Ohmic heating is an advanced thermal processing method that uses direct resistance heating to heat food products. It works by passing an electric current through the food, with the food itself serving as the resistor to generate heat. Ohmic heating allows for rapid and uniform heating throughout the product at rates of 1-100°C/s. It has advantages over conventional heating like reduced nutrient loss, uniform heating, and faster processing times. Some potential applications of ohmic heating in food processing include meat processing, milk pasteurization, fruit and vegetable blanching, and waste water treatment. However, further research is still needed to fully understand and control the process and address issues like preventing electrolysis during heating.
Application of hurdle technology in poultry meat processing & preservationDr. IRSHAD A
This document discusses hurdle technology, which uses a combination of preservation methods or barriers to inhibit microbial spoilage. It defines hurdles as physical, chemical, or microbiological factors that microorganisms must overcome to grow. Examples of hurdles include reduced water activity, acidity, heat treatment, packaging, and use of preservatives. The document provides examples of hurdles used in various products and outlines guidelines for developing shelf-stable foods using hurdle technology, including testing products with spoilage microorganisms and modifying hurdles as needed. Overall, it presents hurdle technology as an effective approach for food preservation and stability that can help reduce waste and extend product shelf life.
Ankit Kumar presents information on novel food processing techniques. He provides details about his background and qualifications. The document then discusses several innovative processing methods including microwave heating, ohmic heating, irradiation, pulsed electric fields, and high pressure processing. It provides explanations of how each technique works and its advantages for food processing applications.
Thermal food processing technologies include various cooking and heat treatment methods like baking, boiling, frying, and more. These methods make food safer, more palatable, and in some cases help preserve it. Common thermal processing techniques discussed include blanching, pasteurization, sterilization, evaporation/concentration, extrusion, dehydration, baking/roasting, and frying. Newer methods like aseptic processing are also covered, which sterilize food outside the package before aseptically filling sterile containers. The document provides details on the principles, equipment used, advantages, and limitations of various thermal food processing technologies.
Novel Thermal Technologies in Food Processing and Preservation.pptxRishabhThakur100
Thermal processing uses heat to reduce microorganisms in food and extend shelf life. Novel thermal technologies like microwave heating can process food faster at lower temperatures than conventional methods, preserving more nutrients and sensory qualities. Microwaves work by causing polar molecules like water to rotate, generating heat. Factors like moisture content, frequency, and product density affect microwave absorption and heating uniformity. Microwave processing offers advantages like shorter times, improved quality, and adaptability to continuous systems.
W.A. Mihiravi Pamuditha gave a presentation on radio frequency (RF) heating technology for food processing. RF heating uses electromagnetic energy to induce volumetric heating within foods. It has advantages over conventional heating like faster and more uniform heating. Some applications of RF heating in food include thawing, baking, drying, pasteurization and using RFID tags for tracking. While it has benefits, high equipment costs are a disadvantage. The future of RF technology may include its expanded use in continuous food processing and integration with technologies like nanotechnology and smart refrigerators.
Ohmic heating is a method of heating food through the direct passage of alternating electric current. It allows for rapid and uniform heating of both liquids and particulate foods from the inside out. During ohmic heating, the food acts as an electrical resistor and generates heat when current is passed through it. This results in minimal thermal degradation compared to conventional surface heating methods. Some applications of ohmic heating include heating soups, juices and other liquid foods with particles.
Ohmic heating is an advanced thermal processing method that uses direct resistance heating to heat food products. It works by passing an electric current through the food, with the food itself serving as the resistor to generate heat. Ohmic heating allows for rapid and uniform heating throughout the product at rates of 1-100°C/s. It has advantages over conventional heating like reduced nutrient loss, uniform heating, and faster processing times. Some potential applications of ohmic heating in food processing include meat processing, milk pasteurization, fruit and vegetable blanching, and waste water treatment. However, further research is still needed to fully understand and control the process and address issues like preventing electrolysis during heating.
Application of hurdle technology in poultry meat processing & preservationDr. IRSHAD A
This document discusses hurdle technology, which uses a combination of preservation methods or barriers to inhibit microbial spoilage. It defines hurdles as physical, chemical, or microbiological factors that microorganisms must overcome to grow. Examples of hurdles include reduced water activity, acidity, heat treatment, packaging, and use of preservatives. The document provides examples of hurdles used in various products and outlines guidelines for developing shelf-stable foods using hurdle technology, including testing products with spoilage microorganisms and modifying hurdles as needed. Overall, it presents hurdle technology as an effective approach for food preservation and stability that can help reduce waste and extend product shelf life.
Ankit Kumar presents information on novel food processing techniques. He provides details about his background and qualifications. The document then discusses several innovative processing methods including microwave heating, ohmic heating, irradiation, pulsed electric fields, and high pressure processing. It provides explanations of how each technique works and its advantages for food processing applications.
Thermal food processing technologies include various cooking and heat treatment methods like baking, boiling, frying, and more. These methods make food safer, more palatable, and in some cases help preserve it. Common thermal processing techniques discussed include blanching, pasteurization, sterilization, evaporation/concentration, extrusion, dehydration, baking/roasting, and frying. Newer methods like aseptic processing are also covered, which sterilize food outside the package before aseptically filling sterile containers. The document provides details on the principles, equipment used, advantages, and limitations of various thermal food processing technologies.
