ANNOUNCEMENTS

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ANNOUNCEMENTS

• Field trip to Kroger Bakery on Monday
• closed shoes, wear pants (no shorts, skirts),
  no jewelry
• meet here at 200
• need drivers

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FOOD PROCESSING PRESERVATION STRATEGIES

• FST 401
• Introduction to Food Processing

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Preservation of Food

• Raw, unprocessed foods
• Processed foods
• Ready to eat (RTE) consumer products
• Not ready to eat food products (require further
  preparation by consumer)

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Goals for Food Preservation
Safety Remove potential hazards

• Microbiological pathogenic microorganisms
• kill and/or prevent growth
• Chemical toxins
• Physical glass, metal, wood, etc.

Question you will have to answer What makes
this product safe?
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Goals for Food Preservation
Sensory Preserve desirable appearance, texture,
flavor and odor. Increase shelf-life by
destroying spoilage microorganisms and enzymes,
stabilizing emulsions, reducing browning etc.
Nutrition Minimize nutrient losses
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The Barrier or Hurdle Concept

• A barrier or hurdle is a processing step or
  ingredient that protects the product from causing
  food borne disease

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Preservation Approaches

• Add heat
• Remove heat
• Remove water
• Reduce pH
• Add preservatives
• Fermentation
• Packaging

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Heat processing objectives

• Increase palatability
• Baking, broiling, roasting (dry heat)
• Frying in oil (320-375F)
• Boiling, stewing

• Increase storage life reduce food borne disease
  risk
• Blanching
• Pasteurization
• Sterilization commercial sterilization

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Heat-induced changes

• Desirable
• Destruction of microorganisms
• Destruction of enzymes
• Alteration of color, flavor, texture
• Improved digestibility

• Undesirable
• Degradation of nutrients
• Degradation of sensory attributes (color, flavor,
  texture)

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Heat-processed foods
Pasteurized Commercially sterile Blanched Hot-fill
ed
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Pasteurization

• Destroys vegetative pathogenic microorganisms
• - Fruit juices, milk, liquid eggs
• Extend product shelf life by reducing microbial
  and enzymatic spoilage
• Fruit juices, milk, liquid eggs
• Beer
• Pickles

Ultra-pasteurization is a more intense heat
treatment to provide a longer shelf-life by
killing more spoilage microorganisms.
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Pasteurization and.
Pasteurization must be combined with another
barrier

• Refrigeration
• Fermentation
• Additives (Anti-microbial agents)
• Low pH

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Commercial sterilization
Destroys both vegetative cells and spores of
pathogenic spoilage microorganisms that would
be capable of growing in the product under normal
storage conditions

• Types of Products
• Retorted
• Aseptically packaged

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Commercially Sterile Foods

• Primary objective
• Destroy the most heat resistance pathogenic
  spore-forming organisms --- ex.- Clostridium
  botulinum in products pH 4.6
• Secondary objective
• Destroy vegetative and spore-forming
  microorganisms that cause spoilage. Spoilage
  spore-formers are usually more heat resistant
  than pathogenic spore formers.

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Microbial Destruction by Heat

• Spores are much more heat resistant than
  vegetative cells
• Lethality Terms
• D-Value
• Z-Value
• FO Value

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D-Value

• D-Value Time (minutes) at a given temperature
  to cause a one log reduction in live cell numbers
  (destroy 90 of population)
• D-Values at 250F
• Bacillus steareothermophilus (flat sour)
• D 250F 4.0 to 5.0 minutes
• Clostridium botulinum
• D 250F 0.21 minutes

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D Value
100 spores 1 D 10 spores Another D 1
spore Another D 0.1 spore or 1 spore in
10 cans
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F0

• Time in minutes at 250 oF to produce a
  commercially sterile product.

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12-D Process
12 D process time/temperature process that will
reduce the Clostridium botulinum spore population
by 12 log cycles. - Required for low acid ( pH
4.6) canned foods. C. botulinum spores 100
spores/can 12 D process C. botulinum spores
10-10 spores/can (1 in 1010 chance)
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Microbial Destruction by Heat

• Factors affecting heat inactivation of
  microorganisms
• pH What is the pH we must know?
• Time and temperature
• Convection vs. conduction
• Package type and size
• Microorganisms present
• Type of product

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High vs. Low Acid Foods

• Foods can be classified on the basis of pH
• pH 4.6 are low acid foods

• Processing times and temperatures are lower for
  acid foods because.
• microorganisms are more easily destroyed in
• an acid environment
• C. botulinum spores cannot germinate below
• pH 4.6.

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Retorted Foods

• Product processed in the package can, flexible
  pouch or glass
• Retorts (Pressure processors)
• Still
• Rotary
• Hydrostatic cooker (pressure provided by a 40
  50 feet of head pressure)
• Processing time depends on heating the most
  slowly heating part of the product.

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Aseptically-packaged foods

• Product processed outside of package, then
  packaged under aseptic (sterile) conditions into
  a sterile package
• UHT (ultra high temperature) sterilizers -
• heat exchanger
• Product is heated and cooled very quickly

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Retort vs. Aseptic packaging

• Both produce a shelf-stable product that retains
  shelf-life for months to years
• Cost and expertise
• Product quality