Water (and calories)
Dr. Thomas J. Montville
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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 (1 C° = 5/9 F°)
• Calorie (kcal) = amt of Energy required to
raise 1 liter H20 1C °
~ 1 quart of water by 0.5 ° F
Dr. Thomas J. Montville
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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 a
liter 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?
Danger of Hyponatremia
Why is sweat good?
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“Energy” Drinks
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Questions?
Comments?
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Water
Friend or Foe?
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Water,
an amazing molecule and our first chemical (ingredient)
1.
2.
3.
4.
5.
Uses in food
Chemistry
Physical properties
Water in foods
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.
9.
10.
11.
12.
13.
Appearance
Heat sink – see next
Chemical reactant and product
Emulsion
Structure
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 = 1
Specific 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 Drier
Low altitude
Low melting point
Low boiling point
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Boling point vs. Altitude
Altitude (Ft)
Temp ( F)
0
Pressure
(mm Hg)
760
2,500
695
207
5,000
645
202
7,500
582
198
10,000
533
194
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212
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Three phases of water
Venus
GAS
Look at
different planets.
Where’s earth?
Temperature
Liquid
Mars
Solid
Pressure
Dr. Thomas J. Montville
Earth
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Three phases of water
Venus
GAS
Where’s Uranus?
Temperature
Liquid
Mars
Solid
Pressure
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Three phases of water
Venus
GAS
Where’s Uranus?
Temperature
Liquid
Mars
Solid
Pressure
Dr. Thomas J. Montville
Due to high
atmospheric
pressure and
large
gravitational
force, water
exists only as
32
solid.
Vapor
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Energy of fusion
= 80 Calories/liter
? to 32 F
32 F
32-212
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Vapor
212 - ?
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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. (IceDr.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
Substance
• You
• Beef & pork
• Chicken
• “hard” fruit
• “soft” fruit
% H20
65
60
75
80-90
90-95
• Need 1 g / cal
expended
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