scholarly journals Effect of Commercial-Scale High-Temperature, Short-Time Pasteurization on the Viability of Mycobacterium paratuberculosis in Naturally Infected Cows' Milk

2002 ◽  
Vol 68 (2) ◽  
pp. 602-607 ◽  
Author(s):  
Irene R. Grant ◽  
Edward I. Hitchings ◽  
Alan McCartney ◽  
Fiona Ferguson ◽  
Michael T. Rowe
Keyword(s):  
High Temperature ◽  
Cetylpyridinium Chloride ◽  
Raw Milk ◽  
Holding Time ◽  
Mycobacterium Paratuberculosis ◽  
Pasteurized Milk ◽  
Milk Samples ◽  
Commercial Scale ◽  
High Temperature Short Time ◽  
Short Time

ABSTRACT Raw cows' milk naturally infected with Mycobacterium paratuberculosis was pasteurized with an APV HXP commercial-scale pasteurizer (capacity 2,000 liters/h) on 12 separate occasions. On each processing occasion, milk was subjected to four different pasteurization treatments, viz., 73�C for 15 s or 25 s with and without prior homogenization (2,500 lb/in2 in two stages), in an APV Manton Gaulin KF6 homogenizer. Raw and pasteurized milk samples were tested for M. paratuberculosis by immunomagnetic separation (IMS)-PCR (to detect the presence of bacteria) and culture after decontamination with 0.75% (wt/vol) cetylpyridinium chloride for 5 h (to confirm bacterial viability). On 10 of the 12 processing occasions, M. paratuberculosis was detectable by IMS-PCR, culture, or both in either raw or pasteurized milk. Overall, viable M. paratuberculosis was cultured from 4 (6.7%) of 60 raw and 10 (6.9%) of 144 pasteurized milk samples. On one processing day, in particular, M. paratuberculosis appeared to have been present in greater abundance in the source raw milk (evidenced by more culture positives and stronger PCR signals), and on this occasion, surviving M. paratuberculosis bacteria were isolated from milk processed by all four heat treatments, i.e., 73�C for 15 and 25 s with and without prior homogenization. On one other occasion, surviving M. paratuberculosis bacteria were isolated from an unhomogenized milk sample that had been heat treated at 73�C for 25 s. Results suggested that homogenization increases the lethality of subsequent heat treatment to some extent with respect to M. paratuberculosis, but the extended 25-s holding time at 73�C was found to be no more effective at killing M. paratuberculosis than the standard 15-s holding time. This study provides clear evidence that M. paratuberculosis bacteria in naturally infected milk are capable of surviving commercial high-temperature, short-time pasteurization if they are present in raw milk in sufficient numbers.

509. Bacteriological studies on pasteurized milk

1953 ◽  
Vol 20 (2) ◽  
pp. 156-176 ◽  
Author(s):  
Hazel Alexander ◽  
Constance Higginbottom
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Geometric Mean ◽  
Raw Milk ◽  
Pasteurized Milk ◽  
High Temperature Short Time ◽  
Cooling Section ◽  
The Mean ◽  
Micro Organisms ◽  
Short Time

1. The numbers and species of micro-organisms surviving in commercial high-temperature short-time pasteurized milks sampled direct from the cooling section of the pasteurizer have been determined and compared with those in the corresponding raw milk and in the raw milk after low-temperature pasteurization in the laboratory.2. The geometric mean counts at 37° C. for twenty-five samples of raw, L.T. and H.T.S.T. pasteurized milks were 74,130, 1,740 and 3,200 per ml. respectively. The corresponding figures at 30° C. were 123,030, 7,080 and 8,510 per ml.3. The percentage destruction of the bacteria was slightly smaller at all four plants for the H.T.S.T. pasteurized milks than for the corresponding L.T. pasteurized milks. The mean percentage destruction for the L.T. pasteurized milks was 97·7% for bacteria growing at 37° C. and 94·3% for bacteria growing at 30° C. The corresponding figures for the H.T.S.T. pasteurized milks were 95·9 and 93·1%.

