APPLIED MICROBIOIloGY, Dec. 1972, p. 958-966CopyrightO 1973 American Society for Microbiology

Vol. 24, No. 6Printed in U.S.A.

Bacteriological Survey of the Blue Crab IndustryFRED A. PHILLIPS AND JAMES T. PEELER

Division of Microbiology, Food and Drug Administration, Washington, D.C. 20204

Received for publication 16 August 1972

During sanitation inspections of 46 crabmeat processing plants on the Atlanticand Gulf Coasts, 487 samples of whole crabs immediately after cooking, cookedcrabs after cooling, backed or washed (or both) crab bodies and whole crab claws,as well as 1,506 retail units of finished product were collected and analyzedbacteriologically. The 1,506 retail units (1-lb [373.24-g ] cans) included 518 cans ofregular (special) meat, 487 cans of claw meat, and 501 cans of lump meat.Statistical analyses showed that crabmeat from plants in Mississippi, Louisiana,and Texas had higher counts in 19 of 24 cases for the four bacteriological indicesthan crabmeat from plants located along the Atlantic Coast and the Gulf Coastof Florida. Aerobic plate counts of retail units collected from a previous day'sproduction were significantly higher than those collected on the day ofinspection. Regular crabmeat had consistently higher aerobic plate counts thanclaw or lump meat. When the product was handled expeditiously under goodsanitary conditions, the bacteriological results were significantly better than theresults from plants operating under poor sanitary conditions. Crabmeat pro-duced in plants operating under good sanitary conditions had the followingbacteriological content: (i) coliform organisms average most-probable-numbervalues (geometric) of less than 20 per g; (ii) no Escherichia coli; (iii) coagulase-positive staphylococci average most-probable-number values (geometric) of lessthan 30 per g in 93% of the plants; (iv) aerobic plate count average values(geometric) of less than 100,000 per g in 93% of the plants, with the counts from85% of these plants below 50,000 per g.

An outbreak of food poisoning in Chicago inSeptember, 1926, from crabmeat containingSalmonella suipestifer led to an investigationby the Food and Drug Administration (FDA) ofthe crabmeat industry in Maryland and Vir-ginia (5). It was determined that crabmeat wasbeing produced under grossly insanitary condi-tions, which were reflected by the high inci-dence of coliform organisms in the finishedproduct. In 1932, additional outbreaks of foodpoisoning in Washington, D.C., Baltimore,Md., and Philadelphia, Pa., were traced tomicrobial contamination in crabmeat (5).During the past 4 decades, the FDA has been

taking regulatory action against firms produc-ing crabmeat under insanitary conditions whenthe observed insanitary conditions were sub-stantiated by the presence of indicator orga-nisms such as E. coli and coagulase-positivestaphylococci, and by high coliform organismsand aerobic plate counts (APC). During the lastdecade, the FDA has been conducting bacterio-logical surveys to determine the numbers andtypes of certain microorganisms in food prod-

ucts and relating their presence to sanitaryconditions observed in the plants (6-9). Thispaper reports the results of such a survey of theblue crab processing industry along the Atlanticand Gulf Coasts in 1968 and 1969. The primarypurpose of this survey was to determine therelationship of industrial sanitary practices tothe microbiological quality of freshly pickedblue crabmeat that was neither frozen norpasteurized.The blue crab (Callinectes sapidus Rathbun)

is fished commercially from Maryland to southof Galveston, Texas. The greatest concentrationof the industry is in the Chesapeake Bay area.Crabs are brought to the processing plant aliveand are generally cooked immediately either inboiling water or in a steam retort. The lattermethod is most common, with cooking timesranging from 7 to 23 min at approximately 121C (approximately 15 psi). Cooked crabs areusually cooled at ambient temperatures for 3 to16 hr. Where the firms are equipped withrefrigeration facilities, the crabs are placed in acooler for storage until the beginning of opera-

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tions. Cooler temperatures are usually between4.4 and 6.7 C, although some were as high as15.6 C at the time of inspection.Two different processes are used to prepare

the crabs for removing the meat (picking): a wetprocess and a dry process. Forty-four percent ofthe firms inspected used the wet process inwhich the crabs are backed (carapace removed)and declawed. The crab bodies are then washedby hand or machine and the meat is removedimmediately, or the bodies may be refrigeratedovernight. The claws are picked separately. Thedry process, most commonly used in the Chesa-peake Bay area, does not include the washingstep. Each employee backs, declaws, and re-moves all the meat from each crab. Sometimesthe claws are picked separately as in the wetprocess.There are three general types of crabmeat: (i)

regular or special, consisting of white bodymeat; (ii) lump or backfin, consisting of thelarge pieces of body meat taken from themuscles which control the back swimming legs;and (iii) claw, consisting of the darker meattaken from the claws. The crabmeat is packedinto 1-lb metal or plastic cans with snap-on lidsor packed into 5- to 6-lb (1866.2 to 2239.4-g)plastic bags. The finished product is placed inwet ice, stored in the cooler, and shipped in wetice, usually within 3 days. The crabmeat in theplastic bags is sold for further processing intocrabcakes, deviled crabs, etc.; crabmeat in the1-lb cans is intended for the retail market.

