Rapid Detection of Psychrotrophic Bacteria In Manufacturing Grade Raw Milks

1991 ◽  
Vol 54 (11) ◽  
pp. 861-867 ◽  
Author(s):  
S. R. TATINI ◽  
P. MEKALA ◽  
A. EL-HABAZ ◽  
M. W. GRIFFITHS
Keyword(s):  
Rapid Detection ◽  
Bacterial Count ◽  
Raw Milk ◽  
Plate Count ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Microscopic Count ◽  
Direct Epifluorescent Filter Technique ◽  
Native Microflora

Methods to rapidly assess the bacteriological quality of raw milk were investigated. Whereas direct microscopic count, modified psychrotrophic plate count, and direct epifluorescent filter technique (DEFT) did not correlate well with initial psychrotrophic bacterial count of raw milk, improvements were obtained after preincubation of the milk samples. The best preincubation conditions were identified as 30°C for 6 h, 21°C for 10 h, 13°C for 15 h, 13°C for 20 h, or 7°C for 37 h. The “square root” equation was applied to the data, and a model was produced for predicting growth of the native microflora of raw milk. Using this equation, a DEFT count after preincubation of the milk at 21°C for 10 h could accurately predict the initial psychrotroph count and the count after storage of the milk at 6°C for 48 h.

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.

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.

THE QUALITY OF RAW MILK FROM SELECTED OHIO MARKETS.

1966 ◽  
Vol 29 (4) ◽  
pp. 118-121 ◽  
Author(s):  
S. P. Ohri ◽  
W. L. Slatter
Keyword(s):  
Raw Milk ◽  
Plate Count ◽  
High Count ◽  
Coliform Count ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Bacteriological Method ◽  
Standard Plate ◽  
Bulk Tank

Summary An 8-month survey of the bacteriological quality of bulk tank produced fluid milk supplies for four major markets in Ohio, was made utilizing the Standard Plate Count (SPC), the preliminary incubation count (PI), the thermoduric (pasteurized milk) count, and the coliform count. In terms of maximum standards of 200,000 and 100,000 organisms/ml, the SPC would have eliminated 13% and 20% of the milk samples, respectively. A SPC of 50,000/ml, a PI count of 200,000/ml, a thermoduric count of 500/ml, and a coliform count of 100/ml would have eliminated 37%, 34%, 40%, and 40%, respectively, of the samples but not all of the samples eliminated by one test were eliminated by another test. All of the tests employed showed a seasonal trend especially in the high count categories but the trend was less noticeable in the results of the preliminary incubation count. A combination of two of the methods was superior to any single bacteriological method employed in detecting unsatisfactory milk. Of the tests used, the combination of the thermoduric count (500/ml) and the coliform count (100/ml) was the most effective in the detection of unsatisfactory milk samples.

scholarly journals Microbiological Profile of the Traditionally Collected Industrial Raw Milk from the Milk Pocket Zones of Bangladesh

1970 ◽  
Vol 25 (1) ◽  
pp. 17-20 ◽  
Author(s):  
Gouranga C Chanda ◽  
Gazi M Noor Uddin ◽  
Aparna Deb ◽  
Tahmina Bilkis ◽  
Sharmin Chowdhury ◽  
...  
Keyword(s):  
Bacterial Count ◽  
Raw Milk ◽  
Total Coliform ◽  
Plate Count ◽  
Coliform Count ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Bacteriological Profile ◽  
Standard Plate ◽  
Viable Bacteria

The study was aimed to evaluate the bacteriological profile of the traditionally collected industrial raw milk from the milk pocket zones of Bangladesh. About 365 raw milk samples were collected from the milk tanker, who brought raw milk from the mother chilling centre where raw milk was chilled at 4°C following traditional method. All milk samples were subjected to perform standard plate count and total coliform count. The average standard plate count was found to be 4.37 x 106 cfu/ml and the highest occurrence of standard plate count was found to be 6.70 x 106 cfu/ml in October and the lowest (3.28 x 106 cfu/ml) in March. The highest occurrence of total viable bacteria was found to be 5.64 x 106 cfu/ml in autumn and the lowest was found to be 3.78 x 106 cfu/ml in summer. On the other hand, the average of the coliform bacterial count was found to be 3.88 x 105 cfu/ml with the highest (5.70 x 105 cfu/ml) occurrence in May and the lowest (1.90 x 105 cfu/ml) in January. Moreover, the highest occurrence of coliform count was found to be 4.84 x 105 cfu/ml in rainy season and the lowest was 2.75 x 105 cfu/ml found in winter.DOI: http://dx.doi.org/10.3329/bjm.v25i1.4849 Bangladesh J Microbiol, Volume 25, Number 1, June 2008, pp 17-20

