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Thermal processing of fruits and vegetables.pptx

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Thermal processing of fruits and vegetables.pptx

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There are two main temperature categories employed in thermal processing: Pasteurization and Sterilization. The basic purpose for the thermal processing of foods is to reduce or destroy microbial activity, reduce or destroy enzyme activity and to produce physical or chemical changes to make the food meet a certain quality standard. e.g. gelatinization of starch & denaturation of proteins to produce edible food.

There are two main temperature categories employed in thermal processing: Pasteurization and Sterilization. The basic purpose for the thermal processing of foods is to reduce or destroy microbial activity, reduce or destroy enzyme activity and to produce physical or chemical changes to make the food meet a certain quality standard. e.g. gelatinization of starch & denaturation of proteins to produce edible food.

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Thermal processing of fruits and vegetables.pptx

  1. 1. Thermal processing of fruits and vegetables Ranit Sarkar 11/16/2022 Ranit Sarkar 1
  2. 2. Index • Introduction – Microbial contamination – Types of bacteria in food poisoning – Growth curve of microorganism – Thermal processing • Blanching • Pasteurization • Sterilization 11/16/2022 Ranit Sarkar 2
  3. 3. Introduction There are two main temperature categories employed in thermal processing: Pasteurization and Sterilization. The basic purpose for the thermal processing of foods is to reduce or destroy microbial activity, reduce or destroy enzyme activity and to produce physical or chemical changes to make the food meet a certain quality standard. e.g. gelatinization of starch & denaturation of proteins to produce edible food. 11/16/2022 Ranit Sarkar 3
  4. 4. Microbial contamination Microbial Contamination refers to the presence in the food of harmful microorganisms which can cause consumer illness major contamination sources are  Water  Air  Dust  Equipment  Sewage  Insects  Rodents  And employees 11/16/2022 Ranit Sarkar 4
  5. 5. Types of bacteria in food poisoning • Norovirus • Salmonella • Clostridium perfringens • Campylobacter • Staphylococcus aureus (Staph) • Clostridium botulinum (botulism)Listeria • Escherichia coli (E. coli)Vibrio 11/16/2022 Ranit Sarkar 5
  6. 6. Growth curve of microorganisms 11/16/2022 Ranit Sarkar 6
  7. 7. Thermal processing Thermal processing is defined as the combination of temperature and time required to eliminate a desired number of microorganisms from a food product . • the term “thermal “ refers to processes involving heat . • Heating food is an effective way of preserving . The basic purposes for the thermal processing food is,  to reduce or destroy microbial activity .  Reduce or destroy enzyme activity .  And to produce physical or chemical changes .  To make the food meet a certain quality standard 11/16/2022 Ranit Sarkar 7
  8. 8. BLANCHING Blanching is a unit operation prior to freezing, canning, or drying in which fruits or vegetables are heated for the purpose of inactivating natural/endogenous enzymes; modifying texture; preserving color, flavor, and nutritional value; and removing trapped air. 11/16/2022 Ranit Sarkar 8
  9. 9. • Blanching serves a variety of functions! --one of the main ones being to destroy enzymatic activity in vegetables and some fruits, prior to further processing by heat. • As such, it is not intended as a sole method of preservation but as a pre-treatment which is normally carried out between the preparation of the raw material and later operations (particularly heat sterilization, dehydration and freezing. • Blanching is also combined with peeling and/or cleaning of food, to achieve savings in energy consumption, space and equipment costs. FUNCTION OF BLANCHING 11/16/2022 Ranit Sarkar 9
  10. 10. REACTION WITHOUT BLANCHING 11/16/2022 Ranit Sarkar 10
  11. 11. OBJECTIVE 1. Inactivate enzymes A. Metabolic B. Maintain color C. Texture D. Flavor E. Nutritive value 11/16/2022 Ranit Sarkar 11
  12. 12. THE FACTORS WHICH INFLUENCE BLANCHING TIME  Type of fruit or vegetable  Size of the pieces of food  Blanching temperature  Method of heating. 11/16/2022 Ranit Sarkar 12
  13. 13. PASTEURIZATION:- Invented By French Scientist Louis Pasteur in 1864. Earlier the process was also used for beer and vinegar. Pasteurization of milk was suggested by Franz von Soxhlet in 1886. Pasteurization is the process of heating usually to less than 100 °C (212 °F), and then rapidly cooling. In this process liquids or food in order to reduce the eliminate of pathogenic micro-organism. 11/16/2022 Ranit Sarkar 13
  14. 14. Methods of pasteurization:- Low temperature holding pasteurisation (LTH) Low Temperature Long Time (LTLT), or Batch High-temperature, short time (HTST) or continuous flow Ultra heat treatment or ultrahigh temperature (UHT) 11/16/2022 Ranit Sarkar 14
