Transcript 106 Food-Cooking-Nutrition

Food, Cooking & Nutrition
Food for thought: “Are we what we eat?”
Dr. Ron Rusay
Spring 2004
© Copyright 2004 R.J. Rusay
Part I: Food for Thought
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Professor Jacqueline Barton
California Institute of Technology
Energy & Life
• Energy is the food of life
• The First Law of Thermodynamics: energy is
conserved
• Energy: what are all of its forms?
• Sun worship, chemistry and life.
Food = Energy
• Energy is the food of life
• The First Law of Thermodynamics: energy is
conserved
• Energy: what are all of its forms?
• Sun worship, chemistry and life. (Beads-UV exp.)
• Photosynthesis (endothermic) storage of energy
and the role of carbon as an energy sponge.
(Carbohydrates)
• Food Web  begins with plants
Carbon as an energy sponge
•Food Web  plants  herbivores 
omnivores
•Releasing the sun’s energy: squeezing the
carbon sponge  Calories!
•Digestion/Oxidation (exothermic): releases
energy
•Catalysts/enzymes
•Body vs. Automobile
•Recycling?….. CO2
•The curse of abundance: Obesity/ Global
Warming
ENERGY
Calories: Fats, Proteins, Carbohydrates
•A Calorie is a Calorie so why the fuss over
where they come from?
•What are fats, proteins and carbohydrates?
•What is their energy content?
•Why are they different from 9 to 5?
•Fats: animal/plant (avocado)
•Protein: animal/plant (soybeans)
•Carbohydrates: plants/ sugars
Fats, Proteins, Carbohydrates
•How do they relate to food, energy, cooking
and enjoyment?
•Boiled vs fried?
•Non-fat pastries & diets
•Sweet n’ Lo
(cyclamates/nutrasweet/saccharin)
•The pleasure of eating and dopamine.
•Do you like groceries and fast food like most
of us do? If so, how do you think the
satisfaction of eating relates to a kiss, to
substance abuse, to addiction?
Fueling the Brain
• The brain has very high metabolism but has no
fuel reserves.
• This means brain needs a constant supply of a
high energy molecule, the carbohydrate, glucose.
• Under severe fasting conditions, the brain can use
a biomolecule, -hydroxybutyrate, from fatty
acids for energy.
• This allows brain to use fat as fuel!…but, at a cost
that cannibalizes the body.
• Is starvation a wise approach for consuming
unwanted Calories?
Metabolism
• Metabolism: the sum of all bio-molecular chemical
reactions in living organisms
• Two Basic Types:
– Catabolism: the breakdown of larger molecules
into smaller ones; a process that releases energy
which can do work (physical or mental).
– Anabolism: building larger molecules from
smaller ones; a process that requires energy
(muscle building)
Endothermic reactions (photosynthesis) &Exothermic reactions
(combustion)
The processes of catabolism and anabolism are
opposite in nature. The first usually produces energy,
and the second usually consumes energy.
Catabolism & Anabolism
Catabolism
Fats
beakdown
of larger
molecules Fatty acids
to smaller and glycerol
ones
Anabolis m
Polysaccharides
Monosaccharides
Small
molecules
oxidation and the
release of energy
Excretion
Proteins
Amino
Acids
Anabolis m
of proteins
Anabolis m
Catabolism
Excretion
Products of anabolis m,
including proteins and
nucleic acids
energy and
reducing
agents
Some nutrients and
products of catabolism
Mass composition data for the human body in terms
of major types of biochemical substances.
The Food Pyramid
The Food Guide
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Carbohydrates (-oses):
Sugars, Saccharides
Photosynthesis
Energy Capture  Carbohydrates
n CO2(g) + n H2O(g) + energy  CARBOHYDRATES
Plants absorb energy; i.e., light that is visible to us.
•Do you normally see
infrared or ultaviolet
radiation?
•You may have seen
infrared images taken
with a camera.
•Can anyone see
ultraviolet images?
http://chemistry.beloit.edu/Stars/EMSpectrum/index.html
Glucose
Carbohydrates
• Formed from the action of light and
chlorophyll in green plants:

n CO2 + n H2O -----> Cn (H2O)n + n O2
Empirical formula = CH2O
 Monosaccharides (simple sugars)
 C5 : pentoses - ribose, arabinose
 C6 : hexoses - fructose, glucose


