Bacterial counts in bulk milk ‐ an underused investigation technique

In Practice ◽  
1997 ◽  
Vol 19 (3) ◽  
pp. 122-127 ◽  
Author(s):  
Roger Blowey ◽  
Jennifer Davis ◽  
Peter Edmondson
Keyword(s):  
Bacterial Counts ◽  
Bulk Milk ◽  
Investigation Technique

RAPID CALCULATION OF LOGARITHMIC AVERAGE BACTERIAL COUNTS OF MILK

1956 ◽  
Vol 19 (11) ◽  
pp. 319-322
Author(s):  
John C. Schilling
Keyword(s):  
Methylene Blue ◽  
Plate Count ◽  
Slide Rule ◽  
Bacterial Counts ◽  
Bulk Milk ◽  
Logarithmic Average ◽  
Rule Type ◽  
Rapid Calculation ◽  
Methylene Blue Test

Determination of logarithmic averages of bacterial counts is a necessary and laborious task in grading raw and pasteurized milk. As the plate count determination replaces the methylene blue test for the ever increasing number of bulk milk producers, the problem becomes greater. A slide rule type of device has been developed that may materially simplify this task. This method is explained with information relative to its principle, application, accuracy, and advantages.

BACTERIAL COUNTS OF BULK MILK FOR INTERSTATE SHIPMENT

1962 ◽  
Vol 25 (6) ◽  
pp. 172-175 ◽  
Author(s):  
A. Richard Brazis ◽  
Luther A. Black
Keyword(s):  
Bacterial Counts ◽  
Bulk Milk

Bacterial counts in bulk milk ‐ an update

In Practice ◽  
1999 ◽  
Vol 21 (9) ◽  
pp. 531-535 ◽  
Author(s):  
Roger Blowey ◽  
Peter Edmondson ◽  
Jennifer Davis
Keyword(s):  
Bacterial Counts ◽  
Bulk Milk

Proteolysis detection in milk: I. Interpretation of tyrosine value data for raw milk supplies in relation to natural variation, bacterial counts and other factors

1973 ◽  
Vol 40 (3) ◽  
pp. 371-381 ◽  
Author(s):  
H. S. Juffs
Keyword(s):  
Amino Acids ◽  
Trichloroacetic Acid ◽  
Natural Variation ◽  
Bacterial Count ◽  
Raw Milk ◽  
Atmospheric Temperature ◽  
Total Bacterial Count ◽  
Positive Relationships ◽  
Bacterial Counts ◽  
Bulk Milk

SummaryA method for detection of proteolysis in milk was evaluated. Amino acids and peptides soluble in trichloroacetic acid were estimated by the Lowry–Folin procedure with expression of results in terms of colour yield equivalent to that of tyrosine (the ‘tyrosine value’ (TV)). Some variables and alternatives in the method of estimation were investigated.TVs for milk freshly drawn from individual cows were extremely varied (0·31–0·92 mg/ml). TVs for samples of refrigerated milk from daily supply farms were in the range 0·40–0·58 mg/ml; no relationships between TV and bacterial counts were evident with these samples. With bulk refrigerated raw milk supplied to Brisbane for liquid consumption from country depots and local farms equipped with bulk vats, significant positive relationships were found between TV and total bacterial count (TBC) for supplies from some sources, but in no instance was a significant relationship found between TV and psychrotroph or proteolytic psychrotroph count. Significant positive relationships were found between TV of bulk milk supplies from some sources and atmospheric temperature, and between TBC of the supplies and atmospheric temperature. The significance of these various relationships for bulk milks is discussed.Natural variation in TV imposed limitations on reliability of the method to provide an index of proteolysis; in general the results indicated that its application was restricted to bulk milk cold-stored for at least 3 days.

scholarly journals Evaluating the effect of storage conditions on milk microbiological quality and composition

2018 ◽  
Vol 57 (1) ◽  
pp. 52-62 ◽  
Author(s):  
L.F. Paludetti ◽  
K. Jordan ◽  
A.L. Kelly ◽  
D. Gleeson
Keyword(s):  
Enzyme Activity ◽  
Storage Time ◽  
Storage Temperature ◽  
Microbiological Quality ◽  
Bacterial Count ◽  
Storage Conditions ◽  
Total Bacterial Count ◽  
Bacterial Counts ◽  
Milk Samples ◽  
Bulk Milk

