Enumeration of Enterococci and Aerobic Mesophilic Plate Count in Dried Soup Using Three Reconstitution Methods

1985 ◽  
Vol 48 (9) ◽  
pp. 770-771 ◽  
Author(s):  
WEI-TSYI TING ◽  
GEORGE J. BANWART
Keyword(s):  
Plate Count ◽  
Plate Count Agar ◽  
Plate Counts

A naturally contaminated dried soup sample was reconstituted by three different methods (1:1 swirl, 1:9 soak and 1:9 rapid rehydration) and analyzed for enterococci on m-enterococcus agar and aerobic mesophilic plate count on plate count agar. The enterococcal counts obtained by the 1:1 swirl and the 1:9 soak methods were 41.6% and 26.5%, respectively, higher than that of the commonly used 1:9 rapid rehydration method. The aerobic mesophilic plate counts for the three systems were not significantly different.

Comparison of the Petrifilm™ Yeast and Mold Culture Film Method to Conventional Methods for Enumerating Yeasts and Molds in Foods

1991 ◽  
Vol 54 (6) ◽  
pp. 443-447 ◽  
Author(s):  
L. R. BEUCHAT ◽  
B. V. NAIL ◽  
R.E. BRACKETT ◽  
T. L. FOX
Keyword(s):  
Correlation Coefficients ◽  
Food Group ◽  
Black Pepper ◽  
Plate Count ◽  
Food Groups ◽  
Plate Count Agar ◽  
Plate Counts ◽  
Yeasts And Molds ◽  
Potential Food ◽  
Film Method

Petrifilm™ Yeast and Mold (YM) plates were compared to acidified potato dextrose agar (APDA) and chloramphenicol-supplemented plate count agar (CPCA) for its suitability to enumerate yeasts and molds in 13 groups of food products. These products consisted of beans (dry and frozen, green), corn meal, flour (wheat), fruit (apple), a meat/vegetable entree (chicken pot pie), a precooked meat (beef), milk (dehydrated, nonfat), nuts (pecans), pasta, potatoes (dehydrated), precooked sausage, and a spice (black pepper). Correlation coefficients of Petrifilm™ YM plates versus APDA and CPCA pour plates for recovering total yeasts and molds from a composite of the thirteen test foods were, respectively, 0.961 and 0.974. Individually, Petrifilm™ YM plate counts were equivalent or higher than APDA and CPCA for some food groups and lower for other food groups. Because food particle interference can make enumeration of yeast and mold colonies on Petrifilm™ YM plates difficult for some food groups, potential food interference will need to be evaluated for each food group tested.

Effect of Delayed Heading on Some Quality Attributes of Penaeus Shrimp1

1979 ◽  
Vol 42 (5) ◽  
pp. 407-409 ◽  
Author(s):  
R. J. ALVAREZ ◽  
J. A. KOBURGER
Keyword(s):  
Panel Data ◽  
Storage Period ◽  
Plate Count ◽  
Sensory Panel ◽  
Bacterial Populations ◽  
Standard Plate Count ◽  
Plate Count Agar ◽  
Pseudomonas Species ◽  
Standard Plate ◽  
Plate Counts

To determine the effect of delayed heading on shrimp quality, shrimp were stored on ice with and without heads for 10 days. Some shrimp were delay-headed after 5 days and returned to ice for the remainder of the storage period. Microbiological studies were conducted at 0, 5 and 10 days of storage. Total aerobic plate counts were done using Standard Plate Count agar with an added 0.5% NaCl. Incubation was at 20 C for 5 days. Analyses indicated similar counts on shrimp tails stored with or without heads and those delayed-headed. Counts ranged from 2.4 × 106 bacteria/gram at 0 day to 1.6 × 109 bacteria/gram on the 10th day. Identification of the flora present revealed that the same major groups of organisms predominated on shrimp tails subjected to the different storage treatments and the head did not alter development of the usual flora. Flavobacterium, Pseudomonas, Planococcus, Moraxella and the Vibrio/Aeromonas group were the major genera encountered. A shift in bacterial populations was observed during storage. Flavobacterium species predominated during the first 5 days of storage; however, after the fifth day Pseudomonas species predominated. Sensory panel data revealed no differences in acceptability between shrimp tails stored with or without heads and those delay-headed.

