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OCR for page 339
Appendix A
Summary Responses
to Specific Contract Items
The following comprises summary responses to the explicit requests
included in the Scope of Work as defined by the Contracting Agencies
The responses are addressed more comprehensively in Chapters 1-11 of
this book.
I. The contractor will initiate a reevaluation of sampling plans employed for
various classes of foods and food ingredients that are determining Salmonella presence
in raw and finished food and food ingredients that are subject to Salmonella contam
1
ination.'
The Committee on Salmonella of the National Research Council (NRC,
1969) emphasized that the sale of foods containing salmonellae cannot be
condoned but at the same time recognized that salmonellae can be found
in many products if a sufficient number of tests are made. The report
called attention to confusion and uncertainty that existed then in the food-
processing industry due to lack of a definitive sampling and testing plan.
The following question was posed: When should we stop testing and
conclude that a product is Salmonella-free (which may simply mean that
the contamination level is below the sensitivity of the sampling plan and
the analytical procedure)?
In recognition of the fact that there is no way to be absolutely certain
that a particular lot of nonsterile food is free of salmonellae, the Committee
on Salmonella recommended two specific actions: (1) evolve a realistic
Excluded from these considerations were raw meats and poultry from which, given existing
technology, salmonellae cannot be eliminated.
339
OCR for page 340
340
APPENDIX A
assessment of the degree of hazard imposed by various foods, feeds, and
drugs, and (2) develop sampling plans that will provide adequate assurance
that the number of salmonellae present, if any, is below a statistically
defined limit that offers minimal hazard to the consumer. The committee
suggested a system by which the degree of hazard presented by any food
could be assessed and it recommended a sampling and testing plan that
could lead to a decision whether to accept or reject a particular lot of
food.
Assessment of the degree of hazard presented by various foods was
based upon three questions: (1) does the food contain a sensitive ingre-
dient, (2) does the processing of the food include a controlled procedure
that will destroy salmonellae, and (3) will salmonellae grow in the product
if it is abused during distribution or after preparation for consumption?
Based upon answers to the foregoing questions, eight different configu-
rations of hazard characteristics are possible. These are delineated in
Table A-1.
Five risk categories were recognized by the Committee on Salmonella:
Category I-foods that are intended for infants, aged, and the infirm,
and that contain a sensitive ingredient.
Category II foods with all three hazard characteristics.
Category III foods with two hazard characteristics.
Category IV foods with one hazard characteristic
Category V foods with none of the three hazard characteristics.
TABLE A-l Categories of Food Products Based on Product Hazard
Characteristics
Hazard characteristics
Type of Food A B C Category
Intended for infants, aged,
and infirm
Intended for general use
+ O
O +
+ or 0 + or 0
+
+ O
O +
O O
O O
+
II
III
III
III
IV
IV
IV
V
aA = Product contains sensitive ingredient.
B = No destructive step during manufacture.
C = Likelihood for growth if abused.
+ = Hazard present; 0 = Hazard not present.
SOURCE: Olson, 1975.
OCR for page 341
APPENDIX A
341
The Committee on Salmonella recommended testing and acceptance
criteria for "questioned" lots of food. These are summarized in Table
A-2. Application of these criteria contemplates the collection of random
sample units from the lot in question. Multiple 25-g analytical units, the
number based upon the risk category of the product, are then analyzed
for Salmonella. The intensity of sampling and analysis is related to the
degree of risk (hazard category) presented by the product. The objective
was to have a sampling and testing plan that would provide adequate
assurance that the number of salmonellae, if present, would be below a
statistically defined limit offering minimal hazard to the consumer. The
limit for each category is given in the last column of Table A-2, i.e., 95%
confidence that the Salmonella contamination level is no more than 1 in
500 g for Category I; no more than 1 in 250 g for Category II; and no
more than 1 in 125 g for Categories III, IV, and V. It will be noted that
within each category, two sampling plans are provided, one permitting
acceptance only if all analytical units tested are found negative for Sal-
monella, the other permitting a single positive result. For example, for
products in Category I, one sampling plan permits acceptance if each of
60 25-g analytical units is analyzed and found negative. The other sampling
plan permits acceptance if one of 92 25-g units is positive. Justification
for the two different sampling plans was based.upon the fact that one
positive result from 92 analytical units or zero positive results from 60
analytical units provides the same probability (95%) that the level of
salmonellae as shown in the last column of Table A-2 is not exceeded.
It should be emphasized that the sampling and testing plan recommended
by the Committee on Salmonella was intended for application to (1) processed
foods or ingredients as contrasted to, e.g., raw meats and poultry; (2) lots
that conform to specific criteria that establish their integrity; and (3) lots
TABLE A-2 Acceptance Criteria
Number of Number of Significancea
Units Tested Units Tested 95% Probability
Product with No with No More than of One Organism
Category Positives One Positive or Less in
I 60 (1,500 g) 92 (2,300 g) 500 g
II 29 (725 g) 48 (1,200 g) 250 g
III 13 (325 g) 22 (550 g) 125 g
IV 13 (325 g) 22 (550 g) 125 g
vb 13 (325 g) 22 (550 g) 125 g
aAccuracy of Attribute Sampling, USDA Consumer and Marketing Service, March 1966.
bNot normally applicable.
SOURCE: NRC, 1969.
