Use of Petrifilm™ to Evaluate the Microflora of Frozen Dessert Mixes1

1989 ◽  
Vol 52 (8) ◽  
pp. 549-551 ◽  
Author(s):  
L. B. SMITH ◽  
E. A. ZOTTOLA ◽  
T. L. FOX ◽  
K. CHAUSSE
Keyword(s):  
Linear Relationship ◽  
Raw Milk ◽  
Microbial Populations ◽  
Plate Count ◽  
Standard Methods ◽  
Naturally Occurring ◽  
Colony Forming Units ◽  
Frozen Dessert ◽  
Evaluation Of Data ◽  
Strong Linear Relationship

Ninety vanilla frozen dessert mix samples were analyzed to determine total microbial populations and coliforms present in samples inoculated with a coliform isolated from raw milk. Standard methods agar (SMA, PCA, Difco) and violet red bile agar (VRBA, Difco) as well as Petrifilm™ (PSM, PVRB) were used for plating of samples. Standard VRBA 1:10 method produced significantly higher counts of colony-forming units (CFU) than PVRB 2:3 and VRBA 2:3 methods. VRBA 2:3 colony-forming unit counts were also significantly higher than those on PVRB 2:3, but both methods showed a moderately strong linear relationship. Repeatabilities of all three coliform plating methods (VRBA 1:10, VRBA 2:3, and PVRB 2:3) were acceptably low. Less than 10% of samples plated on SMA and PSM resulted in total aerobic colony-forming units in the countable range, making evaluation of data difficult and resulting in a lack of strong linear relationship between PSM and SMA. An additional 70 local retail store samples containing naturally occurring coliforms were evaluated using PVRB 2:3 and VRBA 1:10 methodology, confirmed in brilliant green lactose bile broth (BGLB, Difco) and compared to standard VRBA 1:10 previously analyzed. All methods were equivalent for mean log coliforms, i.e., 1.38,1.33, and 1.31 for PVRB 2:3, VRBA 2:3, and VRBA 1:10, respectively. Petrifilm™ methods were comparable to standard methods for enumerating coliforms in frozen dairy products, and would be a valid alternative to standard coliform and total plate count methods.

Temperature Equilibration Times of Plate Count Agar and a Comparison of 50 Versus 45 C for Recovery of Raw-Milk Bacteria1

1975 ◽  
Vol 38 (6) ◽  
pp. 319-322 ◽  
Author(s):  
C. N. HUHTANEN ◽  
A. R. BRAZIS ◽  
W. L. ARLEDGE ◽  
C. B. DONNELLY ◽  
R. E. GINN ◽  
...  
Keyword(s):  
Raw Milk ◽  
Plate Count ◽  
Equilibration Time ◽  
Standard Methods ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Plate Count Agar ◽  
Standard Plate ◽  
Time Required ◽  
Tempering Time

Sixty raw milk samples were plated using “Standard Methods” agar tempered to 45 or 50 ± 1 C. The standard plate count was significantly lower with the agar at 50 C. Tempering time (to 44–46 C) of a flask of agar in a water bath was about 5–10 min longer than that of a comparable flask of water. Time required to reach the desired temperature depended upon the volume of agar in the flasks, the number of flasks, and the volume of the water in the bath. Up to an hour of equilibration time may be necessary for newly autoclaved agar to reach the recommended temperature (44–46 C). Insufficient tempering time might cause an excessively high plating agar temperature which might cause a reduction in bacterial counts, especially of a heat sensitive psychrotrophic bacterium.

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.

scholarly journals Reduction of Microbial Populations on Prunes by Vapor Phase Hydrogen Peroxide

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 815F-815
Author(s):  
Gilbert F. Simmons ◽  
Joseph L. Smilanick ◽  
Shama John ◽  
Dennis A. Margosan
Keyword(s):  
Hydrogen Peroxide ◽  
Vapor Phase ◽  
Culture Medium ◽  
Culture Media ◽  
Microbial Populations ◽  
Plate Count ◽  
Potassium Sorbate ◽  
Plate Count Agar ◽  
Colony Forming Units ◽  
Aerobic Plate Count

