PSYCHROPHILIC BACTERIA AND KEEPING QUALITY OF PASTEURIZED DAIRY PRODUCTSl1,2

1964 ◽  
Vol 27 (3) ◽  
pp. 69-75 ◽  
Author(s):  
P. R. Elliker ◽  
E. L. Sing ◽  
L. J. Christensen ◽  
W. E. Sandine
Keyword(s):  
Shelf Life ◽  
Bacterial Count ◽  
Economic Advantage ◽  
Sampling Techniques ◽  
Careful Study ◽  
Quality Test ◽  
Psychrophilic Bacteria ◽  
Keeping Quality ◽  
Plant Equipment

Summary A study was made showing relationship between post-pasteurization contamination of milk and cream and increase in bacterial count of bottled and paper carton products during storage at 45 F for 5 days. A survey indicated extensive post-pasteurization contamination in plants not employing this type of keeping quality test. The 5-day at 45 F test was more sensitive than the coliform test in detecting post pasteurization contamination. Excessive numbers of thermoduric bacteria in the raw supply also were detected by this method when plant equipment was properly cleaned and sanitized. Special in-line sampling techniques were developed to determine source of contamination. One procedure employed sterile disposable hypodermic syringes inserted through rubber stoppered nipples welded into lines at different locations in the system. Another technique involved removal of samples by insertion of sterile disposable hypodermic syringes through rubber or neoprene gaskets between joints in different locations in the plant. Bottle and paper carton filler equipment offered special cleaning and sanitizing problems and suggestions were made on steps to minimize contamination from these sources. Application of the 5-day at 45 F keeping quality test followed by careful study of contamination sources has greatly improved shelf life of pasteurized fluid milk and cream and has represented a real economic advantage to plants adopting the program.

Effect of oxygen on the keeping quality of milk: II. Effect of available oxygen on bacterial spoilage and oxygen uptake

1982 ◽  
Vol 49 (3) ◽  
pp. 425-437 ◽  
Author(s):  
Monika J. A. Schröder
Keyword(s):  
Oxygen Uptake ◽  
Shelf Life ◽  
Bacterial Growth ◽  
Bacterial Count ◽  
Bacterial Activity ◽  
Pasteurized Milk ◽  
Keeping Quality ◽  
Quality Of Milk ◽  
Effect Of Oxygen

SUMMARYThe effect of limiting the amount of O2 present in commercially pasteurized milk on bacterial growth and on the keeping quality of the milk was investigated. No increase in bacterial count of laboratory pasteurized milk during storage for 9 d at 5 °C was observed and O2 consumption due to bacterial activity was low. In commercial pasteurized milk containing post-pasteurization contamination (PPC) growth of strict aerobes was encouraged by high O2 content while that of coliforms was less dependent on O2 level. The amounts of headspace (HS) O2 consumed in milk with PPC growth were large. Reducing the dissolved O2 content of commercial pasteurized milk stored in O2-impermeable containers without HS had little effect on bacterial activity and shelf-life.

Usefulness of the Benzalkon-Crystal Violet-ATP Method for Predicting the Keeping Quality of Pasteurized Milk

1982 ◽  
Vol 45 (10) ◽  
pp. 928-931 ◽  
Author(s):  
G. M. WAES ◽  
R. G. BOSSUYT
Keyword(s):  
Shelf Life ◽  
Crystal Violet ◽  
Quantitative Estimation ◽  
Bacterial Count ◽  
Total Bacterial Count ◽  
Life Test ◽  
Pasteurized Milk ◽  
Keeping Quality ◽  
Factory Laboratory

Using the benzalkon-crystal violet-ATP method (BC-ATP method), post-pasteurization contamination of pasteurized milk caused by gram-negative bacteria can be determined within 24 h. This study determined to what extent the keeping quality of pasteurized milk can be predicted by applying this BC-ATP method. Results obtained with the BC-ATP method for 100 samples of pasteurized milk were compared with those recorded in the shelf-life test (total bacterial count after 10 d of storage of samples at 7°C; standard: 106 bacteria per ml) and the Moseley test (bacterial count after 5 d of storage at 7°C; standard: 105 bacteria per ml). Using the shelf life test and the Moseley test, 14 and 8% of the results, respectively, did not correspond with those obtained with the BC-ATP method. From the results obtained, it was obvious that the greater the post-pasteurization contamination of the pasteurized milk, the lesser is the keeping quality. A quantitative estimation of the degree of post-pasteurization contamination can be obtained satisfactorily by applying the BC-ATP method to 1000-, 100-, 10- and 1-ml portions. The Moseley test takes too much time to achieve a good coordination between the factory laboratory and the pasteurization and filling sections of the dairy factory. By substituting the BC-ATP method applied to 100-ml portions of pasteurized milk for the Moseley test (5 d at 7°C; standard: 100,000 bacteria per ml) almost the same information is obtained within 24 h.

