Diversity Assessment of Heat Resistance of Listeria monocytogenes Strains in a Continuous-Flow Heating System

2009 ◽  
Vol 72 (5) ◽  
pp. 999-1004 ◽  
Author(s):  
STIJN van der VEEN ◽  
ARJEN WAGENDORP ◽  
TJAKKO ABEE ◽  
MARJON H. J. WELLS-BENNIK
Keyword(s):  
High Temperature ◽  
Listeria Monocytogenes ◽  
Continuous Flow ◽  
Foodborne Pathogen ◽  
Brain Heart Infusion ◽  
Brain Heart Infusion Broth ◽  
Heat Resistant ◽  
High Temperature Short Time ◽  
Diversity Assessment ◽  
Short Time

Listeria monocytogenes is a foodborne pathogen that has the ability to survive relatively high temperatures compared with other nonsporulating foodborne pathogens. This study was performed to determine whether L. monocytogenes strains with relatively high heat resistances are adequately inactivated in a high-temperature, short-time pasteurization process (72°C for 15 s). To obtain heat-resistant strains, 48 strains were exposed to 55°C for up to 3 h. The energy of activation constant and inactivation constant of strains that survived best (strains 1E and NV8) were subsequently determined in a continuous-flow-through system. Strain Scott A was taken along as a reference. The 3 strains were cultured in whole milk and in brain heart infusion broth at 30 and 7°C. Strains 1E and NV8 were significantly more heat resistant than was strain Scott A after growth in brain heart infusion broth at 30°C and after growth in milk at 7°C. From the inactivation parameters, it was calculated that exposure to high-temperature, short-time pasteurization (72°C for 15 s) will result in 12.1-, 14.2-, and 87.5-log reductions for the strains 1E, NV8, and Scott A, respectively. These results demonstrate that industrial pasteurization conditions suffice to inactivate the most heat-resistant L. monocytogenes strains tested in this study.

BACTERIOLOGICAL ASPECTS OF THE EVALUATION OF ADEQUACY OF PASTEURIZATION

1951 ◽  
Vol 14 (6) ◽  
pp. 170-172 ◽  
Author(s):  
Franklin W. Barber
Keyword(s):  
High Temperature ◽  
Dairy Products ◽  
Test Organism ◽  
Additional Information ◽  
Heat Resistant ◽  
Death Time ◽  
High Temperature Short Time ◽  
Thermal Death ◽  
Thermal Death Time ◽  
Short Time

Increased interest in high-temperature, short-time pasteurization of various dairy products has emphasized the need for methods to determine the adequacy of pasteurization. One such method is described, but there is need for additional information. The thermal death time curves of various pathogens should be determined in different dairy products. A suitable heat resistant test organism such as Micrococcus MS-102 should be selected, approved by health officials and made available to others for controlled studies. Data should be accumulated so that curves could be prepared to show any combination of time and temperature which would result in adequate pasteurization.

Factors Influencing Survival of Listeria monocytogenes in Milk in a High-Temperature Short-Time Pasteurizer

1992 ◽  
Vol 55 (12) ◽  
pp. 946-951 ◽  
Author(s):  
J. M. FARBER ◽  
E. DALEY ◽  
F. COATES ◽  
D. B. EMMONS ◽  
R. McKELLAR
Keyword(s):  
High Temperature ◽  
Listeria Monocytogenes ◽  
Most Probable Number ◽  
Probable Number ◽  
High Temperature Short Time ◽  
Whole Milk ◽  
Different Temperatures ◽  
Margin Of Safety ◽  
Short Time ◽  
Adequate Margin