Effect of Stored Pre-Poured Plates on Microbial Enumeration Using the Surface Plate Method1

1980 ◽  
Vol 43 (8) ◽  
pp. 592-594 ◽  
Author(s):  
J. E. KENNEDY ◽  
P. E. PHILLIPS ◽  
J. L. OBLINGER
Keyword(s):  
Correlation Coefficients ◽  
Storage Period ◽  
Regression Coefficients ◽  
Plate Count ◽  
Plate Method ◽  
Plate Count Agar ◽  
Plastic Bags ◽  
Plate Counts ◽  
Microbial Enumeration ◽  
Surface Plate

The surface plate method, using freshly pre-poured agar plates and/or stored pre-poured plates and the pour plate method were compared for enumeration of microorganisms in fresh bologna, fresh ground beef, frozen turkey pot pie and bacterial suspensions of Pseudomonas fluorescens and Streptococcus faecalis. Stored pre-poured Plate Count Agar (PCA) plates were packaged in plastic bags and held at 5 C for up to 6 weeks before use. Aerobic plate counts were derived from plates incubated at 35 C for 48 h, 20 C for 5 days and 7 C for 10 days. Differences in counts between methods for a given sample, incubation and pre-poured plate storage period were less than 0.5 log cycle in 97% of the comparisons. Regression and correlation coefficients between methods were highly significant; correlation coefficients varied from 0.987 to 0.999, and regression coefficients from 0.977 to 1.068 between any pair of methods. Storage of pre-poured plates for up to 6 weeks appeared to have no significant effect on recovery of microorganisms, using the surface plate technique.

Destruction de Microbacterium lacticum, Escherichia coli et Staphylococcus aureus au cours du séchage du lait par atomisation. I. Dénombrement sélectif des bactéries survivantes

1977 ◽  
Vol 23 (6) ◽  
pp. 716-720
Author(s):  
A. Chopin ◽  
G. Mocquot ◽  
Y. Le Graet
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Spray Drying ◽  
Skim Milk ◽  
Resistant Mutant ◽  
Plate Count ◽  
Mannitol Salt Agar ◽  
E Coli ◽  
Plate Count Agar ◽  
Plate Counts

In this paper a method which allows the measure of microbial death rate during spray-drying by means of a streptomycin-resistant mutant that can be grown on a streptomycin-containing agar is described. Plate counts of Microbacterium lacticum, Escherichia coli, and Staphylococcus aureus recovered from skim milk powders were done on plate count agar in the presence and absence of streptomycin and on various selective media. The powders were produced from evaporated milk previously inoculated with those organisms.Our results showed that the proposed method allows the recovery of 78% of M. lacticum, 61% of E. coli, and 100% of S. aureus that survived spray-drying. Recoveries of surviving E. coli on violet bile agar and brilliant green bile 2% were 34% and 29% respectively. Baird-Parker and mannitol salt agar media allow the recovery of all surviving S. aureus, thus showing that S. aureus cells did not lose their ability to grow in media containing 7.5% NaCl. Our results show that physiological injury of the cells during spray-drying differs from injury due to heating only. [Traduit par le journal]

Enumeration of the contaminating bacterial microbiota in unfermented pasteurized milks enriched with probiotic bacteria

2009 ◽  
Vol 55 (4) ◽  
pp. 410-418 ◽  
Author(s):  
C. P. Champagne ◽  
Y. Raymond ◽  
J. Gonthier ◽  
P. Audet
Keyword(s):  
Lactobacillus Rhamnosus ◽  
Microbiological Quality ◽  
Probiotic Bacteria ◽  
Plate Count ◽  
Plate Count Agar ◽  
Bacterial Microbiota ◽  
Standard Plate ◽  
Plate Counts ◽  
Probiotic Lactobacilli ◽  
De Man