Novel Thermal Technologies in Food Processing and Preservation.pptxRishabhThakur100
Thermal processing uses heat to reduce microorganisms in food and extend shelf life. Novel thermal technologies like microwave heating can process food faster at lower temperatures than conventional methods, preserving more nutrients and sensory qualities. Microwaves work by causing polar molecules like water to rotate, generating heat. Factors like moisture content, frequency, and product density affect microwave absorption and heating uniformity. Microwave processing offers advantages like shorter times, improved quality, and adaptability to continuous systems.
W.A. Mihiravi Pamuditha gave a presentation on radio frequency (RF) heating technology for food processing. RF heating uses electromagnetic energy to induce volumetric heating within foods. It has advantages over conventional heating like faster and more uniform heating. Some applications of RF heating in food include thawing, baking, drying, pasteurization and using RFID tags for tracking. While it has benefits, high equipment costs are a disadvantage. The future of RF technology may include its expanded use in continuous food processing and integration with technologies like nanotechnology and smart refrigerators.
Ohmic heating is a method of heating food through the direct passage of alternating electric current. It allows for rapid and uniform heating of both liquids and particulate foods from the inside out. During ohmic heating, the food acts as an electrical resistor and generates heat when current is passed through it. This results in minimal thermal degradation compared to conventional surface heating methods. Some applications of ohmic heating include heating soups, juices and other liquid foods with particles.
Hurdle technology involves using two or more preservation methods together to inhibit microbial spoilage of foods. It allows for safer, stable foods without refrigeration. Common hurdles include reduced pH, increased salt content, reduced water activity, and heat processing. The hurdles work synergistically by disturbing the microbes' homeostasis. This technique is widely used in products like jam, fermented vegetables, meat, fish, and dairy. It improves safety and quality while reducing costs compared to using single preservation methods. However, some limitations exist in fully understanding and applying hurdle effects in practice.
This document discusses thermal processing methods for food including pasteurization and sterilization. Pasteurization and sterilization can be done through batch or continuous processes. Batch processes involve filling, heating, holding, cooling, and emptying vessels between batches, while continuous processes allow for energy savings by reusing heated fluids. Some advantages of continuous processes over batch processes include potential energy savings, easier scale-up and automation, and reduced sterilization times.
Ohmic heating is a novel thermal food processing technique that uses electricity to rapidly and uniformly heat foods. It works by passing electricity through food materials, which act as resistors and generate heat. Key advantages are uniform heating from 1-100°C/s without hot surfaces, higher nutrient retention, and simpler controls than conventional heating methods. Ohmic heating has applications in meat processing, dairy pasteurization, fruit and vegetable blanching, and thawing. Further research is needed to address limitations such as potential metal contamination from electrolysis and difficulties heating non-conductive foods very high or low in moisture.
Radio frequency processing and Microwave heating in food processing prakashsp13
radio frequency and microwave heating ; these slides are explain about its principle and working mechanism ,application in food processing and its advantages .
Novel thermal technologies in food processingRahul1154
The document discusses novel thermal technologies for food processing, including microwave heating, infrared heating, and ohmic heating.
Microwave heating works by exciting water molecules in food, causing friction and generating heat. It is commonly used for drying, thawing, pasteurization, baking, and other applications. Infrared heating works by food absorbing infrared energy and converting it to heat, with the rate depending on surface properties. It is used for drying and processing. Ohmic heating passes electric current directly through food, generating heat from electrical resistance. It allows uniform, rapid heating and is used for pasteurization and other continuous processing.
Hurdle technology for food preservationDeepak Verma
This document discusses hurdle technology, which uses a combination of preservation methods at optimal levels to inhibit microorganisms without compromising food quality. It explains that hurdle technology combines physical hurdles like heat treatment, freezing or modified atmosphere with physic-chemical hurdles like low pH, salt or preservatives. Some examples given are pickles which use acid and salt, and sausages which employ smoke, salt and preservatives. The advantages of hurdle technology are maintaining food safety, quality and nutrition while allowing for minimally processed foods.
Microwave and radiofrequency processing are emerging food processing technologies. Microwaves have a frequency range of 300 MHz to 300 GHz and are used for applications like drying, cooking, and pasteurization. A microwave oven generates microwaves using a magnetron and consists of components like a waveguide and cooking cavity. Microwaves heat food through dielectric and ionic mechanisms. Radiofrequency uses frequencies from 1-300 MHz for applications such as blanching and dehydration. It induces volumetric heating through molecular reorientation and has higher penetration than microwaves. Both technologies provide advantages like faster and more uniform heating compared to conventional methods.
This document discusses pulsed electric field (PEF) processing as a non-thermal food preservation technique. PEF uses short, high-voltage electric pulses to induce pores in microbial cell membranes, leading to cell disintegration and microbial inactivation while minimizing negative impacts on sensory and nutritional properties. The document outlines various PEF applications, factors that influence microbial inactivation, commercially available PEF systems, ongoing research needs, and the potential future of PEF processing.
pulse electric field for food processing technologyMaya Sharma
Pulse electric field (PEF) technology uses high voltage electric pulses to permeabilize microbial and plant cell membranes. It can be used as a non-thermal pasteurization method for foods like juices. PEF systems generate short pulses of 15-80 kV/cm for under 1 second using pulse-forming networks and fast switches. This disrupts microbial and plant cell membranes through electroporation. PEF can inactivate bacteria and yeasts while maintaining sensory and nutritional properties of foods. It has potential applications in juice, dairy, meat, and plant oil extraction processing. However, PEF is not effective against spores and requires further research toward commercialization.