OCR for page 342
342
APPENDIX A
that have been questioned because of the possible presence of salmonellae.
The sampling plan was not designed or intended to replace routine sur-
veillance operations, including testing, that a food manufacturer or a
regulatory agency might employ The plans were intended to be used in
arriving at a final decision in order to accept or reject a particular lot in
question.
After reviewing the report of the Committee on Salmonella, the FDA
began to consider ways of responding to the various committee recom-
mendations (Olson, 19751. It invited Dr. E. M. Foster, Director of the
Food Research Institute, University of Wisconsin, to assemble a group of
knowledgeable people representing both government and industry to de-
velop a classification system and a sampling plan along the lines envisioned
by the Committee on Salmonella. The Interagency-Industry Committee
on Salmonella Control in Foods submitted its report to the FDA in October
1970, and the report was published in March 1971 (Foster, 1971~. This
report embraced the recommendations of the Committee on Salmonella
both with respect to the establishment of categories of food products based
upon product hazard characteristics and the sampling and analytical plans
for determination of the acceptability of questioned lots. Further, it pro-
vided guidance on the assessment of hazard characteristics.
Subsequently FDA announced its position on Salmonella sampling and
testing plans (Olson, 19751. Basically, FDA accepted the recommenda-
tions of the Committee on Salmonella (NRC, 1969) and the Interagency-
Industry Committee (Foster, 1971) with the following exceptions. First,
a sample lot would be accepted only if analyses of all analytical units
were negative for salmonellae. The FDA position was that acceptance of
any lot of food in which salmonellae were shown to be present would not
be administratively feasible. Thus, the sampling plan shown in the second
column of Table A-2 would be employed and the sampling plan shown
in the third column (permitting a single positive among the analytical units
tested) would not be utilized. Second, FDA provided for the compositing
of multiple analytical units, the maximum size of a composite unit being
375 g. The composite unit was to consist of a series of 25-g analytical
units. Finally, the FDA indicated that the acceptance criteria would be
applied to any lot of product tested in connection with any of its surveil-
lance or compliance programs. As previously noted, the two committees
(NRC, 1969; Foster, 1971) had indicated that the sampling plan was not
designed to replace routine surveillance operations, but was intended to
be used in arriving at a final decision whether to accept or reject a particular
lot in question. FDA's position on this point was made clear: "If we
sample a lot we question it; otherwise why sample it?"
The fourth edition of the Bacteriological Analytical Manual for Foods
OCR for page 343
APPENDIX A
343
(BAM) (FDA, 1976) reflected Olson's position paper (Olson, 1975). The
classification of products by hazard categories and the attendant sampling
plans were consistent with the report of the Committee on Salmonella and
the recommendations of the Interagency-Industry Committee on Salmo-
nella Control in Foods. Indeed, a vast number of industry quality control
programs utilized the sampling plans routinely in their Salmonella control
programs, not just for determining the status of suspect lots.
The fifth edition of the BAM (FDA, 1978), set forth a revised Sal-
monella sampling plan, one that departed radically from the recommen-
dations of the Committee on Salmonella. Three categories of food were
identified as follows:
Food Category I- foods that would normally be in Category II except
they are intended for consumption by the aged, the infirm, and infants.
Food Category II foods that would not normally be subjected to a
process lethal to Salmonella between the time of sampling and consump-
tion.
Food Category III foods that would normally be subjected to a process
lethal to Salmonella between the time of sampling and consumption. The
following tabulation shows the number of sample units to be collected in
each food category:
II
Food Number of
Category Sample Units
60
30
III 15
The categorization of foods and the sampling plans prescribed in the 1978
edition of the Bacteriological Analytical Manual depart both in philosophy
and substance from those contained in the 1976 edition of the BAM.
Likewise, of course, they depart from the recommendations of the NAS
Committee on Salmonella and those of the Interagency-Industry Com-
mittee on Salmonella Control in Foods. The present system employed by
the FDA for categorizing foods, as well as the sampling plans tied to such
categorization, are unrelated to risk. The key issue, rather, is whether the
food would normally be subjected to a process lethal to Salmonella be-
tween the time of sampling and consumption. This parameter played no
role in the designation of food categories by the Committee on Salmonella,
the recommendations of which were embraced by the Interagency-Industry
Committee on Salmonella Control in Foods and the FDA. Ignored in the
present classification system are: risk A: the product or an ingredient of
the product has been identified as a significant potential source of sal-
monellae (i.e., it is "sensitively; risk B: the manufacturing process does
OCR for page 344
344
APPENDIX A
not include a controlled step that will destroy salmonellae; and risk C:
there is a substantial likelihood of microbial growth if the product is
mishandled or "abused" in distribution or consumer usage. The present
system utilized by the FDA recognizes, only, that if a product were to be
classified in "new" Category II, it would be classified in Category I if
the product were to be consumed by high-risk groups. It is of interest to
note that the Committee on Salmonella of the NAS classified any food
consumed by high-risk groups in Category I if it contained a sensitive
ingredient (risk factor A). Under the present system, such a product would
be assigned to Category III if the food would normally be subjected to a
process lethal to Salmonella between the time of sampling and consump-
tion. Table A-3 lists examples of foods in Categories II and III as pre-
sented in the 1978 edition of the BAM. Table A-4 shows examples of
"interesting shifts in classification" that have occurred as a result of the
revised Salmonella sampling plan introduced in that edition.
