Bacteria of Foods and Utensils in the Luther College Food Service, Decorah, Iowa

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1 Proeedings of the Iowa Aademy of Siene Volme 81 Nmber Artile Bateria of Foods and Utensils in the Lther College Food Servie, Deorah, Iowa Marilyn Peitso Lther College Cheryl Anderson Lther College John Tjostem Lther College Copyright Copyright 1974 by the Iowa Aademy of Siene, In. Follow this and additional works at: Reommended Citation Peitso, Marilyn; Anderson, Cheryl; and Tjostem, John (1974) "Bateria of Foods and Utensils in the Lther College Food Servie, Deorah, Iowa," Proeedings of the Iowa Aademy of Siene: Vol. 81: No. 3, Artile 3. Available at: This Researh is broght to yo for free and open aess by UNI SholarWorks. It has been aepted for inlsion in Proeedings of the Iowa Aademy of Siene by an athorized editor of UNI SholarWorks. For more information, please ontat sholarworks@ni.ed.

2 Peitso et al.: Bateria of Foods and Utensils in the Lther College Food Servie 9:3 Bateria of Foods and Utensils in the Lther College Food Servie, Deorah, Iowa MARILYN PEITSO, CERYL ANDERSON and JON TJOSTEM1 PE1TS, MARILYN, CERYL ANDERSON and JoN TJOSTEM (Department of Biology, Lther College, Deorah, Iowa 5211). Bateria of Foods and Utensils in the Lther College Food Servie, Deorah, Iowa. Pro. Iowa Aad. Si. 81(3): 93-97, Total bateria onts were obtained from preooked frozen entrees and other frozen food items. All the onts were well below federal and state reommended limits. Total bateria onts were also obtained from representative food preparation srfaes and tensils. While most onts were below aeptable limits, the fiberglass afeteria trays showed onts sbstantially above the limits. Normal wear eventally exposes the fibros tray interior, allowing amlation of solble foodstffs and rapid mltipliation of bateria. Worn fiberglass afeteria trays shold be reognized as a potential health hazard. INDEX DESCRIPTORS: Bateria of Foods, Bateria of Utensils, Food Servie Bateriology. The food servie of Lther College, Deorah, Iowa, has been a pioneer in the se of preooked frozen foods. Lorenzo Prie, food servie diretor, abandoned the onventional kithen in favor of the pre-prepared frozen entree system in 1964 at St. Olaf College, Northfield, Minnesota, and in 1968 at Lther College. At Mr. Prie's reqest the Biology Department ondted a two-year program of mirobiologial testing to investigate the degree of baterial ontamination in frozen foods. Sine the se of pre-prepared frozen foods is gaining aeptane in many instittional afeterias, the reslts of this stdy are relevant to expanding nmbers of people. Tests were rn weekly, and items to be sampled were rotated eah week. Frozen foods and representative srfaes, sh. a'i. '1.\l'ferware, serving pans, oolers and afeteria trays, were tested. Speifi areas of high baterial onts were fn..'t&>e investigated. An edational program for the food servie employees was an important part of the stdy. Many troble spots in food handling develop bease the people involved are not aware of the onditions nder whih bateria florish. In meetings with the employees we disssed foods that reqire speial are. For example, we reommended that frozen whole eggs be thawed in the ooler, rather than at room temperatre, to avoid the growth of pathogeni Salmonella, whih is a ommon ontaminant of eggs (Wistreih, 1973). Frozen Food 15 g \;d 45ml io-1 Blend 2 min. at low speed U 9 ml lm/\ 1-2 ml U 9 ml 1-3 '1\' r Standard Methods Agar BACTEfilA LEVELS IN FROZEN FOODS Inbate for 36 hr. at 32 C. The frozen food samples were taken from the food servie kithen on the day of shipment. A sterile hammer and hisel were sed to ollet the samples, whih were stored for a maximm of three days in