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Novel non thermal preservation technologies

High pressure processing is a non-thermal food processing technique that uses high pressures, usually between 100-1000 MPa, to inactivate microorganisms and extend the shelf life of foods. It has minimal effects on taste, texture, color, and nutrients of foods. HPP is being used commercially for products like guacamole, sliced meats, seafood, juices, and dairy to kill pathogens and spoilage microbes while maintaining quality. The high pressure is applied uniformly from all directions using a pressure vessel filled with water, which compresses the packaged foods within minutes and safely destroys microbes without heat.

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Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. PowerPoint® Lecture Slide Presentation by Robert J. Sullivan, Marist College Dr Ravi Kant Agrawal, MVSc, PhD Senior Scientist (Veterinary Microbiology) Food Microbiology Laboratory Division of Livestock Products Technology ICAR-Indian Veterinary Research Institute Izatnagar 243122 (UP) India
What is Food Processing?  Food processing is the transformation of raw ingredients, by physical or chemical means into food, or food into other forms.  Food processing combines raw food ingredients to produce marketable food products that can be easily prepared and served by the consumer.
Why it should be processed ? Improves the taste of the food Food Processing Increases shelf life Pathogens/ toxin removal enables transportation  Suits our life style can also add extra nutrients
Traditional Processing  Addition of salt, sugars, preservatives, antioxidants, naturally occurring antimicrobial substances .  Also by the processes like drying, freezing, refrigerated storage, smoking, food concentration, canning etc.
The main problem with the thermal processing of food is loss of volatile compounds, nutrients, and flavor. To overcome these problems non-thermal methods came into food industries to increase the production rate and profit. The non-thermal processing is used for all foods for its better quality, acceptance, and for its shelf life. The new processing techniques are mostly employed to the liquid packed foods when compared to solid foods. Since the non-thermal methods are used for bulk quantities of foods, these methods of food preservation are mainly used in the large scale production. The cost of equipments used in the non-thermal processing is high when compared used in thermal processing. After minimizing the investment costs of non-thermal processing methods, it can also be employed in small scale industries. Why Non-thermal?
Novel Food Processing Technologies  High Pressure Processing  Microwave heating  Pulsed Electric Field  Pulsed Light Technology  Ohmic Heating  Ultrasonics  Radiofrequency heating  Infrared heating  Pulsed X-rays  Irradiation  Oscillating Magnetic Field
HIGH PRESSURE PROCESSING (HPP)  High Pressure Processing is also known as “High Hydrostatic Pressure” or “Ultra High Pressure” processing.  High pressure processing (HPP) is a promising “non-thermal” technology that has been developed with the aim of obtaining microbiologically safe food products while avoiding undesirable changes in the sensory, physicochemical, and nutritional properties of foods.  HPP has become one of the innovative food processing technologies most accepted by consumers.  In HPP, the product is packaged in a flexible container (usually a pouch or plastic bottle), the food product to be treated is placed in a pressure vessel capable of sustaining the required pressure, the product is submerged in a liquid which acts as the pressure-transmitting medium.  High pressure processing is carried out with intense pressure in the range of 100 – 1000 Mpa with or without heat, allowing most foods to be preserved with minimal effect on taste, texture and nutritional characteristics.  Non-thermal processing technology (combination with heat possible)  First research in 1890s –milk pathogens  First commercialized in Japan in the early 1990s for pasteurization of acid foods for chilled storage  High pressure treated foodstuffs have been marketed in Japan since 1990, in Europe and the United States since 1996 and Australia since 2001  Rapid commercialization since 2000
High pressure processing (HPP), is a method of preserving and sterilizing food, in which a product is processed under very high pressure, leading to the inactivation of certain microorganisms and enzymes in the food. Also known as PASCALIZATION. High Pressures applied at short periods of time (5-20 minutes). HPP uses up to 1000MPa to kill many of the microorganisms found in foods, even at room temperature without degrading vitamins, flavor and colour molecules in the process. Food packages are loaded onto the vessel and the top is closed. The pressure medium usually water is pumped into the vessel from the bottom. Once the desired pressure is reached, the pumping is stopped, valves are closed, pressure can be maintained without further need for energy input. U.S., Canada, and Mexico, Spain, Italy, Portugal, France, UK, and Germany, Australia, and Asia (Japan, China, and S. Korea) lead the commercialization of high pressure technology. Cost is 0.5-2.5 Million $ (equipment) and HPP treatment costs are quoted as ranging from 4–10 cents/lb (equal to that of thermal processing)
Principle  Le Chatelier’s principle: Any phenomenon (phase transition, change in molecular Configuration, chemical reaction) accompanied by a decrease in volume is enhanced by pressure. Accordingly, pressure shifts the system to that of lowest volume.  Isostatic principle: high pressure is applied in an “isostatic” manner such that all regions of food experience a uniform pressure, unlike heat processing where temperature gradients are established. The food products are compressed by uniform pressure from every direction and then returned to their original shape when the pressure is released. The products are compressed independently of the product size and geometry because transmission of pressure to the core is not mass/time dependant thus the process is minimized If a food product contains sufficient moisture, pressure will not damage the product at the macroscopic levels as long as the pressure is applied uniformly in all directions
Features:  Application of high pressures can cause: Inactivation of Parasites, Plant cells. Vegetative micro-organisms. Some fungal spores. Many foodborne viruses. Enzymes are selectively inactivated. Macromolecules can change conformation. Small molecules (eg: flavors) are generally unaffected  High pressure is instantaneously and uniformly applied to the sample.  Compression is fully reversible.