The document discusses emerging food processing technologies that can help reduce post-harvest losses of fruits and vegetables in India. It provides an overview of technologies like ohmic heating, microwave heating, pulsed electric field, high pressure processing, ultrasound, and pulsed light and explains their principles, components, applications, advantages, and limitations. These emerging technologies can help maintain the quality and safety of foods while being more energy efficient alternatives to conventional thermal processing methods.
The document discusses hurdle technology, which uses a combination of preservation methods like heating, chilling, drying, and addition of preservatives to inhibit microbial growth and improve food quality and safety. Some key hurdles mentioned are temperature, water activity, pH, redox potential, and preservatives. Hurdle technology is useful for foods that can be stored without refrigeration. It allows for milder processing conditions that maintain quality attributes like freshness. Examples discussed include hurdle-stabilized products like paneer, fruit snacks, and sauces.
Power point presentation (ppt) on Ohmic Heating & Extraction Processing by Ra...Ram Niwas Jhajhria
Seminar Presentation by Ram Niwas Jhajhria on the topic of Ohmic Heating & Extraction Processing (M.Tech student in the department of Agricultural & Food Process Engineering, IIT Kharagpur)
Ohmic heating is a method of heating food by passing electricity through it, causing the food itself to heat up rapidly and uniformly from the inside. It differs from conventional heating by directly heating the entire food volume, preventing quality damage. It can process larger food particles than conventional methods and requires less cleaning of equipment. Ohmic heating is suitable for liquids, soups, stews, fruits, eggs, juices and other foods. It inactivates microorganisms through heating and may have additional non-thermal effects. The shelf life of ohmically processed foods is comparable to canned foods. Several commercial ohmically processed products are available. Ohmic heating is more environmentally friendly than conventional methods.
1) Refractance window drying is a novel drying method that uses infrared radiation to dry foods in a more efficient manner than conventional methods like freeze drying or hot air drying.
2) It involves placing a wet food product on a mylar sheet above hot water, where the water and mylar sheet work together to transmit infrared radiation and heat to dry the product quickly in 2-6 minutes.
3) Studies have found refractance window drying produces higher quality dried products than other methods, with lower carotene and nutrient losses. It also uses 50-70% less energy and has lower costs.
Microwave processing is a technique that uses electromagnetic waves to heat and cook food. Microwaves work by causing water and other polar molecules in food to vibrate rapidly, generating heat. A typical microwave oven contains a magnetron that generates microwaves which pass into a cooking cavity to heat food. Microwave heating is more energy efficient than conventional heating as it heats food directly rather than heating the surrounding air. Common applications of microwave processing in the food industry include cooking, baking, thawing, tempering, drying, blanching, pasteurization and sterilization. However, some controversies exist around the effects of microwaves on food quality and potential health impacts from leakage.
Heat application has many benefit for eating quality and sensory properties of many food products. Therefore, this chapter discusses much high-temperature processing such as blanching, pasteurization, sterilization, extrusion, evaporation, dehydration, distillation and rehydration.
Microwave and radio frequency processing are methods of food processing that use electromagnetic waves. Microwaves range from 300MHz to 300GHz and heat food through dielectric heating and dipole rotation of molecules. Radio frequencies range from 20kHz to 3000GHz and heat food through dipole relaxation and ionic conduction. Both methods allow for uniform and rapid heating of foods. Microwave ovens use magnetrons to generate microwaves for heating while radio frequency equipment uses generators and electrodes. Applications include thawing, baking, pasteurization and drying. Advantages are high efficiency and uniform heating while disadvantages include high costs and difficulty controlling different food types and sizes.
1) The document presents a case study on tomato peeling using ohmic heating with lye-salt combinations. Experiments were conducted to determine the effects of electric field strength and salt-lye composition on peeling time and the diffusion of sodium hydroxide through the tomato peel.
2) Results showed that treatments with 0.01/0.5% NaCl/NaOH at 1610 V/m and 0.01/1.0% NaCl/NaOH at 1450 V/m had the shortest peeling times. Diffusivities for lye peeling with ohmic heating were greater than without at both 50 and 65°C.
3) It was concluded that the electric field enhances
Hurdle technology involves using two or more preservation methods together to inhibit microbial spoilage of foods. It allows for safer, stable foods without refrigeration. Common hurdles include reduced pH, increased salt content, reduced water activity, and heat processing. The hurdles work synergistically by disturbing the microbes' homeostasis. This technique is widely used in products like jam, fermented vegetables, meat, fish, and dairy. It improves safety and quality while reducing costs compared to using single preservation methods. However, some limitations exist in fully understanding and applying hurdle effects in practice.
This document discusses thermal processing methods for food including pasteurization and sterilization. Pasteurization and sterilization can be done through batch or continuous processes. Batch processes involve filling, heating, holding, cooling, and emptying vessels between batches, while continuous processes allow for energy savings by reusing heated fluids. Some advantages of continuous processes over batch processes include potential energy savings, easier scale-up and automation, and reduced sterilization times.
Ohmic heating is a novel thermal food processing technique that uses electricity to rapidly and uniformly heat foods. It works by passing electricity through food materials, which act as resistors and generate heat. Key advantages are uniform heating from 1-100°C/s without hot surfaces, higher nutrient retention, and simpler controls than conventional heating methods. Ohmic heating has applications in meat processing, dairy pasteurization, fruit and vegetable blanching, and thawing. Further research is needed to address limitations such as potential metal contamination from electrolysis and difficulties heating non-conductive foods very high or low in moisture.
Radio frequency processing and Microwave heating in food processing prakashsp13
radio frequency and microwave heating ; these slides are explain about its principle and working mechanism ,application in food processing and its advantages .