Moisture is raised in dehydrated prunes to improve palatability before packaging and potassium sorbate is added to inhibit microbial growth. Vapor phase hydrogen peroxide (VPHP) technology uses hydrogen peroxide pulses to disinfect dried prunes. Dried prunes were obtained from dehydrators. The number of colony-forming units per 10 prunes (cfu/p) was compared between untreated and VPHP treated. Three culture media—dichloran rose bengal chloramphenicol agar base (DRBC, Oxoid), aerobic plate count agar (PCA), and potato dextrose agar (PDA)—were used to evaluate cfu/p. Similar mean microbe populations were observed on DRBC (67) and PDA (70); PCA had higher cfu/p (99). Microbes washed from untreated prunes obtained from dehydrators were 58 to 112 cfu/p, depending on the culture medium used. The number of cfu/p assessed on all media on VPHP-treated prunes was near 0 after 100 min exposure. Unlike potassium sorbate, hydrogen peroxide is a microbiocide rather than a microbiostat.

Comparison of a Dry Medium Culture Plate (Petrifilm SM Plates) Method to the Aerobic Plate Count Method for Enumeration of Mesophilic Aerobic Colony-Forming Units in Fresh Ground Beef

1985 ◽  
Vol 48 (12) ◽  
pp. 1044-1045 ◽  
Author(s):  
LORRAINE B. SMITH ◽  
TERRANCE L. FOX ◽  
F. F. BUSTA
Keyword(s):  
Linear Regression Analysis ◽  
Ground Beef ◽  
Microbial Populations ◽  
Plate Count ◽  
Retail Markets ◽  
Count Method ◽  
Colony Forming Units ◽  
Plate Count Method ◽  
Aerobic Plate Count ◽  
Medium Culture

Mesophilic aerobic microbial populations in fresh ground beef were enumerated with a new system, Petrifilm™ SM Plates (PSM), and with the conventional aerobic plate count (APC) method using standard methods agar (SMA). Total colony-forming units were determined in 119 fresh ground beef samples (29 extra-lean, 30 lean and 60 regular) purchased at nine different retail markets over a period of 6 wk. Linear regression analysis of PSM vs. APC counts gave a slope of 0.963, an intercept of −0.027, and a correlation coefficient of 0.951. Mean log10 counts on PSM were 5.86 compared to 6.11 on SMA (P<0.01) or a mean log10 difference of −0.25. These analyses indicate that the Petrifilm SM method would be a possible alternative for the aerobic plate count method.

Evaluation of the Microbial Quality of Raw Milk1

1987 ◽  
Vol 50 (1) ◽  
pp. 47-50 ◽  
Author(s):  
R. B. MAXCY ◽  
R. J. PAUL
Keyword(s):  
Research Laboratory ◽  
Single Cells ◽  
Raw Milk ◽  
Microbial Quality ◽  
Standard Methods ◽  
New Methods ◽  
Colony Forming Units ◽  
Quality Grade

Commercial evaluation of the microbial quality of raw milk presents a major challenge, and new methods are burdened by being compared to imprecise presently used standard methods. Extensive comparisons in commercial and research laboratory environments were made using a method that involved direct enumeration of single cells in comparison to colony forming units. The correlations were from 0.50 to 0.99 depending on treatment of the data. Repetition of all tests on milk from individual farms indicated that inherent variation in quality at the farm, sampling, testing, and evaluating the results showed the extreme inadequacy of the presently established methods of grading raw milk. More frequent tests with appropriate averaging would improve the likelihood of correct decisions on quality grade.

scholarly journals Rapid Microbiological Assessment in Raw Milk: Validation of a Rapid Alternative Method for the Assessment of Microbiological Quality in Raw Milk

Foods ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1186
Author(s):  
Nicla Marri ◽  
Francesca Losito ◽  
Loris Le Boffe ◽  
Gilberto Giangolini ◽  
Simonetta Amatiste ◽  
...  
Keyword(s):  
Microbiological Quality ◽  
Bacterial Count ◽  
Raw Milk ◽  
Plate Count ◽  
Microbiological Analysis ◽  
Biological Survey ◽  
Alternative Method ◽  
Colony Forming Units ◽  
Plate Count Method