sterile sampling bags at -5 C ntil proessing. The samples were analyzed in aordane with reommended proedres (Sharf, 1966). This proedre is otlined in Figre I. Eah item was sampled from one to three times. Limits for nmbers of total bateria present in frozen foods sed in the Lther College food servie were hosen after omparing limits for frozen foods reommended by varios 1 Department of Biology, Lther College, Deorah, Iowa Figre 1. Tehniqe for frozen foods. laboratories and agenies. For instane, the Assoiation of Food and Drg Offiials of the United States has reommended a limit of 1, total bateria/gram of food sampled for preooked frozen beef and hiken pot pies (AFD OUS, 1969). The armed fores have set a limit of 1, total bateria/ gram for preooked frozen meals served to flight rews (Department of Defense, 1964). The Food and Drg Administration has reommended a limit of 5, total bateria/ gram for ertain frozen, ready-to-eat pies (Department of ealth, Edation and Welfare, 1972). Reommended limits for nooked meats range from 25, to 1 million total bateria/ gram (Elliott, et al., 1961). The reommended maxima of 1, total bateria/gram for frozen Pblished by UNI SholarWorks,

3 Proeedings of the Iowa Aademy of Siene, Vol. 81 [1974], No. 3, Art PRo. low A AAn. S1. 81 ( 1974) Reommended limit: 1,/gram 1,, 3. E :!.. - ' 1,D.....a ::i :z: -..: IJ.) IJ.) (fj.-f ;J..Q.µ 1 (fj (fj.µ.µ ClJ O>. ClJ :> 'O IJ.) 'O IJ.) 1-1 x 4-< ::<: 1-1 '"' Vegetables Figre 2. ~ P.. O> (fj ClJ IJ.)..: ~.µ ~ ~..: (fj 1-1.-f P.. O> (fj "' 'O ClJ :>, IJ.) 4-< 4-< 1-1 ~ ;J '"'.µ..: Preooked Entrees.µ ;J O> (fj < IJ.) ClJ P'.l Total bateria in frozen foods. IJ.) 1-1 ClJ O>.µ (fj 1-1 ;J (fj 4-<.-f ~ 4-< (fj IJ.) 1-1 IJ.) P'.l '"' vegetables and preooked frozen foods, and 1 ~ill.ion tot~l bateria/ gram for frozen nooked meats, are md1ated m Figres 2 and 3. Figres 2 and 3 show that all the food tested, frozen vegetables preooked frozen entrees and frozen nooked meats, fell ;ell below the reommended limits for total bateria. Althogh low total baterial onts do not garantee the absene of pathogens, it has been shown that properly handled food is likely to have low baterial onts as well as no pathogens (Elliott and Mihener, 1961). Three separate lots of grond beef patties were sampled. The average ont was 28, bateria/ gram, ranging from 2,6 to 53, bateria/gram. This is a ommendably low ont when ompared with onts from grond beef fond in other stdies. One srvey of spermarket and restarant grond beef showed onts ranging from 8, to 5 million bateria/ gram (Mood, 1971). The onsistently low total bateria onts indiated that frozen foods have been properly handled after leaving the fatory. Improper handling, sh as inadeqate refrigeration dring transit or long periods at room temperatre, wold reslt in elevated total bateria onts. BACTERIA ON DISWARE AND SURFACES Utensils and preparation areas of the food servie were tested weekly aording to U.S. Pbli ealth Servie proe- e :! en - ""'. 5,.. z: Figre 3. ~ ~ >i ~ (fj.µ CJ Ill Q) ri.µ :> Q).-I.µ.-I Ill ri.µ!ll.-i!ll ri Q) ' ~!ll ~ ~ ~ CJ ' Ill Q) Q) Q) Q)!ll Q) Q) Q).Q ;::l..q ' ::a i:q [--< Ill!ll '"d Q).-I ~ ;::l N N ri., l? (/) Total bateria in nooked meats. dres (U.S. Pbli ealth Servie, 1967). Eah sample onsisted of five artiles of the same tensil or srfae. An area 8 in.2 was swabbed on eah of the five a1tiles. After the sample was taken, it was analyzed as dia~ram~ed in Figre 4. Eah item was sampled from two to nme times. The srfaes were divided into two major grops: dishware, and all other srfaes. A lower baterial limit was reommended for the dishware bease these items ome into diret ontat with the food, whereas the other srfaes normally do not. Dishware, shown in Figre 5, w~s wash~d in a dishwasher