COMPARISON OF PLATE LOOP AND AGAR PLATE METHODS FOR BACTERIOLOGICAL EXAMINATION OF MANUFACTURING GRADE RAW MILK1,2

1967 ◽  
Vol 30 (4) ◽  
pp. 112-115 ◽  
Author(s):  
Sita Ramayya Tatini ◽  
Roger Dabbah ◽  
J. C. Olson
Keyword(s):  
Agar Plate ◽  
Bacterial Count ◽  
Raw Milk ◽  
Substantial Improvement ◽  
Plate Count ◽  
Bacteriological Examination ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Standard Plate ◽  
Bulk Tank

Summary Plate loop counts and standard plate counts on each of several manufacturing grade raw milk samples (handled in cans or in farm bulk tanks) have been compared. On the average, the plate loop count (PLC) was lower than the standard plate count (SPC) regardless of the type of handling of milk on the farm, can or bulk tank. Agreement between the SPC and PLC seemed to depend upon the bacterial-count levels present in milk. Statistical analyses indicated significant differences, at 1% level of probability, between the average bacterial count by SPC and PLC methods regardless of count level (≤100,000/ml or >100,000/ml) in case of can milk samples. On the other hand, in case of farm bulk tank milk samples, no significant differences, at the 1% level of probability, between the average bacterial count by SPC and PLC methods were obtained, when the counts were equal to or less than 100,000 per ml; when the counts exceeded 100,000 per ml, significant differences were present. Since the bacterial counts of manufacturing grade raw milk samples are likely to exceed 100,000/ml, the data presented in this investigation indicate that, until the bacteriological quality of manufacturing grade milk supplies undergoes substantial improvement, the PLC method does not appear to be a suitable substitute for the SPC method for routine bacteriological examination of such milk supplies.

Effect of Low-Temperature Cleaning of Milking Equipment on the Microbiological Quality of Raw Milk

1983 ◽  
Vol 46 (1) ◽  
pp. 58-60 ◽  
Author(s):  
J. B. STONE ◽  
A. N. MYHR ◽  
I. DAVIE
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Microbiological Quality ◽  
Bacterial Count ◽  
Raw Milk ◽  
Negative Slope ◽  
Plate Count ◽  
Pipeline System ◽  
Standard Plate Count

Effect on the microbiological quality of milk of using a special cleaning detergent (Diversey-Wyandotte, Inc.) for low-temperature (initial 43.8°C, end of wash 35.4°C) washing in a milking parlor pipeline system was compared to regular high-temperature (initial 73°C, end of wash 43.8°C) wash of the system. Microbiological quality of the milk was determined by standard plate count (SPC) and psychrotrophic bacterial count (PBC). Cleanliness of equipment was evaluated by measurement of calcium deposits and visual inspection. Statistical analysis of data over time (June 5 to September 16, 1980) indicated no difference in SPC and PBC of milk between low-and high-temperature washing and, although there was a significant negative slope of PBC with time, this was due to factors other than treatment. Calcium soil deposition and visible evaluation of the equipment were not different for the wash temperatures.

scholarly journals Prevalence of Psychrotrophic Bacteria During Frozen Storage of Raw Milk

2021 ◽  
Vol 24 (1) ◽  
pp. 65-76
Author(s):  
S Ahmed ◽  
S MMR Sumon ◽  
MD Hossain ◽  
ABM Rubayet Bostami ◽  
MM Rahman
Keyword(s):  
Management Practices ◽  
Bacterial Load ◽  
Frozen Storage ◽  
Storage Period ◽  
Dairy Farms ◽  
Raw Milk ◽  
Plate Count ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Large Farms

The study was aimed to enumerate the load of psychrotrophic bacteria in raw milk stored in freezer. Raw milk was collected from 18 different sized dairy farms located in Gazipur and Mymensingh district. From each location equal number (three of each) of small, medium or large farms were randomly selected. The raw milk samples were stored in freezer (-18 to -22 oC) for 28 days and analyzed for psychrotrophic bacterial load at every 7 days interval. For total viable count, bacteria was grown onto plate count agar at 70C for 10 days. Bacteria grown under such conditions referred as psychrotrophs. However, to determine the type of psychrotrophs selected colonies were grown further onto pseudomonas agar base and gram staining, oxidase, catalase and methyl red test for each isolate were perfomed. The psychrotrophic bacterial load in all the samples were low until 14 days of storage. However, from the third week of storage the bacterial load was observed to increase which reached to as high as 1.1 ± 2.3×107 cfu/mL at the end of the storage period (28 days). The milk samples obtained from large farms were lower (1.3×105 to 6.6×106) than that of medium (1.7×105 to 8.8×106) and small (2.0×105 to 1.1×107) type farms. The bacterial load was significantly (P<0.01) varied among the samples suggesting the heterogeneous management practices in dairy farms. All the morphological and biochemical tests confirmed the isolates as pseudomonas. Based on the present findings, it could be suggested that raw milk can store in the freezer maximum for two weeks in terms of psychrotrophic bacterial load. Ann. Bangladesh Agric. (2020) 24(1) : 65-76

scholarly journals Bacteriological quality of raw milk marketed in and around Guwahati city, Assam, India

