Evaluation of Dry Sheet Medium Culture Plate (Compactdry TC) Method for Determining Numbers of Bacteria in Food Samples

2000 ◽  
Vol 63 (5) ◽  
pp. 665-667 ◽  
Author(s):  
SHINGO MIZUOCHI ◽  
HIDEMASA KODAKA
Keyword(s):  
Cold Water ◽  
Correlation Coefficients ◽  
Food Samples ◽  
Water Soluble ◽  
Gelling Agent ◽  
Plate Count ◽  
Aerobic Bacteria ◽  
Suitable Alternative ◽  
Standard Plate Count ◽  
Standard Plate

The Compactdry, a ready-to-use and self-diffusible dry medium sheet culture system, has been developed by the Nissui Pharmaceutical Co. Ltd. for enumerating bacteria in food. The Compactdry consists of special spread sheet with culture medium that is the same as standard method nutrients, a cold water-soluble gelling agent, and a unique plastic dish. The procedure for bacterial examination in a sample solution (1 ml) is to just inoculate a test solution into the center of the self-diffusible medium and incubate at 35°C for 48 h. The Compactdry TC (CTC) for the enumeration of total aerobic bacteria from 97 food samples was compared with the standard plate count (SPC) method and 3M Petrifilm aerobic count plates (PAC). The correlation coefficients between the CTC and SPC method, the CTC and PAC, and the PAC and SPC method were 0.97, 0.99, and 0.97, respectively. The Compactdry system is useful for the enumeration of total aerobic bacteria in food and may be a possible suitable alternative to the conventional pour-plate or the Petrifilm plate methods.

Evaluation of the 3M Dry Medium Culture Plate (Petrifilm™ SM) Method for Determining Numbers of Bacteria in Raw Milk1

1984 ◽  
Vol 47 (10) ◽  
pp. 753-755 ◽  
Author(s):  
R. E. GINN ◽  
V. S. PACKARD ◽  
T. L. FOX
Keyword(s):  
Cold Water ◽  
Correlation Coefficients ◽  
Raw Milk ◽  
Water Soluble ◽  
Gelling Agent ◽  
Plate Count ◽  
Suitable Alternative ◽  
Standard Plate Count ◽  
Standard Plate ◽  
Indicator Dye

The 3M Company has developed a sample-ready system (Petrifilm ™ SM) for enumerating bacteria in milk and other food products. The testing unit consists of Standard Methods culture medium coated onto a base film and overlaid with a second film coated with a cold-water-soluble gelling agent and tetrazolium indicator dye. As such, the system is ready to accept samples of product. A pipette or 0.001-ml plate loop continuous pipetting syringe can be used for applying samples. In this study, both methods of sample addition were used and results compared with those of the Standard Plate Count (SPC) and standard Plate Loop (PL) methods for determining bacteria numbers in raw milk. In total, 108 samples were analyzed in duplicate by each of the four methods. The correlation coefficients (r) between the 3M-SPC and SPC, 3M-PL and PL, 3M-PL and SPC and PL and SPC were 0.946, 0.935, 0.941, and 0.974, respectively. Repeatability, as measured by mean log10 variance for duplicate determinations, was essentially the same for the four methods, and in all instances less than 0.005. The mean log10 differences between the SPC and 3M-SPC, and SPC and 3M-PL were, respectively, −0.177 and −0.168. The preceding statistical criteria suggest the Petrifilm™ SM method to be a suitable alternative to the SPC or the PL procedure.