Pressures exerted at highest altitudes (0.01 to 0.1 MPa) and deepest part of the oceans (10-100 MPa) are usually considered as High pressures. For food processing, 200-1000MPa pressure is required. For inactivating milk enzymes; alkaline phosphatase and protease about 1000 MPa is needed (as per research articles). Usually, 600MPa is the optimum pressure for processing commercial food products.
High pressure can kill microorganisms by interrupting their cellular function without the use of heat that can damage the taste, texture, and nutrition of the food.
Microbial Efficacy • Inactivates most vegetative pathogenic and spoilage microorganisms at pressures above 200 Mpa at RT. • causes damage to cell membranes and denatures some intracellular proteins leading to cell death. • Inactivation of key enzymes, including those involved in DNA replication and transcription is also mentioned as a possible inactivating mechanism. • The process can also sub-lethally stress or injure bacteria. • Reduced pH is generally synergistic with pressure in eliminating microorganisms. • Bacterial spores >Gram positive > Gram negative > Moulds, Yeast (pressure resistant)
HPP systems are available in two types: Batch process Semi-Continuous process • In-container processing: • Applied to all solid and liquid foods • Minimal risk of post processing contamination and Easier cleaning. • Bulk processing: • Simple material handling • Great flexible in choice of container
A typical HPP batch system consists of four/five key components: 1) Pressure vessel 2) High pressure intensifier pump 3) a system for controlling and monitoring the pressure 4) a product-handling system for transferring product to and from the pressure vessel 5) Compressing medium like water, glycol solutions, silicone oil, sodium benzoate solutions, ethanol solutions, inert gases .
Low-medium moisture, semi-solid/solid foods, vacuum packaged: Dry-cured or cooked meat products Cheese Fish, seafood, marinated products Ready to eat meals, sauces High moisture, solid foods, vacuum packaged: Fruits, marmalades/jams Vegetables High moisture, liquid foods in plastic bottle/flexible packaging: Dairy products Fruit juices Bioactive beverages
Solid foods with air included Bread and cakes Mousse Packaged foods in completely rigid packaging Glass packaging Canned foods Foods with a very low water content Spices Dry fruits Powders
Fruits and Vegetables: Shelf life extension. Inactivate microorganisms and quality-deteriorating enzymes Higher sensorial, functional and nutritional values while improving food safety. Puree, coulis, sauces, juices, smoothies, chunks, slices, ready- to-eat products, these are only some examples of a wide range of fruit and vegetable products that can be processed by HPP. One of the most successful commercial application of HPP nowadays is definitely preservative-free guacamole (avocado puree with spices) because the process maintains avocado flavor, texture, green color without sacrificing food safety or shelf life (upto 6 weeks under chilled conditions).
Meat and Fish Industry: Extends shelf life with no effect on flavor or nutrients. Inactivate microorganisms and quality-deteriorating enzymes. Maintaining high sensorial and nutritional qualities and improving food safety without the need of additives or artificial preservatives. Sliced ham, turkey or chicken cuts, ready-to-eat products, whole pieces of cured ham, these are only some examples of products. One of the most successful commercial application of HPP nowadays is easy shell opening of molluscs, easy meat extraction of crustacean products and helps in increasing the yield upto 45%.
Dairy Industry: Increased shelf-life (3 to 10 times longer than the same product without HPP stored at same temperature). Product Freshness. No impact on sensory, nutritional, or functional properties. Effective elimination of spoilage and pathogenic microorganisms. High Pressure Process Technology works especially well on acidic dairy products such as yogurt because most pressure- tolerant spores are unable to survive in environments with low pH levels. The treatment is very effective on both solid and liquid dairy products. Since high pressure acts quickly and evenly, neither the size of a product’s container nor its thickness.