Novel thermal technologies in food processingRahul1154
The document discusses novel thermal technologies for food processing, including microwave heating, infrared heating, and ohmic heating.
Microwave heating works by exciting water molecules in food, causing friction and generating heat. It is commonly used for drying, thawing, pasteurization, baking, and other applications. Infrared heating works by food absorbing infrared energy and converting it to heat, with the rate depending on surface properties. It is used for drying and processing. Ohmic heating passes electric current directly through food, generating heat from electrical resistance. It allows uniform, rapid heating and is used for pasteurization and other continuous processing.
Hurdle technology for food preservationDeepak Verma
This document discusses hurdle technology, which uses a combination of preservation methods at optimal levels to inhibit microorganisms without compromising food quality. It explains that hurdle technology combines physical hurdles like heat treatment, freezing or modified atmosphere with physic-chemical hurdles like low pH, salt or preservatives. Some examples given are pickles which use acid and salt, and sausages which employ smoke, salt and preservatives. The advantages of hurdle technology are maintaining food safety, quality and nutrition while allowing for minimally processed foods.
Microwave and radiofrequency processing are emerging food processing technologies. Microwaves have a frequency range of 300 MHz to 300 GHz and are used for applications like drying, cooking, and pasteurization. A microwave oven generates microwaves using a magnetron and consists of components like a waveguide and cooking cavity. Microwaves heat food through dielectric and ionic mechanisms. Radiofrequency uses frequencies from 1-300 MHz for applications such as blanching and dehydration. It induces volumetric heating through molecular reorientation and has higher penetration than microwaves. Both technologies provide advantages like faster and more uniform heating compared to conventional methods.
This document discusses pulsed electric field (PEF) processing as a non-thermal food preservation technique. PEF uses short, high-voltage electric pulses to induce pores in microbial cell membranes, leading to cell disintegration and microbial inactivation while minimizing negative impacts on sensory and nutritional properties. The document outlines various PEF applications, factors that influence microbial inactivation, commercially available PEF systems, ongoing research needs, and the potential future of PEF processing.
pulse electric field for food processing technologyMaya Sharma
Pulse electric field (PEF) technology uses high voltage electric pulses to permeabilize microbial and plant cell membranes. It can be used as a non-thermal pasteurization method for foods like juices. PEF systems generate short pulses of 15-80 kV/cm for under 1 second using pulse-forming networks and fast switches. This disrupts microbial and plant cell membranes through electroporation. PEF can inactivate bacteria and yeasts while maintaining sensory and nutritional properties of foods. It has potential applications in juice, dairy, meat, and plant oil extraction processing. However, PEF is not effective against spores and requires further research toward commercialization.
The document discusses emerging food processing technologies that can help reduce post-harvest losses of fruits and vegetables in India. It provides an overview of technologies like ohmic heating, microwave heating, pulsed electric field, high pressure processing, ultrasound, and pulsed light and explains their principles, components, applications, advantages, and limitations. These emerging technologies can help maintain the quality and safety of foods while being more energy efficient alternatives to conventional thermal processing methods.
The document discusses hurdle technology, which uses a combination of preservation methods like heating, chilling, drying, and addition of preservatives to inhibit microbial growth and improve food quality and safety. Some key hurdles mentioned are temperature, water activity, pH, redox potential, and preservatives. Hurdle technology is useful for foods that can be stored without refrigeration. It allows for milder processing conditions that maintain quality attributes like freshness. Examples discussed include hurdle-stabilized products like paneer, fruit snacks, and sauces.
Power point presentation (ppt) on Ohmic Heating & Extraction Processing by Ra...Ram Niwas Jhajhria
Seminar Presentation by Ram Niwas Jhajhria on the topic of Ohmic Heating & Extraction Processing (M.Tech student in the department of Agricultural & Food Process Engineering, IIT Kharagpur)
Ohmic heating is a method of heating food by passing electricity through it, causing the food itself to heat up rapidly and uniformly from the inside. It differs from conventional heating by directly heating the entire food volume, preventing quality damage. It can process larger food particles than conventional methods and requires less cleaning of equipment. Ohmic heating is suitable for liquids, soups, stews, fruits, eggs, juices and other foods. It inactivates microorganisms through heating and may have additional non-thermal effects. The shelf life of ohmically processed foods is comparable to canned foods. Several commercial ohmically processed products are available. Ohmic heating is more environmentally friendly than conventional methods.
1) Refractance window drying is a novel drying method that uses infrared radiation to dry foods in a more efficient manner than conventional methods like freeze drying or hot air drying.
2) It involves placing a wet food product on a mylar sheet above hot water, where the water and mylar sheet work together to transmit infrared radiation and heat to dry the product quickly in 2-6 minutes.
3) Studies have found refractance window drying produces higher quality dried products than other methods, with lower carotene and nutrient losses. It also uses 50-70% less energy and has lower costs.
Microwave processing is a technique that uses electromagnetic waves to heat and cook food. Microwaves work by causing water and other polar molecules in food to vibrate rapidly, generating heat. A typical microwave oven contains a magnetron that generates microwaves which pass into a cooking cavity to heat food. Microwave heating is more energy efficient than conventional heating as it heats food directly rather than heating the surrounding air. Common applications of microwave processing in the food industry include cooking, baking, thawing, tempering, drying, blanching, pasteurization and sterilization. However, some controversies exist around the effects of microwaves on food quality and potential health impacts from leakage.
Heat application has many benefit for eating quality and sensory properties of many food products. Therefore, this chapter discusses much high-temperature processing such as blanching, pasteurization, sterilization, extrusion, evaporation, dehydration, distillation and rehydration.