Abstract In this study, the effect of storage temperature (2 or 4°C) on the composition of milk and microbiological load was investigated over 96 h. Milk samples were collected from farm bulk milk tanks after one complete milking and stored at 2 or 4°C over 96 h. Total bacterial count (TBC), psychrotrophic bacterial count (PBC) and proteolytic bacterial count (PROT) were affected by storage time and temperature and varied significantly between farms (P < 0.05). The levels of TBC, PBC and PROT bacterial count increased from 4.37 to 6.15 log cfu/mL, 4.34 to 6.44 log cfu/mL and 3.72 to 4.81 log cfu/mL, respectively, when the milk was stored for 96 h at 2°C. The milk samples stored at 4°C had higher increases in these bacterial counts after 72 h in comparison to milk samples stored at 2°C. The casein fraction content was lower in milk samples stored at 4°C, which could be due to high levels of PROT bacteria or enzyme activity in these samples. Milk stored for 96 h at 2°C has less impact on composition or processability parameters compared to milk stored at 4°C.

BACTERIAL COUNTS OF BULK MILK FOR INTERSTATE SHIPMENT

1962 ◽  
Vol 25 (8) ◽  
pp. 240-247 ◽  
Author(s):  
A. Richard Brazis ◽  
Luther A. Black
Keyword(s):  
Bacterial Count ◽  
Raw Milk ◽  
Storage Tanks ◽  
Bacterial Counts ◽  
Bulk Milk ◽  
Three Samples ◽  
Break Up ◽  
Sanitary Conditions

During this investigation single samples were collected from 773 milk cans, three samples from each of 416 farm bulk tanks, six samples from each of 158 farm pick-up trucks, single samples from 49 storage vats, twelve samples from each of 98 transport trucks, and single samples from 77 storage tanks. Of the samples collected, 96% had counts under 200,000; 1.9% had counts of 200,000 – 300,000; 0.7% had counts of 300,000 to 400,000 and 1.4% had counts in excess of 400,000 per ml. The bacterial count finding on pumped milk indicated that milk passage through pumps did not appear to contribute to subsequent high counts through the break-up of bacterial clumps which may have been present. When bacterial counts were correlated with observations of the sanitary conditions of milk handling, the data reaffirmed that laxity in cleaning, bactericidal treatment or cooling will be reflected in the bacterial count and may result in the shipment of raw milk having counts in excess of 200,000 per ml.

The effect of udder preparation before milking and contamination from the milking plant on bacterial numbers in bulk milk of eight dairy herds

1990 ◽  
Vol 57 (3) ◽  
pp. 307-318 ◽  
Author(s):  
Charles H. McKinnon ◽  
G. John Rowlands ◽  
A. John Bramley
Keyword(s):  
Bacterial Count ◽  
Raw Milk ◽  
Poor Correlation ◽  
Dairy Herds ◽  
Relative Significance ◽  
Bacterial Counts ◽  
Bulk Milk ◽  
Bulk Tank ◽  
Milking Machine ◽  
One Year

SummaryThe effect of teat washing and drying on bacterial numbers in bulk milk was compared with that of no teat preparation in eight commercial herds over one year. Using in-line milk samplers, milk was collected at various points during its passage through the milking plant and the samples were used to establish the relative significance of the sources of contamination of raw milk. Teat washing and drying of cows housed during winter reduced the total counts by 40% and streptococcal and coliform counts by 50%. Bacterial counts were significantly lower in cows at pasture during the summer and there was no reduction in count due to teat washing and drying. Bacteriological counts increased at each stage as the milk passed through the milking machine. The milking equipment significantly increased the total colony count by between 2000 and 3000/ml, and the bulk tank added a further 1500 to 2000/ml. The mean rinse bacterial counts of the milking equipment were higher in summer than winter, averaging 4·4 x 107bacteria/m2compared with 3·5 x 107/m2respectively. Although this level of bacterial contamination of the equipment is high by current standards, very low bulk milk bacterial counts were nevertheless achieved, particularly in the summer. This confirms that organisms from this source are not a major contaminant of the bulk milk. There was a very poor correlation between rinse counts and the bulk milk bacterial count, but a strong correlation (0·98) between total and streptococcal counts of the bulk milk. The unreliability of the use of rinse techniques to assess the contribution of milking equipment to bacterial counts of raw milk is emphasized.

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