that reahed a temperatre of 68 C drmg the wash yle and 85 C dring the rinse yle. Fifty total bateria/in2, a level easily obtained throgh proper washing, was reommended by s as a gideline. Items in the seond grop, shown in Figre 6, had no presribed method of leaning bt were washed reglarly with detergent and hot water. Two hndred total bateria/in2 served as a gideline for these srfaes. Or experiene ha~ shown these levels to he onsistently attainable and sefl in pointing ot areas of o11- tamination. Most of the srfaes and tensils sampled fell within the reommended limits, as seen in Figres 5 and 6. This indi- 2

4 Peitso et al.: Bateria of Foods and Utensils in the Lther College Food Servie BACTERIA OF Fooos AND UTENSILS b. t 8 in swa per i em xxxxx Limit: 5/in I U 5 ml U 9 ml 4 Standard Methods Agar Inbate for 48 hr. at 32 Figre 4. Fig.4 Tehniqe for srfae tests. A 1-1 ml ates that the general leanliness of the food servie is good. For those items with onts notieably above the reommendations, frther investigation was onsidered. The levels of bateria for the salad bowls and the afeteria trays on whih the stdents arry their food were alarmingly above the limit, even immediately after dishwashing. The salad bowls, w~th an average ont of 45 bateria/in2, and the trays, with 4,3 bateria/in2, both were made of a poros material. A more intensive stdy of the trays was made to investigate the extremely high onts. BACTERIA LEVELS IN WoRN FrnERGLAss TnAYs The afeteria trays were prhased over ten years ago and have been in se sine that time, eah tray having been sed an estimated 4, times. The trays onsist of fiberglass material with an internal metal frame, overed with a nonwoven glossy oat. A grop of new trays of similar omposition was obtained. These trays were pt into normal se in the food servie, so they old be sed in a omparative stdy. This stdy was == 2 "" -~.,; z * to.i..:::: -~ -...,; z.. P.. Q) ;3: Q) >< ;3: ::J.j.) ;3: Q) <1l Q) <1l ~ <1l <1l..Q E-< Q).. ' ~ Q) rel rel Q) >< 4-l <1l <1l :> <1l 4-l ~ <1l <1l.Q..-i E-< rn UJ UJ Figre 5. rel Q) <1l. <1l <1l UJ rn P.. rn..-i Cl ic Total bateria on dishware. designed to determine the ability of the tray to absorb foods, and the nmber of bateria within the tray that srvive dishwashing. Two old trays were ompared with two new trays in eah proedre. The absorbing ability of the trays was determined throgh the following proedre. The trays, taken diretly from the dishwasher, were sterilized by atolaving at 15 lbs. pressre for 15 mintes. The sterile trays were then immersed in 4 ml of ntrient soltion ontaining bateria ltred from trays, and inbated in a overed ontainer for 24 hors. The trays were pt throgh a normal dishwashing yle and immersed for 24 hors in 4 ml sterile saline. This allowed the bateria and ntrients to be drawn ot of the trays into ic Pblished by UNI SholarWorks,

5 Proeedings of the Iowa Aademy of Siene, Vol. 81 [1974], No. 3, Art PROC. low A AAD. S1. 81 ( 1974) 2 Limit: 2/inZ 1.µ ::l ~.µ ry, > ry > > rl 'i::l <tl rl <tl Ql rl rl.µ <tl ::l 'i::l ;:;:: P< rl rl Utensils Conters Coolers Fig. 6 >,.µ.><: > <tl <tl.1 E.µ Q 4-< 'i::l.1 Figre 6. Total bateria on srfaes. the saline, where more growth orred. Conts taken from this soltion showed that the old trays spported a growth of 5 bateria/ml. These data indiate that the old travs, ating very mh like sponges, absorbed bateria and 1;trients, reslting in a growth of bateria not removed by dishwashing. The soltion in whih the old trays were immersed spported almost 2 times more bateria than a similar soltion from new trays. To determine the nmber of bateria that srvive dishwashing, the following proedre was sed. The trays were taken diretly from the dishwasher and immersed in 4 ml of sterile saline