Microwave and radio frequency processing are methods of food processing that use electromagnetic waves. Microwaves range from 300MHz to 300GHz and heat food through dielectric heating and dipole rotation of molecules. Radio frequencies range from 20kHz to 3000GHz and heat food through dipole relaxation and ionic conduction. Both methods allow for uniform and rapid heating of foods. Microwave ovens use magnetrons to generate microwaves for heating while radio frequency equipment uses generators and electrodes. Applications include thawing, baking, pasteurization and drying. Advantages are high efficiency and uniform heating while disadvantages include high costs and difficulty controlling different food types and sizes.
1) The document presents a case study on tomato peeling using ohmic heating with lye-salt combinations. Experiments were conducted to determine the effects of electric field strength and salt-lye composition on peeling time and the diffusion of sodium hydroxide through the tomato peel.
2) Results showed that treatments with 0.01/0.5% NaCl/NaOH at 1610 V/m and 0.01/1.0% NaCl/NaOH at 1450 V/m had the shortest peeling times. Diffusivities for lye peeling with ohmic heating were greater than without at both 50 and 65°C.
3) It was concluded that the electric field enhances
Non thermal processing of food- Pulsed electric field and visible lightT. Tamilselvan
This document provides information on pulsed electric field (PEF) and pulsed visible light processing of foods. PEF uses short electric pulses to preserve foods through electroporation of microbial cell membranes, while minimizing heat production. PEF has been shown to effectively inactivate various microbes in foods like milk, eggs and juices. Pulsed visible light also uses intense, brief pulses of light to inactivate microbes in foods photochemically and through localized heating. Both techniques are non-thermal alternatives to traditional food processing that reduce degradation of nutritional and sensory qualities compared to heat treatments.
This document provides an overview of microwave heating technology presented by Kunwar Pratik Singh. It begins with an introduction to microwaves and their properties. It then discusses the principles of microwave heating through dipole rotation and ionic polarization. Key components of a microwave oven are described including the magnetron, waveguide and stirrer. Applications of microwave heating in various industries are listed. Advantages such as speed, energy efficiency and disadvantages like non-uniform heating are outlined. Research on improving heating uniformity through food shape and size is summarized. The conclusion discusses the growth potential for microwave processing.
Food processing transforms raw ingredients into marketable products through physical or chemical means. Key processing methods include drying, freezing, addition of preservatives, and canning. Emerging non-thermal technologies include pulsed electric fields, high pressure processing, ultrasound, and supercritical fluid extraction. These methods inactivate pathogens and extend shelf life while better retaining nutrients, flavors, and colors compared to thermal processing. Non-thermal processing is gaining popularity for commercial food production due to these advantages.
Microwaves are produced inside the oven by an electron tube called a magnetron. The microwaves are reflected within the metal interior of the oven where they are absorbed by food. Microwaves cause water molecules in food to vibrate, producing heat that cooks the food.MW are electromagnetic waves generated by magnetrons and klystrons.
Frequency 300MHz and 300GHz
Wavelength from 1mm to 1m
industrial heating purposes the available frequencies are 915 and 2450MHz
MW giving up their energy to the material, with a consequential rise in temperature
Two imp mechanisms are:
Ionic polarization: conversion of kinetic energy of the moving ions into thermal energy
Dipole rotation: rotation of polar molecules leads friction with surrounding medium and heat is generated
ENERGY EFFICIENCY:
During microwave heating, electrical energy is first converted into microwave energy
The microwave then interacts with foods and is converted into heat
TWO EFFICIENCIES:
Microwave generation efficiency
Microwave absorption efficiency
ENERGY CONSUMPTION
Specific energy consumption was defined as the total energy supplied divided by the amount of water removed during drying
Overheating could increase the energy consumption due to high moisture loss from the overheated region
CONVERSION OF MICROWAVE ENERGY INTO HEAT
MW Heating is a consequence of the interactions between microwave energy and a dielectric material
PD= 55.61 X 10-14 f’ E2 ἐ tanᵹ
where,
PD Power dissipation W/cm3
f ‘ frequency in Hz
E electric field in v/cm (V/m)
ἐ relative dielectric constant
tanᵹ: loss tangent
MICROWAVE OVEN GENERALLY CONSISTS OF THE FOLLOWING BASIC COMPONENTS
(i) power supply and control: it controls the power to be fed to the magnetron as well as the cooking time
(ii) magnetron: it is a vacuum tube in which electrical energy is converted to an oscillating electromagnetic field. Frequency of 2450 MHz has been set aside for microwave oven for home use
Conti…..
(iii) waveguide: it is a rectangular metal tube which directs the microwaves generated from the magnetron to the cooking cavity
(iv) stirrer: it is commonly used to distribute microwaves from the waveguide and allow more uniform heating of food
(v) cooking cavity: it is a space inside which the food is heated when exposed to microwaves
Conti….
(vi) turntable: it rotates the food products through the fixed hot and cold spots inside the cooking cavity and allows the food products to be evenly exposed to microwaves
(vii) door and choke: it allows the food to the cooking cavity. they prevent microwaves from leaking through the gap between the door and the cooking cavity
FACTORS AFFECTING MICROWAVE HEATING
Dielectric properties
Temperature and frequency
Shape and size of food items
DIELECTRIC PROPERTIES
Penetration of microwave energy inside a material is a function of its dielectric properties.
