Thermal Preservation

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Thermal Preservation
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Definition

• Adding or removing heat to alter shelf-life.
  Shelf-life -- time food can be stored and still
  maintain its quality
• Heat processing -- adding heat to a food to
  destroy enzymes and some spoilage and pathogenic
  bacteria.
• Cold processing -- removing heat from food to
  slow deterioration from enzymes and bacteria.

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Types of Thermal Preservation

• Heat processing
• Blanching
• Commercial sterilization
• Pasteurization
• Sterilization
• Dehydration
• Canning
• Cold processing
• Refrigeration
• Freezing

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Blanching

• Immersing food in boiling water or steam to
  destroy enzymes.
• Often used before freezing or drying foods.
• Product shelf-life is short.

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Commercial Sterilization

• Combines heat and vacuum seal to destroy spoilage
  and pathogenic microorganisms.
• Product shelf-life is long.
• Examples include water bath, retort, or
  hydrostatic cooker and cooler

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Pasteurization

• A low heat treatment that destroys pathogenic
  microorganisms and stops enzyme activity
• Products have a medium shelf-life.
• Examples include batch, high temperature, and
  short-time.

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Sterilization

• A high temperature heat treatment that destroys
  all microorganisms.
• Products have a long shelf-life.
• Examples include aseptic canning.

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Dehydration

• Low temperature heat treatment that involves the
  removal of water as a means to prevent microbial
  growth.
• Products have a long shelf-life.
• Examples include tray, belt, drum, spray, vacuum,
  freeze-drying, sun, and oven drying

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Concentration

• Removal of a portion of water from food to
  prevent microbial growth.
• Products have a medium shelf-life.
• Examples -- open kettle, heat evaporation, vacuum
  evaporation, and filtration

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Refrigeration

• Slows enzyme activity and microbial growth.
• Products have a short shelf-life.

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Freezing

• Slows enzyme activity and microbial growth
• Products have a long shelf-life