It is difficult for this subcommittee to understand the rationale for the
changes in food category classification and sampling plans between the
1976 and the 1978 editions of the BAM and thus, in effect, the rationale
for the FDA rejection of the recommendations of the NRC Committee on
Salmonella. In section A, Sampling Plans for Salmonella of Chapter 1 of
the 1978 BAM the following statements are made: "Generally, the as-
signment of food categories has depended on the sensitivity of a consumer
group (e.g., the aged, the infirm and infants), the history of the food, and
whether there was a step lethal to Salmonella during the manufacturing
process or in the home. Of these criteria the sensitivity of the consumer
group and whether the food normally underwent a process lethal to Sal-
monella either at the manufacturing or consumer level appeared to be the
most important considerations in the selection of a sampling plan. The
history of the food would be more important in a decision on whether to
sample rather than how many sample units to take." This subcommittee
offers the following comments on these statements:
1. As stated, the sensitivity of the consumer group influences the as-
signment of food categories. But, as indicated above, the present FDA
system would classify foods containing sensitive ingredients in Category III
if such foods were normally subjected to a process lethal to Salmonella
between the time of sampling and consumption. The NRC Committee on
Salmonella would classify the same foods in Category I if they contained
a sensitive ingredient regardless of their "normal" subsequent handling.
The present FDA system simply assigns products in Category II to Category I
if high-risk groups are involved. But if the same foods were "normally"
subjected to a process lethal to Salmonella between the time of sampling
OCR for page 345
APPENDIX A
345
TABLE A-3 Food Categories II and III
Food Category II Foods that would normally be subjected to a process lethal to Salmonella
between the time of sampling and consumption.
Product
Code Food
03 Bread, rolls, buns, sugared breads, crackers, custard and cream-filled sweet goods
05 Breakfast cereals, ready-to-eat
07 Pretzels, chips, and specialty items
09 Butter and butter products; pasteurized milk and raw fluid milk and fluid milk
products for consumption; pasteurized and unpasteurized concentrated liquid milk
products for consumption; dried milk and dried milk products for consumption
Cheese and cheese products
Ice cream from pasteurized milk and related products that have been pasteurized;
raw ice cream mix and related unpasteurized products for consumption
14 Pasteurized and unpasteurized imitation dairy products for consumption.
Pasteurized eggs, egg products from pasteurized eggs; unpasteurized eggs and egg
products from unpasteurized eggs for consumption without further cooking
16 Canned and cured fish, vertebrates; other fish products; fresh and frozen raw oysters
and raw clams, shellfish and crustacean products; smoked fish, shellfish, and
crustaceans for consumption
17 Unflavored gelatin
20-22 Fresh, frozen, and canned fruits and juices, concentrates, and nectars; dried fruits
33
34
35
for consumption; jams, jellies, preserves, and butters
23 Nuts and nut products for consumption
26 Oils consumed directly without further processing; oleomargarine
27 Dressings and condiments (including mayonnaise), salad dressing, vinegar
28 Spices, including salt; flavors and extracts
29 Soft drinks and water
30 Beverage bases
31 Coffee and tea
Candy, chewing gum
Chocolate and cocoa products
Pudding mixes not cooked prior to consumption, gelatin products
36 Syrups, sugars, and honey
38 Soups
39 Prepared salads
Food Category III Foods that would normally be subjected to a process lethal to Salmonella
between the time of sampling and consumption.
Product
Code Food
02 Whole grain, processed grain, and starch products for human use
04 Macaroni and noodle products
16 Fresh and frozen fish; vertebrates (except that eaten raw); fresh and frozen shellfish
and crustaceans (except raw oysters and raw clams for consumption); other
aquatic animals (including frog legs)
24 Fresh vegetables, frozen vegetables, dried vegetables, cured and processed
vegetable products normally cooked before consumption
26 Vegetable oils, oil stock, and vegetable shortening
35 Dry dessert and pudding mixes that are cooked prior to consumption
37 Frozen dinners, multiple food dinners
45-46 Food chemicals (direct additives)
SOURCE: FDA, 1978.
OCR for page 346
346
APPENDIX A
TABLE A-4 Selected Examples of Categories BAM
1976 vs. BAM 1978
Foods
BAM Classification
1976 1978
Salt, flavors and extracts, mayonnaise, CAT. IIIb CAT. IIa
fresh fruits and juices, jams, soft
drinks, water, beverage basest cof
fee, tea, snack items (dry), syrups.
Frozen dinners.
Fresh and frozen shellfish and crusta
ceans (ex. raw oysters and clams),
other aquatic animals, fresh vegeta
bles.
II III
III III
Sampling:
aCategory II: Thirty 25-g samples.
bCategory III: Fifteen 25-g samples.
SOURCE: Silliker, 1980.
and consumption, these foods would be assigned to Category III regard-
less of the group at risk.
