THE KEEPING QUALITY OF PASTEURIZED MILK AS INFLUENCED BY THE GROWTH OF PSYCHROPHILIC BACTERIA AND THE ADDITION OF AUREOMYCIN*

1953 ◽  
Vol 16 (5) ◽  
pp. 213-219 ◽  
Author(s):  
J. C. Olson ◽  
D. S. Willoughby ◽  
E. L. Thomas ◽  
H. A. Morris
Keyword(s):  
Storage Life ◽  
Psychrophilic Bacteria ◽  
Bacterial Counts ◽  
Pasteurized Milk ◽  
Complete Destruction ◽  
Reliable Indication ◽  
Keeping Quality ◽  
Long Storage

In studies of the keeping quality of pasteurized milk, it was found that past records from milk plants showing good bacterial counts of finished products, afforded a rather reliable indication that milk from such plants may show better keeping quality than milk from plants with poor past records. Proper pasteurization resulted in extensive if not complete destruction of psychrophiles. Negative coliform counts of freshly pasteurized milk were not reliable as indicators of good keeping quality during storage at the temperature used in these studies. The mere absence of psychrophiles in one or two milliliters of milk was not found to be a guarantee of long storage life. The presence of aureomycin in the concentration used in these studies had no effect in extending the keeping quality of pasteurized milk.

scholarly journals THE KEEPING QUALITY OF THE PASTEURIZED MILK PRODUCED IN THESSALONIKI - GREECE

1973 ◽  
Vol 24 (2) ◽  
pp. 87
Author(s):  
Α. ΠΑΝΕΤΣΟΣ ◽  
Π. ΚΑΡΑΙΩΑΝΝΟΓΛΟΥ ◽  
Α. ΜΑΝΤΗΣ
Keyword(s):  
Bacterial Counts ◽  
Pasteurized Milk ◽  
Keeping Quality

The keeping quality of the pasteurized milk produced in the district of Thessaloniki was examined. It was found that pasteurized milk which was stored at 4° C, continued to have the same bacterial counts, low acidity, and no off flavours after 48 hours. The results were compared with those obtained from samples of milk collected from different stores.

Effect of psychrotrophic post-pasteurization contamination on the keeping quality at 11 and 5 °C of HTST-pasteurized milk in the UK

1982 ◽  
Vol 49 (4) ◽  
pp. 619-630 ◽  
Author(s):  
Monika J. A. Schröder ◽  
Christina M. Cousins ◽  
Charles H. McKinnon
Keyword(s):  
Shelf Life ◽  
Storage Temperature ◽  
Bacterial Counts ◽  
Pasteurized Milk ◽  
Colony Forming Units ◽  
Keeping Quality ◽  
The Uk ◽  
Spoilage Microflora

SummaryThe keeping quality of commercial HTST-pasteurized milk and laboratory pasteurized milk from a common bulk raw supply has been investigated for 5 dairies. Spoilage occurred at levels of total bacterial counts around 107 colony forming units/ml, but with a slightly higher off-flavour threshold for the commercial milks than the laboratory pasteurized milks. The predominant microflora at spoilage and the type of off-flavour produced differed between the 2 types of milk. Raising the storage temperature from 5 to 11 °C caused a slight shift in the spoilage microflora and led to an average reduction in the shelf life of the laboratory pasteurized milk from 28 to 6 d and of the commercial pasteurized milk from 13 to 5 d. Changes in the level of post-pasteurization contamination (PPC) were reflected in changes in keeping quality, particularly at 5 °C. However, the greatest improvements were found in the absence of PPC.

Keeping Quality of Pacific Coast Dogfish

1959 ◽  
Vol 16 (6) ◽  
pp. 791-794 ◽  
Author(s):  
R. H. Moyer ◽  
B. A. Southcott ◽  
E. G. Baker ◽  
H. L. A. Tarr
Keyword(s):  
Pacific Coast ◽  
Sea Water ◽  
Total Volatile ◽  
Bacterial Counts ◽  
Ph Values ◽  
Appreciable Increase ◽  
Muscle Ph ◽  
Keeping Quality ◽  
Viable Bacteria

Pacific coast dogfish (Squalus suckleyi) were held 21 days in ice and in refrigerated sea water with and without added chlortetracycline, viable bacterial counts and volatile bases being determined periodically. Viable bacteria increased sharply after about 14 days but the muscle pH values showed little or no increase. No appreciable increase in the total volatile base or trimethylamine content of the muscle was noted until the fish were stored for more than 2 weeks, and then the increases observed were comparatively small.

400. Factors influencing the keeping quality of ghee

1949 ◽  
Vol 16 (3) ◽  
pp. 356-362 ◽  
Author(s):  
D. P. Persai ◽  
C. R. Barnicoat
Keyword(s):  
Heat Treatment ◽  
Bacterial Culture ◽  
Storage Life ◽  
Summer Temperature ◽  
Final Temperature ◽  
Marked Influence ◽  
Factors Influencing ◽  
Keeping Quality ◽  
Main Factors

Of the four main factors commonly regarded as influencing keeping properties of ghee, viz. moisture content, acidity, heat treatment and type of bacterial culture used in souring, the heat treatment was found to be the most important.In general, the higher the final temperature (110° C. and higher) attained during evaporation, the better were the keeping properties of the product, providing that the butter had been heated in contact with curd, boiled as rapidly as possible, and given a minimum amount of stirring.The improved keeping properties conferred on ghee heated to 110–150° C. were promoted by antioxidants (apparently phospholipids) extracted from the curd during cooking.Initial acidity and moisture contents had no effect on storage life of ghee at 38° C., and the practice of grading ghee according to its acidity would appear to be of questionable value. Souring of milk to give 2·5–3·0% lactic acid and the accompanying desirable flavour did not detract from the keeping quality of the ghee made from it.The type of bacterial culture used for souring had only slight influence on keeping quality of ghee, but a marked influence on flavour.Storage life of ghee at 38° C. (‘Indian summer temperature’) could be predicted with fair accuracy from its rate of oxidation at 100° C. in a ‘Swift oxidation tester’.