scholarly journals Keeping Quality of Milk and the Age on Testing for Total Bacterial Count

1931 ◽  
Vol 31 (3) ◽  
pp. 373-374 ◽  
Author(s):  
H. Barkworth
Keyword(s):  
Bacterial Count ◽  
Total Bacterial Count ◽  
Keeping Quality ◽  
Quality Of Milk

During the period 1923–29 inclusive nearly six thousand samples of milk were tested at Wye for both total bacterial count and also keeping quality. An examination of the results shows that on the average the afternoon milks showed nine hours less keeping quality than morning milks of the same total bacterial count, see Table I. The age of the milk on testing for total bacterial count (reckoned from the time of milking) is 27–29 hours for morning milks and 20–24 hours for afternoon milks.

scholarly journals Shelf-life of Dahi (Yogurt) with or without potato mash

2012 ◽  
Vol 29 (1) ◽  
pp. 22-30
Author(s):  
M R Amin ◽  
M N Islam ◽  
M A Habib ◽  
F Islam
Keyword(s):  
Shelf Life ◽  
Room Temperature ◽  
Storage Period ◽  
Keeping Quality ◽  
Different Types

Four different types of Dahi (Yogurt) were prepared and kept at room and   refrigeration temperatures with different concentrations of potato mash (0, 5, 10 and 15%). These Dahi samples were analyzed for smell and taste, body and consistency, colour, texture and acidity and pH at pre and post storage period. The quality of Dahi deteriorated quickly at room temperature than at refrigeration temperature. With (5%) or without potato mash keeping quality was preserved for up to three days but at refrigeration temperature they were suitable up to 12 days. Addition of 10% and 15% potato mashes were suitable for keeping Dahi up to two days at room temperature while in refrigeration temperature it was acceptable up to ten and eight days, respectively. Preparation of Dahi in incorporating potato mash may be economically feasible without compromising it qualities. DOI: http://dx.doi.org/10.3329/bvet.v29i1.11886 Bangl. vet. 2012. Vol. 29, No. 1, 22-30 

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.

SANITATION PROBLEMS IN THE MANUFACTURE OF COTTAGE CHEESE1

1957 ◽  
Vol 20 (6) ◽  
pp. 157-160 ◽  
Author(s):  
J. C. Boyd
Keyword(s):  
Shelf Life ◽  
Cottage Cheese ◽  
Keeping Quality ◽  
Manufacturing Procedure

Cottage cheese is the result of a controlled bacteriological fermentation. Its successful manufacture and distribution is, therefare, largely a matter of controlling certain bacteriological and sanitation problems. These problems are discussed under three catagories: namely, those that affect the manufacturing procedure; those that affect the shelf life or keeping quality of the finished product; and those that affect the spread of disease.

The Shelf Life of Pasteurized Fresh Milk Manufactured in Saudi Arabia

1988 ◽  
Vol 51 (12) ◽  
pp. 976-978 ◽  
Author(s):  
JOSEPH S. SALJI ◽  
SUHAYL R. SAADI ◽  
AHMED MASHHADI
Keyword(s):  
Saudi Arabia ◽  
Shelf Life ◽  
Sensory Attributes ◽  
Fresh Milk ◽  
C Storage ◽  
Keeping Quality ◽  
Sensory Qualities ◽  
Standard Organization ◽  
Mold And Yeast

The keeping quality of pasteurized fresh milk was investigated. At 7°C storage, the product conformed to the Saudi Arabian Standard Organization for as long as 7 d and as short as 2 d with ≤10 cfu/ml coliform, ≤10 cfu/ml mold and yeast, ≤50,000 cfu/ml SPC and acceptable sensory qualities. Acceptable sensory attributes with coliform counts of <10 cfu/ml were maintained in the product for 10 d at 7°C. Molds, yeasts and psychrotrophs were instrumental in cutting down the shelf life of the product beyond 10 d at 7°C. The possibility of extending the shelf life from 3 to 5 d should not be denied provided the product is stored at temperatures not exceeding 7°C.

