Food spilage and wastage(science)

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Food spilage and wastage(science)

  1. 1. Sharmin Nayek Roll No - 42 B.ED 2010-2011 Food Spoilage & Wastage
  2. 4. Content <ul><li>Definition of Food Spoilage </li></ul><ul><li>Types of undesirable changes </li></ul><ul><li>Factors causing Food Spoilage </li></ul><ul><li>Factors affecting growth of Micro-organism </li></ul><ul><li>Definition of Food Preservation </li></ul><ul><li>Principles of Food Preservation </li></ul><ul><li>Methods of Food Preservation </li></ul>
  3. 5. Food Spoilage <ul><li>Loss in nutritive value </li></ul><ul><li>Creates dangerous toxins </li></ul><ul><li>Loss in fresh appearance </li></ul>
  4. 6. Definition Food Spoilage can be defined as undesirable changes occurring in food, making it unfit & unacceptable for human consumption.
  5. 7. Types of undesirable changes <ul><li>Change in colour </li></ul><ul><li>Change in smell </li></ul><ul><li>Change in consistency </li></ul><ul><li>Change in Texture </li></ul><ul><li>Change due to mechanical damage </li></ul>
  6. 8. Factors causing Food spoilage <ul><li>Intrinsic Factors </li></ul><ul><li>Extrinsic Factors </li></ul>
  7. 9. Intrinsic Factors <ul><li>Enzymatic reactions :- Enzymes present in food starts degrading the food resulting into spoilage of Food. </li></ul><ul><li>example - blackening of bananas & apples. </li></ul><ul><li>Chemical reactions : - Certain chemical reactions takes place within the food which leads to food spoilage. </li></ul><ul><li>example – cut meat kept for long time. </li></ul>
  8. 10. Extrinsic Factors <ul><li>Mechanical damages :- Physical damages due to improper handling. </li></ul><ul><li>example : If food is handled improperly while plucking, transporting, drying, preserving, etc.it may cause bruising of Food tissues. </li></ul>
  9. 11. 2. Chemical reactions due to contact with metal :- Foods of acidic or alkaline nature may react with metal container leading to undesirable change. Example : Butter milk kept in brass vessel.
  10. 12. 3. Micro-organism :- Growth & Multiplication of micro-organisms leads to food spoilage. Example : Yeast, bacteria etc contaminate the food which cause food poisoning.
  11. 13. 4. Insects, rodents, birds :- Foods are mechanically damaged by insects, rodents, birds, etc. Example : The holes on surface of tomatoes, cucumber, brinjal indicate that they are harboring larvae of insects.
  12. 14. Factors affecting growth of Micro-organism <ul><li>Nutrients in food – presence of easily utilizable nutrients encourage faster growth of micro-organism. </li></ul><ul><li>Water content – Micro-organism require a lot of water for their growth. </li></ul>
  13. 15. 3. Physical, environmental Factors – Temperature, PH value of food influence microbial activity. 4. Availability of Oxygen – Most of the micro-organism require oxygen for their growth such micro-organism are called ‘Aerobic’ micro-organisms and those which do not require oxygen for their growth are called ‘Anaerobic ’ micro-organisms .
  14. 16. Food Preservation A process by which certain foods like fruits & vegetables are prevented from getting spoilt for a long period of time.
  15. 17. Principles of Food Preservation <ul><li>Preventing the spoilage by micro-organism </li></ul><ul><li>Keeping out micro-organism Example : Covering the food, packaging or removing the spoiled food. </li></ul><ul><li>Removing micro-organism Example : If you want to preserve green leafy vegetable you have to remove the water from the leaves. </li></ul>
  16. 18. <ul><li>Inhibiting the growth of micro-organism Example : Drying, lowering or increasing temperature, salting or adding too much of sugar or other preservatives. </li></ul>d) Killing of micro-organism Example : Boiling, cooking, pasteurization.
  17. 19. 2. Preventing self decomposition of Food a) Destroying enzymes in Food : Enzymes found in food can be inactivated by changing their conditions such as temperature & moisture. b) Preventing auto-oxidation : by adding antioxidants. 3. Removal of insects, rodents, birds, etc : By proper storage, use of permissible insects repellants.
  18. 20. Methods of Food Preservation <ul><li>Keeping out of micro-organism : Cleanliness, use of clean water, utensils, covering & packaging. </li></ul><ul><li>Use of High temperature : Heating, boiling, cooking. </li></ul>
  19. 21. <ul><li>3. Use of low temperature : </li></ul><ul><li>Refrigeration 4°C to 7°C </li></ul><ul><li>Cold storage -1°C to -4°C </li></ul><ul><li>Freezing -18°C or below </li></ul><ul><li>4. Drying : Dry food grains remain unspoiled for long period under proper storage. </li></ul>
  20. 22. <ul><li>5. Preservatives : </li></ul><ul><li>There are 2 types of Preservatives : </li></ul><ul><li>Natural Preservatives - Salt, sugar, vinegar, acid salts etc. </li></ul><ul><li>Chemical Preservatives - Sodium chloride, sodium benzoate, citric acid. </li></ul><ul><li>6. Preservation by irradiation - Ionizing radiation such as gamma rays & cathode rays can kill the micro- organism in food. </li></ul>
  21. 23. Evaluation 1. Define Food spoilage Ans : Food spoilage can be defined as undesirable changes occurring in food, making it unfit & unacceptable for human consumption.
  22. 24. 2. What are the extrinsic factors causing Food spoilage Ans : Extrinsic Factors : a) Mechanical damage b) Chemical reactions due to contact with metal c) Micro-organisms d) Insects, rodents, birds, etc.
  23. 25. 3. What are the methods of Food Preservation Ans : a) Keeping out of micro-organisms b) Use of high temperature c) Use of low temperature d) Drying e) Preservatives f) Irradiation
  24. 26. THANK YOU

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