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S H E L F L I F E AS AFFECJED BY M I C R O B I A L C O N T A M I N A T I O N

JOHN C. BARD O S C A R MAYER & COMPANY

MAD I S O N , WI S C O N S I N ______--___-_-______--- . . - . - - - - . - - . - - - . . - - - -*----- . - . - . - - . - -

Many bacteriological studies have been carr ied out regarding spoilage problems i n meat. reveal a multitude of surveys relat ing contamination and keeping t i m e .

Even a cursory review of t he l i t e r a t u r e w i l l

For exanrple, i n 1933, Haines & Smith reported t h a t t he control of surface contamination of f resh meats is the most important fac tor i n de- termining i t s shelf l i f e . Table I i l l u s t r a t e s t h e i r r e su l t s obtained i n studies with lean beef a t various levels of contamination with storage at Oo C . (32O F.).

TABLE I

Effect of I n i t i d Contamination on the Storage L i f e of Lean Beef

I n i t i a l Bacterial Count org. per sq. cm.

DWS at O'C. Before Slime Development

100,000 8

10,000 10

1,000 13

100 15

10 18

Other research workers have reported similar resu l t s from studies involving fresh processed, and prepackaged meats at storage temperatures ranging from 32 6 F. t o 50' F.

Even w i t h t he development of hermetically sealed vacuum packages, which w i l l prevent growth of molds, shelf l i fe i s s t i l l extremely dependent upon the i n i t i a l bac te r ia l contamination level .

Once contamination t o any level has taken place, storage tempera- t u re becomes t h e major factor of importance i n determining shelf l i f e .

Table I1 illustrates data from the Haines & Smith studies on lean beef stored at various temperatures.

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TABU I1

Storage Temperature Days Before Slime Cevelopment

32O F. 10

34O F. 7

37' F. 4

41' F. 3

50' F.

61' F.

2

1

American Meat Ins t i t u t e Circular No. 53 issued i n October 1959 summarizes the importance of storage temperature as follows: "Under prac t ica l conditions a product will keep at l ea s t twice as long when held a t 3 p F . as will the same product with a similar level of contamination at 40' F. It w i l l keep at least four t i m e s as long at 32O F. as at 50° F."

Self service merchandising and prepackaging presented both a new opportunity and new problems t o the meat processor. mitted brand ident i f icat ion all t h e way to the consumer's kitchen. Obviously quali ty control and product r e l i a b i l i t y assumed much mre im- portance t o the packer i n t h i s si tuation.

Prepackaging per-

A t Oscar Mayer & Co. we have approached t h e product r e l i a b i l i t y problem i n a carefully integrated program of process control and package development coupled with employee and customer education.

From the literature we w e r e convinced that bacteriological spoilage could be effectively controlled by first preventing or minimizing bac ter ia l contamination and second, by maintaining low temperature storage, delivery and display conditions. garding product :

We sum t h i s up by two basic rules re-

KEEP IT CLEAN! KEEP IT COLD!

Analysis of conventional wiener processing methods revealed that the major source of contamination was associated with operations involving handling and packaging the product. ways: - we adopted extremely r ig id standards for sanitation of process- ing equipment. = - we launched a vigorous program of machine development and process automation t o eliminate the need f o r operators t o handle product during the manufacturing and packaging operations; and Three - - we in i t i a t ed and have continued an extensive program of employee hygiene education and enforcement.

W e attacked t h i s problem i n several

Our employee education program includes demonstrations emphasizing the importance of hand-washing rules. In these demonstrations, our bacteriologists go in to the production department and conduct pe t r i dish finger-printing tes t s among production workers who have washed t h e i r hands t o various degrees of cleanliness.

233.

After incubation the dishes are again shown t o the employees who then can actually observe the relationship between hand washing methods and resu l t s obtained. (Slide)

Exhibits actually demonstrating the relationship of storage t e m - perature and bac ter ia l growth are used t o help educate both our technical people and production supervision. of petri dishes seeded with approximately 1,000 org/ml incubated 48 hours at 32' F.> 42' F., 52' F. and 60' F. organisms after 48 hours. A t 42' F. there w a s a ten-fold increase and at 52' F. there was a hundredfold increase. considered T.N.T.C.

This slide i l l u s t r a t e s a comparison

A t 3 2 O F. there w a s no increase i n

Colonies on the 62O F. p l a t e were

As a fur ther follow through we have and are continuing t o conduct educational courses f o r our operating and sales personnel. Several thousand copies of our educational brochure, " L i f e Begins at 400 F." have been dis- t r ibuted t o our production supervisors, salesmen and t o many meat department managers at t h e retail level.

As you might surmize f romthe t i t l e of t h i s brochure, we designed t h i s program t o emphasize the importance of adequate product refrigeration. We w e r e not attempting t o minimize the sanitation aspect of producing a clean product. W e did want t o emphasize that what we were doing t o produce a clean product could be undone awfully fast i f there was a poor follow through on observance of proper storage temperature control all the w a y t o t h e consumer.

W e intend t o continue our t o t a l program and know that f o r the benefit of the consumer and the industry that continued emphasis by all extension workers, agricultural experiment stations, trade associations, and industry meat technologists on the "Keep -- it Clean and Keep -- it Cold" approach w i l l pay off i n be t t e r meat products.

DR. WELLINGTON: Thank you, M r . Bard, and sincere thanks t o Oscar Mayer & Company. I think we w i l l withhold questions u n t i l the end of t he period. Professor Bratzler i s prepared t o lead our discussion as you have seen on the program and w i l l handle the questions at that t i m e . Moving now t o t h e next speaker, we welcome our own D r . N e i l Webb back t o t h e group. I haven't had a chance t o visit with h i m but I ' m sure tha t he is aware tha t w e have m a d e a place f o r indus t r ia l people l i k e N e i l i n the new association, and we hope that we w i l l see h i m a t our meetings frequently. Dr. Webb i s director of technology f o r Eckert Packing Company at Defiance, Ohio, and h is topic i s "Commercial Processing Problems of Most Concern t o Industry". D r . Webb.

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