121.

MICROBIOLOGICAL C R I T € R t A FOR FRESH MEAT' A. W . KOTULA

U N I T E D S T A T E S D E P A R T M E N T O F A G R I C U L T U R E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Though concern about microbial contamination of meat and con- comitant standards f o r microbiological qua l i ty , can be t raced t o the tu rn of t he century, as far as can be ascertained there are no microbiological standards t h a t are present ly being enforced f o r f r e sh meat. E l l i o t t and Michener (1961) reviewed the l i t e r a t u r e r e l a t i v e t o microbiological. standards and handling codes f o r ch i l l ed and frozen foods up t o 1960. Table 1 sum- mar izes t h e port ion of h i s review which dea ls w i t h f r e s h meat. bac te r io logica l l i m i t s are as high as lo6 or l o 7 viable aerobes per gram. Because off odor w i l l develop at about lo8 organisms per gram ( K i r s h -- e t al., 1952, Barnes 1957) o n l y a few days shelf l i f e can be expected f o r such a product even under optimum storage temperatures. But extended shelf l i f e i s not our only concern during t h e consideration of microbiological c r i t e r i a . The purpose of microbiological c r i t e r i a are threefold:

Some of t h e

1. To iden t i fy and eliminate slaughter and marketing prac t ices which might allow meat t o reach marketing channels, when it might be de le te r ious t o consumer heal th by v i r tue of i t s microbial content.

2. To increase the l e v e l of wholesomeness of all meat and meat products .

3. To enhance consumer s a t i s f a c t i o n and confidence i n m e a t as a food.

Table 2 shows the microbiological l i m i t s for f r e sh meats t h a t have been proposed since the E l l i o t t review of 1961. used to mean m e a t t h a t has not been cured, smoked, or canned, not t o express t i m e post mortem. r a the r than "standards" t o more r ead i ly r e l a t e t o other groups such as the Food Protect ion Committee of the National Research Council, who already have spent many years evaluating microbiological l e v e l s and have developed a precise terminology for microbiological c r i t e r i a . l o g i c a l c r i t e r i o n as "any specif icat ion, recommended l i m i t , or standard". Further , a spec i f ica t ion i s a m a x i m u m l eve l s e t by an agency or f i r m purchas- ing food f o r i t s own use; a l i m i t i s a recommended leve l , and a standard i s t h a t p a r t of a l a w or administrative regulat ion designating the m a x i m u m acceptable number of microorganism.

The term "fresh meats" i s

The proposals of Table 2 are re fer red t o as " l i m i t s "

They define a microbio-

- 1/ Appreciation i s expressed t o members of t h e Microbiology Committee, D r s . J . A. Carpenter, R. H. Gothard and J. M. Jay for the information which they contributed f o r t h i s presentation.

122.

E l l i o t t (1970) proposed the use of y e t another term, "guideline", which i s a l e v e l of bac te r i a i n a f i n a l product t h a t necess i ta tes ident i - f i c a t i o n and cor rec t ion of caus i t ive f ac to r s i n current or fu ture production and handling.

Table 2, therefore , dea ls with microbiological l i m i t s f o r f r e sh m e a t . The limits involve both spoilage and pathogenic microorganisms.

Table 2 does not include the pos i t ion statement by the Consumer and Marketing Service of the U. S. Departnent of Agriculture concerning Salmonella i n r e d meats and t h e i r products. This statement ind ica tes t h a t ready-to-eat and warm-and-eat meat products must be free of salmonellae. R a w red mat products found t o be heavily contaminated w i l l be re ta ined and improvements i n san i t a t ion w i l l be required t o protect fu tu re production. Heavy contamination i s indicated by (1) a high incidence of pos i t ive findings, (2) a high l e v e l of Salmonella c e l l s or (3) a higher incidence of Salmonella i n the product than i n the animals from which it i s produced.

The microbiological l imits proposed i n Table 2 would probably be of l i t t l e use t o the meat industry. There appears t o be a lack of agreement as t o which organisms, other than t o t a l aerobes, are important. Also the proposed l i m i t s are incomplete f o r some of t he f r e sh meat categories . Rather than t o f u r t h e r evaluate t h e limits proposed i n the s i x t i e s , l e t ' s look at t h e s teps t o be taken, if indeed such s teps are warranted, t o develop and improve the usefulness of microbiological l i m i t s i n the seventies.