Pasteurized and unfermented milks supplemented with probiotic bacteria are appearing on the market. It then becomes a challenge to ascertain the undesirable contamination microbiota in the presence of a largely superior population of probiotic bacteria. A method to enumerate the contaminating microbial microbiota in such probiotic-enriched milks was developed. The probiotic cultures, Lactobacillus rhamnosus Lb-Immuni-T™ and Bifidobacterium animalis subsp. lactis BB-12®, were added to a pasteurized unfermented milk to reach a minimum of 1 billion CFU per 250 mL portion, as ascertained by plating on de Man – Rogosa – Sharpe (MRS) agar in anaerobic conditions. No growth of B. animalis subsp. lactis BB-12 was noted on plate count agar (PCA) or Petrifilm™ plates, and the presence of this culture did not affect standard plate counts (SPC) of contaminating bacteria. However, L. rhamnosus formed colonies on PCA and Petrifilm™ plates. Attempts were thus made to inhibit the growth of the probiotic lactobacilli in PCA. The addition of 2% sodium phosphate (SP) or 5% glycerophosphate (GP) inhibited the growth of the lactobacilli in broths, but pin-point colonies of L. rhamnosus Lb-Immuni-T nevertheless appeared on PCA supplemented with phosphates. SPC could be obtained on PCA + 2% SP by only counting the large colonies, but this resulted in a significant (4.4 fold) underestimation of SPC values. On Petrifilm™ AC, at dilutions 0 to 2, all colonies were considered as being contaminants, while at dilutions 3 and 4, only large colonies were counted for SPC determinations. There was a direct correlation (R2 = 0.99) between SPC values with Petrifilm™ in uninoculated milks and those obtained on probiotic-enriched milks. The high correlation obtained over the 102 to 106 CFU/mL range of SPC values show that this Petrifilm™ method is appropriate to evaluate the microbiological quality of pasteurized milks enriched with L. rhamnosus Lb-Immuni-T and B. animalis subsp. lactis BB-12.

Refrigeration of Oyster Shellstock: Conditions Which Minimize the Outgrowth of Vibrio vulnificus

1997 ◽  
Vol 60 (4) ◽  
pp. 349-352 ◽  
Author(s):  
DAVID W. COOK
Keyword(s):  
Vibrio Vulnificus ◽  
Plate Count ◽  
Plate Count Agar ◽  
Standard Plate ◽  
Plate Counts

The multiplication of Vibrio vulnificus in summer harvest oyster shellstock held without refrigeration was followed over a 14 h postharvest period. Mean (n = 7) increases were 0,75, 1.30, 1.74, and 1.94 log units at 3.5 h, 7 h, 10.5 h, and 14 h postharvest, respectively. Aerobic plate counts (spread plates on plate count agar [PCA] containing 1% NaCl, 25°C) but not standard plate counts (pour plates, PCA, 35°C) showed a similar trend in increase. Reducing the time oyster shellstock remains outside refrigeration can decrease consumer exposure to high numbers of V. vulnificus, but shellstock must be cooled immediately after harvest to eliminate postharvest growth of this bacterium.

Effects of Diacetyl and Carbon Dioxide on Spoilage Microflora in Ground Beef

2002 ◽  
Vol 65 (3) ◽  
pp. 523-527 ◽  
Author(s):  
ANISHA M. WILLIAMS-CAMPBELL ◽  
JAMES M. JAY
Keyword(s):  
Ground Beef ◽  
Plate Count ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Plate Count Agar ◽  
Plate Counts ◽  
Meat Samples ◽  
Spoilage Microflora

The effect of CO2 and diacetyl, alone or in combination, on spoilage microflora in ground beef was determined. Ground beef was treated with 20, 30, or 40% CO2 for 22 days (study I); 20, 50, or 100 μg/g diacetyl for 26 days (study II); or a combination of 20% CO2 and 100 μg/g diacetyl for 40 days (study III). Antimicrobial effectiveness was determined by aerobic plate counts (log10 CFU/g) using plate count agar (total aerobic bacteria), deMan Rogosa Sharpe (MRS) Lactobacillus agar (gram-positive bacteria), MacConkey agar (gram-negative bacteria), pH, and informal organoleptic assessments (by appearance and by odor). In study I, total bacteria and pH increased by day 4 in control meat samples. For all CO2 levels, gram-negative bacteria decreased and gram-positive bacteria increased compared with untreated controls. The pH remained constant for CO2-treated meat. Control samples had an off-odor and a brown appearance, while CO2-treated samples had no off-odor but did have a brown appearance. For samples treated with diacetyl (study II), spoilage was evident by day 7 for samples treated with 0, 20, and 50 μg/g diacetyl for all parameters examined. Ground beef treated with 100 μg/g diacetyl was spoiled on day 12. Diacetyl was detected (by odor) in samples that were treated with 100 μg/g diacetyl and had a brown appearance. Meat samples treated with the combination of CO2 and diacetyl (study III) showed that the addition of diacetyl did not have an additive effect on microbial growth. Combination-treated meat maintained a red appearance and no off-odor. Diacetyl and CO2 could be used in combination to maintain a red color and inhibit spoilage microorganisms.