Heat resistance experiments were carried out with Listeria monocytogenes which had been grown at three different temperatures (30, 39, and 43°C). Heated whole milk was inoculated with L. monocytogenes and then passed through a high-temperature short-time system at 72, 69, 66, and 63°C for a minimum holding time of 16.2 s. Heated cells were recovered both aerobically and anaerobically using four different methods: direct plating, most probable number, cold enrichment, and warm enrichment. Significant differences in recovery of L. monocytogenes were observed depending on the growth temperature. Cells grown at 43, 39, or 30°C, held 1 d at 4°C, and then heated at 69°C showed an overall decrease in numbers of approximately 2.1, 2.8, and 4.1 logs, respectively. Cells grown at 39°C and then held 3 d at 4°C appeared to be the most heat sensitive. Although cells grown at 43 and 39°C were capable of surviving at the minimum high-temperature short-time temperature (72°C), those grown at 30°C were not. In some instances, anaerobic incubation enhanced the recovery of L. monocytogenes, as compared to cells recovered aerobically, although these differences were not statistically significant. While L. monocytogenes can survive minimum pasteurization treatment (71.7°C/16 s) under certain conditions, common methods of handling, processing, and storing fluid milk will provide an adequate margin of safety.

Effectiveness of on‐farm continuous flow high‐temperature short‐time pasteurization for inactivation of bovine leukemia virus in milk

2020 ◽  
Vol 91 (1) ◽  
Author(s):  
Keisuke Tomita ◽  
Sonoko Miyauchi ◽  
Yuzuru Katagiri ◽  
Syuji Yoneyama ◽  
Leng Dongze ◽  
...  
Keyword(s):  
High Temperature ◽  
Bovine Leukemia Virus ◽  
Continuous Flow ◽  
Leukemia Virus ◽  
High Temperature Short Time ◽  
Short Time ◽  
On Farm

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.

Influences of High-Temperature Short-Time Endurance Performance of Heat Resistant Steel for Ultra Supercritical Units

2013 ◽  
Vol 749 ◽  
pp. 361-365
Author(s):  
Hua Tang ◽  
Feng Xiao ◽  
Jian Sheng Ding ◽  
Zhi Hong Li
Keyword(s):  
High Temperature ◽  
Grain Boundary ◽  
Experimental Testing ◽  
Endurance Performance ◽  
Second Phase ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
High Temperature Short Time ◽  
Short Time

Heat-resistant steel (12%wt. Cr) used in the ultra supercritical set blade was quenched and tempered by vacuum heat treatment furnace, the mechanical properties and metallographic structures at room temperature can meet the specific requirements. However, there are some problems existed on high-temperature short-time lasting performance. To improve the high temperature endurance performance of materials, the experimental testing and analysis were carried out fro different types of specimen. The research showed that short-time rupture is a kind of creep fracture, and short lasting strength was closely related to test temperatures between laths and grain boundary and carbide coarsening. Energy spectrum analysis revealed that cast in the hole had high B element content (19.98%wt.), which meant grain boundaries of the B at high temperature began to migrate and form in the crystal B in that second phase particles are contained, and grain boundary strength was obviously decreased. The enduring high temperature experiment indicated that the strength were declined rapidly and fractured suddenly at high temperature.

scholarly journals Survival of Listeria monocytogenes in milk during high-temperature, short-time pasteurization.

1987 ◽  
Vol 53 (7) ◽  
pp. 1433-1438 ◽  
Author(s):  
M P Doyle ◽  
K A Glass ◽  
J T Beery ◽  
G A Garcia ◽  
D J Pollard ◽  
...  
Keyword(s):  
High Temperature ◽  
Listeria Monocytogenes ◽  
High Temperature Short Time ◽  
Short Time

scholarly journals Differential impact of Holder and High Temperature Short Time pasteurization on the dynamic in vitro digestion of human milk in a preterm newborn model

2020 ◽  
Vol 328 ◽  
pp. 127126 ◽  
Author(s):  
Stefano Nebbia ◽  
Marzia Giribaldi ◽  
Laura Cavallarin ◽  
Enrico Bertino ◽  
Alessandra Coscia ◽  
...  
Keyword(s):  
High Temperature ◽  
Human Milk ◽  
In Vitro Digestion ◽  
Preterm Newborn ◽  
Differential Impact ◽  
High Temperature Short Time ◽  
Short Time

scholarly journals High-Temperature Short-Time and Holder Pasteurization of Donor Milk: Impact on Milk Composition