2. The term "history of the food" is difficult for the subcommittee to
interpret. One might equate this to a food with a history indicating it to
be a Salmonella problem, i.e., a sensitive product. It is stated that the
history of the food would be more important in a decision on whether to
sample rather than on how many sample units to take. Thus, it would
appear, and logic would dictate this, that one might be more concerned
with a product in Category III (one containing a sensitive ingredient) than
one in Category II. For example, one would certainly be more concerned
with dry dessert and pudding mixes that are cooked prior to consumption
or frozen dinners than with salad dressing or vinegar. Yet the former are
classified in Category III and the latter in II. It seems, however, that to
classify salad dressing and vinegar in Category II is ill-advised. These
products are classified in Category II solely on the basis that they "would
not normally be subjected to a process lethal to Salmonella between the
time of sampling and consumption." Vinegar, for example, clearly be-
longs in Category V (according to the report of the Committee on Sal-
monella), because (1) it contains no sensitive ingredient, (2) its acidity
would destroy Salmonella, and (3) salmonellae are incapable of growth
in the product. Yet the 1978 edition of the BAM would clearly place this
product in Category II with a sampling plan "twice as stringent" as would
be applied to dry dessert and pudding mixes or frozen dinners.
3. It is stated: "Of these criteria, the sensitivity of the consumer group
and whether the food normally underwent a process lethal to Salmonella
OCR for page 347
APPENDIX A
347
either at the manufacturing or consumer level appeared to be the most
important considerations in selection of a sampling plan." The report of
the Committee on Salmonella with reference to classification of food
products according to risk is concerned with whether the manufacturing
process does not include a controlled step that would destroy salmonellae.
In this regard, the hazard relates to the manufacturing process, not to what
occurs in the hands of the consumer. The report did recognize: "Ob-
viously, the food or ingredient that will ultimately be used under conditions
resulting in Salmonella destruction is far less hazardous than one that will
be consumed without decontamination and quantitative guidelines take
this into account. This does not ignore the danger of bringing the con-
taminated food into the kitchen or processing area but does recognize that
the level of risk entailed is influenced by the ultimate usage." These
considerations result, for example, in placing sensitive products, such as
frozen dinners in Category III, even though such products contain
(1) sensitive ingredients, (2) no final kill step at the manufacturing level,
and (3) the potential of Salmonella growth if mishandled.
4. If "the history of food" is to be equated to whether it contains a
"sensitive ingredient," then this characteristic of the product is not "more
important in a decision on whether to sample rather than how many sample
units to take," according to the recommendations of the Committee on
Salmonella. It is, indeed, one of four factors that are considered in clas-
sification of a food into one of the five hazard categories. The others are
the population at risk, whether the food is subject to a "pasteurizing"
step at the manufacturing level, and whether Salmonella growth may occur
in the product if it i' mishandled. The present FDA scheme eliminates
the "history of the food" as a determinant of the sampling plan when,
indeed, the Committee on Salmonella gave equal weight to this and two
other factors (kill step and potential of growth) in establishing its classi-
fication scheme'
This subcommittee supports the recommendations of the NRC Com-
mittee on Salmonella with respect to the classification of foods into five
categories and the establishment of sampling plans, the stringency of which
is related to the degree of hazard. It feels that the present FDA catego-
rization of foods, and the sampling plans tied to these, ignore the rec-
ommenda~jons of the NRC Committee on Salmonella and substitute these
with a less effective system.
The recommendations of the NRC Committee on Salmonella not only
were endorsed by the Interagency-Industry Committee on Salmonella Con--
trol in Foods and by the 1976 edition of the BAM but in addition by the
International Commission on Microbiological Specifications for Foods
(ICMSF, 19741.
OCR for page 348
348
APPENDIX A
II. The contractor will evaluate whether or not suitable microbiological testing
procedures and data bases have been developed and validated sufficiently to be useful
for: regulatory purposes, for purchasing specifications, and/or for quality control
purposes. If further work is indicated, the contractor will list priorities for the tasks
that must be completed so that suitable microbiological tests and data bases will be
available for the various purposes listed above.
Test procedures for pathogenic and indicator organisms are discussed
and evaluated in Chapters 4 and 5 of this report. Adequate procedures are
available for the aerobic plate count and the quantitation of coliform, fecal
coliform, Escherichia colt, Staphylococcus aureus, Clostridium perfrin-
gens, enterococci, and yeasts and molds. Reliable procedures exist for
the detection of Salmonella, staphylococcal enterotoxins, C. perfringens
alpha toxin, and Clostridium botulinum toxins.
Additional satisfactory procedures are available (Compendium of Meth-
ods for the Microbiological Examination of Foods, APHA, 1984) for the
direct microscopic count, and to detect and/or enumerate psychrotrophic,
thermoduric, lipolytic, proteolytic, halophilic, osmophilic, pectinolytic,
and acid-producing microorganisms, as well as for mesophilic aerobic
sporeformers, mesophilic anaerobic sporeformers, aciduric flat-sour spore-
formers, thermophilic flat-sour sporeformers, thermophilic anaerobic spore-
formers, and sulfide spoilage sporeformers.
At present, E. cold is the most reliable bacterial indicator of fecal con-
tamination. The standard enrichment-plating procedures routinely applied
to detect and enumerate this organism in foods are time-consuming, la-
borious, and expensive, and there is some question about their accuracy.
There are more rapid and accurate procedures for E. cold such as the
Anderson-Baird-Parker direct plating method and recent modifications of
this procedure.
Although existing procedures for Bacillus cereus and Vibrio parahae-
molyticus seem to perform well in some laboratories, certain problems
are encountered with these procedures. In the detection and enumeration
of B. cereus, existing procedures do not always clearly separate this or-
ganism from other contaminants. In the case of V. parahaemolyticus, a
recent study (ICMSF, in preparation) has revealed some inconsistencies
regarding the MEN procedure.
