Identification and Control of Processing Variables That Affect the Quality and Safety of Fluid Milk

1999 ◽  
Vol 62 (6) ◽  
pp. 625-631 ◽  
Author(s):  
THOMAS J. GRUETZMACHER ◽  
ROBERT L. BRADLEY
Keyword(s):  
Shelf Life ◽  
Sequential Analysis ◽  
Microbiological Quality ◽  
Processing System ◽  
Plate Count ◽  
Quality And Safety ◽  
Standard Plate Count ◽  
Standard Plate ◽  
And Control ◽  
Fluid Milk

The objective of this study was to increase quality and safety of fluid milk by eliminating postpasteurization contamination as measured by extended shelf life. Milk shelf life was defined as the number of days for standard plate count to reach 20,000 CFU/ml in milk stored at 7°C. Sequential analysis of the fluid milk processing system indicated filling machine and pasteurizer were significant sources of postpasteurization contamination. Aseptically sampled milk from the pasteurizer outlet indicated a maximum shelf life of more than 30 days could be achieved. The pasteurizer can be a source of contamination when inadequately cleaned or maintained. The filling machine was a significant source of contamination. Shelf life of milk in 236-ml containers was reduced 20 days compared with milk sampled before the filling machine. Carton-forming mandrels, filling heads, and airborne microorganisms were sources of contamination within the filling machine. Eliminating sources of post-pasteurization contamination and proper cleaning followed by sanitizing with chlorine significantly increased milk shelf life in paperboard containers to 20.4 days from an initial shelf life of 9 days. Changing the sanitizing agent to peroxyacetic acid significantly increased milk shelf life to 33.9 days. Enclosing the filling chamber and adding sterile laminar flowing air significantly improved microbiological quality of air inside the chamber and reduced variance among milk shelf life samples.

Estimation of Potential Shelf-life of Pasteurized Fluid Milk Utilizing Bacterial Numbers and Metabolites

1985 ◽  
Vol 48 (8) ◽  
pp. 663-667 ◽  
Author(s):  
J. R. BISHOP ◽  
C. H. WHITE
Keyword(s):  
Shelf Life ◽  
Skim Milk ◽  
Daily Basis ◽  
Prediction Equation ◽  
Plate Count ◽  
Regression Equations ◽  
Psychrotrophic Bacteria ◽  
Standard Plate Count ◽  
Standard Plate ◽  
Fluid Milk

A study was conducted on use of bacterial numbers and their metabolites, and any possible interaction thereof, as estimators of the potential shelf-life of pasteurized fluid milk. Whole and skim milk samples were obtained on the day of processing. Samples of each milk were inoculated in duplicate with 0, 1,000, or 100,000 bacteria/ml with a pure strain of Pseudomonas fluorescens P27. Samples, stored at 7°C, were analyzed for microbiological and bioichemical parameters every 5 d for up to 20 d, with organoleptic evaluations conducted on a daily basis. On days of analysis, each sample was subjected to various preliminary incubations. Bacterial enumerations conducted were psychrotrophic bacteria count, standard plate count, gram-negative bacteria count, and modified psychrotrophic bacteria count. Lipopolysaccharide (endotoxin) concentrations, degree of proteolysis and impedance detection were also determined. All bacterial enumerations and proteolysis were significantly related to potential shelf-life of pasteurized fluid milk (whole, skim, and combined) but were of little predictive value. Endotoxin concentration and impedance detection were highly significantly related to shelf-life, and provided predictive regression equations. Using combined data from whole and skim milk, impedance detection resulted in the preferred prediction equation suitable for pasteurized fluid milks.

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.

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.

Subpasteurization Heat Treatment to Inactivate Lipase and Control Bacterial Growth in Raw Milk

1982 ◽  
Vol 45 (6) ◽  
pp. 513-515 ◽  
Author(s):  
G. F. SENYK ◽  
R. R. ZALL ◽  
W. F. SHIPE
Keyword(s):  
Heat Treatment ◽  
Lipase Activity ◽  
Raw Milk ◽  
Heat Treatments ◽  
Plate Count ◽  
Psychrotrophic Bacteria ◽  
Standard Plate Count ◽  
Heat Treated ◽  
Standard Plate ◽  
And Control

Raw milk was heat-treated under subpasteurization and suprapasteurization conditions, cooled and stored for up to 72 h at 4.4 and 6.7°C. Milk lipase activity and bacteria counts were monitored in both unheated and heated milks. Inhibition of milk lipase activity ranged from 42 to 98% for treatments of 57.2°C for 10 sec to 73.9°C for 10 sec, respectively. The logs of Standard Plate Count after 72 h of storage at 6.7°C were 6.56, 4.86, 4.31, 4.00 and 2.82 for unheated and 10-sec heat treatments at 57.2, 65.6, 73.9 and 82.2°C, respectively. Psychrotrophic Bacteria Counts were also lower in the heated milks than in the unheated milk. The logs of Psychrotrophic Bacteria Counts after 72 h of storage at 6.7°C were 6.21, 2.45, 2.27, 1.33 and 1.00 for unheated and 10-sec heat treatments at 57.2, 65.6, 73.9 and 82.2°C, respectively. Heat treatment of raw milk supplies would result in limiting action of the milk lipase system and growth of bacteria.

