Practical Water Management in Food Systems

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Practical Water Management in Food Systems

• Justin Shimek
• Discussion Hour 5
• FST 100A

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(No Transcript)
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Important Tasks of the Food Scientist

• Some key activities
• Prevent spoilage (keep consumers stock holders
  happy)
• Minimize quality loss (sensory, nutritional)
• Ensure food safety (a must!)
• Lengthen shelf-life (distribution chain
  simplified)
• How?
• Use water management as a unifying concept. The
  relationship between water content/availability
  and food stability and palatability has long been
  recognized.

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Describing Water in Foods

• To manage water we must first be able to describe
  and quantify water that is in a food
• Several approaches
• 1) Water content (traditional)
• simple in concept and measurement
• 2) Water activity, aw (1950s ?)
• accounts for effects of solutes and differences
  between foods
• 3) Molecular mobility (Slade Levine, 1988)
• treats food as polymer matrix, water as key
  plasticizer
• glass transition explains some irregularities in
  aw data
• Each approach is individually imperfect, together
  they are complimentary

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Overall Food Stability Map

• Rate of microbial and chemical reactions in food
  intimately tied to the water activity (aw )

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Preservation Strategies

• Q What have people done to preserve food from
  spoilage?
• What are some of historical, current, and
  futuristic approaches to food preservation?
• Use water management as a theme. What can be
  done to minimize the availability of water for
  microbial and chemical reactions

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Unexpected Benefits of Spoilage Preservation
Strategies

• Ancient practices also resulted in characteristic
  flavors, textures, attributes that continue to be
  desirable
• New processes intended to control water make new
  products possible
• Freeze drying (backpacker meals)
• Spray drying (milk powder)

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Case Study 1 Raisin Bran

• Multi-component food in same package
• want flakes crispy, raisins moist throughout
  shelf life
• Fundamental problem water migration
• Water activity values determine direction of
  water migration
• high aw low aw
• Possible solutions???

Raisin Bran
Raisins high aw
Flakes low aw
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Case Study 2 Packaged Cookies

• Homemade cookies contain sucrose (sugar) and are
  consumed in short time
• Cookies with a strictly homemade formula will
  harden over time due to sucrose crystallization

• However, sucrose may be key to giving the right
  texture, flavor, and label appearance
• If you are the food scientist in charge of making
  cookies so soft theyll taste like they are
  right from the oven, what might you do?

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Ingredient Choices