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Food spilage and wastage(science)

Food spilage and wastage(science)



K J Somiaya college of education. PPT presentation of CAP

K J Somiaya college of education. PPT presentation of CAP



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    Food spilage and wastage(science) Food spilage and wastage(science) Presentation Transcript

    • Sharmin Nayek Roll No - 42 B.ED 2010-2011 Food Spoilage & Wastage
    • Content
      • Definition of Food Spoilage
      • Types of undesirable changes
      • Factors causing Food Spoilage
      • Factors affecting growth of Micro-organism
      • Definition of Food Preservation
      • Principles of Food Preservation
      • Methods of Food Preservation
    • Food Spoilage
      • Loss in nutritive value
      • Creates dangerous toxins
      • Loss in fresh appearance
    • Definition Food Spoilage can be defined as undesirable changes occurring in food, making it unfit & unacceptable for human consumption.
    • Types of undesirable changes
      • Change in colour
      • Change in smell
      • Change in consistency
      • Change in Texture
      • Change due to mechanical damage
    • Factors causing Food spoilage
      • Intrinsic Factors
      • Extrinsic Factors
    • Intrinsic Factors
      • Enzymatic reactions :- Enzymes present in food starts degrading the food resulting into spoilage of Food.
      • example - blackening of bananas & apples.
      • Chemical reactions : - Certain chemical reactions takes place within the food which leads to food spoilage.
      • example – cut meat kept for long time.
    • Extrinsic Factors
      • Mechanical damages :- Physical damages due to improper handling.
      • example : If food is handled improperly while plucking, transporting, drying, preserving, etc.it may cause bruising of Food tissues.
    • 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.
    • 3. Micro-organism :- Growth & Multiplication of micro-organisms leads to food spoilage. Example : Yeast, bacteria etc contaminate the food which cause food poisoning.
    • 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.
    • Factors affecting growth of Micro-organism
      • Nutrients in food – presence of easily utilizable nutrients encourage faster growth of micro-organism.
      • Water content – Micro-organism require a lot of water for their growth.
    • 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 .
    • Food Preservation A process by which certain foods like fruits & vegetables are prevented from getting spoilt for a long period of time.
    • Principles of Food Preservation
      • Preventing the spoilage by micro-organism
      • Keeping out micro-organism Example : Covering the food, packaging or removing the spoiled food.
      • Removing micro-organism Example : If you want to preserve green leafy vegetable you have to remove the water from the leaves.
      • Inhibiting the growth of micro-organism Example : Drying, lowering or increasing temperature, salting or adding too much of sugar or other preservatives.
      d) Killing of micro-organism Example : Boiling, cooking, pasteurization.
    • 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.
    • Methods of Food Preservation
      • Keeping out of micro-organism : Cleanliness, use of clean water, utensils, covering & packaging.
      • Use of High temperature : Heating, boiling, cooking.
      • 3. Use of low temperature :
      • Refrigeration 4°C to 7°C
      • Cold storage -1°C to -4°C
      • Freezing -18°C or below
      • 4. Drying : Dry food grains remain unspoiled for long period under proper storage.
      • 5. Preservatives :
      • There are 2 types of Preservatives :
      • Natural Preservatives - Salt, sugar, vinegar, acid salts etc.
      • Chemical Preservatives - Sodium chloride, sodium benzoate, citric acid.
      • 6. Preservation by irradiation - Ionizing radiation such as gamma rays & cathode rays can kill the micro- organism in food.
    • Evaluation 1. Define Food spoilage Ans : Food spoilage can be defined as undesirable changes occurring in food, making it unfit & unacceptable for human consumption.
    • 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.
    • 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