Products Pressure (Mpa) (1-5mins) Shelf life (at 4 deg C) Inhibits (pathogens and spoilage) Advantage Meat and meat products (sliced, marinated, whole) 31% 500-600 More than 90 days (45 days without HPP) Listeria, Salmonella , E. coli, moulds , yeast etc. Effective in eliminating pathogenic micro- organisms. Dairy products (milk , cheese) 6% 400-600 3-10 times Yeast , moulds, E. coli etc. No impact on sensory, nutritional and functional properties Sea food (Molluska, ready to eat ) 16% 350 - 400 2 times Salmonella, Vibrio, Anisakis etc Shucking and meat extraction Fruits and Vegetables (juices , sauces, onions ) 47% 400-600 3-10 times Spoiling microbes ( yeast etc) and pathogens. Healthier food rich in vitamins, minerals etc
Product Pressure(Mpa) Holding time (min.) Temperature (ºC) Potato cubes, Carrot 400 15 5-50 Apricot nectar 600-900 1-20 20 Orange juice 350 1 30 Vegetable juices, tomatoes, cauliflower, spinach, 300,370 10 35 Guacamole Salsa 600 3 - Minced beef muscle 200-500 20 25 Pork slurries 300 10 20 Hams 300 5,15,25 20 Molluscs 550 2 - Crustacean 200-300 5 - Raw Milk 100-400 10-60 20 Skim Milk 310 0.05 25 Whey protein concentrate 200,400 or 800 10,20 or 40 20 Whipped and coffee cream 100-550 10 10-24
HPP is the best option to preserve and respect the functionality of thermosensitive bioactive components present in colostrum such as immunoglobulins, lactoferrin and growth factors.
Effects on Food Color & Flavor: Fresh or marinated meat: Iron in the myoglobin changes from ferrous to ferric and globin is denatured-the red color is lost. Cooked meat color meat is largely unaffected. Cooked meals are not affected. Fruits and Vegetables: Slight modification Fruit juices: Little or no affect. Flavors are mostly unaffected. Effects on Food Texture: Slight softening in foods with cell wall structures. Effects on Fats and Lipids: Reversible crystallization
Effects on Proteins and Enzymes: Inhibition or stimulation of the enzymatic activity (depending on processing conditions). Proteins are partially denatured in products where proteins have not been previously modified by other process such as heating, drying and fermentation etc. Pressures affects hydrophobic bonds and electrostatic interactions. Pressure denaturation is complex, at pressures >200 Mpa denaturation usually irreversible.
HPP equipment are of two types. Horizontal Model Vertical Model Product in/out Processed Product in Processed Product out
The standard in HPP industrial equipment: Horizontal design for traceability and easy installation. Special design for food industry (stainless steel, cleanable) Automatic loading/unloading system Working pressure up to 600 MPa (6000 bar).
 Flexible packaging (>15% volume contraction)  Extra tight seals.  Rounded and reinforced edges.  Minimal head space.  Modified Atmospheric Packaging (MAP) possible  Tear strength, puncture resistance and surface smoothness generally not affected by HPP.  Often flexible pouches or bottles are inserted in secondary cardboard containers after processing.
 Plastic-Laminated Materials  Nylon/Coextruded Ethyl Vinyl Alcohol (EVOH)  Nylon/pp  Nylon/ Aluminum Oxide (ALOx) /CPP  PET/PE  Aluminum foil-Laminated Pouches  PET/AI/PP  Nylon/AI/PP  Deposited coatings of Silicon Oxide (SIOx)  Blenders of polymers  Nano composite materials Nylon Coextruded EVOH Aluminum Foil
 USDA has approved HPP as an intervention method for listeria contaminated pre-packed ready-to-eat (RTE) meat products.  U.S. Food & Drug Administration (FDA) has accepted the commercial use of HPP for application of low acid foods.
Uses • Increased product shelf life: even for food which is sensitive to heat • Low-temperature preservation method: no loss in product quality compared to heat pasteurization. • Enhanced food safety: due to inactivation of spoilage organisms and relevant food borne pathogens • Processing in final consumer packaging is possible, free preservation of food by using only pressure • Production of “natural”, safe, value-added food with a superior quality • Homogenous effect of HPP: Results are independent of product size and geometry • Further benefits like large yield increase compared to traditional processes (e.g. extraction of lobster meat from the shell) • Waste-free and environmentally friendly, sustainable technology: only water and electricity are needed
Consumers: HPP is a consumer acceptable, environmental friendly, scientifically recognized method to achieve higher quality in certain foods Processing: Pressure transmission is instantaneous, uniform, short processing times, assured safety in whole pack, suitable for solids and liquids Quality: Retains flavor and nutrition Environmentally: Safe and no process by-products, no emissions Packaging: Package design, geometry and format should be tailored for HPP, Packaging films and laminate structure generally survive HPP well, but MAP and HPP at high temperature can cause delamination and defects.