MICROBIAL COUNTS OF INDIVIDUAL PRODUCER AND COMMINGLED GRADE A RAW MILK1

1973 ◽  
Vol 36 (3) ◽  
pp. 146-151 ◽  
Author(s):  
H. E. Randolph ◽  
B. K. Chakraborty ◽  
Otto Hampton ◽  
D. L. Bogart
Keyword(s):  
Statistical Significance ◽  
Correlation Coefficients ◽  
Raw Milk ◽  
Microbial Populations ◽  
Plate Count ◽  
Microbial Counts ◽  
Standard Plate Count ◽  
Standard Plate ◽  
Bulk Tank ◽  
Highly Correlated

Microbial populations of Grade A raw milk samples from 105 individual producers and 74 bulk tank trucks (commingled) were enumerated by Standard Plate Count (SPC), psychrotrophic count (PBC), coliform count (CC), laboratory pasteurized count (LPC), thermophilic count (TBC), yeast and mold count (Y&M), and special penicillin (PEN) and crystal violet tetrazolium (CVT) agar count procedures. In addition, microbial populations were determined by the SPC, PBC, PEN, and CVT procedures after preliminary incubation (PI) of samples. Initial mean counts obtained on individual producer samples were generally lower than those for commingled samples. However, producer samples had higher mean counts after PI. Growth ratios were lower for commingled than for individual producer samples indicating slower growth during PI. Results obtained by the PBC, PEN, and CVT procedures were similar when viewed as correlation coefficients, distribution of samples according to microbial counts, mean counts, and growth ratios during PI. Before PI, the correlation between these three tests was poor and lacked statistical significance when the PBC was <50,000/ml. After PI, the tests were highly correlated (P<0.01) and the r values ranged from 0.8 to 0.9 for samples with PBC levels above 108/ml.

A New Medium for Determining the Total Plate Count in Food

1999 ◽  
Vol 62 (12) ◽  
pp. 1404-1410 ◽  
Author(s):  
C. F. SMITH ◽  
D. E. TOWNSEND
Keyword(s):  
Linear Regression Analysis ◽  
Alternative Methods ◽  
Plate Count ◽  
Most Probable Number ◽  
Suitable Alternative ◽  
Probable Number ◽  
Standard Plate Count ◽  
Plate Count Agar ◽  
Total Plate Count ◽  
Standard Plate

SimPlate for Total Plate Count–Color Indicator (TPC-CI, IDEXX Laboratories, Inc., Westbrook, Me.) is a new medium that incorporates the redox dye resazurin to detect and quantify bacteria in food. Enumeration is achieved by the most probable number method using a SimPlate device. Viable bacteria are detected in each well of the SimPlate device by the biochemical reduction of resazurin, which is blue, to the pink resorufin or the clear dihydroresorufin indicators. Results after 24 h of incubation for TPC-CI are highly correlated with standard plate count agar after 48 h of incubation. Correlation coefficients from studies conducted at five laboratories ranged from 0.94 to 0.98 in side-by-side comparisons against standard plate count agar. Four additional test sites, using alternative methods for determining the aerobic plate count in food, reported similar results in comparison studies (r = 0.91 to 0.97). The slopes from linear regression analysis at all sites ranged from 0.91 to 0.98, with y intercepts ranging from 0.11 to 0.84. Samples used for the validation of TPC-CI included raw food products (i.e., liver and grains), which may contain natural enzymes that interfere with enzyme-based detection methods. No interference was seen from the foods tested. These results suggest that TPC-CI is a suitable alternative to existing plate count methods and has reduced incubation time.

Evaluation of the Spiral Plating Method for the Enumeration of Microorganisms throughout the Manufacturing and Ripening of a Raw Goat's Milk Cheese

2002 ◽  
Vol 65 (2) ◽  
pp. 339-344 ◽  
Author(s):  
CARLOS ALONSO-CALLEJA ◽  
JAVIER CARBALLO ◽  
ROSA CAPITA ◽  
ANA BERNARDO ◽  
MARÍA LUISA GARCÍA-LÓPEZ
Keyword(s):  
Correlation Coefficients ◽  
Plate Count ◽  
Standard Plate Count ◽  
Goat’S Milk ◽  
Plating Method ◽  
Standard Plate ◽  
Microbial Group ◽  
Goat's Milk ◽  
Microbial Groups ◽  
Spiral Plate