An estuarine agar medium for enumeration of aerobic heterotrophic bacteria associated with water, sediment, and shellfish

1980 ◽  
Vol 26 (11) ◽  
pp. 1366-1369 ◽  
Author(s):  
Ronald M. Weiner ◽  
David Hussong ◽  
Rita R. Colwell
Keyword(s):  
Yeast Extract ◽  
Heterotrophic Bacteria ◽  
Agar Medium ◽  
Plate Count ◽  
Bacterial Populations ◽  
Standard Plate Count ◽  
Plate Count Agar ◽  
Standard Plate ◽  
Plate Counts ◽  
Yeast Extract Agar

A plate count agar was formulated for use in bacteriological analysis of estuarine samples and was tested together with standard plate count agar and an estuarine salts yeast extract agar for growth of aerobic, heterotrophic bacteria in water, sediment, and oysters. The estuarine agar was found to be efficient for enumerating aerobic, heterotrophic bacterial populations of water, sediment, and oysters, and is recommended for plate counts of estuarine samples.

Microbiological investigations of rainwater and graywater collected for toilet flushing

2002 ◽  
Vol 46 (6-7) ◽  
pp. 311-316 ◽  
Author(s):  
H.-J. Albrechtsen
Keyword(s):  
Campylobacter Jejuni ◽  
Microbiological Quality ◽  
Plate Count ◽  
Microbial Water Quality ◽  
E Coli ◽  
Plate Count Agar ◽  
Hand Wash ◽  
Plate Counts ◽  
Heterotrophic Plate Counts ◽  
Micro Organisms

Seven Danish rainwater systems were investigated with respect to the microbial water quality. The general microbiological quality (total numbers of bacteria (AODC)), and heterotrophic plate counts on R2A and Plate Count Agar in the toilets supplied with rainwater were approximately the same as in the reference toilets supplied with drinking water. However, in 12 of the 27 analysed samples one or more pathogens were observed (Aeromonas sp., Pseudomonas aeruginosa, Legionella non-pneumophila, Campylobacter jejuni, Mycobacterium avium, and Cryptosporidium sp.). These pathogens were not found in any of the reference toilets (32 toilets). This means that the use of rainwater introduced new, potentially pathogenic micro-organisms into the households which would normally not occur in toilets supplied with water from waterworks. Furthermore, four graywater systems were investigated where water from the shower and hand wash basin was reused. The graywater systems gave more problems in terms of bad smell and substantially higher numbers of E. coli and Enterococcus in some toilet bowls supplied with graywater.

A Review of Aerobic and Psychrotrophic Plate Count Procedures for Fresh Meat and Poultry Products

2002 ◽  
Vol 65 (7) ◽  
pp. 1200-1206 ◽  
Author(s):  
J. M. JAY
Keyword(s):  
Low Temperature ◽  
Incubation Temperature ◽  
Plate Count ◽  
Fresh Meat ◽  
Poultry Products ◽  
Plate Count Agar ◽  
Plate Counts ◽  
Incubation Temperatures ◽  
Temperature Time ◽  
Yeast Extract Agar

This is a review of reports that employed aerobic plate counts on fresh meat and poultry products since 1985; it lists synopses of 100 applications. A total of 15 different plating media were used, with 48 (48%) being either plate count agar (PCA) or tryptone glucose yeast extract agar. The temperature-time relations ranged from a low temperature of 20°C for 120 h to 37°C for 24 h. Some 29 different temperature-time combinations were used among the total of 109, with 21 (19.3%) being 35°C/48 h, followed by 12 (11.0%) at 32°C/48 h, 11 (10.1%) at 25°C/48 h, and 9 (8.3%) at 25°C/72 h. Fifty-four (49.5%) plate count applications employed incubation temperatures of 30°C and below. From the 26 reports that employed psychrotrophic counts, 16 (61.5%) used PCA; 18 different temperature-time combinations were used, with 7°C/10 d employed by only four. Twenty-one (80.8%) employed an incubation temperature at or <10°C, and five employed an incubation temperature >10°C. There is a serious need for some consensus on methodologies for aerobic and psychrotrophic counts on fresh meat and poultry products.

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