Non thermal process in preservation of foodGazanfar Abass
The document discusses various non-thermal food processing techniques as alternatives to traditional thermal processing. It provides examples of different non-thermal methods like pulsed electric field, high pressure processing, pulsed light technology, microwave heating, ohmic heating, and irradiation. These methods allow for higher production rates and better retention of nutrients, flavors and quality compared to thermal processing. While the equipment costs are initially higher, non-thermal processing is increasingly being used in both large-scale and small-scale food industries.
Non thermal process in preservation of foodGazanfar Abass
The document discusses various non-thermal food processing techniques as alternatives to traditional thermal processing. It provides examples of different non-thermal methods like pulsed electric field, high pressure processing, pulsed light technology, microwave heating, ohmic heating, and irradiation. These methods aim to increase production rates and profits for food industries while maintaining better quality, nutrients, flavor and extending shelf life compared to thermal processing which can result in loss of volatile compounds. The non-thermal methods are particularly suitable for large scale and liquid food production.
Non thermal process in preservation of foodGazanfar Abass
The document discusses various non-thermal food processing techniques as alternatives to traditional thermal processing. It provides examples of different non-thermal methods like pulsed electric field, high pressure processing, pulsed light technology, microwave heating, ohmic heating, and irradiation. These methods allow for higher production rates and better retention of nutrients, flavors and quality compared to thermal processing. While the equipment costs are initially higher, non-thermal processing is increasingly being used in both large-scale and small-scale food industries.
Non thermal process in preservation of foodGazanfar Abass
The document discusses various non-thermal food processing techniques as alternatives to traditional thermal processing. It provides examples of different non-thermal methods like pulsed electric field, high pressure processing, pulsed light technology, microwave heating, ohmic heating, and irradiation. These methods allow for higher production rates and better retention of nutrients, flavors and quality compared to thermal processing. While the equipment costs are initially higher, non-thermal processing is increasingly being used in both large-scale and small-scale food industries.
Microwave heating is used in many food processing applications like reheating, precooking, tempering, baking, drying, pasteurization and sterilization. Microwaves are electromagnetic waves with frequencies between 300 MHz to 300 GHz that travel at the speed of light. Microwave ovens operate at 2.45 GHz. Microwaves penetrate foods and are absorbed, causing molecules to vibrate and generate heat. The dielectric properties of foods like water content, temperature and composition determine how microwaves interact with them. Microwave heating has advantages like short cooking times and lower nutrient loss but also disadvantages like difficulty controlling heat and risk of overheating closed containers. It can both positively and negatively impact the nutrient content of foods.
Dielectric, ohmic, infrared_heating for food productsramavatarmeena
Dielectric, ohmic, and infrared heating are forms of electromagnetic energy used to heat foods. Dielectric and ohmic heating directly generate heat within the food, while infrared heating relies on external heat application. Ohmic heating passes electric current through food, using its electrical resistance to directly convert electricity to heat throughout. Dielectric heating induces molecular friction in water to generate uniform heat. Infrared heating absorbs energy at the surface. These methods can rapidly thaw, dry, bake, and pasteurize foods with precise temperature control and minimal damage.
A microwave oven, is a kitchen appliance that can come in many different sizes and styles employing microwave radiation primarily to cook or heat food. This is accomplished by using microwaves, almost always emitted from a magnetron, to excite water (primarily) and other polarized molecules within the food to be heated. This excitation is fairly uniform, leading to food being heated everywhere all at once
A microwave oven, is a kitchen appliance that can come in many different sizes and styles employing microwave radiation primarily to cook or heat food. This is accomplished by using microwaves, almost always emitted from a magnetron, to excite water (primarily) and other polarized molecules within the food to be heated. This excitation is fairly uniform, leading to food being heated everywhere all at once
Microwaves are electromagnetic waves with wavelengths between 1 mm and 1 m that are used for heating. Microwave ovens generate microwaves at a frequency of 2.45 GHz to heat food through rotation and ionic conduction, causing more efficient heating than conventional methods. The key components of a microwave oven are the magnetron which generates microwaves, the waveguide which directs the waves, and the cooking cavity where food is placed. Microwaves are also used for industrial applications like pasteurization, sterilization, drying and heating materials.
The document discusses microwave assisted reactions for green chemistry. It begins with introducing green chemistry and its focus on reducing hazardous substances. It then discusses how microwave heating allows for faster, more energy efficient reactions by directly coupling with polar molecules. Key advantages of microwave heating include uniform and rapid heating throughout the reaction mixture. This leads to increased reaction rates, higher yields, and less waste generation compared to conventional heating methods. The document provides an overview of the mechanisms of microwave heating and its applications in organic synthesis.
Cold plasma technology uses plasma generated at ambient temperature to sterilize food products and improve shelf life without degrading heat-liable nutrients. It works by using energized gases to inactivate microbes via UV light and reactive chemical byproducts. Different methods like dielectric barrier discharge can be used to generate cold plasma, which has applications in food processing. The technology offers advantages like minimal effects on sensory and nutritional properties of food while reducing risks from thermal and chemical processing. However, limitations include difficulty treating bulky or irregular foods and limited penetration into products.
Heritage Conservation.Strategies and Options for Preserving India HeritageJIT KUMAR GUPTA
Presentation looks at the role , relevance and importance of built and natural heritage, issues faced by heritage in the Indian context and options which can be leveraged to preserve and conserve the heritage.It also lists the challenges faced by the heritage due to rapid urbanisation, land speculation and commercialisation in the urban areas. In addition, ppt lays down the roadmap for the preservation, conservation and making value addition to the available heritage by making it integral part of the planning , designing and management of the human settlements.