A statistical comparison of the spiral plate count (SPLPC) and the standard plate count (SPC) methods for enumeration of microorganisms in raw goat's milk cheese throughout its manufacturing and ripening was carried out. Enumeration of mesophiles, lactic acid bacteria (presumptive lactococci, presumptive leuconostocs, and presumptive lactobacilli), Micrococcaceae, Enterobacteriaceae, and molds and yeasts was carried out for milk, curd, and 2-, 5-, 10-, 17-, and 27-day-old cheeses. Average counts for the SPLPC and SPC methods differed by less than half of a log cycle for all microbial groups studied (range of difference, −0.1386 [mesophiles] to +0.4397 [presumptive lactobacilli]). The results of the SPLPC method compared favorably with the results of the SPC procedure for mesophiles, presumptive lactococci, presumptive leuconostocs, Enterobacteriaceae, and molds and yeasts (the variance between replicate platings was close to 0.005, and correlation coefficients were >0.9). Correlation coefficients were lower for Micrococcaceae (r = 0.824) and presumptive lactobacilli (r = 0.670). Analysis of variance showed that the plating method was a significant factor (P < 0.05) for presumptive lactobacilli counts. In general, results from the SPLPC method compared favorably with results from SPC procedure in the enumeration of microorganisms in goat cheese throughout its manufacturing and ripening processes. However, the suitability of the SPLPC method depends mainly on the microbial group studied.

Evaluation of a Rapid Impedimetric Method for Determining the Keeping Quality of Milk

1982 ◽  
Vol 45 (13) ◽  
pp. 1221-1226 ◽  
Author(s):  
S. B. MARTINS ◽  
S. HODAPP ◽  
S. W. DUFOUR ◽  
S. J. KRAEGER
Keyword(s):  
Shelf Life ◽  
Correlation Coefficients ◽  
Sample Volume ◽  
Plate Count ◽  
Impedance Method ◽  
Detection Time ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Standard Plate ◽  
Quality Of Milk

Shelf-life of 151 pasteurized milk samples was recorded and correlation coefficients calculated using various microbiological factors: standard plate count (SPC), psychrotrophic plate count (PPC), coliform count (CC), and the impedance response detection time (DT) with incubation at both 21 and 32°C. These data were obtained for milk samples on the day of pasteurization as well as 4 and 8 d thereafter. Various treatments (media, dilution factors, temperature and sample volume) were compared. Of the SPC, PPC, CC and DT taken on the day of pasteurization, only the DT achieved a significant correlation with shelf-life. A correlation coefficient of 0.55 was obtained for one treatment applied to 61 samples and correlation coefficients of 0.28 to 0.32 were obtained for several other treatments applied to the entire 151 samples. Values as large as these could occur by chance in uncorrelated data with p<0.0005. Thus, of the total 61 samples, 80% were correctly classified by the impedance detection time test. It is concluded that for prediction of shelf-life on the day of pasteurization, the impedance method is superior to the SPC and the PPC. In addition, the impedance method is more rapid, i.e., 14 h vs.2 d for the SPC and 10 d for the PPC.

EVALUATION OF PRODUCTION CONDITIONS OF MANUFACTURING-GRADE RAW MILK BY FIELDMEN RATINGS AND BY BACTERIAL TESTS

1971 ◽  
Vol 34 (4) ◽  
pp. 200-203 ◽  
Author(s):  
Roger Dabbah ◽  
W. A. Moats ◽  
J. C. Olson
Keyword(s):  
Correlation Coefficients ◽  
Raw Milk ◽  
Plate Count ◽  
Standard Plate Count ◽  
Reduction Test ◽  
Sanitary Condition ◽  
Methylene Blue Reduction ◽  
Standard Plate ◽  
Microscopic Count ◽  
Production Conditions

Standard microbiological tests, Standard Plate Count, direct microscopic count, methylene blue reduction test, and several variations of the resazurin reduction test were correlated with fieldmen's ratings of sanitary condition of milking area, milk house, and milking utensils. Correlation coefficients were low, in general, approximately 0.2. The effect of different production facilities and practices on these correlations was variable. Results suggest that bacterial tests and fieldmen's inspection be used concurrently since they appear to measure different sanitary factors on the producing farms.