Although rapid progress is being made, procedures for the detection of
Yersinia enterocolitica, Yersinia pseudotuberculosis, and Campylobacter
fetus subsp. jejuni (Campylobacter jejunilcoli) from foods require addi-
tional studies.
Continued studies are recommended for the detection and quantification
of mycotoxins, particularly to develop more practical and precise methods.
Similar recommendations are proposed for toxins important in certain fish
OCR for page 349
APPENDIX A
349
and shellfish such as ciguatoxin, saxitoxins, and closely related toxins.
One of the most severe problems related to microbiological criteria is
the time necessary to obtain the results of microbiological test procedures.
For this reason, additional studies are needed to develop microbiological
techniques that require a minimum of time, are simple, sensitive, cost-
effective, and usable on-site, in-process as part of microbiological control
programs.
Microbiological criteria for viruses in foods are not feasible at the
present time primarily because of lack of practical methods. Development
of methods for the detection of viruses in foods that can cause human
illness is highly recommended.
An evaluation of available data bases for microbiological criteria of
various foods has been made in Chapter 9. Additional information related
to this contract item can be found in Chapters 4, 5, and 9.
III. The contractor will determine the relative merits of: aerobic plate count, fecal
coliform, coliform, E. colt, and coagulase-positive Staphylococcus procedures cur-
rently used to identify contamination of foods during and after processing.
In perishable foods, the aerobic plate count (APC) can reflect the mi-
crobial condition of the raw materials and ingredients used, the effec-
tiveness of processing methods (for example heat treatment), the efficacy
of cleaning and sanitation procedures employed, the microbiological con-
dition of the processing equipment, and the conditions of storage (time-
temperature abuse). One or more of these conditions, if not adequately
controlled, can be responsible for higher than expected APC during and
after processing. Thus, to identify a specific cause of contamination by
the APC, it would be necessary to eliminate the other potential causes.
Results of testing final products only do not tell which events may have
caused a high APC, but if used in conjunction with observations made
during plant inspection they may provide information to make some in-
ferences. To identify where contamination occurred, APCs of line samples
before and after critical control points have merit. In shelf-stable foods
that do not support microbial growth, results on finished products also
will not give information about specific causes of high APC. Contami-
nation, however, can be identified by APC as described for perishable
foods. In fermented food, the APC offers no information about contam-
ination.
From their original fecal, water, soil, or plant environment, coliform
bacteria can reach the food processing and preparation environments and
become established there. The principal value of determining coliform
bacteria is as an index of postprocessing contamination of foods that are
heat processed for safety. Coliform bacteria are used for this purpose,
OCR for page 355
APPENDIX A
355
in which the level was < 1/g using a MPN technique. Taking into account
the precision and accuracy of current MPN procedures, a microbiological
limit of < 1 S. aureus per gram of food does not appear meaningful. In
conclusion, zero tolerances (~1/g of food) for either E. cold or S. aureus
are meaningless unless they take into account the variability of the MPN
procedures.
Additional information related to this contract item can be found in
Chapters 4 and 5.
VI. The contractor will determine whether aerobic plate count together with col-
iform or E. cold counts are complimentary or redundant for processed foods.
The same basic conditions may be responsible for higher than normal
APC, coliform, or E. cold counts in processed foods, namely: inferior
quality raw materials and ingredients, inadequate heat processing, post-
heat processing contamination, and time-temperature abuse. However, this
does not mean that these counts are affected to the same degree by these
conditions. In a heat-processed food there may be some postprocessing
contamination that does not result in significant changes in APC. However,
the presence of a few coliforms may indicate that some lack of good
manufacturing practices existed. For example, the presence of 1-10 col-
iform bacteria per ml of pasteurized milk still constitutes a legal product
but this count should alert the processor that postpasteurization contam-
ination has taken place.
As pointed out earlier (no. III in this appendix), a distinction should
be made in the merits of the E. cold and coliform counts. E. coli, a member
of the coliform group, is presently the most reliable bacterial indicator of
fecal contamination. However, the presence of coliform bacteria in a
processed food does not necessarily mean the presence of either E. cold
or fecal contamination. For example, in Grade A pasteurized milk, the
presence of a few coliform bacteria is unrelated to fecal contamination
but results in most cases from contamination of improperly cleaned and
sanitized equipment used to store, transport, or package the pasteurized
product.
In northern Europe, the coliform test has been supplanted by the En-
terobacteriaceae test, simply because this encompasses a larger group of
organisms that share properties with the more restricted group of the
coliforms. In summary, the three determinations clearly are not redundant.
Additional information related to this contract item can be found in
Chapter 5.
VII. The contractor will evaluate the public health relevance of Salmonella and
other foodborne pathogens of similar resistance to heat in raw seafoods, in food-
processing plants, in restaurants and in family kitchens.
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356
APPENDIX A
Small numbers of a variety of pathogens such as Salmonella, Yersinia,
Campylobacter, and Vibrio may be associated particularly with raw animal
foods such as fresh raw meats, poultry, milk, or fish. For example, Sal-
monella with raw meats and poultry; Yersinia with raw meats, particularly
pork; Campylobacter with raw milk and poultry; V. parahaemolyticus with
seafood; and V. cholerae with shellfish. S. aureus can be readily trans-
ferred to foods as they are handled by people.
