Mathematical modeling of ohmic heating for inactivation of acid-adapted foodborne pathogens in tomato juice

2020 ◽  
Vol 16 (4) ◽  
Author(s):  
Sang-Soon Kim ◽  
Won Choi ◽  
Sang-Hyun Park ◽  
Dong-Hyun Kang
Keyword(s):  
Mathematical Model ◽  
Foodborne Pathogens ◽  
Ohmic Heating ◽  
Electric Heating ◽  
Tomato Juice ◽  
Heat Transfer Fluid ◽  
Cold Spot ◽  
Pathogen Inactivation ◽  
Heating Chamber ◽  
Ohmic Heater

AbstractThe objective of the present study was to predict the inactivation trends of acid-adapted foodborne pathogens in tomato juice by ohmic heating through a numerical analysis method. The mathematical model based on finite element method (FEM) was used to simulate the multiphysics phenomena including electric heating, heat transfer, fluid dynamics, and pathogen inactivation. A cold spot was observed in the corner part of the ohmic heating chamber, where some pathogens survived even though all pathogens were inactivated elsewhere. Challenges of this study were how to reflect the increased resistance of pathogen by acid-adaptation. After simulation, we verified that inactivation level of acid-adapted foodborne pathogens by 25 Vrms/cm ohmic heating (1 kHz), predicted with the developed mathematical model, had no significant differences with experimental results (p > 0.05). Therefore, the mathematical approaches described in the present study will help juice processors determine the processing conditions necessary to ensure microbial safety at the cold point of a rectangular type batch ohmic heater.

SUBSTANTIATION OF OPTIMAL PARAMETERS AND DEVELOPMENT OF HIGH-TEMPERATURE STERILIZATION MODES FOR COMPOTE FROM PEARS IN HEATED AIR FLOW

2020 ◽  
Author(s):  
М.Э. Ахмедов ◽  
А.Ф. Демирова ◽  
Г.И. Касьянов ◽  
Ю.Ф. Росляков ◽  
М.М. Рахманова
Keyword(s):  
Mathematical Model ◽  
High Temperature ◽  
High Speed ◽  
Heat Transfer Fluid ◽  
Initial Product ◽  
Hot Air ◽  
Heated Air ◽  
Sterilization Process ◽  
Thermal Sterilization ◽  
Heat Carriers

Разработаны новые режимы стерилизации компота из груш в стеклотаре СКО 1-82-1000 с использованием высокотемпературных скоростных теплоносителей. Получена математическая модель расчета продолжительности процесса стерилизации в зависимости от параметров теплоносителя. Для получения математической модели использован метод математического планирования эксперимента. Предложен технологический прием ускоренной стерилизации компота из груш в стеклобанке объемом 1 дм3. Разработаны новые режимы тепловой обработки (стерилизации) компота из груш в стеклобанке 1-82-1000 при различных параметрах горячего воздуха и разных начальных температурах продукта, °С: 70, 80, 85 и 90. Наименьшая продолжительность процесса тепловой стерилизации достигнута при скорости теплоносителя 7,5 м/с при начальной температуре продукта 90°С. New modes of sterilization of compote from pears in glass containers of SKO 1-82-1000 using high-temperature high-speed heat carriers have been developed. A mathematical model for calculating the duration of the sterilization process depending on the parameters of the heat carrier is obtained. To obtain a mathematical model, we used the method of mathematical planning of the experiment. A technological method for accelerated sterilization of pear compote in a glass jar with a volume of 1 dm3 is proposed. The research made it possible to develop new modes of heat treatment (sterilization) of compote from pears in a glass jar 1-82-1000 at different parameters of hot air and different initial temperatures of the product, °C: 70, 80, 85 and 90. The shortest duration of the thermal sterilization process is achieved at the heat transfer fluid speed of 7,5 m/s at the initial product temperature of 90°C.

Inactivation of Salmonella enterica serovar Typhimurium and Staphylococcus aureus in rice by radio-frequency heating

2021 ◽  
Author(s):  
Ki-Ok Jeong ◽  
Sang-Soon Kim ◽  
Sang-Hyun Park ◽  
Dong-Hyun Kang
Keyword(s):  
Staphylococcus Aureus ◽  
Radio Frequency ◽  
Heating Rate ◽  
Foodborne Pathogens ◽  
Color Change ◽  
Oryza Sativa L ◽  
Rf Heating ◽  
Pathogen Inactivation ◽  
Treatment Conditions ◽  
And Staphylococcus Aureus