Evaluation of the 3M™ Petrifilm™ Rapid Aerobic Count Plate for the Enumeration of Aerobic Bacteria: Collaborative Study, First Action 2015.13

2016 ◽  
Vol 99 (3) ◽  
pp. 664-675
Author(s):  
Patrick Bird ◽  
Jonathan Flannery ◽  
Erin Crowley ◽  
James Agin ◽  
David Goins ◽  
...  
Keyword(s):  
Collaborative Study ◽  
Skim Milk ◽  
Plate Count ◽  
Aerobic Bacteria ◽  
Contamination Level ◽  
Standard Plate Count ◽  
Dual Sensor ◽  
Standard Plate ◽  
Aerobic Plate Count ◽  
Contamination Levels

Abstract The 3M™ Petrifilm™ Rapid Aerobic Count (RAC) Plate is a sample-ready culture medium system containing dual-sensor indicator technology for the rapid quantification of aerobic bacteria in food products. The 3M Petrifilm RAC Plate was compared to the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA BAM) Chapter 3 (Aerobic Plate Count) for the enumeration of aerobic bacteria in raw easy-peel shrimp and the Standard Methods for the Examination of Dairy Products (SMEDP) Chapter 6 (Standard Plate Count Method) for the enumeration of aerobic bacteria in pasteurized skim milk and instant nonfat dry milk (instant NFDM). The 3M Petrifilm RAC Plate was evaluated using a paired study design in a multilaboratory collaborative study following current AOAC validation guidelines. Three target contamination levels (low, 10–100 CFU/g; medium, 100–1000 CFU/g; and high 1000–10 000 CFU/g) were evaluated for naturally occurring aerobic microflora for each matrix. For raw easy-peel shrimp, duplicate 3M Petrifilm RAC Plates were enumerated after 24 ± 2 h incubation at both 32 and 35°C. Pasteurized skim milk 3M Petrifilm RAC Plates were enumerated after 24 ± 2 h incubation at 32°C, and instant NFDM 3M Petrifilm RAC Plates were enumerated after 48 ± 3 h incubation at 32°C. No statistical difference was observed between 3M Petrifilm RAC Plate and FDA BAM or SMEDP reference methods for each contamination level.

EFFECT OF PLATE INCUBATION TEMPERATURE ON BACTERIAL COUNTS OF GRADE A RAW MILK1

1973 ◽  
Vol 36 (3) ◽  
pp. 152-154 ◽  
Author(s):  
H. E. Randolph ◽  
B. K. Chakraborty ◽  
Otto Hampton ◽  
D. L. Bogart
Keyword(s):  
Incubation Temperature ◽  
Statistical Significance ◽  
Correlation Coefficients ◽  
Raw Milk ◽  
Plate Count ◽  
Bacterial Counts ◽  
Standard Plate Count ◽  
Standard Plate ◽  
The Mean ◽  
Incubation Temperatures

Bacterial counts on 155 raw milk samples obtained with plate incubation temperatures of 27 and 32 C were closely correlated (r = 0.96) . Correlation coefficients between counts obtained at both 27 and 32 C and psychrotrophic (7 C-10 days) counts for all samples were relatively low, but statistically significant ( P < 0.01). The correlation to psychrotrophic counts was especially low and in some instances lacking in statistical significance in the sample groups with counts ( 27 and 32 C) <100,000/ml. Eighty-four of the samples had higher counts at 32 C and 62 samples had higher counts at 27 C. The mean psychrotrophic count of the samples with higher counts at 27 C was higher than the mean psychrotrophic count of the other samples. However, the correlation coefficients were higher for samples with counts higher at 32 C. Incubation at 27 C does not appear to offer significant advantages over the 32 C incubation temperature used in the Standard Plate Count.