In most instances, foodborne illness resulting from the above-mentioned
pathogens has its genesis in the occurrence of these organisms in raw
foods of animal origin. For example, man becomes infected with Sal-
monella, in the vast majority of cases, because the potential occurrence
of Salmonella in raw foods of animal origin is not taken into account
although the routes and circumstances leading to human infection from
such raw foods are fairly well understood. The incidence of foodborne
illness caused by these pathogens will be reduced only if the potential
presence of these organisms in raw foods of animal origin is taken into
account and raw and processed animal foods are not mishandled. This
involves application of the HACCP system at the food-processing plant
and food service establishment (see Chapter 101. Thus, everyone through-
out the entire food chain has to recognize the potential problems that these
organisms can pose. Control of these organisms and hence elimination of
public health hazards usually can be achieved (a) by proper heat processing
of the food, and (b) by avoiding recontamination of the heat-processed
food with the same or other pathogens from contaminated surfaces of
equipment or utensils and through poor hygienic practices of food handlers.
Application of proper refrigeration also is important in minimizing the
hazard because in many foodborne disease outbreaks there is not only a
history of contamination but also one of time-temperature abuse. Though
low numbers of some pathogens may lead to illness, the likelihood of
disease is greatly increased with increasing dosage.
In summary, a variety of pathogens can be expected as part of the
normal flora of various raw foods of animal origin. They do pose definite
health hazards in the entire food chain if proper preventive and control
measures are not applied. Meat and poultry are the most important sources
of foodborne illness in the United States, and failure to handle the raw
and cooked materials properly in food-processing plants, food service
operations, and in the home is the major cause of foodborne disease
involving these foods in the U.S. Contamination of seafoods with path-
ogens of similar heat resistance as Salmonella do not cause, generally,
the same foodborne disease problem in the United States as do red meat
and poultry though shellfish are not an insignificant source of other types
of foodborne disease.
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357
Additional information related to this contract item can be found in
Chapters 4 and 9.
VIII. The contractor will define the purposes for microbiological criteria and will
make cost vs. benefit assessment for their use in regulatory control of raw and heat-
processed foods.
The overall purposes of microbiological criteria for foods have been
discussed in Chapter 2. This contract item requests that purposes of criteria
for (1) raw and (2) heat-processed foods be defined. The subcommittee's
response to this contract item is presented in Chapters 2, 3, 10, and
particularly in Chapter 9. No summary response can do justice to this
contract item; thus only a few isolated examples are given below.
Raw Foods
The usefulness of criteria for raw foods will vary depending upon food
type (see Chapters 3 and 91. For example, sound raw fruits and vegetables
may harbor high populations of microorganisms. Within reason, however,
these numbers have little relationship to quality or production practices.
Even when eaten raw, they have not presented a serious health problem
in the United States. The routine testing of these foods for viable micro-
organisms offers few benefits. Microbiological standards for raw meat
and poultry would prevent neither spoilage nor foodborne illness. On the
other hand, the application of criteria to raw foods such as shellfish can
be extremely useful. Shellfish harvested from polluted waters present a
potential public health problem because they often are eaten raw. Criteria
that include limits on fecal indicator organisms provide a very necessary
safeguard for this class of food.
Heat-Processed Foods
There are a variety of thermal processes for foods ranging from the
pasteurization of wines at relatively low temperatures to the use of retorts
for the commercial sterilization of low-acid canned vegetables. The use-
fulness of microbiological criteria for regulatory control will vary with
the process and the type of food. The application of criteria to foods such
as pasteurized milk and egg products aids in assessing adequacy of the
process and in the detection of contamination following heat treatment
(see Chapter 9, parts A and F). Guidelines are useful for frozen vegetables
to detect poor manufacturing practices following blanching. If proper
action is taken, application of microbiological criteria to precooked ready-
to-eat products can lead to rejection of product that has the potential to
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APPENDIX A
cause a public health problem. Criteria based on microscopic mold counts
for certain canned fruits and vegetables aid in detecting poor quality raw
materials and insanitary processing lines.
Cost/Benefits
Foods most amenable to microbiological criteria are those that have
relatively stable microbial populations such as certain dried, heat-pro-
cessed, and frozen products.
Benefits to be derived from microbiological criteria and appropriate
actions on test results include:
1. An improvement in food safety by rejecting unsafe product on the
basis of detection of pathogens or toxins.
2. Results indicating poor manufacturing practices may lead to action
resulting in good manufacturing practices (better sanitation, improved
process control, and monitoring of critical control points).
A disadvantage to the expanded use of microbiological criteria for
finished products is increased costs that undoubtedly would be passed on
to the consumer. Two of the sources of the costs are:
1. The costs of conducting a greater number of analyses by the pro-
cessor and by regulatory agencies.
2. An increased holding time becomes a disadvantage when the man-
ufacturer must delay shipments pending availability of test results.
It is extremely difficult to make an accurate assessment of the cost/
benefit of the use of microbiological criteria. A few attempts have been
made to establish the economic losses of foodborne illness. For example,
some information has been presented relative to the economic losses of
human salmonellosis (NRC, 19691.
Additional information related to this contract item can be found in
Chapters 2, 3, 9, and 10.