Can be either an aldose (aldehyde + alcohols)
or ketose (ketone + alcohols)
Aldose
Aldose or Ketose?
Ketose
C
Aldose or Ketose?
Aldose
Ketose
Cyclization:
Carbohydrates
• Disaccharides
– (2 cyclic monosaccharides joined by a
“glycoside” linkage [ether])
- e.g. (glucose + fructose)
sucrose
• Polysaccharides
– (many linked monosaccharide units)
- e.g. starch, cellulose
(termites, enzymes & wood……cellulose?)
D-glucose can cyclize through the intramolecular
reaction between the carbonyl group and the
hydroxyl group on carbon 5.
The three forms of maltose present in aqueous
solution.
The glucose content of urine can be determined by
dipping a plastic strip treated with oxidizing agents
into the urine sample and comparing the color
change of the strip to a color chart that indicates
glucose concentration. Blood is much more difficult.
Blood Type
Also Rh factor, + or -
•Would an animal in the isoptera family feed
on the following molecule?
•Would homo sapiens feed on it?
The structures of cellulose (a) and chitin (b). In both
substances, all glycosidic linkages are of the -(1, 4)
type.
What would an insect’s food pyramid look like?
http://www.nps.gov/kefj/Kids/Goatpuzzle/Goat3.htm
There are approximately 1,900 species of termites.
Adults briefly have two equal
sized wings (iso="equal", ptera="wings"). The adults
retain their wings for a brief mating flight and then
before mating, the wings are detached and shed.
Termites not only feed, groom and protect each other
within colonies, but the offspring of one generation
assist the parents in raising the next generation.
Termites are social insects. Termite colonies are
highly organized societies of several hundred
thousand to 1 million or more individuals within a
loose collection of underground tunnels and
chambers.
Some polysaccharides like cellulose are linear chain
structures (a); others have a branched chain structure (b).
Polysaccharide: amylopectin. (a) Molecular
structure of amylopectin. (b) An overview of the
branching that occurs in the amylopectin structure.
Each circle is a glucose unit.
Chemical Portraits:
Biologically Imported Disaccharides
Chemistry at a
Glance:
Biochemically
Important
Carbohydrates
Different Sugars
Sugars/Glucose & Insulin
Protein binding & Taste Receptors
•Sweet
•Sour
•Bitter
•Salty
•Umami
Sweetness factor = 1.0
Sweetness factor = 0.74
Should the following molecule be included
or excluded from the Atkins diet?
Glucose
FATS =
Esters of fatty
acids from
glycerol, a triol (3 -OH s)
Lipids:
Fats & Steroids
Selected Fatty Acids of Biological Importance.
Space-filling models of four 18-carbon fatty acids,
which differ in the number of double bonds present.
Note how the presence of double bonds changes the
shape of the molecule.
Chemical Portraits:
Essential Fatty Acids
The melting point of a fatty acid depends on the
length of the carbon chain and on the number of
double bonds present in the carbon chain.
Triple esterification reaction between glycerol and three
molecules of stearic acid (18:0 acid). Three molecules of
water are a by-product of this reaction.
Structure of a mixed triacylglycerol in which three
different fatty acid residues are present.
Saturated
Mono-unsaturated (cis)
Polyunsaturated (cis)
How do fat molecules differ?
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The collapse of movie theater popcorn sales!
• What is cholesterol?
•Is there such a thing as “good” vs. “bad”
cholesterol?
• How does it relate to fat?
A schematic representation of a eukaryotic cell
with selected internal components identified.
Cell Wall
Cross section of a lipid bilayer. The circles represent
the polar heads of the lipid components, and the
wavy lines represent the nonpolar tails of the lipid
components. The “heads” occupy surface positions,
and the “tails” occupy internal positions.
The kinks associated with cis double bonds in fatty
acid chains prevent tight packing of the lipid
molecules in a lipid bilayer.
Cholesterol molecules fit between fatty acid chains in a
lipid bilayer. They regulate the rigidity of the structure.
Steroids
A molecular model showing the compact
nature of the cholesterol molecule.
The Cholesterol Content of Selected Meats and
Dairy Products.
Structures of selected steroids. (Sex hormones and
synthetic compounds that have similar actions.)
Anabolic Steroids
Balco: Barry, is it so?
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An Asian Tiger Mosquito that has pierced the skin of a poor
graduate student with her proboscis. Notice the swelling
abdomen as it fills with blood. Only female mosquitoes feed on
blood; males feed on plant nectar and juices.
Normal bone and Osteoporotic bone
Normal red blood cells
Anemic red blood cells
What is produced from the following 4 ingredients?
Water
“zymase”
Grain/ Barley/ Oats
Hops