Quality and Shelf Life of Mango (Mangifera Indica L. cv. `Tainong') Coated by Using Chitosan and Polyphenols

2007 ◽  
Vol 13 (4) ◽  
pp. 317-322 ◽  
Author(s):  
J. Wang ◽  
B. Wang ◽  
W. Jiang ◽  
Y. Zhao
Keyword(s):  
Shelf Life ◽  
Sensory Quality ◽  
Mangifera Indica ◽  
Titratable Acidity ◽  
Chitosan Solution ◽  
Life Extension ◽  
Mango Fruit ◽  
Chitosan Coating ◽  
Keeping Quality

Chitosan-based coatings were used to delay ripening and prolong shelf-life of mango fruit stored at 15±1°C and 85—90% RH for 35 days. Mango fruits were treated with 2% chitosan solution or with 2% chitosan containing 1% tea polyphenols (TP—chitosan). Samples were taken at regular intervals for analysis. Results indicated that chitosan coating alone could decrease the decay incidence and weight loss, and delay the change in colour, pH and titratable acidity of mango fruit during storage. While coating the fruit with TP—chitosan was more effective at keeping quality of the fruit during storage. Firmness of the control fruit declined rapidly to 18.6 N after 5 days of storage at 15°C, which was 22.8% or 71.5% lower than that of the fruit treated with chitosan or TP—chitosan, respectively. Sensory quality of mango was enhanced significantly by the TP—chitosan coating compared with chitosan coating alone. These results suggested that treatment with chitosan containing TP exhibited high potential for shelf-life extension of mango fruit.

The alcohol test applied to sterilized milk

1960 ◽  
Vol 27 (2) ◽  
pp. 259-265
Author(s):  
Constance Higginbottom ◽  
Margaret M. Taylor
Keyword(s):  
Bacillus Subtilis ◽  
Population Density ◽  
Stationary Phase ◽  
Incubation Period ◽  
Bacterial Count ◽  
Keeping Quality ◽  
Lower Maximum ◽  
Sterilized Milk ◽  
Maximum Population Density

SummaryA positive 80% alcohol test was not obtained in sterilized milks containing fewer than 105 bacteria/ml with Bacillus subtilis, B. licheniformis and B. cereus, and usually did not occur until the stationary phase of growth had been maintained for some days. A positive alcohol test with less than 105 bacteria/ml was associated with the lower maximum population density of B. brevis and B. circulans 152.The alcohol test after 24 h at 37°C was found unreliable as an indicator of the keeping quality of sterilized milk at 22°C. The possibility of using the alcohol test after 3 days at 37°C or a bacterial count after the same incubation period is discussed briefly.

scholarly journals EFFECTS OF PRESERVATIVE TREATMENTS ON THE MICROBIOLOGICAL AND STORAGE QUALITY OF TIGER NUT MILK DRINK

2021 ◽  
Vol 5 (11) ◽  
Author(s):  
Olofu A. Victor ◽  
Adeshina O. Gbonjubola ◽  
O. Busayo ◽  
Mshelia M. Bata
Keyword(s):  
Shelf Life ◽  
Standard Procedure ◽  
Bacterial Count ◽  
Total Coliform ◽  
Total Bacterial Count ◽  
Storage Quality ◽  
Microbial Stability ◽  
Total Fungi ◽  
And Storage

Tiger nut milk drink is a milk-like aqueous extract from tiger nut, which is highly nutritious and is consumed in most parts of the world especially in the Northern part of Nigeria. However, its availability is limited due to its short shelf life. The aim of this present study was to determine the effects of preservatives treatments on the microbiological and storage quality of tiger nut milk drink. Fresh tiger nut milk drink was produced according to the standard procedure with portable water and also with sterile distilled water. The milk was divided into 16 aliquots, kept in a sterile container for analysis of the different treatments, and preservatives were added according to the experimental design. The color, odor and consistency of the milk were observed daily for a period of seven days. The total bacteria count (TBC), total coliform count (TCC), total Staphylococcal count (TSC) and total fungi count (TFC) (yeast and mold) were evaluated every two days to monitor the microbial stability. Fresh tiger nut milk without any treatment spoiled within few hours after production, while the aliquot supplemented with all the preservatives; pasteurized and then stored under refrigerated temperature for up to seven days. The range of total bacterial count was from 8.00×104 -1.20×107 CFU/ml. The most prevalent bacterial isolates were; Escherichia coli (17.79%), Staphylococcus aureus (10.53%) and Micrococcus spp. (9.78%), whereas the dominant fungi were Candida tropicalis (16.27%), Saccharomyces spp. (11.63%) and Aspergillus spp. (11.63%). This study showed that tiger nut milk drink has a rich microbial content which affects its shelf life and the addition of natural (spices) and chemical preservatives is important to stabilize the drink; thus there is an urgent need to standardize the use of preservatives.

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