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  2. 2. NON THERMAL PRESERVATION TECHNIQUES Zarqa Azam (Roll# 27) Riaheen Shahbaz (Roll# 29) B.Sc. (Hons.) Food Science and Technology Semester 8th –Regular FST-609. Food Quality Management Institute of Food Science and Nutrition (IFSN) University of Sargodha, Sargodha 2016. 2
  3. 3. OUTLINE:  Introduction  Problems  Uses  Cost of equipments  Objectives  Types of non-thermal preservation techniques  High pressure processing  Irradiation  Ozonation  Ultrasound 3
  4. 4. CONTI..  Oscillating magnetic field  Pulsed electric field  Hurdle technologies  Pulsed light processing  Processing with E-Beam  Sanitizer washes  Natural antimicrobials  Conclusion 4
  5. 5. INTRODUCTION  Method use for processing and preservation.  Keeping the temperature of food to minimum as much as possible.  Method use without heat.  Destroy pathogens.  Keep foods safe to eat .  Retaining the sensory attributes.  Nutrient content similar to raw or fresh products. 5
  6. 6. PROBLEMS  Problem with the thermal processing :  Loss of volatile compounds  Nutrients  Flavour  To overcome these problems non thermal method  came into food industries:  To increase the production rate  Profit. 6
  7. 7. USES OF NON THERMAL PRESERVATION  Used for bulk quantities of foods.  Mainly used in the large scale production. Cost of equipments:  Used in the non thermal processing is high then used in thermal processing.  After minimizing the investment costs of non thermal processing methods it can also be employed in small scale industries 7
  8. 8. OBJECTIVES  Extend shelf life  Good quality  Safe food with better nutrition  Meet consumer requirements  Better financial return to industry 8
  9. 9. TYPES  High pressure processing  Irradiation  Ozonation  Ultrasound  Oscillating magnetic field  Pulsed electric field  Hurdle technologies  Pulsed light processing  Processing with E-Beam  Sanitizer washes  Natural antimicrobials 9
  10. 10. HIGH PRESSURE PROCESSING  “High Hydrostatic Pressure” or “Ultra High Pressure” processing.  Method of preserving and sterilizing food  Product processed under very high pressure  High Pressures applied at short periods of time (20minutes)  The high pressure used in HPP kills most micro- organisms :  By damaging cell components such as cell membranes 10
  11. 11. HOW MUCH PRESSURE?  For food processing 200-800MPa pressure is required. For inactivating milk enzymes;  Alkaline phosphates and protease about 1000 MPa is needed.  600MPa is the optimum pressure for processing commercial food products. 11
  12. 12. COMPONENTS  A pressure vessel and its closure  A pressure generation system  A temperature control device  A materials handling system 12
  13. 13. 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 13
  14. 14. ADVANTAGES  It kills vegetative bacteria and spores  Reduced processing time.  Freshness, flavor, nutrients, color, and taste retained  Shelf life is increased  Low energy consumption  Elimination of chemical preservatives 14
  15. 15. APPLICATIONS:  Used in pasteurization and sterilization of fruits and fruit products  Tenderization of meat  Sterilization of heat sensitive ingredients like shellfish, flavorings, and vitamins 15
  16. 16. OZONATION  Powerful sanitizer similar to chlorine or common bleach  Ozone can reduce contamination on food and increase storage life.  Toxic to humans at very high doses  Should not be used to treat high fat foods. Principle Ozone does not act as a systemic poison to microorganisms, but rather, destroys them by oxidation. Consequently, it is impossible for a microorganism to build up any resistance to oxidation 16
  17. 17. ADVANTAGES OF OZONE  Instantly destroys microbes  Eliminates chemical storage  Environmentally friendly  Does not affect product taste  No harmful by-products  Can be used in air and water  It leaves no residues in food or water. 17
  18. 18. IRRADIATION  Technology that improves the safety and extends the shelf life of food by reducing or eliminating microorganisms and insects.  Irradiation can make food safer for the consumer  Irradiation to a dose of between 1 kGy and 10 kGy is an effective method of reducing the microbial load of food. 18
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  20. 20. ADVANTAGES  Extend the shelf life  Irradiation may also inactivate enzymes..  Low dose irradiation (less than 1 kGy) is also used to inhibit sprouting (e.g. onion, garlic, potato)  Used for the purpose of insect disinfestations and inactivation 20
  21. 21. ULTRASOUND  Form of energy generated by sound waves of frequencies that are too high to be detected by human ear, i.e.16KHz  Ultrasound can be propagate in liquid,gasses,solids.  Effective for inactivation of microorganisms and enzymes.  Produce intracellular cavitations due to micro mechanical shocks 21
  22. 22. ULTRASOUND IN INDUSTRY  Major significant to industry and consumer  Better quality and healthy food  High efficiency  Saves energy and cost  Minimizing of flavor loss 22
  23. 23. OSCILLATING MAGNETIC FIELD  A magnetic field is defined as the region in which magnetic material is able to magnetize the surrounding particles.  Magnetic field may be static or oscillating  In order to inactivate microorganisms, flux density of 5 to 50 tesla (T) is required, corresponding to very high intensity magnetic fields. 23
  24. 24. CONT.. HOW HIGH INTENSITY MAGNETIC FIELDS ARE GENERATED?  Generated by an electric current passing through a coil  Capacitor is charged by high voltage DC power supply  By closing the switch  An oscillating current is produced inside the capacitor  And then an oscillating magnetic field is induced to the food placed inside the magnet coil  For high magnetic fields, superconductor coils are used  40KA current is required 24
  25. 25. CONTI.. 25