The consumption of dairy products and the dairy industry are one of the main global agri-food sectors for its size, economic importance, and level of technology. Microbiological quality of pasteurized milk or other milk products is dependent on microbiological quality of raw milk. A variety of microbiological count methods is available for monitoring the hygienic quality of raw milk. Among them, the pour plate method is the official essay for counting the number of colony-forming units in milk samples according to International Organization for Standardization (ISO) No. 4833-1:2013. The aim of the present study is the validation of the Micro Biological Survey (MBS) method, against the reference plate-count method, for the assessment of the microbiological quality of raw milk. This comparative study, performed in collaboration with the Istituto Zooprofilattico Sperimentale del Lazio e della Toscana M. Aleandri (IZSLT), demonstrates the accuracy of this alternative method for the determination of total viable bacterial count in cow’s raw milk. The results obtained with the MBS method highlight its potential as a valid tool for reliable microbiological analysis in dairy industries.

scholarly journals Rapid Microbiological Assessment in Raw Milk. Validation of a Rapid Alternative Method for the Assessment of Microbiological Quality in Raw Milk.

2020 ◽  
Author(s):  
Nicla Marri ◽  
Francesca Losito ◽  
Loris Le Boffe ◽  
Gilberto Giangolini ◽  
Simonetta Amatiste ◽  
...  
Keyword(s):  
Microbiological Quality ◽  
Bacterial Count ◽  
Raw Milk ◽  
Plate Count ◽  
Microbiological Analysis ◽  
Biological Survey ◽  
Alternative Method ◽  
Colony Forming Units ◽  
Plate Count Method

The consumption of dairy products and the dairy industry is one of the main global agro-food sectors for size, economic importance and level of technology. Microbiological quality of pasteurized milk or other milk products is dependent on microbiological quality of raw milk. A variety of microbiological count methods is available for monitoring the hygienic quality of raw milk. Among them, the pour plate method is the official essay for counting the number of colony forming units in milk samples according to ISO 4833-1:2013. The aim of the present study is the validation of the Micro Biological Survey (MBS) method, against the reference plate count method, for the assessment of the microbiological quality of raw milk. This comparative study, performed in collaboration with the “Istituto Zooprofilattico Sperimentale del Lazio e della Toscana M. Aleandri” (IZSLT), demonstrates the accuracy of this alternative method for the determination of total viable bacterial count in cow’s raw milk. The results obtained with the MBS method highlighting its potential as a valid tool for reliable microbiological analysis in dairy industries.

BACTERIOLOGICAL TESTING OF MILK FOR REGULATORY PURPOSES–USEFULNESS OF CURRENT PROCEDURES AND RECOMMENDATIONS FOR CHANGE

1971 ◽  
Vol 34 (5) ◽  
pp. 260-263 ◽  
Author(s):  
George W. Reinbold
Keyword(s):  
Agar Plate ◽  
Raw Milk ◽  
Plate Count ◽  
Test Results ◽  
Standard Methods ◽  
Selective Media ◽  
Training And Supervision ◽  
Bacteriological Testing ◽  
Incubation Temperatures ◽  
Colony Productivity

The present systems for bacteriological testing of raw milk for quality and regulatory purposes are briefly discussed. Recommendations are made to partially bridge the lack of relationship between test results and farm conditions. These suggestions include: (a) further standardization of “standard methods”; (b) an increase in training and supervision of testing personnel; (c) use of more milking time inspections; (d) the revision of routine agar plate count testing to include automation, selective media, and enhanced colony productivity by the use of lower incubation temperatures and longer incubation times; (e) making results of bacteriological testing more readily available and understandable to the producer and the fieldman; and (f) increasing the stringency of our bacterial standards for raw milk.

scholarly journals Changes in Microbial Population Numbers during Composting of Some Organic Wastes in Greenhouse

2019 ◽  
pp. 1-10
Author(s):  
E. C. Chinakwe ◽  
U. N. Nwogwugwu ◽  
V. I. Ibekwe ◽  
I. N. Nwachukwu ◽  
C. E. Ihejirika ◽  
...  
Keyword(s):  
Thermophilic Bacteria ◽  
Organic Wastes ◽  
Microbial Populations ◽  
Research Centre ◽  
Plate Count ◽  
Cow Dung ◽  
Faecal Coliforms ◽  
Bacterial Colony ◽  
Microbiological Methods ◽  
Colony Forming Units

