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.

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.

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.

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.

The Microbiological Quality of Honey as Determined by Aerobic Colony Counts

1993 ◽  
Vol 56 (4) ◽  
pp. 336-337 ◽  
Author(s):  
JOSEP SERRA BONVEHI ◽  
ROSSEND ESCOLÁ JORDÁ
Keyword(s):  
Membrane Filter ◽  
Microbiological Quality ◽  
Plate Count ◽  
Filter Method ◽  
Filter Methods ◽  
Plate Counts ◽  
Multifloral Honey ◽  
Plate Count Method ◽  
Membrane Filter Method

The number of mesophilic aerobic colonies was determined in 72 samples of mono- and multifloral honey from various sources by the plate count and the membrane filter methods. The presence of motile colonies made the plate counts unreliable. The microorganism producing these colonies was identified as Bacillus alvei. Colony counts could only be carried out in 27 of the samples when using the plate count method, while with the membrane filter method the number of colonies was counted in all the samples.

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.

Microbiological Quality of Shellfish-Growing Waters in Chesapeake Bay

1994 ◽  
Vol 57 (3) ◽  
pp. 229-234 ◽  
Author(s):  
TUU-JYI CHAI ◽  
TZYY-JAN HAN ◽  
RALPH R. COCKEY
Keyword(s):  
Escherichia Coli ◽  
Chesapeake Bay ◽  
Water Samples ◽  
Microbiological Quality ◽  
Geographic Area ◽  
Water Area ◽  
Fecal Coliforms ◽  
Plate Count ◽  
Standard Plate Count ◽  
Standard Plate

A total of 338 water samples were collected at 20 stations from three geographically shellfish-growing areas in Chesapeake Bay from May to September 1989. Samples were examined for standard plate count, total coliforms, fecal coliforms, Escherichia coli and coliphages. Salinity, dissolved oxygen and temperature varied slightly with the depth, season, and geographic area of water samples. The geometric means of standard plate count for the three areas were 135, 355 and 275/ml, respectively. The range of means of fecal coliform for these areas was from <3 to 93/100 mi. Escherichia coli counts were also low with a range of <3 to 93/100 mi and a mean of < 3/100 mi. The growing water area adjacent to cropland was found to have higher bacterial counts than those of the other two areas. Levels of male-specific phages were very low. Results indicate that shellfish-growing waters in all three areas were of satisfactory bacteriological quality.

Determination of Viable Bacterial Populations in Raw Milk within 20 Minutes by Using a Direct Epifluorescent Filter Technique

1997 ◽  
Vol 60 (7) ◽  
pp. 874-876 ◽  
Author(s):  
CLAUDE P. CHAMPAGNE ◽  
NANCY J. GARDNER ◽  
JULIE FONTAINE ◽  
JACQUES RICHARD
Keyword(s):  
Raw Milk ◽  
Plate Count ◽  
Bacterial Populations ◽  
Filter Technique ◽  
Milk Samples ◽  
Standard Plate ◽  
Plate Counts ◽  
Direct Epifluorescent Filter Technique ◽  
Triton X

The results from a shortened procedure for the direct epifluorescent filter technique (DEFT) determination of viable bacterial populations in raw milk were compared to standard plate counts. Shortening the prefiltration trypsin-Triton X-100 incubation period from 10 to 3 min enabled the completion of the analysis within 20 min. The short DEFT method results had a correlation coefficient (r) of 0.81 with plate counts. With respect to precision, the average difference between values of duplicate plate count analyses was 0.16 log units; that of the short DEFT was 0.14 log units. The slopes of the regressions equations were less than 1, indicating that a direct correlation is not achieved. Short DEFT values were 0.17 log units higher than those of plate counts on milk samples containing less than 10,000 CFU/ml. For milk samples containing counts over 10,000 CFU/ml, short DEFT values averaged only 0.05 log units above plate count readings. Daily preparation of the stain appears unnecessary since acridine orange solutions stored for up to 2 days at 4°C did not produce results significantly (P > 0.05) different from those obtained with fresh solutions. The short DEFT method has potential for the assessment of the bacteriological quality of raw milk in tanker deliveries.