Comparison between the EC plate count test at 21 °C and an accelerated plate count method for assessing the keeping quality of pasteurized milk

1992 ◽  
Vol 59 (3) ◽  
pp. 431-436 ◽  
Author(s):  
Sarah A. Langford ◽  
Rohan G. Kroll
Keyword(s):  
Plate Count ◽  
Gram Negative ◽  
Rapid Methods ◽  
Pasteurized Milk ◽  
Psychrotrophic Bacteria ◽  
Commercial Interest ◽  
Count Method ◽  
Keeping Quality ◽  
Plate Count Method

The keeping quality of properly refrigerated pasteurized milk and cream is primarily determined by post-pasteurization contamination by Gram-negative psychrotrophic bacteria (Phillips et al. 1981; Schröder et al. 1982). Reliable and rapid methods of assessing the levels of contamination by these organisms are therefore of commercial interest.

scholarly journals Measurement of Off-Flavoring Volatile Compounds and Microbial Load as a Probable Marker for Keeping Quality of Pasteurized Milk

2019 ◽  
Vol 9 (5) ◽  
pp. 959 ◽  
Author(s):  
Anjum Rashid ◽  
Imran Javed ◽  
Barbara Rasco ◽  
Shyam Sablani ◽  
Muhammad Ayaz ◽  
...  
Keyword(s):  
Volatile Compounds ◽  
Solid Phase ◽  
Storage Period ◽  
Microbial Load ◽  
Plate Count ◽  
Milk Product ◽  
Pasteurized Milk ◽  
Keeping Quality ◽  
Different Temperatures

(1) Background: Multiple attempts have been conducted to correlate milk keeping quality with chemical, physical or bacteriological parameters. These methods only measure the chemical changes in milk produced by bacteria. Headspace solid-phase micro-extraction (HS-SPME) is an economic and recent method used to measure both volatile compounds and microbial load in milk, also allowing to keep the quality of the milk product. (2) Methods: The present study was conducted to identify and measure the off-flavoring volatile compounds through gas chromatography coupled with flame ionization detector (GC-FID) and the microbial load of pasteurized fluid milk stored at different temperatures, as a possible indicator of its keeping quality. (3) Results: The highest results were obtained to acetone, followed by butanone, pentanal and ethanol. These mean values were significantly enhanced from the 0 to 19th day of storage, at 10 °C. At day 19th, the minimum score for aroma, flavor and overall acceptability were also recorded as 4.33 ± 0.17, 4.02 ± 0.06, 4.00 ± 0.04, respectively. Likewise, maximum values for standard plate count (Log10 CFU 15.54 ± 0.40 mL−1) and total psychotroph count (Log10 CFU 11.67 ± 0.30mL−1) were reported at 10 °C and 4 °C. (4) Conclusion: HS-SPME/GC-FID methodology revealed to be very sensitive and capable to be applied in volatile compounds quantification in pasteurized milk produced during the storage period at different temperatures.

THE KEEPING QUALITY OF DEHYDRATED MIXTURES OF EGG AND MILK

1946 ◽  
Vol 24f (1) ◽  
pp. 70-76 ◽  
Author(s):  
Jesse A. Pearce ◽  
W. A. Bryce ◽  
Joan Whittaker ◽  
H. Tessier
Keyword(s):  
Carbon Dioxide ◽  
Beneficial Effect ◽  
Milk Powder ◽  
Storage Life ◽  
Carbohydrate Content ◽  
Added Sugar ◽  
Fluorescence Measurements ◽  
Similar Protein ◽  
Keeping Quality

The storage life of a dehydrated mixture of egg and milk, when assessed by both palatability and fluorescence measurements, was shorter than the life of milk powder of similar protein, fat, and carbohydrate content. Increased quantities of egg in the mixture decreased the quality of the mixture, both initially and during 16 weeks' storage. These effects were noticeable at all temperatures studied between 40° and 140° F. but were most marked above 80° F. After 16 weeks at 80° F., material packed under carbon dioxide usually had better palatability than the air-packed products. The effect of added sugar was most noticeable at 120° and 140° F. Lactose had a slightly beneficial effect; sucrose was more effective.

A Membrane-Filter Technique to Test for the Significance of Sublethally Injured Bacteria in Retail Pasteurized Milk

1975 ◽  
Vol 38 (2) ◽  
pp. 87-88 ◽  
Author(s):  
T. J. CLAYDON
Keyword(s):  
Shelf Life ◽  
Membrane Filter ◽  
Selective Medium ◽  
Pasteurized Milk ◽  
Filter Technique ◽  
Litmus Milk ◽  
Keeping Quality ◽  
Membrane Transfer

A membrane transfer procedure previously described was used to study the possible role of sublethally injured bacteria in the keeping quality of retail pasteurized milk. Trypticase soy broth (TSB) was used as nonselective medium and TSB plus NaCl at pH 6.0 (TSBS 6.0), as the selective medium inhibitory to injured organisms. In pasteurized milk at early stages of storage, colony counts on the latter medium were much lower than on the former. Subsequent transfer of the TSBS 6.0 filters to fresh TSB and further incubation usually increased the counts to about the initial TSB range. Generally the organisms presumed injured and subsequently recovered were the same types as those considered uninjured. They were mainly streptococci and micrococci that produced only slow changes in litmus milk at 5 C, so they are of doubtful significance in the shelf life of retail milk at refrigerator temperatures.

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