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 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.

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.

scholarly journals Effect of Thermal Treatments on Quality and Aroma of Watermelon Juice

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yubin Wang ◽  
Wu Li ◽  
Yue Ma ◽  
Xiaoyan Zhao ◽  
Chao Zhang
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Shelf Life ◽  
Color Difference ◽  
Thermal Treatments ◽  
Watermelon Juice ◽  
High Temperature Short Time ◽  
Long Time ◽  
Ultrahigh Temperature ◽  
Short Time

The effect of thermal treatments on the quality and aroma of watermelon juice was evaluated. Watermelon juice was pasteurized via ultrahigh temperature (UHT, pasteurized at 135°C for 2 s), low temperature long time (LTLT, pasteurized at 60°C for 30 min), and high temperature short time (HTST, pasteurized at 100°C for 5 min), respectively. UHT and LTLT reduced the total flora count and maintained the color of the pasteurized juice, while the HTST led to a significant color difference. A total of 27, 21, 22, and 21 volatiles were identified in the unpasteurized juice, UHT, LTLT, and HTST, respectively. The typical watermelon aroma, including (3Z)-3-nonen-1-ol, (E)-2-nonen-1-ol, 1-nonanal, (2E)-2-nonenal, and (E,Z)-2,6-nonadienal, was abundant in the LTLT. Consequently, the aroma of the LTLT was similar to that of unpasteurized juice. Moreover, the shelf life of the LTLT reached 101 and 14 days at 4 and 25°C, respectively. Hence, the LTLT was the best way to maintain the quality and aroma of watermelon juice.

scholarly journals PENGONTROL SUHU PADA PASTEURISASI SUSU DI KUBE PSP DESA KEMIRI KECAMATAN JABUNG MALANG

2019 ◽  
Vol 9 (2) ◽  
pp. 1-9
Author(s):  
Eko Urcahyo ◽  
Choirul Saleh ◽  
Bambang Prio Hartono
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Trial And Error ◽  
High Temperature Short Time ◽  
Long Time ◽  
Short Time

Pasteurisasi adalah suatu proses pemanasan pada suhu dibawah 100ºC dalam jangka waktu tertentu yang dapat mematikan mikroba yang ada dalam susu. Saat ini dikenal dengan dua metode yang lazim digunakan pada proses pasteurisasi susu, yaitu LTLT (low temperature long time) dan HTST (high temperature short time ). Metode LT LT pada dasarnya dilakukan dengan pemanasan susu antara suhu 63-65º C dan dipertahankan pada suhu tersebut selama 30 menit. Sedangkan metode HTST dilakukan dengan pemanasan susu selama 5-10 menit pada suhu 70-71ºC. Dengan pemanasan ini diharapkan akan dapat membunuh bakteri pantogen yang membahayakan kesehatan manusia dan meminimalisasi perkembangan bakteri lain, baik selama pemanasan maupun pada saat penyimpanan. Untuk itu dirancang sebuah alat untuk mengontrol suhu pada pasteurisasi susu dengan kontrol PID di Kube PSP Desa Kemiri Kecamatan Jabung Malang menggunakan sensor DS18B20 yang berfungsi untuk mengetahui suhu pada susu. Perancangan ini menggunakan servo dan dimmer untuk mengatur suhu pada susu. Dari hasil pengujian, alat dapat menurunkan dan menaikkan suhu ketika suhu melewati batas setpoint yang ditentukan oleh pengguna. Untuk mencapai setpoint 65ºC pemanasan membutuhkan waktu yang cukup lama, yaitu 2 jam 56 menit 51 detik sedangkan hasil tuning PID secara trial and error, servo dapat memutar dengan baik untuk nilai kp = 1,5, ki = 0,2, kd = 8 dengan setpoint 65ºC.

scholarly journals Kinetika Pengeringan Cabai dengan Perlakuan Blansing Suhu Rendah-Waktu Lama

2021 ◽  
Vol 10 (1) ◽  
pp. 24-35
Author(s):  
Andi Muhammad Irfan ◽  
Nunik Lestari ◽  
Arimansyah Arimansyah ◽  
A Ramli Rasyid
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Drying Rate ◽  
Suitable Model ◽  
Drying Time ◽  
Drying Characteristics ◽  
High Temperature Short Time ◽  
Long Time ◽  
Short Time ◽  
Kinetics Of

