Low temperature storage

• Terms associated with low temperature storage:
• Low temperature storage is a physical approach to food preservation
• Low temperature storage can preserve food
• Low temperature storage may also be done as an adjunct to other food preservation methods
• Two general methods of low temperature storage:
• Oxidation of fat, growth of microorganisms, enzymatic reactions, and loss of surface moisture can occur on long storage of frozen foods
• Moisture loss:

  • Fast cooling and freezing can prevent moisture loss or dehydration
  • Freezer burn can be prevented by using thick moisture-proof packaging
• Nutritional value of frozen foods:

  • Freezing can potentially preserve the greatest quantity of nutrients if done properly
  • Water-soluble vitamins are lost in the drip while thawing frozen meats
  • Blanching is necessary but can destroy Vitamin C and B-vitamins
• Freezing processes:
• Fluidized bed:

  • Food products placed on a mesh belt with cold air forced upwards to lift particles, resembling a boiling fluid
• Plate freezing:

  • Contact freezing used for products frozen in packaged boxes or blocks between metal plates cooled with ammonia
• Block freezing:

  • Product embedded in a block of ice to reduce vulnerability to temperature fluctuations during storage, handling, and transport
• Glazing:

  • Applying a coat of ice over frozen food to prevent moisture loss during storage
  • Gel glaze can be used as a skin to prevent moisture loss