The objectives of this study were to determine the effect of the milling degree (MD) of Oryza sativa L. (Korean rice) on the heating rate, pathogen inactivation (Salmonella Typhimurium and Staphylococcus aureus), and color change resulting from radio-frequency (RF) heating. Rice samples inoculated with pathogens were placed in a polypropylene jar and subjected to RF heating for 0-75 s. The heating rate of rice with a 2% MD was the highest during RF heating, followed by those with a 0, 8, and 10% MD, and the reduction of pathogens showed the same trend. The reduction of the levels of pathogens in rice with a MD 0 and 2% was significantly higher than that observed for rice with a MD of 8 and 10% under the same treatment conditions. For example, log reductions of S. Typhimurium in rice by 55 s RF heating were 3.64, 5.19, 2.18, and 1.80 for milling degree of 0, 2, 8, and 10%, respectively. At the same treatment conditions, log reduction of S. aureus were 2.77, 5.08, 1.15, and 0.90 for milling degree of 0, 2, 8, and 10%, respectively. The color of rice measured according to L*, a*, and b* was not significantly altered after RF heating, regardless of the MD. Therefore, the MD of rice should be considered before RF heating is applied to inactivate foodborne pathogens.

Evaluation of foodborne pathogen die-off in back-sweetened wine and apple cider models

2021 ◽  
Author(s):  
Zirui Ray Xiong ◽  
Anqi Chen ◽  
Glycine Zhujun Jiang ◽  
Alisha G Lewis ◽  
Christine D Sislak ◽  
...  
Keyword(s):  
Foodborne Pathogens ◽  
Apple Juice ◽  
Foodborne Pathogen ◽  
Grape Juice ◽  
White Wine ◽  
Low Ph ◽  
Alcoholic Beverages ◽  
Pathogen Inactivation ◽  
Apple Cider ◽  
Log Reduction

Wine and alcoholic apple cider are commonly back-sweetened with unpasteurized juice to produce fresh, natural, and palatable sweetened alcoholic beverages. Foodborne pathogens may be introduced from unpasteurized juice into alcoholic beverages through this back-sweetening process. Although pathogens generally do not survive under low pH conditions or high alcohol environment, the die-off of these pathogens has not been established to ensure the safety of the products. To determine the safety of these back-sweetened beverages, we evaluated the survival of three common foodborne pathogens, E. coli O157:H7, Salmonella enterica , and Listeria monocytogenes in modified white grape juice and apple juice models. White grape juice and apple juice were modified with hydrochloric acid/sodium hydroxide and ethanol to achieve conditions that are similar to the back-sweetened white wine and alcoholic apple cider. Pathogen cocktails were inoculated separately into modified juice models and their survival in the juice models were recorded over a 96-hour period. Our results show that a combination of low pH and high ethanol content resulted in a faster pathogen die-off compared to higher pH and lower ethanol conditions. The holding times required for different combinations of pH and ethanol concentration for each juice model to achieve 5-log reduction were reported. This research provides data to validate pathogen die-off to comply with Juice HACCP 5-log pathogen inactivation requirements for back-sweetened wine and alcoholic apple cider.

Effect of Power Levels on Inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in Tomato Paste Using 915-Megahertz Microwave and Ohmic Heating

2016 ◽  
Vol 79 (9) ◽  
pp. 1616-1622 ◽  
Author(s):  
SANG-SOON KIM ◽  
HYE-JUNG SUNG ◽  
HYO-SUN KWAK ◽  
IN-SUN JOO ◽  
JEONG-SU LEE ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Salmonella Typhimurium ◽  
Ohmic Heating ◽  
Power Level ◽  
Escherichia Coli O157 ◽  
Pathogen Inactivation ◽  
Tomato Paste ◽  
Quality Aspects ◽  
Heating Uniformity

ABSTRACT The effect of power levels on inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in tomato paste was investigated using 915-MHz microwave heating (MW) and ohmic heating (OH). Heating uniformity, pathogen inactivation, and quality aspects were determined with 1.8-, 2.1-, 2.4-, and 3.0-kW MW and corresponding OH. GInaFit was used to analyze pathogen inactivation. The heating uniformity of MW-treated samples was inferior to that of OH-treated samples at low power levels of 1.8 to 2.4 kW but improved as the power level increased. Pathogen inactivation of MW-treated samples was significantly higher than that of OH-treated samples at low power levels of 1.8 to 2.4 kW (P < 0.05) but was not significantly different at the highest power level of 3.0 kW (P > 0.05). Quality aspects (color, pH, and lycopene content), except for L*, of MW-treated samples were not significantly degraded (P > 0.05) by increased power levels. Our results indicate that increasing power levels of MW ensures heating uniformity and microbiological safety and preserves quality aspects of tomato paste.

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