  26. 26. CONTI.. HOW THIS MECHANISM INACTIVATES M/O  Magnetic fields alter the growth and reproduction of microorganisms by both genetic and bio chemical phenomena  Effect may be due to magnetic field or induced electric field  Depending upon both features of magnetic field and properties of food and microbial:  The growth of microbial may be inhibited  Or unaltered by this technique 26
  27. 27. CONTI.. APPLICATIONS  Some packed liquid foods such as milk, yoghurt, orange juices etc  They may be subjected to oscillating magnetic field with a frequency between 5 and 550 kHz.  For a total exposure time between 25µs and 10ms.  Performed at atmospheric pressure and room temperature, resulting in a temperature increase not higher than 5˚C  Therefore a good retention of nutritional and sensory properties of foods is assured. 27
  28. 28. PULSED ELECTRIC FIELD (PEF)  Another non-thermal technology that can be use to inactivate bacterial cells at ambient temperatures  More suitable for liquids and semi liquid foods which can be easily pumped  Can be used to increase the shelf life of soups, milk, whole liquid eggs and fruit juices 28
  29. 29. CONTI.. HOW THIS PROCESS OCCURS?  Process involves placing the food material between two electrodes  And passing pulses of high electric field strength (1-50 kV/cm)  Since the pulses are applied for short durations (2µs to 1ms) the negative impact on food quality due to heat processing is highly diminished 29
  30. 30. CONTI.. APPLICATION OF PEF RESULTS IN:  Cellular death due to generation of pores (electroporation) in the bacterial cell membrane  Without having an effect on enzymes or proteins present in foods 30
  31. 31. CONTI.. EFFECTIVENESS  The effectiveness of this technique will strongly depend upon  Treatment time  Electric field strength  Specific energy of the pulses  Although this technique is useful, inactivation has only been achieved in the range of 3-4 logs. 31
  32. 32. CONTI.. ADVANTAGES AND LIMITATIONS  Advantages:  Pulse applied for shirt period so no generation of heat  Less usage of energy  Limitations:  Cannot be applied to the foods which cannot withstand high fields  And foods that form bubbles 32
  33. 33. HURDLE TECHNOLOGY OR SYNERGISM  Hurdle approach or process of using multiple technologies is an effective approach to microbial decontamination in comparison to that of a single technology alone  Deliberate and intelligent combination of preservative treatment can help in maintaining the quality of food and delivering almost similar level of microbial destruction  At the same time it warranties to counteract the negative effect of individual technologies on food quality 33
  34. 34. CONTI..  The choice of hurdles will strongly depends on  The type of food it is being applied to in addition to the mode of inactivation  For example:  Exposure of egg shells contaminated with S.Enteritidis with UV radiation (1500-2500 µW/cm²) followed by ozone (5 lb/in² gauge for 1min) resulted in an inactivation of 4.6 logs or more in a total treatment time of 2 min 34
  35. 35. PULSED LIGHT (PL) PROCESSING  Non thermal technology that uses short, intense pulses of white light which include ultraviolet, infrared, visible light  Treatment of foods by PL has been approved by FDA (21 CFRI79.41)  PL is like a camera flash but far more intense 35
  36. 36. CONTI.. HOW IT WORKS?  When this light is flashed on foods, it kills microorganisms but has minimal impact on foods  Short flashes of this intense light are used to prevent the temperature of the food from increasing  Within PL there is ultraviolet light that kills the pathogens by disrupting their DNA. 36
  37. 37. PROCESSING WITH E-BEAM  Non-thermal technology where the high energy electrons (close to the speed of light) are aimed at solid or liquid foods  Reducing the number of or eliminating pathogens, pests or insects  Unlike Gamma radiations this technology uses no radioactive isotopes 37
  38. 38. CONTI.. HOW IT WORKS?  E-beam may work against pathogens such as viruses and bacteria  by breaking the linkages in RNA or DNA  and by disrupting other parts that are essential to organisms  Some Drawbacks include:  Limited penetration depth through food  High initial cost 38
  39. 39. NATURAL ANTIMICROBIALS  Since ancient times spices and herbs have been used for preventing food spoilage and deterioration  Also for extending shelf life and food quality  The antimicrobial effect of these components is a result of an increase in permeability of the cytoplasmic membrane which leads to the loss of cellular constituents 39
  40. 40. CONTI.. EXTRACTS FROM VEGETABLES, HERBS  Plants secondary metabolites such as essential oils and natural plant extracts have also been reported to have antimicrobial, antifungal and anti-insecticidal properties  Extracts from capsicum, seaweeds and green tea have been found to inhibit the growth of Salmonella spp.  Tomatoes treated with 100ppm oregano (herb) results in 2.78 log reduction. 40
  41. 41. USING SANITIZER WASHES  Sanitizers like chlorine, are used by the food industry that helps to kill pathogens in food and on equipments/utensil surfaces  FDA regulates the sanitizers to be used by food industry  Microorganisms attach to the food, can lower the effectiveness of sanitizer and to address this problem  Use of surfactants (components of detergents) is being studied to enhance the effectiveness of sanitizer 41
  42. 42. CONTI.. HOW IT WORKS  Combining food grade surfactants with sanitizers  Improves the killing effectiveness  When applied to surface of food  By “Loosing” microorganisms attachment  Allowing the sanitizer to be more potent antimicrobial agent  The combination of sanitizer and surfactants has not yet been commercialized but shows greater potential. 42
  43. 43. HENCE:  Non Thermal or Alternative Food Processing Methods Enhance the  MICROBIAL SAFETY  FOOD QUALITY 43
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