MATERIALS AND METHODSCollection of samples. A total of 53 inspections of

46 processing plants were made by inspector-microbi-ologist teams during May to October in 1968 and1969. The inspected plants were located in threegeographical areas: Baltimore (Maryland, Virginia,and North Carolina); Atlanta (South Carolina, Geor-gia, and Florida); New Orleans-Dallas (Mississippi,Louisiana, and Texas). The majority of the inspectedplants were located on the Gulf and southern AtlanticCoasts.

During each inspection, samples were collectedaseptically at various stages of processing. Thesesamples were limited to whole crabs immediatelyafter cooking, whole cooked crabs after cooling over-night, backed or washed (or both) crab bodies, andwhole crab claws. Retail units (1-lb cans) of each typeof crabmeat were collected from that produced on theday of inspection. When available, retail units of atleast one type of crabmeat produced on a date prior tothe inspection were collected. Immediately aftercollection, the samples were placed in wet ice in thefirm's cooler. After the inspection was completed,samples were packed in an ice chest with wet ice andtransported to the laboratory. The analyses, in whichfour FDA district laboratories participated, were

started within 48 hr after collection. A total of 1,506retail units were collected including 518 cans ofregular meat, 487 cans of claw meat and 501 cans oflump meat. Also, 487 samples were collected of wholecrabs immediately after cooking, cooked crabs aftercooling, backed or washed (or both) crab bodies,and whole crab claws.

Analytical procedures. Aerobic plate counts,coliform, E. coli, and coagulase-positive staphylococ-cus counts were determined on samples by the officialfirst action method for the examination of frozen,chilled, precooked, or prepared foods (41.013-41.018)of the Association of Official Analytical Chemists (1).

Correlation of bacterial findings with inspec-tional evidence. Establishment inspection reportsprepared by the inspectors were evaluated, and thefirms were classified as good or poor based on thedegree of the insanitary conditions observed. Plantswhich received good ratings were not necessarilyoperating under ideal sanitary conditions, but theiroperations were visibly cleaner than those of poorplants. The bacteriological results were statisticallyanalyzed to determine if significant differences oc-curred (i) between plants rated good versus thoserated poor; (ii) among the three types of crabmeatexamined; (iii) among the three geographical areas;and (iv) between production lots.

Statistical procedures. Tests of significance wereperformed by using logarithms of counts per gramand percentage of positive units. The logarithms ofthe counts were assumed to be normally distributed,and tests of significance and confidence limits werecomputed by using normal theory (Ostle [3D. Thedifferences between good and poor plants and be-tween geographical areas were examined by using thewithin-lot variation as the estimate of random error.

Since a large number of observations were reportedas <3, frequency distributions and percentage ofpositive units were found to be more useful inevaluating the differences for coliform organisms, E.coli, and coagulase-positive staphylococci.

RESULTSPlants operating under poor sanitary condi-

tions displayed many poor employee practices,building and equipment defects, and opera-tional inadequacies which contributed to con-tamination of the finished product. Flies andother insects entered through various windowsand door openings. Equipment such as cartsand dollies used to transport cooked crabs inwire baskets were rusted and pitted and werevery seldom cleaned or sanitized. Cooked crabscame into contact with unsanitized objects suchas retort hoist chain, cooler walls, employees'clothing, and rusted storage racks, and wereusually air-cooled in areas subject to dust andflies. Cooked crabs frequently were not rotatedon the picking tables, so that some crabs re-mained at room temperature for several hours.In addition, some picked crabmeat was left atroom temperature for several hours before