scholarly journals Exploring the Use of a Modified High-Temperature, Short-Time Continuous Heat Exchanger with Extended Holding Time (HTST-EHT) for Thermal Inactivation of Trypsin Following Selective Enzymatic Hydrolysis of the β-Lactoglobulin Fraction in Whey Protein Isolate

Foods ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 367 ◽  
Author(s):  
Laura Sáez ◽  
Eoin Murphy ◽  
Richard J. FitzGerald ◽  
Phil Kelly
Keyword(s):  
High Temperature ◽  
Heat Exchanger ◽  
Whey Protein ◽  
Protein Isolate ◽  
Holding Time ◽  
High Temperature Short Time ◽  
Incubation Periods ◽  
Short Time ◽  
Β Lactoglobulin ◽  
Hydrolysis Of

Tryptic hydrolysis of whey protein isolate under specific incubation conditions including a relatively high enzyme:substrate (E:S) ratio of 1:10 is known to preferentially hydrolyse β-lactoglobulin (β-LG), while retaining the other major whey protein fraction, i.e., α-lactalbumin (α-LA) mainly intact. An objective of the present work was to explore the effects of reducing E:S (1:10, 1:30, 1:50, 1:100) on the selective hydrolysis of β-LG by trypsin at pH 8.5 and 25 °C in a 5% (w/v) WPI solution during incubation periods ranging from 1 to 7 h. In addition, the use of a pilot-scale continuous high-temperature, short-time (HTST) heat exchanger with an extended holding time (EHT) of 5 min as a means of inactivating trypsin to terminate hydrolysis was compared with laboratory-based acidification to <pH 3 by the addition of HCl, and batch sample heating in a water bath at 85 °C. An E:S of 1:10 resulted in 100% and 30% of β-LG and α-LA hydrolysis, respectively, after 3 h, while an E:S reduction to 1:30 and 1:50 led >90% β-LG hydrolysis after respective incubation periods of 4 and 6 h, with <5% hydrolysis of α-LA in the case of 1:50. Continuous HTST-EHT treatment was shown to be an effective inactivation process allowing for the maintenance of substrate selectivity. However, HTST-EHT heating resulted in protein aggregation, which negatively impacts the downstream recovery of intact α-LA. An optimum E:S was determined to be 1:50, with an incubation time ranging from 3 h to 7 h leading to 90% β-LG hydrolysis and minimal degradation of α-LA. Alternative batch heating by means of a water bath to inactivate trypsin caused considerable digestion of α-LA, while acidification to <pH 3.0 restricted subsequent functional applications of the protein.

Thermal Resistance of Listeria spp. in Milk

1991 ◽  
Vol 54 (1) ◽  
pp. 12-14 ◽  
Author(s):  
JOE G. BRADSHAW ◽  
JAMES T. PEELER ◽  
ROBERT M. TWEDT
Keyword(s):  
High Temperature ◽  
Thermal Resistance ◽  
Heat Resistance ◽  
Raw Milk ◽  
The Other ◽  
Time Processing ◽  
Listeria Ivanovii ◽  
High Temperature Short Time ◽  
The Difference ◽  
Short Time

The thermal resistance of one strain each of Listeria ivanovii, L. seeligeri, and L. welshimeri and three L. monocytogenes strains was determined in raw and sterile milk. Listeria spp. suspended in milk at concentrations of 1 × 105 cells/ml were heated at temperatures ranging from 52.2 to 71.1°C for various contact times. The heat resistance of L. monocytogenes appeared somewhat greater than that of the other Listeria spp. in both milks, but the difference was not statistically significant (α = 0.05). High-temperature, short-time processing is adequate for pasteurization of raw milk.