IX. The contractor will evaluate at which level in the food chain microbial path-
ogens should be tested for in foods, by food class.
As indicated previously, small numbers of certain pathogens can be
expected on part of our raw foods of animal origin. With few exceptions
there is little merit in testing these foods for pathogens. In some instances
raw imported foods (shrimp and frog legs, for example) are tested for
Salmonella to detect gross mismanagement of these foods or the harvesting
from fecal-polluted waters. In the case of shellfish, the water and the
product are checked for either coliform or fecal coliform bacteria, which
are used as an index of potential fecal contamination. In processed foods,
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359
relevant tests for pathogens are best conducted at the processing level,
before the foods leave the processing plant, or at least before control of
the product is lost by the manufacturer in trade channels. In addition to
microbiological tests to check for effective processing at critical control
points, "control at source" requires that control be exercised over in-
spection and maintenance of equipment and practice of sanitation in the
processing plant, i.e., HACCP supplemented with appropriate finished
product testing. When conditions related to a food after it has left the
processing plant result in the introduction of pathogens and/or growth of
pathogens, and in some cases production of toxin, then tests for pathogens
might be necessary during transportation, warehousing, or at the retail
level. Tests for pathogens might even be appropriately made in food
service establishments such as a large food preparation and catering es-
tablishment where mishandling may result in growth of pathogenic or-
ganisms and in some cases attendant toxin production. In most cases,
"control at source" will be most effective, but for certain foods and in
certain uses of foods it may be necessary to conduct tests for pathogenic
microorganisms at other points in the food chain. Regulatory agencies
might appropriately test foods at any point along the food chain.
The presence and growth of pathogens in a food depends upon many
factors, including the nature and source of the food, the physical-chemical
properties of the food, and the conditions of processing, packaging, stor-
age, and distribution. Therefore, only those pathogens should be tested
for that are of public health relevance in a particular food. Chapter 9 of
this report presents the relevant pathogens for which specific groups of
foods should be tested and at which level in the food chain tests should
be applied.
X. The contractor will examine relationships between food quality and micro-
biological characteristics and criteria of foods.
Food quality in the broad sense includes flavor, color, texture, nutri-
tional value, and safety. At some point sufficient microbial growth will
occur on a perishable food to affect its organoleptic properties, usually
adversely. Volatile compounds may be generated that change flavor; pig-
ments may be degraded or new colors produced; texture may be altered
due to the activity of microbial proteases, pectinases, cellulases, and other
hydrolytic enzymes; the utilization of food constituents and the release of
metabolic products may influence nutritive properties.
The numbers needed to produce detectable changes will be influenced
by food type and the predominant microorganisms. In terms of criteria
established according to the principles of this report, the value of m
represents levels consistent with Good Manufacturing Practices and is set
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APPENDIX A
at a level below that at which these characteristics become evident. The
value of M relates to a point, and approaches to it, where the changes are
or soon will be evident. Foods meeting these criteria will not show man-
ifestations of quality deterioration (see Chapters 6 and 91.
When high microbial populations originate from contaminated equip-
ment only, rather than from actual microbial growth on the food, fewer
changes, either detectable or nondetectable, will occur. The types of mi-
croorganisms also can be important. Growth of lactic acid bacteria on
meats, for example, produces less flavor change than comparable growth
of certain pseudomonads.
While high counts may reflect lower quality or poor processing con-
ditions, the opposite is not necessarily true. Low counts may result because
the food was given a lethal treatment at a stage near the end of the process,
or because many of the contaminating microorganisms had died off during
storage of the food. The presence of pathogenic microorganisms, espe-
cially on ready-to-eat foods, is of course evidence of poor quality. The
finding of excessive numbers of mold mycelia in certain foods such as
catsup is evidence that it was made from raw materials containing rots.
Additional information related to this contract item can be found in
Chapters 2, 6, and 9.
XI. The contractor will evaluate at which level during harvesting, processing,
storage, and distribution needed microbiological criteria can be best applied.
The objective of the criterion will determine when microbiological anal-
yses should be performed.
If the criterion is a purchase specification that, for example, limits the
number of heat-resistant mold spores in an ingredient, analyses usually
are conducted by the purchaser when the shipment is first received at the
plant. Frequently, the supplier analyzes the product before it is shipped
to the purchaser.
If the criterion is a guideline designed to monitor a critical control point
in a process, samples collected immediately after the unit operation might
be analyzed.
If the objective is to assess good manufacturing practices, the levels
at which microbiological testing should be conducted depends upon the
processes to which such food is subjected. For some foods, microbiological
testing of finished product after packaging may be appropriate to assess
good manufacturing practices. With certain processes the analysis of the
finished product would not be particularly useful to assess good manu-
facturing practices, for example, with a product subjected to a heat treat-
ment. There are many situations where evaluating manufacturing practices
would require microbiological testing at points other than finished prod-
ucts, for example, sanitary conditions of equipment.
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361
If the concern is abuse or contamination during transport of the food
or while it is held in the marketplace or food service establishment, samples
collected at the retail level should be analyzed. Furthermore, samples may
be collected to monitor critical control points in food service establishments
as well as in processing plants. Additional information related to this
contract item can be found in Chapters 2 and 9.
XII. The contractor will determine the validity of aerobic and coliform plate counts
as indicators of insanitation and of time-temperature abuse of foods.