A comparative study between ohmic and microwave heating in food processing
1. SEMINAR REPORT
On
A Comparative Study Of Ohmic And Microwave Heating
In Food Processing
Submitted by:
NAME - MARIAH SADAF
UNIVERSITY ROLL NO-1300341-----
2017-2021
Submitted at
Department of Food Technology
TECHNO MAIN SALT LAKE
EM-4/1, SALT LAKE, SECTOR – V
KOLKATA-700091
Affiliated To:
MAULANA ABUL KALAM AZAD UNIVERSITY OF
TECHNOLOGY, WB
BF-142, BIDHAN NAGAR, SECTOR -1, KOLKATA -64
2. INTRODUCTION
Thermal processing is a food sterilization technique in which the food is
heated at a temperature high enough to destroy microbes and enzymes. The
specific amount of time required depends upon the specific food and the
growth habits of the enzymes or microbes. Both the texture and the
nutritional content of the food may be altered due to thermal processing.
OHMIC HEATING
Ohmic heating, a thermal electrical heating method, is also termed as
resistance heating. It is direct heating method where food is in contact with the
electrodes. The concept of ohmic heating is quite simple. The passage of
electric current through an electrically conductive food material obeys Ohm’s
law (V = IR); and heat is generated due to the electrical resistance of the food. A
large number of potential applications exist for ohmic heating, including
blanching, evaporation, dehydration, fermentation, sterilization, pasteurization,
and heating of foods. Beyond heating, applied electric field under ohmic
heating causes electroporation of cell membranes, which increase extraction
rates, and reduce gelatinization temperature and enthalpy. Ohmic heating
results in faster heating of food along with maintenance of color and nutritional
value of food. Water absorption index, water solubility index, thermal
properties, and pasting properties are altered with the application of ohmic
heating.
The interaction between the local field strength and local electrical
conductivity will govern the local heat generation by this equation:
Q = E²k = λJ²
Where Q is heat generation rate per unit
volume (W/m³)
E is the electric field strength (V/cm)
k is the electrical conductivity (S/m)
λ is the resistivity (ohm-meter)
J is the current density (A/m²)
The actual heating rate for the substance can then be calculated from
the equation: dT /dt = Q/ ρC Where T is temperature in °C
t is the time in second
ρC is the volumetric heat capacity
3. MECHANISM & APPLICATION
Applications Advantages Food Items
Sterilization, heating liquid
foods containing large
particulates and heat sensitive
liquids, aseptic processing
Attractive appearance, firmness properties,
pasteurization of milk without protein
denaturation
Cauliflower florets, soups,
stews, fruit slices in syrups
and sauces, ready to cook
meals containing
particulates, milk, juices, and
fruit purees
Ohmic cooking of solid foods The cooking time could be reduced
significantly. The center temperature rises
much faster than in conventional heating,
improving the final sterility of the product,
less power consumption and safer product
Hamburger patties, meat
patties, minced beef,
vegetable pieces, chicken,
pork cuts
Ohmic thawing Thawing without increase in moisture
content of the product
Shrimp blocks
Inactivation of spores and
enzymes
To improve food safety and enhance shelf
life, increased stability and energy
efficiency, Reduced time for inactivation of
lipoxygenase and polyphenol oxidase,
inactivation of enzymes without affecting
flavor
Process fish cake, orange
juice, juices
Blanching and extraction Enhanced moisture loss and increase in
juice yield
Potato slices, vegetable
purees extraction of sucrose
from sugar beets, extraction
of soy milk from soy beans
Food Product
Conducts
Electricity
Collision Of
Molecules
Momentum
Transfer To
These
Molecules
Increase In
Kinetic
Energy
Thereby
Heating The
Product
4. OHMIC HEATING: ADVANTAGES AND
DISADVANTAGES
ADVANTAGES
High energy efficiency (90% electrical energy is converted into heat).
Rapid and uniform heating
Better nutrient and vitamins retention
No theoretical upper temperature limit.
No hot surface for heat transfer; less risk of surface fouling and burning of
the product.
Reduced maintenance cost
Process can simply be controlled with switch on and off.
Environmentally friendly.
Product with large size (15mm) and high concentration of solid (up to 80%)
can easily be processed
DISADVANTAGES
Electrolysis of product and corrosion of electrode occur at low frequency that
may result in metal contamination to food which may be hazardous at high
concentration.
Too high installation and initial operating cost.
This system is unable to heat a product with high fat and oil and dried food
system. Since fats are non-conductive (due to absence of water and ions), it
may bypass current and slow heating may occurs.
Runaway heating may occur at high temperature due to increase in
electrical conductivity.
5. MICROWAVE HEATING
Microwaves are part of electromagnetic spectrum in the frequency range falling
between radio and infrared region. Frequency 2450MHz – 915MHz (for
food).Microwave heating is a method that offers technique of heating requiring
intermolecular friction,conduction and convection. Microwave generates heat
within the food rapidly raising the temperature to the desired extent. The waves
can be absorbed by water, fat or sugar in foods and thus is converted into heat.
Microwave heating is caused by the ability of the materials to absorb microwave
energy and convert it to heat. Microwave heating is caused by the ability of the
materials to absorb microwave energy and convert it into heat. Microwave
heating of food materials mainly occurs due to dipolar and ionic mechanisms.
Presence of moisture or water causes dielectric heating due to dipolar nature of
water. When an oscillating electric field is incident on the water molecules, the
permanently polarized dipolar molecules try to realign in the direction of the
electric field. Due to high frequency electric field, this realignment occurs at
million times per second and causes internal friction of molecules resulting in
the volumetric heating of the material. Microwave heating might also occur due
to the oscillatory migration of ions in the food which generates heat in presence
of high frequency oscillating electric field.
