General Methods of Food Preservation by G2ED1p


									 Prevents and delay microbial
  decomposition and damage from
  mechanical causes, insects and
 Ensures more interesting and
  nutritionally adequate family meals
 Ensure a safer food intake
Provides means of
Availability of off-
 season products
Prevents food wastage
A.    Cold Temperatures (Freezing)
      reduces the rate of growth
       of microorganisms
      Converts large percentage
       of water content of food to
       ice, making it unavailable
       for microorganisms
      Prevents breakdown of cells
       caused by enzymes
B. Hot Temperatures
  (Heating/Cooking, Pasteurization)
  Destroy microorganisms and
  Yeast, mold, enzyme – easily
   destroyed at boiling temperature
  Bacteria – sometimes heat resistant
 Pasteurization – food is
 heated in a closed system,
 cooked fast and placed in a
 sealed container
  Ex: milk
   Commonly used in meat
    and fish and less in fruits
    and vegetables
   In some foods, salting is
    combined with other
    methods like smoking,
    fermenting, drying,
   Examples: ham, bacon,
    salted eggs, sausage,
 Sodium Chloride (NaCl) preserves food
  by removing water content through
 Osmosis – movement of solvent
  through a semi-permeable membrane
  into a solution of higher solute
  concentration that tends to equalize
  the concentration of the two solutes
 When food is salted, its water
 content is drawn out, freeing the
 food or reducing the moisture
 content which makes the food
 less susceptible to
 Others functions of salt:
  Inhibit growth of microorganisms because
   microbial cells lose their water and
   become plasmolyzed
  Salt ionizes and yields chlorine which is
   harmful to microorganisms
  Reduces solubility of oxygen and deprives
   aerobic organisms oxygen they need
  Denatures protein
 Higher the salt concentration =
   rapid drawing out of water
 One of the oldest methods
  of food preservation
 Reduction of moisture
  content thus preventing
  microbial growth
 Exposure to air/artificial
 Dried foods are
  lightweight and easier to
 Usually combined
  with salting and
 Used to preserve
  fish and meat
 Gives the food
  good appearance,
  flavor and odor
 Draws out water through osmosis
 Commons sugar preserves:
   Jelly – cooking fruit juice with sugar, transparent
    and bright colored
   Jam – cooking crushed fruit and sugar
   Marmalade – contains citrus peels
   Conserve – uses two or more kinds of fruits
   Candied – fruit is concentrated with syrup
   Glazed – candied first and dipped in fresh glucose
    for shiny appearance
 Not all microorganisms are
  harmful to food
 Some organisms are able to
  produce acid which can stop
  the growth of harmful
 Fermentation – oxidation of
  carbohydrates, resulting in
  the production of acid and
   Sugar in the food is converted to ethyl
    alcohol through reaction of yeast
   Initial materials: fruit juices/rice solution

                     Oxidation of
    Sugar           Saccharomyces          Alcohol
   Acetic bacteria through the presence of
    oxygen produce acetic acid
   Initial materials: sugar can juice, nipa sap.
    Coconut water, pineapple and orange juices

                   Oxidation of
 Ethyl                                  Acetic
                   Acetobactin           Acid
Alcohol               Aceti
 Brought about by certain
  bacteria which ferment sugar in
  fruits and vegetables producing
  lactic acid
 Lactic acid: 0.8-1.5 % acid
 Pure coarse salt
 Soft water
  (hard water contain minerals
  which interfere with normal
   Generally applies to food that is preserved in
    brine or vinegar
   Essential Ingredients:
     Fruits and vegetables (firm, flesh, free of
       Vinegar (renders a characteristic flavor, preserves
        by inhibiting growth of microorganisms)
       Sugar (acts as a preservative, adds sweetness)
       Spices (gives flavor)
       Other preservatives (alum/tawas- crispness)
 Packing food in tightly
  sealed tin cans or
  canning jars and heated
  at high temperature
 Heating destroys
  harmful microorganisms
 Sealing prevents the
  growth of aerobic
 Foods are
  subjected to
  gamma rays
 Still being
  researched to
  ensure safety of
  treated product

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