  15. 15. Low temperature holding pasteurisation (LTH) or Batch:-  The (LTLT) process is the traditional method of pasteurizing milk.  In the vat the milk is heated to 62.8 C and held for 30 minutes followed by rapid cooling.  In this method low temperature applied for long duration .  Its self life very shorter duration. High-temperature, short time or continuous flow:-  HTST plate pasteurizer from 72*C (162*F) to 95*C (203*F) For 15 seconds.  This Pasteurizer is a plate pasteurizer for pasteurizing milk, juice, and egg products.  In this method high temperature applied for short duration . 11/16/2022 Ranit Sarkar 15
  16. 16. Ultraheat treatment or ultrahigh temperature (UHT):- This UHT method food by heating it above 130°C (275°F), the temperature required to kill spores in milk, for 1 to 3 seconds. UHT is most commonly used in milk production, but the process is also used for fruit juices, cream, soy milk, yogurt, wine, soups, honey. OTHER PROCESSES USED TO PASTEURIZED FOODS :- * Steam Pasteurization * Irradiation Pasteurization 11/16/2022 Ranit Sarkar 16
  17. 17. PASTEURIZED PRODUCTS:- 11/16/2022 Ranit Sarkar 17
  18. 18. Sterilization 1. Pasteurized products : • heat sensitive bacteria: deleted • heat resistant microorganisms: accepted 2. Sterilization products: destruction of all bacteria including their spores. 3. Food products -> sealed containers -> exposed to temperatures above 100°C in pressure cookers. 4. Temperatures above 100°C, usually ranging from 110-121°C 5. Products are kept for a defined period of time at temperature levels required for the sterilization. 11/16/2022 Ranit Sarkar 18
  19. 19. Factors affecting Growth of Micro-organism • Food • Acid • Time – Temperature • Oxygen • Moisture 11/16/2022 Ranit Sarkar 19
  20. 20. Nutrient Composition • Yeast – food with simple sugar • Molds – Capable of growth in difficult conditions • Bacterial Pathogens – Protein Based food Factors affecting Growth of Micro-organism • Food • Acid • Time – Temperature • Oxygen • Moisture 11/16/2022 Ranit Sarkar 20
  21. 21. Factors affecting Growth of Micro-organism • Food • Acid • Time – Temperature • Oxygen • Moisture 11/16/2022 Ranit Sarkar 21
  22. 22. Factors affecting Growth of Micro-organism • Food • Acid • Time – Temperature • Oxygen • Moisture 11/16/2022 Ranit Sarkar 22
  23. 23. Factors affecting Growth of Micro-organism Optimal temperature range for growth: • Thermophile – thrives high temperature 41-121°C • Mesophile – grows at moderate temperature 20-45°C • Psychrophile – grows at low temperature 0-20°C • Food • Acid • Time – Temperature • Oxygen • Moisture 11/16/2022 Ranit Sarkar 23
  24. 24. Factors affecting Growth of Micro-organism • Food • Acid • Time – Temperature • Oxygen • Moisture 11/16/2022 Ranit Sarkar 24
  25. 25. aw = 0.90 Factors affecting Growth of Micro-organism • Food • Acid • Time – Temperature • Oxygen • Moisture aw = 0.95 aw = 0.93 aw = 0.93 11/16/2022 Ranit Sarkar 25
  26. 26. Sterilisation Process Sterilization Phase 1 heating phase Phase 2 Holding phase Phase 3 Cooling phase 11/16/2022 Ranit Sarkar 26
  27. 27. Sterilisation equipment 1. Lid/Door: The lid should be sealed tightly to prevent contamination and proper sterilization. The top is sealed tightly with the help of an airtight screw. 2. Pressure Chamber: stain less steel , materials are placed inside the inner part of the vessel, 3. Whistle: release the pressure of the chamber before opening the lid after sterilizing the materials. 4. Safety valve: to avoid an accident when the pressure inside the vessel is exceptionally high. 5. Electrical heater: heating element attached to the jacket; that heats the water to produce steam. 6. Water releasing valve: replacing and cleaning the water 11/16/2022 Ranit Sarkar 27
  28. 28. source 11/16/2022 Ranit Sarkar 28
  29. 29. Autoclave types 11/16/2022 Ranit Sarkar 29
  30. 30. Design of heat Sterilization Processes • Take account of the type of microorganism (determined largely by food conductions e.g. acidity) and its heat resistance. • Result in an acceptably low probability of survival of spores • Be effective in every part of the food 11/16/2022 Ranit Sarkar 30
  31. 31. Canned Food • Shelf stable (can itself should be in good condition : no rust, dents, or swelling) • They should be ‘commercially sterile’ (microbes incapable of growing in favorable condition) Types of containers to be used Metal containers Glass jars Retortable pouches 11/16/2022 Ranit Sarkar 31
  32. 32. About Services Portfolio Team Contact Ranit Sarkar Need presentation assistance? https://www.linkedin.com/in/ranit-sarkar- 83b295209/ mailto:ranitsarkar71@gmail.com https://t.me/Ranit_0_1 https://www.youtube.com/channel/UCirfpHbkvkM 9l4K4MVYh-Pw 11/16/2022 Ranit Sarkar 32
  33. 33. Thank you 11/16/2022 Ranit Sarkar 33

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