This study was aimed to determine the drying kinetics of chilies that have been pretreated with low temperature long time (LTLT) blanching. Drying chilies with LTLT blanching pretreatment at 60, 70, and 80 oC for 20 minutes was assigned as treatment in this research. Drying chillies with high temperature short time (HTST) blanching pretreatment, without blanching pretreatment in the dryer, and without blanching pretreatment in direct sunlight were also studied as the comparison. The results showed that chilies treated with blanching pretreatment, both LTLT and HTST, have a faster drying rate and achieve the target moisture content faster than chilies that were not blanched. The color of dried chilies that were dried in a dryer was also better than dried chilies that were dried in the sun. Of all the blanching treatments, chilies with LTLT blanching pretreatment at 80 oC for 20 minutes had the fastest drying rate, a drying time of 34 hours, and the attractive dried chilli color. The evaluation results also showed that the Page model was the most suitable model to describe the drying characteristics of chilies with LTLT pretreatment blanching, with R2 ranging from 0.9913-0.9935, X2 ranging from 0.0005-0.0009, and RSME ranging from 0.0221-0.0293. Keywords: Chili; blanching; color; drying; mathematical model   ABSTRAK Penelitian ini bertujuan untuk mengetahui kinetika pengeringan cabai yang diberi perlakuan awal low temperature long time (LTLT) blanching atau blansing pada suhu rendah dalam waktu yang relatif lama. Perlakuan pada penelitian ini yaitu pengeringan cabai dengan blansing metode LTLT pada suhu 60o, 70o, dan 80oC selama 20 menit. Sebagai pembanding, dilakukan juga pengeringan dengan perlakuan awal metode high temperature short time (HTST) blanching, pengeringan cabai tanpa perlakuan awal blansing di dalam alat pengering, serta pengeringan cabai tanpa perlakuan awal blansing di bawah sinar matahari secara langsung. Hasil penelitian menunjukkan bahwa cabai dengan perlakuan awal blansing, baik blansing metode LTLT maupun HTST, memiliki laju pengeringan yang lebih tinggi sehingga lebih cepat mencapai kadar air target dibandingkan dengan cabai tanpa perlakuan blansing. Warna cabai kering yang dihasilkan pada alat pengering juga lebih baik dari cabai kering yang dikeringkan langsung di bawah sinar matahari. Dari seluruh perlakuan yang melibatkan proses blansing, cabai dengan blansing metode LTLT pada suhu 80oC selama 20 menit merupakan perlakuan dengan laju pengeringan tercepat, dengan waktu pengeringan selama 34 jam, dan warna produk cabai kering yang menarik. Hasil evaluasi juga menunjukkan bahwa model Page adalah model yang paling sesuai untuk menggambarkan karakteristik pengeringan cabai dengan perlakuan awal blansing metode LTLT, dengan R2 berkisar antara 0.9913-0.9935, X2 berkisar antara 0.0005-0.0009, dan RSME berkisar antara 0.0221-0.0293. Kata kunci: Blansing; cabai; model matematika; pengeringan; warna

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.

scholarly journals Treatment of Fungal Bioaerosols by a High-Temperature, Short-Time Process in a Continuous-Flow System

2009 ◽  
Vol 75 (9) ◽  
pp. 2742-2749 ◽  
Author(s):  
Jae Hee Jung ◽  
Jung Eun Lee ◽  
Chang Ho Lee ◽  
Sang Soo Kim ◽  
Byung Uk Lee
Keyword(s):  
High Temperature ◽  
Continuous Flow ◽  
Geometric Mean ◽  
Airborne Fungi ◽  
Plant Diseases ◽  
Heating Process ◽  
Thermal Heating ◽  
High Temperature Short Time ◽  
Living Organisms ◽  
Short Time

ABSTRACT Airborne fungi, termed fungal bioaerosols, have received attention due to the association with public health problems and the effects on living organisms in nature. There are growing concerns that fungal bioaerosols are relevant to the occurrence of allergies, opportunistic diseases in hospitals, and outbreaks of plant diseases. The search for ways of preventing and curing the harmful effects of fungal bioaerosols has created a high demand for the study and development of an efficient method of controlling bioaerosols. However, almost all modern microbiological studies and theories have focused on microorganisms in liquid and solid phases. We investigated the thermal heating effects on fungal bioaerosols in a continuous-flow environment. Although the thermal heating process has long been a traditional method of controlling microorganisms, the effect of a continuous high-temperature, short-time (HTST) process on airborne microorganisms has not been quantitatively investigated in terms of various aerosol properties. Our experimental results show that the geometric mean diameter of the tested fungal bioaerosols decreased when they were exposed to increases in the surrounding temperature. The HTST process produced a significant decline in the (1→3)-β-d-glucan concentration of fungal bioaerosols. More than 99% of the Aspergillus versicolor and Cladosporium cladosporioides bioaerosols lost their culturability in about 0.2 s when the surrounding temperature exceeded 350°C and 400°C, respectively. The instantaneous exposure to high temperature significantly changed the surface morphology of the fungal bioaerosols.

Use of Microwave Ovens to Pasteurize Milk

1988 ◽  
Vol 51 (9) ◽  
pp. 715-719 ◽  
Author(s):  
KATHLEEN M. KNUTSON ◽  
ELMER H. MARTH ◽  
MARY K. WAGNER
Keyword(s):  
Escherichia Coli ◽  
High Temperature ◽  
Low Temperature ◽  
Salmonella Typhimurium ◽  
Pseudomonas Fluorescens ◽  
Water Bath ◽  
Streptococcus Faecalis ◽  
High Temperature Short Time ◽  
Long Time ◽  
Short Time

High-temperature short-time (HTST) and low-temperature long-time (LTLT) pasteurization were simulated using uninoculated and inoculated milks that were heated in microwave ovens. Heating milk (76 ml) for 59 s at 700 W achieved a temperature of 71.7°C, but heating for 60–65 s and holding for 15 s failed to inactivate all added cells of Salmonella typhimurium, Escherichia coli or Pseudomonas fluorescens. Milk, 453.6 g (ca. one-half quart) or 604.8 g (ca. two-thirds quart), was heated to >62.8°C, but <71.7°C, in 4.5 to 5 min, depending on power (550 or 700 W) that was used, and refrigerated overnight. Such treatments failed to reduce the population of Streptococcus faecalis in the milks by the degree that occurred when inoculated milk was heated in a water bath at 62.8°C for 30 min.

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