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PHILLIPS AND PEELER

being iced.Other practices observed in poor plants in-

cluded failure of employees to wash and sani-tize their hands after touching unsanitized ob-jects, reuse of paper towels and rags, andchlorine dip stations for hands and equipmentwith less than an effective amount of residualchlorine. Floor filth was introduced to cookedcrabs by splatter from water during clean-upoperations or by contact of baskets of crabsdirectly with the floor. Crab claws were left atroom temperature most of the day and pickedlast. In contrast, the plants operating undergood conditions of sanitation had fewer insani-tary infractions by employees, handled theproduct quickly, and maintained buildings andequipment in reasonably good condition. How-ever, some of the plants classified as good hadvery few employees present on the day ofinspection, and other plants operated only partof a day. Thus, the opportunity for bacterialbuildup was minimized.The cooking times and temperatures, with

the exception of the processing plants thatboiled crabs, were usually difficult to establishdue to either the lack or the malfunctioning, or

both, of temperature and pressure gauges. Inmost cases, the cooking times for the crabs were

not sufficient to sterilize them. Sample resultsof whole crabs collected immediately aftercooking showed that 83% of the 104 samplescollected had APC values below 10,000/g. Threesamples were over 100,0001g.

Table 1 shows a comparison of bacteriologicalresults of samples collected at various stages ofprocessing for plants observing good and poor

sanitary practices. In the plant operating undergood sanitary practices, crabs were cooked for23 min at approximately 121 C, which was

sufficient to reduce the population density toless than 300/g. The plant operating under poor

sanitary conditions cooked the crabs for 10 minat the same temperature, and the geometricaverage APC of two samples was 1,800/g; one

sample had an APC of 310,000/g. All samples ofcooked crabs were free of coliform organisms, E.coli, and coagulase-positive staphylococci. Theresults for the poor plant show an increase incounts for all four bacteriological indices afterbacking, washing, and cooling overnight. Theresults for the good plant showed an increasein APC after overnight cooling and the appear-

ance of low numbers of coliform organisms, butthe samples contained no E. coli and only lownumbers of coagulase-positive staphylococciafter handling by the employees removing themeat. The low level of counts in the good plantwas probably due to the expeditious handling ofthe crabs. The whole claws were grossly mishan-dled in the poor plant (Table 1). They were leftat room temperature for several hours andallowed to touch unsanitized or rusty equip-ment, or both. Since claws are more difficult topick than are the bodies, they remained on thepicking tables at room temperature for longerperiods of time.

TABLE 1. Comparison of bacteriological results at various stages ofprocessing for plants observing good andpoor sanitary practices

Good plant Poor plant

Coag- Coag-Coli- E. ulase- Coli E ulase-

Description of samples" forms coli positive forms coli positive

(MPN/ (MPN/ staphy- APC/g (MPN/ (MPN/ staphy- APC/gg g) lococci

g glococcig~ ) (MPN/ g g) (MPN/

g) g)

Whole cooked crab after retorting <3 <3 <3 <300 <3 <3 <3 1,800Backed cooked crabs after wash-

ing ......................... 1.9 <3 <3 400 240 25 <3 340,000Backed cooked crabs after cooling

overnight (3.3 C).<3 <3 <3 100,000 510 3 8.1 11,000,000Backed cooked crabs from picking

table.1.9 <3 <3 5,500 330 2.7 23 890,000Cooked crab bodies from pickingemployee.1.9 <3 1.9 1,200 220 <3 3.9 2,000,000

Whole claws after cooling overnight(3.3 C) ........................ 1.9 <3 <3 3,200 > 1,100 1.9 16 19,000,000

Whole claws from picking table .... 3.6 <3 <3 7,400 100 <3 <3 750,000

a Results are geometric averages of two samples collected at each site.5MPN, most-probable-number.

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APC (geometric means) and 99% confidencelimits for three geographical areas and threetypes of meat produced in good and poor plantsare shown in Table 2. Significant differencesbetween the New Orleans-Dallas area and theother two areas were observed for regular andlump meat in both good and poor plants byDuncan's (2) test. This difference was probablydue to the higher mean temperature and hu-midity in the New Orleans-Dallas area, whichafforded better incubation conditions. The clawmeat did not show significant differencesamong the New Orleans-Dallas, Baltimore, andAtlanta areas for good plants, but did showsignificant differences between good and poorplants. This was probably due to the differencesin operating procedures in the various areas.Some poor plants in the Baltimore area allowedthe claws to remain in wooden baskets all day atroom temperature and were picked last,whereas in the other areas the claws werepicked simultaneously with the crab bodies.When the claws were handled expeditiously andkept cool, the counts remained at a low level allthrough the process. As further evidence of thedifferences between good and poor plants, theoverall APC geometric mean per gram was: forregular meat, 18,000 for good plants and 190,000for poor plants; for claw meat, 15,000 for goodplants and 170,000 for poor plants; for lumpmeat, 7,900 for good plants and 75,000 for poorplants. The overall within-lot variance in log,0units was about the same for all three types ofmeat. Values for regular, claw, and lump meatwere 0.37594, 0.34005, and 0.35397, with 465,436, and 444 degrees of freedom.