2021 ◽  
Vol 14 (3) ◽  
pp. 656-660
Author(s):  
Smita Kakati ◽  
Archana Talukdar ◽  
Razibuddin Ahmed Hazarika ◽  
Masuk Raquib ◽  
Saurabh Kumar Laskar ◽  
...  
Keyword(s):  
Standard Procedure ◽  
Raw Milk ◽  
Poor Quality ◽  
Plate Count ◽  
Coliform Count ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Guwahati City ◽  
Standard Plate

Background and Aim: Milk is a highly perishable commodity, which is subjected to various types of contamination right from the farm level to the consumers' table. This study aimed to assess the quality of raw milk sold in and around Guwahati city based on the microbial load. Materials and Methods: A total of 200 raw pooled milk samples collected from 25 different locations in and around Guwahati city were subjected to quality evaluation based on the methylene blue reduction test (MBRT), standard plate count, and coliform count as per the standard procedure. Results: Out of the 200 samples evaluated, more than 50% of them were graded as poor to very poor quality based on the MBRT results. None of the samples could be graded as excellent quality and only 14.5% were graded as good quality. The standard plate count and coliform count of all the raw milk samples were found to be significantly higher than the legal standard. A highly significant (p<0.01) difference was observed for standard plate count and coliform count among the different locations in and around Guwahati city. Conclusion: From the present study, it could be inferred that raw milk sold in most parts of Guwahati city do not confer to the legal microbiological standard and may pose a high risk of milk-borne illness among consumers of the city, which needs a systematic series of actions to be implemented properly.

scholarly journals Effect of acidification of raw milk on psychrotrophic microrganims.

2013 ◽  
Vol 2 (2) ◽  
Author(s):  
Marianne Ayumi Shirai ◽  
Maria Lucia Masson
Keyword(s):  
Dairy Products ◽  
Inhibitory Action ◽  
Raw Milk ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
Ph Reduction ◽  
Quality Of Milk ◽  
Micro Organisms ◽  
Milk And Dairy Products

<p>The contamination of raw milk with psychrotrophic micro-organisms has become a concern because they are able to multiply at refrigeration temperatures and produce heat resistant enzymes that affect the quality of milk and dairy products. The objective of this study was to evaluate the effect of acidification with CO<sub>2</sub> and HCl on mesophilic and psychrotrophic bacteria present in raw milk during cold storage. Raw milk samples were acidified with CO<sub>2</sub> and HCl 1N until pH 6,0 and stored at 5 &deg;C for 10 days. The results showed an average reduction of 1 logarithmic cycle in the growth of psychrotrophic and mesophilic microorganisms in samples treated with CO<sub>2</sub>. Acidification with HCl showed no effect, indicating that inhibitory action was due to CO<sub>2</sub> not by pH reduction.</p><p>&nbsp;</p><p>DOI: http://dx.doi.org/10.14685/rebrapa.v2i2.68</p>

scholarly journals Microbiological quality of raw milk attributable to prolonged refrigeration conditions

2017 ◽  
Vol 84 (1) ◽  
pp. 92-101 ◽  
Author(s):  
Nuwan R Vithanage ◽  
Muditha Dissanayake ◽  
Greg Bolge ◽  
Enzo A Palombo ◽  
Thomas R Yeager ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
Microbiological Quality ◽  
Bacterial Count ◽  
Raw Milk ◽  
Storage Conditions ◽  
Storage Life ◽  
Plate Count ◽  
Industry Standard ◽  
And Storage

Refrigerated storage of raw milk is a prerequisite in dairy industry. However, temperature abused conditions in the farming and processing environments can significantly affect the microbiological quality of raw milk. Thus, the present study investigated the effect of different refrigeration conditions such as 2, 4, 6, 8, 10 and 12 °C on microbiological quality of raw milk from three different dairy farms with significantly different initial microbial counts. The bacterial counts (BC), protease activity (PA), proteolysis (PL) and microbial diversity in raw milk were determined during storage. The effect of combined heating (75 ± 0·5 °C for 15 s) and refrigeration on controlling those contaminating microorganisms was also investigated. Results of the present study indicated that all of the samples showed increasing BC, PA and PL as a function of temperature, time and initial BC with a significant increase in those criteria ≥6 °C. Similar trends in BC, PA and PL were observed during the extended storage of raw milk at 4 °C. Both PA and PL showed strong correlation with the psychrotrophic proteolytic count (PPrBC: at ≥4 °C) and thermoduric psychrotrophic count (TDPC: at ≥8 °C) compared to total plate count (TPC) and psychrotrophic bacterial count (PBC), that are often used as the industry standard. Significant increases in PA and PL were observed when PPrBC and TDPC reached 5 × 104cfu/ml and 1 × 104cfu/ml, and were defined as storage life for quality (SLQ), and storage life for safety (SLS) aspects, respectively. The storage conditions also significantly affected the microbial diversity, wherePseudomonas fluorescensandBacillus cereuswere found to be the most predominant isolates. However, deep cooling (2 °C) and combination of heating and refrigeration (≤4 °C) significantly extended theSLQandSLsof raw milk.

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