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 114
Author(s):  
Diana Escuder-Vieco ◽  
Juan M. Rodríguez ◽  
Irene Espinosa-Martos ◽  
Nieves Corzo ◽  
Antonia Montilla ◽  
...  
Keyword(s):  
High Temperature ◽  
Human Milk ◽  
Milk Composition ◽  
Donor Human Milk ◽  
High Temperature Short Time ◽  
Lactose Concentration ◽  
C 30 ◽  
Milk Banks ◽  
Short Time

Holder pasteurization (HoP; 62.5 °C, 30 min) is commonly used to ensure the microbiological safety of donor human milk (DHM) but diminishes its nutritional properties. A high-temperature short-time (HTST) system was designed as an alternative for human milk banks. The objective of this study was to evaluate the effect of this HTST system on different nutrients and the bile salt stimulated lipase (BSSL) activity of DHM. DHM was processed in the HTST system and by standard HoP. Macronutrients were measured with a mid-infrared analyzer. Lactose, glucose, myo-inositol, vitamins and lipids were assayed using chromatographic techniques. BSSL activity was determined using a kit. The duration of HTST treatment had a greater influence on the nutrient composition of DHM than did the tested temperature. The lactose concentration and the percentage of phospholipids and PUFAs were higher in HTST-treated than in raw DHM, while the fat concentration and the percentage of monoacylglycerides and SFAs were lower. Other nutrients did not change after HTST processing. The retained BSSL activity was higher after short HTST treatment than that following HoP. Overall, HTST treatment resulted in better preservation of the nutritional quality of DHM than HoP because relevant thermosensitive components (phospholipids, PUFAs, and BSSL) were less affected.

Influence of Guar Gum on the Thermal Stability of Listeria innocua, Listeria monocytogenes, and γ-Glutamyl Transpeptidase during High-Temperature Short-Time Pasteurization of Bovine Milk

1999 ◽  
Vol 62 (8) ◽  
pp. 861-866 ◽  
Author(s):  
PUNIDADAS PIYASENA ◽  
ROBIN C. McKELLAR
Keyword(s):  
High Temperature ◽  
Laminar Flow ◽  
Protective Effect ◽  
Guar Gum ◽  
Listeria Innocua ◽  
Water Mixture ◽  
High Temperature Short Time ◽  
Whole Milk ◽  
Short Time ◽  
Glutamyl Transpeptidase

Mathematical models describing the thermal inactivation of γ-glutamyl transpeptidase (TP) and Listeria innocua in milk during high-temperature short-time (HTST) pasteurization were validated with data from TP, L. innocua, and L. monocytogenes trials in guar gum–milk. Holding tube times were determined for turbulent flow using water, and for laminar flow using a guar gum (0.27% wt/wt)–sucrose (5.3% wt/wt)–water mixture. Inactivation of TP and L. innocua was lower in a solution of guar gum (0.25% wt/wt) in whole milk than was predicted by models derived from studies with whole milk alone. Use of laminar flow timings improved model fit but did not completely account for the observed protective effect. L. monocytogenes survival was close to that predicted by the L. innocua model, although some protection was afforded this pathogen under laminar flow. Considerable intertrial variability was noted for L. monocytogenes. Risk analysis simulations using @RISK, a Lotus 1-2–3W add-in, were used to account for intertrial variability. Simulated log10 %reductions consistently underpredicted experimental L. monocytogenes survival (fail-safe), thus the L. innocua model derived in milk is suitable for estimating L. monocytogenes survival in viscous products. Increased thermal tolerance during laminar flow may be attributed to the protective effect of stabilizer.

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