Mossel (1969) suggests t h a t t he f i r s t s tep i n developing micro- b io logica l c r i t e r i a should be a carefu l study of t he microorganisms associated with a pa r t i cu la r food. bac te r ia , actinomycetes, molds, and yeasts i so la ted from ref r igera ted beef. Two minor modifications have been made i n Table 3. Aerobacter and Paracolo- bactrum were r ec l a s s i f i ed as Enterobacter according t o Edwards and Ewing (1966). organisms. i l l n e s s i n 1968 w e r e :

Table 3, compiled by A p e s (1960), c l a s s i f i e s

This grouping can be broken down f u r t h e r i n t o pathogens and spoilage Hall (1969) s t a t ed t h a t t he bac te r i a responsible f o r f oodborne

Number of I l l n e s s e s Percent

- C perf ringens S t aDhvloc occus , ." S almone 11 a Streptococcus E. c o l i

5,966 4,419 1,287 1,282 1,234 - -

Shige l la 407 Brucel la 12 C . bolulinum 10

Total 14,617 -

40.8 30.2 8.8 8.8 8.4 2.8

< l . O <l.O

Mossel (1969) would add Baci l lus cereus and Vibrio parahemolyticus t o t h i s l i s t of pathogens as being of current i n t e r e s t from the standpoint of out- breaks of food-borne diseases, r ea l i z ing t h a t Vibrio parahemolyticus has been associated with f i s h .

123

Van Schothorst (1970) recognized t h a t no pathogens should be allowed i n food, but there would not be much food t o eat if regulat ions were t h a t s t r i c t . Mossel (1969) indicated t h a t t o obtain czrcasses with a t o l e r - able degree of Salmonella contamination, the meat industry must consider pathogen-free young animals, bacter iological control of feed, and consider- able improvement of the san i ta ry conditions of the a n i m a l s on the farm, during t ransportat ion, and while awaiting slaughter.

Fortunately, while the industry i s s t r iv ing towards t h i s g o a , proper san i ta t ion and inherent microbial. antagonisms help t o maintain patho- gens a t low leve ls . For example, mil l ions of viable - C . perfringens bac ter ia must be ingested t o cause i l l n e s s (anonymous, 1970). meat product at less than 10°C w i l l i nh ib i t t h e development of such numbers (Patterson, 1967, H a l 1 and Angelotti, 1965) . Patterson (1967) , indicated t h a t growth of Salmonella and Staphylococcus a u e u s are a l s o inhibi ted below 10°C. the danger from pathogens i s avoided.

Refrigeration of the

Thus if meat i s not abused by improper storage temperatures, much of

Hartman (1968) indicated t h a t t he Committee on Environmental Health of the Cal i forn ia Conference of Local Health Off icers concluded t h a t standasds based on b a c t e r i d counts associated with disease, although desirable , were not f eas ib l e at present. It seemed more p rac t i ca l t o proceed t o e s t ab l i sh standards, based on b a c t e r i a l counts i n foods, associated with current production prac t ices .

How do current prac t ices a f f ec t t he microbiological qua l i ty of meat? Vanderzant and Nickelson (1969) reported t h a t muscle t i s sue of healthy l i v i n g animals contains f e w or no microorganisms and t h z t there are no psychrotrophic bac te r i a i n f r e s h t i s s u e s of pork, lamb, or beef. S t r inger 5 &., (1969) found t h a t contamination occurs immediately a f t e r slaughter, and t h a t moist carcass areas axe contaminated most highly. rump, br i ske t , and fore legs are l i k e l y t o show the grea tes t contamination according t o Murray (1969).

The

The generic d i s t r ibu t ion of i so l a t e s between f r e sh and spoiled beef as found by Jay (1967) includes:

Genus

Pseudomonas Achr omob ac ter Aeromonas - Proteus F 1 avob ac t e r i u n Alcoliaene s

No. of beef i so l a t e s Fresh Spoiled

34 4 2 3 1 2 2 1 1

16 1 1 0 1 0 0 0 0

Table 4 summarizes bac te r i a l numbers found i n f r e sh m e a t as reported during the l as t decade. uniform among the various researchers and i n some instances was not reported at all. The usefulness of such da ta f o r developing microbiological c r i t e r i a i s limited unless sampling methods, treatment of samples, and methods

Methodology i n the determinations w a s not

124.

of bac ter io logica l examination are r i g i d l y followed (Murray 1969). paper presented methodology, as shown i n Table 5 taken from Rey e t al., (1970), comparison of t h e counts would be simplified. In te rna t iona l Association of Microbiological Soc ie t ies has published methods f o r de tec t ion of food-borne pathogens and indicator organisms (Thatcher and Clark, 1969): an agreement on the optimum methodology f o r non-pathogens.