in a overed ontainer for 24 hors to draw bateria from the trays into the soltion. Dring the 24-hor period, the trays were kept at 4 C to prevent mltipliation of bateria. The saline in whih old trays were immersed ontained 7, bateria/ml, while that of new trays ontained 1 bateria/ml. This stdy shows that the old trays, after dishwashing, harbored 7 times more bateria than the new trays. DISCUSSION We believe that the se of worn fiberglass trays onstittes a potential health hazard. Throgh normal se the glossy, impervios finish develops raks and wears off, exposing the poros fiberglass interior of the tray. Solble and partilate food, ntrients for the growth of bateria, beome lodged in the rather spongy interior. Dishwashing does not remove all of the food and the inslating property of the fiberglass apparently protets the bateria from the heat of the dishwasher. Staking the moist, warm trays after washing provides the ideal environment for rapid growth of bater,;a. R~&ta'.l se of worn trays reslts in the amlation of ntrients and bateria within the fiberglass interior. Persons sing the trays often pt food, sh as peant btter, bread, frits and desserts, on the trays. The health hazard lies in the possibility of pathogeni bateria beoming lodged in the trays. Food and water-borne pathogens, sh as Salmonella and Shiglla, old mltiply within the trays and ase disease. Shold a tray beome ontaminated with sh pathogens, the warm, moist, losely staked trays wold provide an ideal sitation for rapid growth and spreading of the organism from one tray to another. Throgh ontined se of these trays, many people old he infeted before the sore of ontamination was deteted. This possihi.lity is emphasized by the abndane of Gram-negative rods present in ltres obtained from freshly washed trays. Or onern over old, poros fiberglass trays as a l1otential health hazard extends to all instittional afeterias bease of the widespread se of these trays. ospital kithens, espeially, nm the risk of spreading pathogeni bateria throgh the se of worn fiberglass trays. Every instittional food fa. 4

6 Peitso et al.: Bateria of Foods and Utensils in the Lther College Food Servie BACTERIA OF Foons AND UTENSILS 97 ility shold be aware that, throgh normal se, fiberglass trays deteriorate to a point where they beome laden with bateria that srvive the dishwashing proess. We reommend that a stdy of the dration of the oter oat of the trays be made. De to srathing or marring it is possible for the interior of the trays to be exposed after a single se. vve also reommended that nonporos materials be onsidered as a replaement for fibros material now ommonly sed in the manfatre of afeteria trays. LITERATURE CITED Asso1Ano~ OF Foon A:o.;n DRUG OFFICIALS of TE UNITED STATES Reommended baterial limits for preooked beef and hiken pot pies. Asso. Food and Drg Offiials of U.S. Qart. Bll., Spp. Isse. DEPARTMENT OF DEFE:-ISE Military Speifiation MIL-M C. DEPARTMENT of EALT, EDUCATION AND WELFARE Part II-Mirobiologial qality standards for foods for whih there are no standards of identity. Federal Register. 37:238. ELLIOTT, R. P., and. D. MICENER Mirobiologial standards and handling odes for hilled and frozen foods: A review. Appl. M irobiol. 9: l\ioon, R Sbrb hambrger stdy shoks tester. la, 14A. ambrger tested by Bloomington. lb. The Washington Star (De. 1). SAF, J. M Reommended Methods for the Mirobiologial Examination of Foods. Amerian Pbli ealth Asso., Washington, D.C. U.S. PUBLIC EALT SE1w1E Proedre for the Bateriologial Examinaton of Food Utensils and/or Food Eqipment Srfaes. Tehnial Information Bll. No. 1. Pbli ealth Servie Pbliation No WISTEIC, G. A., and M. D. LECTMAN Mirobiology and man Disease. Glenoe Press, New York. Pblished by UNI SholarWorks,