Tables 3 and 4 summarize the results of thebacteriological examinations of regular meatretail units from plants operating under goodand poor sanitary conditions, respectively.Most of the samples from good plants con-

tained coliform organisms and coagulase-posi-tive staphylococci, but the geometric averageswere very low because most of the retail unitswere negative (Table 3). The APC geometricaverages were below 50,000/g with the excep-tion of plant no. 4. The higher APC average inthis sample could not be explained, since theclaw and lump meat collected the same day hadmuch lower counts. None of the retail unitsfrom the good plants contained E. coli.Table 5 shows the percentage of good and

poor plants with aerobic plate counts in sevencount ranges for the three types of crabmeat.Regular meat from good plants had APC values(geometric means) below 100,000/g 93% of thetime; all samples of claw and lump meat werebelow this level. This compares with 41, 34, and51% for regular claw and lump meat (poorplants), respectively, which were below100,000/g. The regular meat APC values (geo-metric means) from poor plants were above1,100,000/g 23% of the time, with the claw andlump meat each above this level 5% of the time.Table 6 summarizes the results for coliform

organisms, E. coli, and coagulase-positivestaphylococci by the percentage and number ofplants having geometric averages in four countranges. All coliform counts (geometric means)for all three types of crabmeat from good plantswere below 20/g (most-probable number[MPN D. Coliform counts (geometric means) forregular, claw, and lump meat were below 10/g(MPN) in 39, 42, and 49% of the poor plants,respectively, while the counts were above 50/g(MPN) in 36, 21, and 23% of the poor plants. Allvalues (geometric means) for E. coli, good, andpoor plants, were below 10/g (MPN). Coagu-lase-positive staphylococci values (geometricmeans ) for regular, claw, and lump meat were

below 10/g in 79, 69, and 77% of the goodplants, respectively. The counts were below

TABLE 2. Aerobic plate count per gram geometric means for three geographical areas and three types ofcrabmeat produced in good and poor plants

Reagular T Claw LumpSource Mean 99% Confi- Mean 99% Confi- Mean 99% Confi-

dence limits dence limits dence limits

Good plantsBaltimore .............. 16,000 (70)a 10,000-26,000 10,000 (57) 6,000-19,000 9,000 (57) 5,400-15,000Atlanta ................ 18,000 (58) 11,000-27.000 21,000 (50) 14,000-32,000 5,800 (49) 4,000-8,400New Orleans-Dallas .... 45,000 (10) 39,000-53,000 21,000 (10) 8,200-51,000 18,000 (10) 6,100-51,000

Poor plantsBaltimore .............. 140,000 (85) 95,000-220,000 250,000 (85) 140,000-440,000 53,000 (85) 37,000-77,000Atlanta ................ 140,000 (160) 100,000-180,000 180,000 (150) 140,000-230,000 66,000 (160) 49,000-90,000New Orleans-Dallas .... 320,000 (135) 230,000-440,000 120,000 (135) 99,000-160,000 110,000 (140) 77,000-150,000

a Number of observations per mean.

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TABLE 3. Results of analysis of regular crabmeat collected from plants operating under good sanitaryconditions

MPN ofMPN of MPN of coagulase-

No.o'coiform E. clilg positive APC/gPlant Area units' organismslg . cometiC/ staphylo- (geometric Range of APC/g

(geometric (emetric cocci/g mean)memean) ean (geometric

mean)

1 BLTc 10 4.6d (3)e <3 2.8 (4)e 25,000 2,700-18,000,0002 BLT 10 2.2 (2) < 3 1.8 (4) 19,000 6,500-67,0003 BLT 10 3.7 (6) <3 <3 4,300 1,300-19,0004 BLT 10 <3 < 3 < 3 150,000 2,700-740,0005 BLT 10 <3 <3 1.8 (3) 8,900 4,300-42,0003 BLT 10 1.7 (4) <3 6.6 (9) 11,000 5,000-26,0006 BLT 10 <3 <3 7.4 (8) 9,500 3,400-39,0007 ATL 10 3.2 (7) <3 1.1 (1) 17,000 5,100-430,0008 ATL 8 1.8 (3) < 3 1.8 (2) 18,000 5,500-68,0009 ATL 10 3.2 (5) <3 14.0 (8) 17,000 6,100-150,00010 ATL 10 2.0 (3) <3 37.0 (8) 17,000 5,600-130,0009 ATL 10 4.1 (7) <3 3.4 (6) 17,000 3,000-150,0008 ATL 10 1.6 (3) <3 1.2 (1) 16,000 3,800-350,000

11 NOL-DAL 10 11.0 (7) <3 29.0 (9) 45,000 20,000-110,000

a A unit, 1-lb retail package." MPN, most-probable-number.C BLT, Baltimore; ATL, Atlanta; NOL-DAL, New Orleans-Dallas.d Indicates that one or more unit(s) had an MPN of >1,100/g. In these cases, the value of 1,100/g was used

to calculate the geometric mean.e Number in parentheses indicates number of units positive.

