to ammonia
via nitrites
Nitrite formation

Soil organic nitrogen

Ammonia oxidized to nitrite by
nitrosomonas

Excretion products of animals,
dead animals, and plant tissue
deposited in soil

Ammonia formation
(Ammonification)

Microorganisms utilize
ammonia as nitrogen
source and synthesize
cellular proteins

Amino acids deaminated by many

microorganisms; ammonia one of
the end products of this process

Organic nitrogen degradation
Proteins, nucleic acids, etc..
attacked by a wide variety of
microorganisms; complete
breakdown yields mixtures of
amino acids

Figure 2-1 Nitrogen cycle in nature is here depicted schematically to show the role of microorganisms. Source:
From Microbiology by MJ. Pelczar and R. Reid, copyright © 1965 by McGraw-Hill Book Company, used with
permission of the publisher.

methods, alone or in combination with some of
the more traditional methods:
• DNA homology and mol% G + C content
ofDNA
• 23S, 16S, and 5S rRNA sequence similarities
• Oligonucleotide cataloging
• Numerical taxonomic analysis of total
soluble proteins or of a battery of morphological and biochemical characteristics
• Cell wall analysis
• Serological profiles
• Cellular fatty acid profiles

Although some of these have been employed for
many years (e.g., cell wall analysis and serological profiles) others (e.g., ribosomal RNA [rRNA]
sequence similarity) came into wide use only during the 1980s. The methods that are the most
powerful as bacterial taxonomic tools are outlined and briefly discussed below.

rRNA Analyses
Taxonomic information can be obtained from
RNA in the production of nucleotide catalogs and
the determination of RNA sequence similarities.


First, the prokaryotic ribosome is a 70S (Svedberg) unit, which is composed of two separate
functional subunits: 5OS and 30S. The 50S subunit is composed of 23 S and 5 S RNA in addition to about 34 proteins, whereas the 30S subunit is composed of 16S RNA plus about 21
proteins.
Ribosome
70S

/

16S

3OS
/
\

21 34

\
50S
/

\

23S + 5S

Proteins

The 16S subunit is highly conserved and is considered to be an excellent chronometer of bacteria over time.48 By use of reverse transcriptase,
16S rRNA can be sequenced to produce long
stretches (about 95% of the total sequence) to
allow for the determination of precise phylogenetic relationships.26 Because of its smaller size,
5 S RNA has been sequenced totally.
To sequence 16S rRNA, a single-stranded
DNA copy is made by use of reverse transcriptase
with the RNA as template. When the singlestranded DNA is made in the presence of
dideoxynucleotides, DNA fragments of various
sizes result that can be sequenced by the Sanger
method. From the DNA sequences, the template
16S rRNA sequence can be deduced. It was
through studies of 16S rRNA sequences that led
Woese and his associates to propose the establishment of three kingdoms of life-forms: Eukaryotes, Archaebacteria, and Prokaryotes. The
last include the cyanobacteria and the eubacteria,
with the bacteria of importance in foods being
eubacteria. Sequence similarities of 16S rRNA
are widely employed, and some of the new
foodborne taxa were created primarily by its use
along with other information. Libraries of
eubacterial 5 S rRNA sequences also exist, but
they are fewer than for 16S.
Nucleotide catalogs of 16S rRNA have been
prepared for a number of organisms, and exten-

sive libraries exist. By this method, 16S rRNA is
subjected to digestion by RNAse Tl, which

cleaves the molecule at G(uanine) residues. Sequences (-mers) of 6-20 bases are produced and
separated, and similarities SAB (Dice-type coefficient) between organisms can be compared. Although the relationship between SAB and percentage similarity is not good below SAB value of 0.40,
the information derived is useful at the phylum
level. The sequencing of 16S rRNA by reverse
transcriptase is preferred to oligonucleotide cataloging, as longer stretches of rRNA can be sequenced.
Analysis of DNA
The mol% G + C of bacterial DNA has been
employed in bacterial taxonomy for several decades, and its use in combination with 16S and
5 S rRNA sequence data makes it even more
meaningful. By 16S rRNA analysis, the grampositive eubacteria fall into two groups at the
phylum level: one group with mol% G + C >55,
and the other <50.48 The former includes the genera Streptomyces, Propionibacterium, Micrococcus, Bifidobacterium, Corynebacterium, Brevibacterium, and others. The group with the lower
G + C values include the genera Clostridium,
Bacillus, Staphylococcus, Lactobacillus, Pediococcus, Leuconostoc, Listeria, Erysipelothrix,
and others. The latter group is referred to as the
Clostridium branch of the eubacterial tree. When
two organisms differ in G + C content by more
than 10%, they have few base sequences in common.
DNA-DNA or DNA-RNA hybridization has
been employed for some time, and this technique
continues to be of great value in bacterial systematics. It has been noted that the ideal reference system for bacterial taxonomy would be the
complete DNA sequence of an organism.44 It is
generally accepted that bacterial species can be
defined in phylogenetic terms by use of DNADNA hybridization results, where 70% or greater
relatedness and 50C or less Tm (melting point)
defines a species.44 When DNA-DNA hybridiza-


tion is employed, phenotypic characteristics are
not allowed to override except in exceptional

cases.44 Although a genus is more difficult to
define phylogenetically, 20% sequence similarity is considered to be the minimum level of
DNA-DNA homology.44
Even if there is not yet a satisfactory phylogenetic definition of a bacterial genus, the continued application of nucleic acid techniques, along

with some of the other methods listed above,
should lead ultimately to a phylogenetically
based system of bacterial systematics. In the
meantime, changes in the extant taxa may be
expected to continue to occur.
Some of the important genera known to occur
in foods are listed below in alphabetical order.
Some are desirable in certain foods; others bring
about spoilage or cause gastroenteritis.

Bacteria
Acinetobacter
Aeromonas
Alcaligenes
Arcobacter
Bacillus
Brochothrix
Campylobacter
Carnobacterium
Citrobacter
Clostridium
Coryneb acterium
Enterobacter
Enterococcus

Erwinia
Escherichia
Flavobacterium
Hafnia
Kocuria
Lactococcus
Lactobacillus
Leuconostoc
Listeria
Micrococcus
Moraxella
Paenibacillus
Pantoea

Pediococcus
Proteus
Pseudomonas
Psychrobacter
Salmonella
Serratia
Shewanella
Shigella
Staphylococcus
Vagococcus
Vibrio
Weiss ella
Yersinia

Molds
Alternaria

Aspergillus
Aureobasidium
Botrytis
Byssochlamys

Cladosporium
Colletotrichum
Fusarium
Geotrichum
Monilia

Mucor
Penicillium
Rhizopus
Trichothecium
Wallemia
Xeromyces

Yeasts
Brettanomyces
Candida
Cryptococcus
Debaryomyces
Hanseniaspora

Issatchenkia
Kluyveromyces
Pichia
Rhodotorula
Saccharomyces

Schizosaccharomyces
Torulaspora
Trichosporon
Zygosaccharomyces

Protozoa
Cryptosporidium parvum
Entamoeba histolytica
Cyclospora cayetanensis
Giardia lamblia
Toxoplasma gondii