High aerobic plate counts (APCs) in finished products or in products
during processing may be caused by either poor sanitation or time-tem-
perature abuse or both. Several other conditions, however, may be in-
volved, such as the quality of raw materials and ingredients and adequacy
of a heat-processing procedure if one is used. Hence, the APC can be a
valid indicator of insanitation or of time-temperature abuse (primarily in
perishable foods) if other potential causes are eliminated. The relationship
of APC to insanitation or to time-temperature abuse can be determined
best by a thorough understanding of the microbiology of the product
(hazard analysis) and examination of line samples taken at critical control
points. For example, a high APC of packaged ground beef may have
resulted from (a) poor-quality trimmings, (b) poor sanitation of equipment
(for example, grinder), and (c) holding of the product for too long or at
marginal temperatures at which normal aerobic, psychrotrophic, gram-
negative rods continue to multiply.
Coliform bacteria are particularly valuable as indicators of postpro-
cessing contamination of foods treated for safety. The validity of coliform
counts as an indicator of insanitation and of time-temperature abuse re-
quires a thorough understanding of the microbiology of a food. In some
foods they have little relationship to the above-mentioned conditions, in
others they have more. Coliforms can be a valid indicator of poor sanitation
if it can be shown that their presence at a particular point in the processing
and handling of a food is not expected or their numbers are at a level
beyond what is considered normal. For example, small numbers of col-
iforms are common in raw milk, vegetables, and meats. Large numbers
in raw milk indicate insanitation and likely time-temperature abuse. Even
small numbers of coliforms in pasteurized milk indicate postpasteurization
contamination. In heat-processed foods, the presence of coliforms indi-
cates most likely contamination (poor sanitation) after heating that may
be accentuated by time-temperature abuse of the food.
Additional information related to this contract item can be found in
Chapter 5.
XIII. The contractor will determine the validity of aerobic and coliform counts
as significant or useful indices as one facet of food "quality."
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APPENDIX A
This question has been discussed extensively in Chapter 2 of this report.
Appropriate sections are repeated here to emphasize certain aspects of this
question.
The term quality as commonly applied to food summarizes its desirable
characteristics. Quality of a food as perceived by the public can be de-
scribed as a value related to flavor (taste and odor), color, and texture.
It also includes imperceptible traits such as nutritional value and safety.
Excluding safety and utility from this discussion, from the microbiological
viewpoint quality includes: (a) shelf-life, as perceived by attributes such
as flavor and appearance, and (b) adherence to Good Manufacturing Prac-
tices.
Each of these attributes is measurable to some extent microbiologically;
the decisive question, however, is to what extent.
The ultimate shelf-life of a perishable food can be estimated to some
degree through the application of microbiological criteria. Assuming that
storage conditions are the same, a perishable food with a low number of
spoilage microorganisms will have a longer shelf-life than the same product
with larger numbers of such organisms. However, relationships between
common microbiological parameters such as aerobic plate counts and
coliform counts and the shelf-life of a food are inexact. Some types of
microorganisms, because of enzyme systems acting upon the constituents
of a food, cause marked changes in perceptible quality characteristics of
a food while others are relatively inert biochemically and thus produce
little change. In addition, the effect of certain levels and/or types of
microorganisms on perceptible quality characteristics often differs from
food to food and is also subject to changes in environmental conditions
such as temperature and gaseous atmosphere.
Lack of adherence to Good Manufacturing Practices often can be related
to APC and/or coliform counts in excess of those present in a food produced
under good conditions. The use of poor-quality materials, inadequate heat
processing, careless handling, or insanitation may result in a higher bac-
terial count in the finished product. This relationship may not always be
valid, however, because a heat treatment or other lethal treatment in the
process can cover up the grossest evidence of malpractice, and organisms
may die off during storage of frozen, dried, or fermented foods. Low
counts in a finished product or ingredient, therefore, do not necessarily
indicate good manufacturing practices or even food safety. High aerobic
plate counts, on the other hand, do not necessarily mean careless handling
or lack of wholesomeness. For example, ground beef prepared from the
trimmings from carcasses may yield a high aerobic plate count, but this
may merely reflect the growth of harmless psychrotrophic bacteria during
refrigerated storage. On the other hand, it could also represent poor san-
itary conditions and/or time-temperature abuse.
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363
The relationship between the microbiology of a food and adherence to
good manufacturing practices must be established by conducting repeated
surveys of processing lines to obtain statistically valid data. The critical
control points must be identified and the microbiology of the food at the
different stages of processing must be determined. Through these studies
one can arrive for some foods at numbers and types of organisms that
characterize the flora of a food produced under a given set of conditions,
and thus provide a basis for the establishment of a microbiological cri-
terion. Even then an allowance has to be made for variations because of
differences in processing procedures and equipment. Finished foods that
exceeded the criterion might reasonably be expected to have been mis-
handled somehow during production and/or storage.
In recent years microbiological quality standards (APC and coliform
counts) have been proposed for various foods under Section 401 of the
Food, Drug and Cosmetic Act. Recently, they have been recommended
for frozen fish sticks, fish cakes, and crab cakes. This has been discussed
extensively in Chapter 2.
Additional information related to this contract item can be found in
Chapters 2 and 5.
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APPENDIX A
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Representative terms from entire chapter:
manufacturing practices