Pyruvate as an Indicator of Quality in Grading Nonfat Dry Milk1

1982 ◽  
Vol 45 (6) ◽  
pp. 561-565 ◽  
Author(s):  
R. T. MARSHALL ◽  
Y. H. LEE ◽  
B. L. O'BRIEN ◽  
W. A. MOATS
Keyword(s):  
Geometric Mean ◽  
Regression Line ◽  
Skim Milk ◽  
Plate Count ◽  
Department Of Agriculture ◽  
Standard Plate Count ◽  
Geometric Average ◽  
Dry Milk ◽  
Standard Plate ◽  
Microscopic Count

Samples of skim milk and nonfat dry milk (NDM) made from it were collected, paired and tested for pyruvate concentration, [P], and Direct Microscopic count (DMC). The skim milk was tested for Standard Plate Count (SPC) and Psychrotrophic Plate Count (PPC). The geometric average DMC of skim milk was more than three times higher than that of the paired NDM samples. However, [P] of NDM was not significantly different from that of the skim milk. Although [P] of skim milk was poorly correlated with SPC and PPC, r = .31 and .26, respectively, it was relatively well correlated with DMC, r = .64. Data were widely dispersed around the regression line when [P] was ≤ 4.0 mg/L. However, [P] increased rapidly when DMCs were > 106/ml. A limit of 10 mg/L of [P] in NDM reconstituted 1:9 was chosen to represent the current U.S. Department of Agriculture Standard for DMC in NDM. This limit failed to classify about 10% of the samples correctly, assuming that each geometric mean DMC was correct. However, the probability that samples meeting the DMC standard would be rejected by the pyruvate test was quite low and the probability was moderate that samples which would be acceptable by the pyruvate test would be rejected by the DMC. For the latter, 28% of the samples having DMCs of ≥ 107/ml contained < 10 mg/L of pyruvate. No sample having ≥ 10 mg/L of pyruvate had a DMC of ≤ 107/ml. Pyruvate concentration in NDM did not change during storage at 5 or 32°C for 90 days.

Bioluminescence: A Rapid Indicator of Escherichia Coli O157:H7 in Selected Yogurt and Cheese Varieties

1997 ◽  
Vol 60 (8) ◽  
pp. 891-897 ◽  
Author(s):  
L. M. HUDSON ◽  
J. CHEN ◽  
A. R. HILL ◽  
M. W. GRIFFITHS
Keyword(s):  
Escherichia Coli ◽  
Enterohemorrhagic Escherichia Coli ◽  
Cottage Cheese ◽  
Plate Count ◽  
Escherichia Coli O157 ◽  
Potential Hazard ◽  
Growth And Survival ◽  
E Coli ◽  
Standard Plate Count ◽  
Standard Plate

Outbreaks of enterohemorrhagic Escherichia coli O157:H7 have been commonly associated with products derived from ground beef, but recently the organism has been implicated as the causative agent in outbreaks involving yogurt and cheese. This finding has raised concern about the potential for its growth and survival in fermented dairy products. A bioluminescent strain of E. coli O157:H7 was used to determine postprocessing survival in yogurt with live cultures at pH 4.17, 4.39, and 4.47 stored at 4 and 10°C. In addition, survival of E. coli O157:H7 was monitored during the manufacture of Cottage, Colby, Romano, and Feta cheeses. Results indicated survival for 8 and 5 days at 4 and 10°C respectively in yogurt at pH 4.17, 17 and 15 days at 4 and 10°C respectively in yogurt at pH 4.39, and 17days at both 4 and 10°C in yogurt at pH 4.47. E. coli O157:H7 did not survive cooking procedures at 56°C in Cottage cheese. However, the pathogen survived for 27, 30, and 27 days in Colby, Romano, and Feta cheeses respectively. A high correlation of r2 > 0.89 was obtained between counts of bioluminescenct colonies and standard plate count for all yogurt and cheese varieties, indicating that bioluminescence was a sensitive and rapid indicator of cellular viability for E. coli O157:H7. Survival of the pathogen, as indicated by this method, is possible in highly acidic environments even at refrigeration temperatures. This poses a potential hazard should postprocessing contamination occur.

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