The microwaves are generated by special oscillator tubes called "Magnetrons
and Keltron”. The electromagnetic energy, at microwave frequency is conducted
through a coaxial tube or wave guide at a point of usage. Both Magnetron and
Keltron are electron tubes which generate microwaves.
1. Magnetron: The Magnetron is a vacuum valve in which the electron,
emitted by the cathode, turn around under the action of a continuous
electric field produced by the power supply and of a continuous magnetic
field. The movement produces the electro-magnetic radiation.
2. Keltron: Keltron uses the transit time between two given points to
produce this modulated electron stream which then delivers pulsating
energy to a cavity resonator and sustain oscillation within the cavity.
6. MECHANISM & APPLICATION
Food
product(cont
aining
water,sugar
and fats
which act as
dipole)
Microwave
passes
through and
the polar
components
align
themselves
with electric
field
Intermolecular
friction and
Heat is
generated
Simultaneously
conduction
(solid),
convection
(liquid) takes
place and is
distributed
uniformly
Heated
product
APPLICATION USE FOOD ITEM
Baking For internal heating
microwave, for external heating
hot air (electric coil) or infrared
for crust formation
Cakes, cupcakes,
pastries and pattis
Concentrating Of heat sensitive fluids and
slurries at relatively short time
Fruit juice, syrup and
jam
Cooking It cooks relatively larger pieces
without high temperature
gradients between surfaces
and interior
Meat and meat
products
Blanching Rapid and uniform heating
inactivates enzymes without
leaching of essential nutrients.
Vegetables and fruits
Drying and
Pasteurization
Heats uniformly with little
amount of heat.
Milk and vegetables
Pre-cooking Is well suited for pre-cooking
‘heat and serve’ as there is no
cooking associated.
Bacon and tenderloin
7. MICROWAVE HEATING: ADVANTAGES AND
DISADVANTAGES
ADVANTAGES
o Rapid heating
o Reduced loss of nutrients
o No contamination of foods by products of combustion
o Equipment is small, compact, clean in operation
o Surface of the food does not overheat
o Automatic process control
DISADVANTAGES
o Low penetration depth
o Product may hazardous to health
o High initial cost
o Non uniform heating
o Less energy efficient
8. COMPARISON BETWEEN OHMIC AND
MICROWAVE HEATING
OHMIC HEATING MICROWAVE HEATING
Uses the electrical resistance of foods Forms of electromagnetic energy
Heat is generated due to electrical
current
Heat is generated by molecular
friction
Depends on the electrical resistance
of the food
Depends on moisture content of the
food
Penetrates throughout the food Limited penetration depth
SUGGESTIONS FOR IMPROVEMENT
Develop predictive, determinable and reliable models.
Reliable feedback control to adjust the supply power according
to the conductivity changes occurring.
Developing real time-temperature monitoring techniques for
locating cold-spots and overheated regions during heating.
Developing adequate safety and quality-assurance protocols in
order to commercialize these heating technology.
9. CONCLUSION
Thus, individually or in combination these two types of heating
methods are very beneficial in the food industry.
Helps in food preservation.
Increases the shelf life.
Inactivates microbes.
Gives the scope to bring about innovation in terms of
preservation.
High rate of heating during processing results in short
processing time.
Higher retention of nutrients and vitamins
Further research have to be carried out in order to identify
cold-spot, decrease cost and improve electrode so that
electrolysis is prevent.
The usage of microwave and ohmic heating for food processing is
continuously developing globally. Shorter processing time, high
energy efficiency and faster heating are the main advantages that
the microwave and ohmic heating offer. Although there are still
some problems associated with the process. These are in terms of
food quality and the non-uniform heating of foods. Hence research
has been focused on avenues to overcome these problems.
Currently, the research terrains are directed on the new food
formulation, changing of the oven design and the amalgamation of
microwaves and other heating methods in order to achieve an
efficient material interaction.
10. REFERENCES
Microwave heating by By A.C. Metaxas
Andrew Proctor, 2011. “Alternatives to Conventional Food
Processing”. Royal Society of Chemistry. 307-334.
Ohmic heating in food processing. Ramaswamy, Hosahalli S.
Boca Raton, FL: CRC Press. 2014.
Varghese, K. Shiby; Pandey, M. C.; Radhakrishna, K.; Bawa,
A. S. (October 2014). "Technology, applications and modelling
of ohmic heating: a review"
Ohmic Heating in food processing. CRC Press. 2014
The Facts about Microwave Ovens by John R. Free, Popular
Science, February 1973.
Acierno, D., Barba, A. A., & d’ Amore, M. (2004). Heat transfer
phenomena during processing materials with microwave
energy. Heat and Mass Transfer, 40(5), 413-420.
Alajaji, S.A., & El-Adawy, T.A. (2006). Nutritional composition
of chickpea (Cicer arietinum L.) as affected by microwave
cooking and other traditional cooking methods. Journal of
Food Composition and Analysis, 19, 806-812.
Alibas, I. (2007). Microwave, air and combined microwave-air-
drying parameters of pumpkin slices. LWT-Food Science and
Technology, 40, 1445-1451.
Aparna, K., Basak, T., & Balakrishnan, A.R. (2007) Role of
metallic and composite (ceramic-metallic) supports on
microwave heating of porous dielectrics. International Journal
of Heat and Mass Transfer, 50, 3072-3089