Microbiological Studies of Chesapeake Bay Soft-shell Clams (Mya arenaria)

1990 ◽  
Vol 53 (12) ◽  
pp. 1052-1057 ◽  
Author(s):  
TUU-JYI CHAI ◽  
TZYY-JAN HAN ◽  
RALPH R. COCKEY ◽  
PATRICIA C. HENRY
Keyword(s):  
Chesapeake Bay ◽  
Microbiological Quality ◽  
Total Coliform ◽  
Mya Arenaria ◽  
Fecal Coliforms ◽  
Plate Count ◽  
Geometric Means ◽  
Standard Plate Count ◽  
Soft Shell ◽  
Standard Plate

A total of 472 samples of soft-shell clams (Mya arenaria), collected from three major clam harvest areas in the Chesapeake Bay and dockside check stations, was analyzed for standard plate count (SPC), total coliforms, fecal coliforms, Escherichia coli, and coliphages. SPC increased during the summer season. SPC geometric means of 2.6 × 104, 6.9 × 104, and 7.2 × 104/g, respectively, were found in three major harvest areas. Fecal coliforms remained relatively stable with geometric means of 30, 54, and 62/100 g. As seasonal temperatures increased, the total coliform geometric means declined slightly ranging from 1,500 to 6,300/100 g. E. coli means were low (< 27/100 g). The occurrence and levels of male-specific coliphages were also low and did not correlate with bacteriological quality. No significant microbiological quality difference was found between soft-shell clams sampled from harvest waters and check stations. Results indicate that the microbiological quality of soft-shell clams either at harvest or check stations was satisfactory.

Bacteriological Quality of Fresh Seafood Products from Seattle Retail Markets

1983 ◽  
Vol 46 (10) ◽  
pp. 901-909 ◽  
Author(s):  
CARLOS ABEYTA
Keyword(s):  
Puget Sound ◽  
Microbiological Quality ◽  
Mean Value ◽  
Plate Count ◽  
Arithmetic Means ◽  
Retail Markets ◽  
Standard Plate Count ◽  
Standard Plate ◽  
Seafood Products

A microbiological survey of 287 (fresh) seafood products from Puget Sound retail markets was conducted over a period of 1 year. The microbiological quality of fresh seafood was high, with only 2.1 % of the samples exceeding the maximum limit for acceptability as suggested by the International Commission on Microbiological Specifications for Foods (ICMSF). The overall microbiological data of positive units given as arithmetic means were: coliforms MPN/g, 199; Escherichia coli MPN/g, 21; coagulase-positive Staphylococcus aureus MPN/g, 66; enterococci/g, 9121; Clostridium perfringens/g, 18; Bacillus cereus/g, 100; and Vibrio parahaemolyticus MPN/g, 3.7. The standard plate count means 1.0 × 103 to 2.5 × 107 colony-forming units (CFU)/g, giving a mean value of 2.0 × 105 CFU/g. The percentages of seafood samples positive for pathogens were S. aureus, 37.6; Yersinia enterocolitica, 3.8; V. parahaemolyticus, 2.8; C. perfringens, 2.4; and B. cereus, 0.7. Vibrio cholerae, Clostridium botulinum, Salmonella and Shigella species were not isolated.

scholarly journals Comparison of Physicochemical, Microbiological Properties and Bioactive Compounds Content of Grassland Honey and other Floral Origin Honeys

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2932 ◽  
Author(s):  
Laura Agripina Scripcă ◽  
Liliana Norocel ◽  
Sonia Amariei
Keyword(s):  
Microbiological Quality ◽  
Principal Component ◽  
Plate Count ◽  
Standard Plate Count ◽  
Hay Meadows ◽  
Floral Diversity ◽  
Microbiological Characteristics ◽  
Standard Plate ◽  
Unifloral Honey ◽  
Antioxidant Characteristics

The aim of this study was to compare the physicochemical, the microbiological, and the antioxidant characteristics of unifloral honey, polyfloral honey, honeydew, and hay meadows honey. Hay meadow is type of semi-natural grassland with a great floral diversity, an important resource for pollinators. Grasslands are the source of the spring nectar honey obtained in May and June. Water content, sugars (fructose, glucose, sucrose, trehalose, melezitose, maltose, erlose, turanose, and raffinose), electrical conductivity, phenolic content (gallic acid, protocatechuic acid, 4-hydrxybenzoic acid, vanilic acid, chlorogenic acid, caffeic acid, p-coumaric acid, rosmarinic acid, myricetin, quercitin, luteolin, kaempferol), color, viscosity, and microbiological characteristics were performed for all samples of honey. The total polyphenols content was significant for grassland honey (21.50 mg/100 g) and honeydew (30.49 mg/100 g) and less significant for acacia (0.08 mg/100 g) and rape honey (0.14 mg/100 g). All samples were microbiologically safe, and standard plate count (SPC) values were <10 cfu/g for all the samples, but the grassland honey had the highest microbiological quality: 33.3% of samples without microorganisms, 50.0% with the presence of yeast under limit, and 16.7% with yeast and mold under limit, a situation that does not meet other types of honey. The results of statistical analysis obtained with principal component analysis (PCA) showed a major difference between the grassland honey and the other types of honey.