10/g (MPN) in 54, 55, and 62% of the poor

plants, and above 50/g (MPN) in 21, 24, and15% of the poor plants. Since coagulase-posi-tive staphylococci are normally found on thehuman skin and crabmeat is picked by hand, itwas expected that these organisms would bepresent in the finished product. In some cases,

coagulase-positive staphylococci counts fromfinished product units within a lot variedgreatly, even when collected from good plants.This could be due, in part, to the difference inthe microflora of each employee's hands, sincemost retail units of finished product repre-

sented crabmeat picked by one employee. Thisdifference was demonstrated by Puncocharand Pottinger (4). However, where the productwas handled expeditiously and under goodsanitary conditions, the finished productcounts were usually low.Tables 7 and 8 show the percentage of retail

units positive for coliform organisms, E. coli,and coagulase-positive staphylococci for goodand poor plants, respectively, and compareproducts from the three geographical areas. Inall three analytical categories and all types ofcrabmeat, except the coliform results of clawmeat from the Atlanta area poor plants, thepercentage of units positive was significantlyhigher in the New Orleans-Dallas area than in

the Baltimore and Atlanta areas, regardless ofwhether the retail units were from good or poorplants. There was very little difference among

the types of meat for all geographical areas andall analytical categories. Some differences were

noted between good and poor plants in thepercentage of units positive for coliform orga-nisms. The percentage of units positive for E.coli in the Baltimore and Atlanta area poorplants was relatively low compared with theNew Orleans-Dallas area, and, as stated before,the products of the good plants had no E. coli.Coagulase-positive staphylococci results didnot vary significantly, although the poor plantshad a slightly higher percentage of units posi-tive for most of the types of meat in theBaltimore and Atlanta areas. The retail unitsfrom the New Orleans-Dallas area good plants,however, were higher than the units from thepoor plants. This could be due to the fact thatfewer units were examined from good plants,since coagulase-positive staphylococci resultswere shown to vary considerably between lots,regardless of whether the samples were fromgood or poor plants.

Tests were performed on geometric means

observed on retail units packed the day of theinspection and units packed on a date prior tothe inspection. The APC results in Table 9

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BACTERIOLOGICAL SURVEY OF BLUE CRAB INDUSTRY 963

TABLE 4. Results of analysis of regular crabmeat collected from plants operating under poor sanitaryconditions

____________*~. MPN ofMPN of MPN of coagulase-

No. of coliform E. coliljg positive APC/gPlant Area organisms/g (geome ticstaphylo- (geometric Range ofAPC/g

(geometric ) Cocci/g mean)mean)' mean (geometric

mean)

12.0 (9)d95.1 (5)<3

1.3 (1)11.0 (8)

200.0 (9)2.4 (3)

38.0 (10)24.0 (9)1.2 (1)6.9 (7)4.5 (6)4.1 (4)1.9 (3)

16.0 (9)10.0 (9)9.5 (8)2.1 (3)7.0 (5)4.5 (5)3.8 (4)6.2 (8)1.5 (2)

11.0 (8)36.0 (9)4.9 (7)2.3 (4)

24.0 (8)43.0 (8)

450.0 (5)620.0 (10)72.0 (10)

260.0 (10)1.3 (2)

21.0 (10)1,070.0 (9)

74.3 (10)9.5 (8)7.3 (9)

36,00050,000

1,000,00035,000

2,200,0001,100,000

7,100150,00096,000190,00022,00094,00069,000

1,200,000120,00038,00089,000360,00033,00014,000

140,0002,100,0001,200,000380,00047,000

360,000620,00017,000

120,0002,000,000

38,00074,000

270,000420,000700,000

1,500,0003,800,000110,000

2,500,000

12,000-240,00033,000-71,0001,300-18,000,0005,900-250,000

840,000-8,800,000300,000-3,600,000

5,000-11,00019,000-3,000,0002,600-480,000

34,000-2,000,0006,100-690,0006,900-750,0009,000-770,000

440,000-6,900,00033,000-1,200,0004,300-580,000

30,000-400,00014,000-11,000,00011,000-75,0002,400-790,0007,000-2,400,000

540,000-9,500,000330,000-5,600,00036,000-2,700,00012,000-240,000

100,000-12,000,00055,000-3,300,0008,800-40,00012,000-310,000

950,000-16,000,00030,000-61,0009,600-420,000

110,000-570,00094,000-4,000,00057,000-3,500,00065,000-16,000,00050,000-97,000,00027,000-1,400,000