If each

A committee of the

It would be highly desirable f o r microbiologists t o come t o

The Association of Food and Drug Of f i c i a l s of the U. S. have developed the microbiological c r i t e r i a f o r beef pot pies, shown i n Table 2, using what appears t o be the most s c i e n t i f i c approach t o date . Four independent labora tor ies cooperated t o provide microbiological da t a on f i v e beef p i e s from each of 2 4 commercial l o t s . Sampling, plat ing, and incubating procedures were standardized before the study was i n i t i a t e d . The labora tor ies then determined coliform, E . co l i , Staphylococcus, and Streptococcus by the most probable number m e t h g (m and also viable aerobes, coliforms, Staphylococcus and Streptococcus by p l a t e count. Results of t h i s study are reported i n the l a t t e r past of Table 4. The Committee on Research and Methodology decided not t o recommend examination f o r staphylococci because the level of contamination w a s t oo low t o serve as a sens i t ive index of qua l i ty . p i e s because the labora tor ies encountered d i f f i c u l t y with the KF Medium from one commercial source. The Committee's f i n a l recommendation s ta ted t h a t a t o t a l z r o b i c p l a t e count of l O O , O O O / g and 200 coliform/g by the MPN method should be used t o evaluate the qua l i ty of precooked frozen beef pie. p i e s from each l o t would be sampled and if the average of the log 10 count exceeded the l i m i t s , t he l o t would be unacceptable. means of 150,000 aerobic organisms/g and 380 coliform/g would be accepted 5 times i n 1000. aerobes/g and 50 coliform/g would not r i s k exceeding the limits i n more than 1 l o t of 1000. Though t h i s approach i s sound, it would have been advantageous if a grea te r number of p lan ts could have been included i n the study t o repre- sent a greater divergence i n f i n a l product qual i ty . The effect iveness of the c r i t e r i a a l so could have been strengthened if microbial counts had been r e l a t ed t o t h e standards of s an i t a t ion practiced within each plant. This idea i s not new. (1963), and E l l i o t t (1969) f o r many years because, u n t i l improved biological techniques of evaluation are developed, it i s more f eas ib l e t o control qua l i t y by a preventative system of plant san i ta t ion than by the ana ly t ica l approach.

Fecal s t reptococci were not used as an index of q u d i t y of beef

Ten

By t h i s method l o t s with

A processor who regular ly produces p i e s having 43,000

It has been advocated by Mossel (1969), Shiffman and Kronick,

summary

Microbiological limits proposed f o r f r e sh meats are reviewed. None of t he suggested limits are idea l standards f o r the following reasons: (1) methodology f o r sampling and p l a t ing w a s nei ther uniform nor w a s it described i n d e t a i l ; (2) decisions were based on too few samples; ( 3 ) some f r e sh m e a t i t e m s were not evaluated; (4) samples representing grea te r divergence i n f i n a l product qua l i t y were needed; and (5) microbiological counts should have been correlated t o standards of san i ta t ion practiced within each plant . References describing microbial counts associated with f r e sh meats are l i s t e d . However, counts i n these repor t s are of l imited value f o r use i n formulating micro- b io logica l limits because procedures were not uniform and sampling w a s , i n some instances, inadequate. Thus, if microbiological standards or limits are deemed necessary, a cooperative e f f o r t involving industry, university, and government microbiologists should be i n i t i a t e d t o standardize and publish

125.

preferred sampling techniques and methods of enumerating microorganisms. Furthermore, each f r e s h meat i t e m should be evaluated systematically t o ensure t h a t samples representing many l e v e l s of qual i ty , as r e l a t ed t o in- plant san i ta ry pract ices , are included i n the t e s t i n g by the various labora tor ies . Data from such s tudies would reflect the "state of the a r t " i n t he meat packing industry and could then become t h e basis for microbio- l og ica l l i m i t s f o r f r e s h meat.

126.

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Table 3. C las s i f i ca t ion of Microorganisms Iso la ted from Refrigerated Beef. (Ayres 1960).

Bacter ia and Actinomycetes

Sc h i z omyc e t e s Pseudomonadale s

Pseudomonadace ae Pseudomonas Aeromonas

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Actinomycetales

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T orulop s i s

C r y p t o w A f t e r Lodder &

Candida Rhodot orul a

S t r e i t omycet aceae S t r e p t omyc e s

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