scholarly journals Microbiological Quality of Ice Cream Available in Chittagong

1970 ◽  
Vol 25 (2) ◽  
pp. 135-136
Author(s):  
M Tarek Hossain ◽  
AKM Humayun Kober
Keyword(s):  
Microbiological Quality ◽  
Ice Cream ◽  
Viable Count ◽  
Coliform Bacteria ◽  
Plate Count ◽  
Total Viable Count ◽  
Coliform Count ◽  
Standard Plate Count ◽  
Standard Plate

A study was carried out to investigate microbiological quality of ice cream available in Chittagong area of Bangladesh during June to July 2008. Each brand of ice cream was collected from retail stores of Chittagong City. Standard plate count (SPC) and coliform count were done for bacteriological assessment of the ice cream samples. The average SPC count of Kwality, Igloo and Sub Zero ice cream samples were 2 x 103, 3 x 103 and 4 x 103 cfu/g respectively. Coliform organisms were detected in all the ice cream samples and the average coliform counts of the ice cream samples from Kwality, Igloo and Sub Zero were 12, 18 and 42 cfu/g respectively. Coliform bacteria exceeded standard limits, which can cause serious health problems. Keyword: Total viable Count; Coliform countDOI: http://dx.doi.org/10.3329/bjm.v25i2.4876Bangladesh J Microbiol, Volume 25, Number 2, December 2008, pp 135-136

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

1978 ◽  
Vol 41 (11) ◽  
pp. 902-906 ◽  
Author(s):  
DARRELL L. BIGALKE
Keyword(s):  
New York ◽  
Microbiological Quality ◽  
Raw Milk ◽  
Solution Temperature ◽  
Plate Count ◽  
Psychrotrophic Bacteria ◽  
Standard Plate Count ◽  
Wash Solution ◽  
Standard Plate

Milking equipment on four farms each in the St. Paul. Minnesota area and the Ithaca, New York area was cleaned at wash solution starting temperatures of 120, 130, 140, 150, and 160 F. The effect of wash solution temperature on raw milk microbiological quality was determined by the Standard Plate Count (SPC), Psychrotrophic Bacteria Count (PBC). Coliform Count (CC) and Laboratory Pasteurized Count (LPC). Cleanliness of the farm milking equipment was determined by microbiological counts (SPC, PBC, CC) of circulated sterile water, visual examination and determination of residual calcium on the equipment. Statistical analysis of the data indicated that Klenzade farm detergents and Agway farm detergents can be used at temperatures such that the final wash solution temperature does not drop below 105 F and have no significant effect on cleaning performance, microbiological quality of raw milk or microbiological status of the milking equipment.

Evaluation of a Rapid Impedimetric Method for Determining the Keeping Quality of Milk

1982 ◽  
Vol 45 (13) ◽  
pp. 1221-1226 ◽  
Author(s):  
S. B. MARTINS ◽  
S. HODAPP ◽  
S. W. DUFOUR ◽  
S. J. KRAEGER
Keyword(s):  
Shelf Life ◽  
Correlation Coefficients ◽  
Sample Volume ◽  
Plate Count ◽  
Impedance Method ◽  
Detection Time ◽  
Standard Plate Count ◽  
Milk Samples ◽  
Standard Plate ◽  
Quality Of Milk

Shelf-life of 151 pasteurized milk samples was recorded and correlation coefficients calculated using various microbiological factors: standard plate count (SPC), psychrotrophic plate count (PPC), coliform count (CC), and the impedance response detection time (DT) with incubation at both 21 and 32°C. These data were obtained for milk samples on the day of pasteurization as well as 4 and 8 d thereafter. Various treatments (media, dilution factors, temperature and sample volume) were compared. Of the SPC, PPC, CC and DT taken on the day of pasteurization, only the DT achieved a significant correlation with shelf-life. A correlation coefficient of 0.55 was obtained for one treatment applied to 61 samples and correlation coefficients of 0.28 to 0.32 were obtained for several other treatments applied to the entire 151 samples. Values as large as these could occur by chance in uncorrelated data with p&lt;0.0005. Thus, of the total 61 samples, 80% were correctly classified by the impedance detection time test. It is concluded that for prediction of shelf-life on the day of pasteurization, the impedance method is superior to the SPC and the PPC. In addition, the impedance method is more rapid, i.e., 14 h vs.2 d for the SPC and 10 d for the PPC.

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