400,000-5,800,000

aA unit, 1-lb retail package.MPN, most-probable-number.

c BLT, Baltimore; ATL, Atlanta; NOL-DAL, New Orleans-Dallas.d Number in parentheses indicates number of units positive.eIndicates that one or more units had an MPN of >1,100/g. In these cases, the MPN value of 1,100/g was

used to calculate the geometric mean.

indicate that the previous day's samples tend tohave a higher mean count per gram. Thisdifference was significant for all three types ofmeat. APC geometric means from a previousday's production were higher than those ob-tained on the day of inspection in 14 of 21

instances for the plants packing regular meat,11 of 12 instances for plants packing claw meat,and 5 of 8 instances for plants packing lumpmeat. This difference has been observed previ-ously with other food samples analyzed byFDA, and seems to indicate that most firms are

VOL. 24, 1972

121314151617181419202122232425262722272829302431323334353637383940414243444546

BLTcBLTBLTBLTBLTBLTBLTBLTBLTATLATLATLATLATLATLATLATLATLATLATLATLATLATLATLATLNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DALNOL-DAL

1051010101010101010101010101010101010101010101010101010105101010101010101010

4.7 (6)d<310.0 (7)15.0 (8)

311.Oe (10)23.0 (9)2.0 (3)4.5 (6)1.6 (2)

100.Oe (10)1.7 (4)2.9 (5)4.8 (8)6.2 (8)12.0 (10)1.3 (2)2.8 (4)5.8 (6)

19.0e (7)2.1 (3)

120.Oe (10)450.Oe (10)12.Oe (7)90.0 (10)38.0 (10)20.0 (9)

140.Oe (10)61.0 (10)

320.Oe (10)500.0 (5)

1.7 (3)11.0 (6)33.0 (10)83.0 (10)89.1 (10)74.7 (10)98.6e (9)26.8 (9)

390.8e (10)

<3<32.4 (4)d

<31.4 (2)2.5 (4)1.2 (1)

<3<3

1.1 (1)<3<3<3<3

1.1 (1)<3<3

1.1 (1)<3<3<3

1.5 (1)<3<3

1.5 (3)2.6 (5)2.8 (4)2.5 (4)3.5 (4)3.8 (3)1.1 (1)

<31.1 (1)1.6 (3)1.4 (2)1.4 (1)6.4 (4)1.4 (2)

10.5 (7)II I I I

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TABLE 5. Percentage of plants with aerobic plate counts (geometric means) in severs count ranges

Count ranges of APC/g Good plants Poor plants(geometric mean) Regular Claw Lump Regular Claw Lump

0-100,000 92.9 100.0 100.0 41.0 34.2 51.3110,000-200,000 7.1 0.0 0.0 17.9 18.4 17.9210,000-400,000 0.0 0.0 0.0 12.8 21.0 10.3410,000-600,000 0.0 0.0 0.0 0.0 13.1 5.1610,000-800,000 0.0 0.0 0.0 2.6 7.8 5.1810,000-1,000,000 0.0 0.0 0.0 2.6 0.0 5.1

1,100,000-up 0.0 0.0 0.0 23.1 5.2 5.1

No. of plants 14 13 13 39 38 39

TABLE 6. Percentage and number of plants having geometric means in four count ranges for coliformorganisms, E. coli, and coagulase-positive staphylococci

Count Regular Claw Lump

conditions range No of No. of | No. of | o(emti)plants plants plants

Coliform organisms Good plants 0-10 13 92.9 12 93.0 13 100.011-20 1 7.1 1 7.0 0 0.0

Poor plants 0-10 15 38.5 16 42.1 19 48.711-30 8 20.5 8 21.1 9 23.131-50 2 5.1 6 15.8 2 5.251-up 14 35.9 8 21.0 9 23.0

E. coli Good plants 0-10 14 100.0 13 100.0 13 100.0Poor plants 0-10 39 100.0 38 100.0 39 100.0

Coagulase-positive Good plants 0-10 11 78.6 9 69.2 10 76.9staphylococci 11-30 2 14.2 3 23.1 1 7.7

31-50 1 7.1 0 0.0 1 7.751-up 0 0.0 1 7.7 1 7.7

Poor plants 0-10 21 53.8 21 55.3 24 61.511-30 7 17.9 7 18.4 7 17.931-50 3 7.7 1 2.6 2 5.151-up 8 20.5 9 23.7 6 15.4

on their best behavior during inspection and areaware of certain good manufacturing practices.Although the possibility exists that the higher

mean counts of the previous day's productioncould have been due to the additional 24-hrincubation period, even though the product wasstored in ice, the probability of significantbacterial growth during this period is not likely.