Microbiological Evaluation of Shrimp (Pandalus borealis) Processing

1978 ◽  
Vol 41 (1) ◽  
pp. 40-43 ◽  
Author(s):  
STEPHEN C. RIDLEY ◽  
BOHDAN M. SLABY J
Keyword(s):  
Salt Water ◽  
Bacterial Load ◽  
Microbiological Quality ◽  
Plate Count ◽  
Water Medium ◽  
Pandalus Borealis ◽  
Plate Count Agar ◽  
Cooking Process ◽  
Processing Plants ◽  
Aerobic Plate Count

Line samples from three different shrimp processing plants (brine-cooked shell-on, hand-peeled raw, and machine-peeled cooked) in Maine were examined for microbiological quality. Aerobic plate count (APC) of freshly caught shrimp (Pandalus borealis) was found to be about 530/g (Plate Count Agar at 35 C) while salt-requiring (SR) organisms were at significantly higher concentration (1.11 ×105/g; Salt Water Medium at 21 C). Some increase in psychrotrophic-mesophilic flora of shrimp delivered to the plant was observed. Cooking in-plant or on board the boat drastically reduced the SR flora, which was subsequently observed to increase after culling and inspection in the brine-cooked shell-on process. No such significant fluctuation due to processing was detected in APC. Shrimp sampled from steel barrels before a hand-peeled raw operation exhibited relatively high APC (7.2 × 104/g) and SR microflora (2.78 × 106/g). Heading and hand-peeling reduced the APC and SR bacterial loads by 71 and 95%, respectively. Subsequent processing and holding at room temperature resulted in a product with an APC and SR load of about 4 × 104/g. Similarly, high APC (1.66 × 105/g) and SR bacterial loads (1.84 × 105/g) were detected in samples obtained from a storage hopper of the machine-peeled cooking process. Although significant reduction in bacterial load was detected on line samples of this process (fluming, preheating, and cooking), the total bacterial load reached about 4 × 104/g before the canning step. Low levels of contamination with coliform and/or coagulase-positive staphylococci were detected in the three processes studied.

Preliminary Incubation Count as an Index of Raw Milk Microbiological Quality During Storage

1984 ◽  
Vol 47 (3) ◽  
pp. 206-208 ◽  
Author(s):  
J. J. RYAN ◽  
R. H. GOUGH ◽  
C. H. WHITE
Keyword(s):  
Microbiological Quality ◽  
Storage Period ◽  
Raw Milk ◽  
Plate Count ◽  
Bacterial Counts ◽  
Sample Group ◽  
Psychrotrophic Bacteria ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Standard Plate

During a 5-month period, 200 raw milk samples were collected from two Louisiana milk plants. Standard Plate Count (SPC), Psychrotrophic Bacteria Count (PBC), and Proteolytic Count (PC) of each sample were initially determined, then monitored daily during a 5-d storage period at 2.2°C. As hypothesized, all bacterial counts increased during the storage period. The magnitude of the increase in bacterial numbers during storage was further investigated by dividing the milk samples into bacteriologically acceptable and unacceptable groups based on SPC or Preliminary Incubation (PI) count. An SPC of 1.0 × 105/ml and PI counts of 1.0 × 105/ml, 1.5 × 105/ml, 2.3 × 105/ml, and 3.0 × 105/ml were used to repeatedly dichotomize the 200 raw milk samples into two groups. Median SPC, PBC, and PC for each acceptable and unacceptable group were then calculated. Dichotomization based on PI counts yielded acceptable sample groups having consistently lower bacterial counts during storage than did the acceptable sample group, which resulted from the dichotomization based on a SPC of 1.0 × 105/ml. The results of this study indicated that the PI count is of considerable value for raw milk quality control.

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