STUDIES ON THERMAL METHODS OF MEASURING THE HOLDING TIME IN HIGH-TEMPERATURE SHORT-TIME PASTEURIZERS

1953 ◽  
Vol 16 (1) ◽  
pp. 15-25 ◽  
Author(s):  
W. K. Jordan ◽  
R. F. Holland
Keyword(s):  
High Temperature ◽  
Correction Factor ◽  
Holding Time ◽  
Thermal Waves ◽  
Thermal Methods ◽  
Thermal Test ◽  
High Temperature Short Time ◽  
The Difference ◽  
Short Time

Data are presented on the properties of thermal waves produced by several means of suddenly increasing or decreasing the temperature of the fluid moving through the holding tube of a high-temperature short-time pasteurizer. Thermal holding-time measurements made with eight instruments or methods are compared with the holding time measured by the 3-A standard salt test. The reasons for variation in the correction factor, the difference beween the holding times measured by the salt test and a thermal test, are discussed.

Method for Predicting Minimum Detectable Residual Alkaline Phosphatase in High-Temperature, Short-Time Processed Dairy Products

1980 ◽  
Vol 43 (1) ◽  
pp. 46-48 ◽  
Author(s):  
G. K. MURTHY ◽  
J. T. PEELER
Keyword(s):  
Alkaline Phosphatase ◽  
High Temperature ◽  
Control Sample ◽  
Rank Correlation ◽  
Raw Milk ◽  
Milk Product ◽  
Colorimetric Test ◽  
High Temperature Short Time ◽  
Highly Correlated ◽  
Short Time

High-temperature, short-time (HTST) processed milk, cream and buttermilk were mixed with small portions (0 to 0.6%) of the raw milk product to obtain desired levels of residual alkaline phosphatase. Samples were subjected to the differential test to discern reactivation and analyzed for phosphatase activity by the rapid colorimetric test. The experimental data were fitted to a linear statistical model to determine the minimum detectable residual phosphatase (Eo) in the product. These observed values and the computed expected values were highly correlated, with a rank correlation coefficient of 0.956, which was significant at a = 0.05 level. The values of [Eo] varied depending upon the extent of phosphatase reactivation in the HTST product when the residual phosphatase was zero. As the differential values of reactivation (reactivated [E] of the control sample minus the reactivated [E] of diluted sample containing magnesium) increased, the [Eo] increased also. In general, the [Eo] in cream was greater than that in milk. A method is proposed for predicting [Eo] in liquid HTST products.

Incidence of Aflatoxin M1 in Thai Milk Products

1997 ◽  
Vol 60 (8) ◽  
pp. 1010-1012 ◽  
Author(s):  
KRIENGSAG SAITANU
Keyword(s):  
High Temperature ◽  
Raw Milk ◽  
Aflatoxin M1 ◽  
Test Results ◽  
Powdered Milk ◽  
Milk Products ◽  
Pasteurized Milk ◽  
Milk Samples ◽  
Two Samples ◽  
Sterilized Milk

Two hundred seventy samples of raw milk and off-the-shelf milk products were examined for aflatoxin M1 content using a radioimmunoassay. Aflatoxin M1 was found in the majority of milk samples except 1 sample of raw milk and 11 samples of imported powdered milk. All cases of aflatoxin M1 content greater than 0.5 ppb were found in 18% (48) of the samples including raw milk (17/67), pasteurized milk (20/63), ultra high temperature milk (7/60), sterilized milk (3/60), and pelleted milk (1/7). All powdered milk samples were negative for aflatoxin M1 except two samples with less than 0.1 ppb. The positive aflatoxin M1 test results for five of the raw milk samples were confirmed by HPLC.

Implementing high-temperature short-time media treatment in commercial-scale cell culture manufacturing processes

2013 ◽  
Vol 98 (7) ◽  
pp. 2965-2971 ◽  
Author(s):  
Michael Pohlscheidt ◽  
Salim Charaniya ◽  
Fikret Kulenovic ◽  
Mahalia Corrales ◽  
Masaru Shiratori ◽  
...  
Keyword(s):  
Cell Culture ◽  
High Temperature ◽  
Manufacturing Processes ◽  
Commercial Scale ◽  
High Temperature Short Time ◽  
Short Time
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