Meat&SeaFoods ReadyMeals Juices&Smoothies Sauces&Spreads
Microwave Heating • Refers to the use of electromagnetic waves of certain frequencies (2450MHz and 915MHz) to generate heat in material. • Container with food is placed in a microwave oven • And then a oven is activated, the food at the edge of the container heats faster and a temperature gradient develops between the centre and the edges
Mechanism Dipolar interaction:  Polar molecules such as water molecules (dipole) inside the food will rotate according to the alternating electromagnetic field.  The rotation of water molecules would generate heat for cooking Ionic interaction:  Ionic compounds (i.e. dissolved salts) in food can also be accelerated by the electromagnetic field and collided with other molecules to produce heat
Basic Components  Power supply and control: It controls the power.  Magnetron: It is a vacuum tube in which electrical energy is converted to an oscillating electromagnetic field.  Waveguide: It is a rectangular metal tube which directs the microwaves generated from the magnetron to the cooking cavity.  Stirrer: Distribute microwaves from the waveguide and allow more uniform heating of food.  Turntable: It rotates the food products through the fixed hot and cold spots inside the cooking cavity.  Cooking cavity: It is a space inside which the food is heated when exposed to microwaves  Door and choke: The door and choke are specially engineered that they prevent microwaves from leaking through the gap between the door and the cooking cavity.
Materials: Plastic containers, high density polyethylene, papers and boards. Application: Baking, concentration, cooking, curing, drying, finish drying, freeze drying, pasteurising, sterilizing, tempering and thawing.
PULSED ELECTRIC FIELD (PEF) TECHNOLOGY • PEF is a non-thermal food preservation technology that involves the discharge of high voltage electric pulses (up to 70 kV/cm) into the food product, which is placed between two electrodes for a few microseconds. • An external electric field is used to exceed a critical transmembrane potential of one volt. • This result in a rapid electric breakdown and conformational changes of cell membranes, which leads to the release of intracellular liquid, and cell death. • PEF treatment shows changes in tissue structure leading to weight increase and greater water holding capacity and less loss during cooking.
Mechanisms of Microbial Inactivation Electrical Breakdown: • The normal resisting potential difference across the membrane is 10 mV and is proportional to the field strength and radius of the cell. The increase in the membrane potential leads to reduction in the cell membrane thickness. Electroporation: • The plasma membranes of cells become permeable to small molecules after being exposed to an electric field, and permeation then causes swelling and eventual rupture of the cell membrane
A power supply: this may be an ordinary direct current power supply or a capacitor charging power supply. An energy storage element: either electric (capacitive) or magnetic (inductive). A switch which may be either closing or opening. A pulse shaping and triggering circuit in some cases. A treatment chamber: a wide variety of designs have been developed. A pump to supply a feed of product to the chamber. A cooling system to control the temperature of the feed and/or output material
Applications: PEF is used in processing of apple juice, orange juice, processing of milk, liquid whole eggs, baking applications and processing of green pea soup. Advantages: • Kills vegetative cells. • Colours, flavours and nutrients are preserved. • Short treatment time
Pulsed Light (Or) High Intensity Light Technology • High Intensity Light Technology can be used for the rapid inactivation of microorganisms on food surfaces, equipments and food packaging materials. • High intensity white light and UV light food preservation methods employ light wave lengths ranging from ultra violet to near infra-red in short intense pulse. • Pulses of light used for food processing applications typically emit one to twenty flashes per second of electromagnetic energy • The principle involved in generating high intensity light is that a gradual increase of low to moderate power energy can be released in highly concentrated bursts of more powerful energy • The key component of a Pulsed Light unit is a flash lamp filled with an inert gas • A high-voltage, high-current electrical pulse is applied to the inert gas in the lamp, and the strong collision between electrons and gas molecules cause excitation of the latter, which then emit an intense, very short light pulse • It is generally accepted that UV plays a critical role in microbial inactivation. • The treatment is most effective on smooth, nonreflecting surfaces or in liquids that are free of suspended particulates. • In surface treatments, rough surfaces hinder inactivation due to cell hiding.
Applications of High Intensity Light Technology •Used in decontamination of vegetables, dairy products. •Also used in microbial inactivation of water, sanitation of packaging materials and disinfection of equipment surfaces .
Ohmic heating • Ohmic heating is an advanced terminal processing method wherein the food material which serves as an electrical resistor, is heated by passing electricity through Which result in rapid & uniform heating • Electrical resistance heating or joule heating or electro-heating
Important benefits 1. Fast Processing 2. Homogeneous Treatment 3. More effective method 48
Thanks Acknowledgement: All the material/presentations available online on the subject are duly acknowledged. Disclaimer: The author bear no responsibility with regard to the source and authenticity of the content. Questions???