DISCUSSIONTobin and McCleskey (10) showed that the

steaming process destroyed all coliform orga-nisms and greatly reduced the numbers of otherbacteria in the whole crabs. The results fromthe few samples of cooked crabs analyzed in oursurvey confirmed their findings. Furthermore,our survey detected no coagulase-positivestaphylococci after the crabs were cooked

either by steam retort or boiling. Thus, thepresence of large numbers of either coliformorganisms or coagulase-positive staphylococciin the finished product indicates insanitaryconditions during processing.As a result of a study of the sanitary require-

ments for crabmeat processing plants, Punco-char and Pottinger (4) reviewed the state of theindustry and also made suggestions for techno-logical improvements. The cooking times theyreported ranged from 15 to 22 min at pressuresof 12 to 18 psi, and were sufficient to kill allbacteria except for a few heat-resistant spore-formers. However, our survey indicated that theindustry is generally cooking for 8 to 12 min atapproximately 15 psi and, therefore, is notgetting a sterile cook. Their study also showed amarked increase in total counts on cooked crabscooled overnight. Industry practices have

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BACTERIOLOGICAL SURVEY OF BLUE CRAB INDUSTRY

changed in that most firms air-cool for only a

few hours and then refrigerate, rather thanair-cool all night. However, the coolers usednow are not of a construction design to insuresanitary conditions, and the crabs contact rustyracks, cooler walls, and sometimes raw fish usedas crab bait. Since the crabs are not generallysterile when placed in the coolers, which are

usually above 4.4 C, there is the possibility ofbacterial growth during the overnight cool-down cycle. This may explain why the samplesof cooked, cooled crabs in our survey showed a

marked increase in counts over the cookedcrabs taken out of the retort.

Punochar and Pottinger (4) also studied themicroflora of the employee's hands and foundthat 44% were carriers of E. coli. Washing withsoap and water followed by sanitizing in a

chlorine solution greatly reduced the microfloraof the hands, if done periodically throughoutthe day. Many of the plants inspected hadinadequate toilet facilities. Some had no handwashing facilities in or near the toilets, whichmeant the employees had to enter the proces-sing area to wash their hands. Doors, faucets,and other objects handled before washing couldthen become a source of contamination with E.coli and other bacteria. The employees also

TABLE 7. Percentage of retail units positive for coliform organisms, E. coli, and coagulase-positivestaphylococci in three geographical areas collected from plants operating under good sanitary conditions

Aranen 99% Con-Organism Area Regular Claw Lump | Aid|nte

Coliform organisms Baltimore 21.4a (70)b 10.5 (57) 14.0 (57) 25.2 (341) 20-34Atlanta 48.3 (58) 36.0 (50) 22.4 (49) .New Orleans- 70.0 (10) 90.0 (10) 60.0 (10) 73.3 (30) 48-87

Dallas

E. coli Baltimore 0 (70) 0 (57) 0 (57) 0Atlanta 0 (58) 0 (50) 0 (49) 0New Orleans- 0 (10) 0 (10) 0 (10) 0

Dallas

Coagulase-positive Baltimore 40.0 (70) 42.1 (57) 40.4 (57)staphylococci Atlanta 44.8 (58) 56.0 (50) 40.8 (49) 43.7 (341) 35-50

New Orleans- 90.0 (10) 80.0 (10) 100.0 (10) 90.0 (30) 67-96Dallas

a Percentage of retail units positive.° Number of retail units.

