(L3) PRINCIPLES AND METHODS OF FOOD PRESERVATION

• food preservation


  methods to keep food from spoilage after harvest or slaughter
• Ways/Methods of Food Presevation:

  Asepsis, Drying, Smoking, Food Concentration
• Use of High Sugar or Salt Content:

  Sugaring, Pickling, Salting or Curing, Freezing, Fermenting
• asepsis


  is a process of keeping microorganisms out of food.
• Asepsis Steps:

  Washing, Trimming Ingredients, Discarding Dirt, Filtering, Centrifugation
• centrifugation


  It is used to separate immiscible liquids, e.g., vegetable oil and water of solids from liquid
• drying


  • is one of the oldest and simplest methods of preserving food
  • refers to the removal of water from the food.
• Types of Drying:

  sun drying, mechanical/artificial drying, freeze drying
• sun drying


  a slow process involving the risk of contamination

  and spoilage
• mechanical or artificial drying


  the use of controlled conditions of heating, with the forced circulation of air in contrast to sun drying
• freeze drying


  the product is first frozen and then water is removed under vacuum as vapor by sublimation
• smoking


  • has been used as a method of food preservation from time immemorial
  • foods are exposed to smoke by burning some special kinds of wood
• adding desired flavoring and preserving


  two main purposes of burning some special kinds of wood in smoking:
• Food Concentration


  Relatively few liquid foods, involving preservative action of reduction in water activity (aw) and development of osmotic pressure.
• reduction in volume, weight, and packaging, storage and transport costs, better microbial stability, and convenience.


  Concentration of food is usually done for many reasons:
• Sugaring


  A strong sugar solution draws water from microbial cells and thus, inhibits the growth of microbes
• 68% or more


  How much is a strong sugar solution?
• Pickles


  are the relishing accompaniments to most meals
• Pickling


  uses the salt combined with acid, such as acetic acid (vinegar)
• Salting or Curing


  preserves the food by drawing moisture from the meat through osmosis
• organic acids


  are used in food preservation because acid conditions inhibit the growth of many spoilage microorganisms
• Freezing


  placing food under a very low temperature to prevent the growth of microorganisms and maintain the freshness and nutrients of the food
• Fermenting


  This is achieved by soaking or suturing the food in an adequate amount of salt to prevent spoiling and would even have a better taste.