Post on 22-Jan-2016
Dr. Thomas J. Montville 1
Water (and calories)
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(Note change of topic order)
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Energy and Engineering Properties
• calorie = amt of Energy required to raise 1 gram H20 1°C
• Calorie (kcal) = amt of Energy required to raise 1 liter H20 1C °
~ 1 quart of water by 0.5 ° F
(1 C° = 5/9 F°)
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More on Calories
How many Calories does an ounce of water have?
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More on Calories
How many Calories does an ounce of water have?
None
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More on Calories
What about steam? It has energy?
Steam stores or transfers energy.
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Consider the ice water diet
• How much ice water would you have to drink to lose 1 pound?
• How many Calories would it take to raise 1 liter of water from 0 to 37 C?
• 37 Calories to raise 1 liter (~quart),
3500 C/pound 37 C per qt. = 94 quarts or
~ 24 gal
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Consider sweat
Energy of vaporization =
540 Calories to evaporate aliter of sweat
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“Hydrate, Urinate, Celebrate”
If a cyclist expends 540 calories/hour riding a bike, how much fluid should he be drinking?
If his urine is dark and only 100 ml/hr, what does that mean?
Why is sweat good? Danger of Hyponatremia
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“Energy” Drinks
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Questions?
Comments?
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WaterFriend or Foe?
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Water,an amazing molecule and our first
chemical (ingredient)
1. Uses in food
2. Chemistry
3. Physical properties
4. Water in foods
5. Water in nutrition
http://www.estrellamountain.edu/faculty/farabee/biobk/biobooktoc.html
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Uses of water in food
1. Solvent
2. Carrier – (Lakes, emulsion)
3. Force – (Cleaning)
4. Product
5. Adulterant
6. Preserve Freshness
7. Texture - (Juiciness)
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“Water added”
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More uses of water in food
8. Appearance 9. Heat sink – see next10. Chemical reactant and product11. Emulsion12. Structure13. Energy (microwave heating) • http://www.koreus.com/video/telephone-portable-mais-popcorn.html•
14. Agriculture
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Heat Sink due to Specific Heat Specific Heat = amount of energy required to raise 1 gram of water 1°C.
The specific heat of water = 1Specific heat of air = 0.25
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Water Chemistry“Hydrogen bonding” is nothing more than the attraction of positive and negative.
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Hydrogen bonding Physical Properties
Hydrogen bonds are relatively weak.
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Boling Point vs. Altitude
High altitude
High boiling point
(Vacuum) Freeze DrierLow altitudeLow melting pointLow boiling point
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Boling point vs. Altitude
Altitude (Ft) Pressure
(mm Hg)
Temp ( F)
0 760 212
2,500 695 207
5,000 645 202
7,500 582 198
10,000 533 194
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Three phases of water
GAS
Liquid
Solid
Venus
Mars
Pressure
Temperature
Look at different planets.Where’s earth?
Earth
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Three phases of water
GAS
Liquid
Solid
Venus
Mars
Pressure
Temperature
Where’s Uranus?
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Three phases of water
GAS
Liquid
Solid
Venus
Mars
Pressure
Temperature
Where’s Uranus?
Due to high atmospheric pressure and large gravitational force, water exists only as solid.
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Vapor
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Vapor
? to 32 F 32 F 32-212 212 - ?
Energy of fusion = 80 Calories/liter
Energ
y of v
apor
izatio
n
= 54
0 Calo
ries/l
iter
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Physical Properties of Water
• Three phases• Low freezing point• High boiling point• High heat capacity• Polarity• Low density• Expands when frozen• Ability to conduct heat” ice 4x faster than water, 4x
faster than air. (Ice melts faster than water freezes.)
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Water in Food, Three types
• Constitutive water– < 0.3% in high water food– Immobile, unfreezable
• Multilayer water– 0.5 – 3%– Some solvent capacity
• Bulk water– 96%, free & entrapped, reactive, freezeable,
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Water activity concept
Salad dressing and honey are both ~ 50% water, but the availability of the water is different.
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Water and Nutrition
• Essential to life– Chemical
– Carrier of water soluble vitamins
– Incompressible• Amniotic fluid
– Temperature regulation
• Need 1 g / cal expended
Substance % H20
• You 65• Beef & pork 60• Chicken 75• “hard” fruit 80-90• “soft” fruit 90-95
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