Aim: This study identified and enumerated microorganisms associated with the composting of some organic wastes using the plate count method Study Design: The wastes were allowed to decompose for 70 days in greenhouse using the modified windrow method of composting. Standard methods were employed to monitor temperature changes in compost piles as well as changes in bacterial and fungal populations. Place and Duration of Study: This study was carried out at in the Agricultural Research Centre of the Federal University of Technology, Owerri, Nigeria. Methodology: The organic wastes  namely Poultry Litter (PL), Pig waste (PW), Cow dung (CD) and Source-Separated Municipal Solid Waste (MSW) were composted/co-composted using the windrow method as modified .Sixty kilograms (60) each of PW, PL, CD and MSW were introduced respectively into 100-litre(L) buckets that had previously been perforated at several points. In the co-composted piles, 30 kg of both samples were introduced into the same 100 L bucket that had previously been perforated and then mixed thoroughly. The organic wastes were allowed to decompose at room temperature at a corner of the greenhouse. and initial microbial populations as well as subsequent populations  in the compost bins were studied using standard microbiological methods Results: Microbial populations increased concurrently with temperature during the first 3 – 4 weeks of composting except, however, for faecal coliforms and Salmonella. The highest temperature recorded was 60°C for cow dung (CD) compost pile though at maturity the temperature in all compost piles ranged between 27°C to 30°C. The bacterial colony forming units were higher than fungal colony forming units throughout the composting period for both mesopholic and themophilic microorganisms. The population of mesophilic organisms increased in the first 14 – 15 days; for cow dung, the initial total heterotrophic bacteria count (THBC) and total  coliform count (TCC) were 2.4 x107 cfu/g and 5.0 x105 cfu/g respectively and  increased to 2.5x108 cfu/g  and 1.7x107 cfu/g  for THBC and TCC, respectively, after the 14th day. Thermophilic bacteria dominated all the composting systems after the 21st day and lasted to the 35th day except for cow dung compost where thermophilic temperatures were still observed on the 45th day with a THBC of 6.3x106 cfu/g on the 49th day. Faecal coliforms and Salmonella were completely eliminated in all the compost systems after the 28th day with temperature values between 47°C – 60°C. Conclusion: Organic wastes when managed properly through the application of knowledge of composting can be transformed into beneficial materials for human and agricultural use.

Effect of Various Combinations of Medium, Diluent and Incubation Conditions on Recovery of Bacteria from Manufacturing Grade and Grade A Raw Milk1

1977 ◽  
Vol 40 (4) ◽  
pp. 222-227 ◽  
Author(s):  
B. E. LANGLOIS ◽  
CHAMRAS SANGHIRUM
Keyword(s):  
Incubation Temperature ◽  
Raw Milk ◽  
Ringer Solution ◽  
Plate Count ◽  
Distilled Water ◽  
Standard Methods ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Peptone Water ◽  
Standard Plate

Recovery of microorganisms from manufacturing grade and Grade A raw milk was determined using 18 plating combinations which consisted of three media, three diluents, and two incubation temperatures. Plating conditions specified in Standard Methods for doing the Standard Plate Count was one of the 18 combinations used. Combinations studied consisted of Standard Methods Agar, Schaedler Agar, and Eugonagar as plating medium; phosphate buffered distilled water, 0.1% peptone water, and Ringer solution as diluent; and 28 C for 72 h and 32 C for 48 h as incubation temperature. Forty manufacturing grade and 40 Grade A raw milk samples were plated using each of the 18 combinations. Highest mean counts were obtained for both grades of milk with the combination of Standard Methods Agar, phosphate buffered distilled water, and 28 C for 72 h. Samples, diluents, media, and samples × diluents interaction had a highly significant (P<.01) effect on counts of manufacturing grade milk samples; while samples, media, and temperatures had a highly significant (P<.01) effect on counts of the Grade A raw milk samples. Nonsignificant differences were obtained in counts of the manufacturing gradesamples with eight of 17 plating combinations when compared with counts obtained with Standard Methods. Counts for Grade A samples obtained with six of 17 combinations were similar to counts obtained with Standard Methods.

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