TABLE 8. Percentage of retail units positive for coliform organisms, E. coli, and coagulase-positivestaphylococci in three geographical areas from plants operating under poor sanitary conditions

Aemen 99% Con-Organism Area Regular Claw Lump Area mean fidence

%) interval

Coliform organisms Baltimore 60.0a (85)" 52.9 (85) 48.4 (85) 65.1 (725)Atlanta 71.3 (160) 79.3 (150) 63.1 (160) 59-70New Orleans- 90.4 (135) 90.4 (135) 85.0 (140) 88.5 (410) 85-93

Dallas

E. coli Baltimore 12.9 (85) 7.1 (85) 7.1 (85)6.3 (725)

Atlanta 4.4 (160) 6.0 (150) 4.4 (160) . 3-8New Orleans- 30.4 (135) 22.2 (135) 15.0 (140) 22.4 (410) 17-26

Dallas

Coagulase-positive Baltimore 64.7 (85) 65.9 (85) 51.8 (85) 55.6 (725)staphylococci Atlanta 56.9 (160) 60.7 (150) 40.6 (160) . 50-60

New Orleans- 81.5 (135) 83.0 (135) 81.4 (410) 82.0 (410) 74-86Dallas

a Percentage of retail units positive." Number of retail units.

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PHILLIPS AND PEELER

TABLE 9. Comparison of APC results from samplesproduced on day of inspection and samples of a

previous day's production

No. ofplants

Geometric Geometric havingSource means, same means, pre- t means

day vious test previouswaylOUS aay~~day >sameday

Regular .... 250,000 (210)' 340,000(199) 3.82' 14/21Claw ... 76,000 (120) 200,000 (103) 7.71' 11/12Lump ... 45,000 (63) 120,000 (55)4.03' 5/8

aFinished product units per mean.b Significant at the a = 0.01 level.

handled many unsanitized objects duringprocessing and continued picking or packingcrabmeat without washing or sanitizing theirhands.

Picking and packing tables can also be asource of contamination. Puncochar and Pot-tinger (4) recommended that the tables becleaned and sanitized each time the supply ofcrabs is exhausted. This procedure is seldomfollowed; if it were, two problems could besolved. (i) It would minimize bacterial buildupon the table surface, and (ii) it would allow forthe rotation of crabs so that those at the bottomof a pile would not remain at room temperaturefor long periods of time.Although significant differences were ob-

served between certain geographical areas, re-sults of this survey indicate that crabmeatprocessors should be able to achieve a productwith good microbiological quality by applyingsimple rules of sanitation. Plants operatingunder good sanitary conditions produced crab-meat with average MPN values (geometric) ofless than 20 coliform organisms per g, no E. coli,coagulase-positive staphylococci average MPNvalues (geometric) of less than 30/g 93% of the

time, and an average APC (geometric) of lessthan 100,000/g in 93% of the plants, with 85%of the plants below 50,000/g. Our findingsconfirm the premise previously established bySurkiewicz et al. (6-9) that insanitary condi-tions during the processing of food products arereflected in the bacteriological results of thefinished product.

ACKNOWLEDGMENTS

We thank the inspectors and microbiologists in Baltimore,Atlanta, New Orleans, and Dallas Districts for their fullcooperation and professional assistance, which were essentialfor the conduct of this survey.

LITERATURE CITED

1. AOAC. 1970. Official methods of analysis of the Asso-ciation of Official Analytical Chemists, 11th ed.Washington, D.C.

2. Duncan, D. B. 1955. Multiple range and multiple F tests.Biometrics 11:1-42.

3. Ostle, B. 1963. Statistics in research, 2nd ed. Iowa StateUniversity Press, Ames, Iowa.

4. Puncochar, J. F., and S. R. Pottinger. 1954. Commercialproduction of meat from the blue crab (Callinectessapidus). A study of sanitary requirements of handlingoperations and suggestions for technological improve-ment. U.S. Dept. Interior Fish and Wildlife Service,Commercial Fisheries TL8.

5. Slocum, G. G. 1955. Bacteriology of crabmeat as relatedto factory sanitation. Ass. Food Drug Officials, U.S.Quart. Bull. 19:43-50.

6. Surkiewicz, B. F. 1966. Bacteriological survey of thefrozen prepared foods industry. I. Frozen cream-typepies. Appl. Microbiol. 14:21-26.

7. Surkiewicz, B. F., R. J. Groomes and A. P. Padron. 1967.Bacteriological survey of the frozen prepared foodsindustry. III. Potato products. Appl. Microbiol.15:1324-1331.

8. Surkiewicz, B. F., R. J. Groomes, and L. R. Shelton, Jr.1968. Bacteriological survey of the frozen preparedfoods industry. IV. Frozen breaded fish. Appl. Micro-biol. 16:147-150.

9. Surkiewicz, B. F., J. B. Hyndman, and M. V. Yancey.1967. Bacteriological survey of the frozen preparedfoods industry. II. Frozen raw breaded shrimp. Appl.Microbiol. 15:1-9.

10. Tobin, L. C., and C. S. McCleskey. 1941. Bacteriologicalstudies of fresh crabmeat. Food Res. 6:157-167.

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