Module 8 food chemistry, nutrition, and traditional foods

Module 8: Food Chemistry,
Nutrition, and Traditional Foods
Food: Any substances that can be
metabolized by an organism to give energy
and build tissue
Types: Carbohydrates, Proteins, Fats & Oils
Others: Vitamins, Minerals, Salts


Molecules of Food: Carbohydrates
6-C rings, 5-C rings
Mono-saccharides (sugar, fructose)
Dissacharides (lactose, sucrose)
Polysaccharides (starch, fibre, glycogen)
Carbohydrates are assimilated in the body
as “mono-saccharides” following digestion



Glucose: Body’s Primary Fuels
Lactic Acid + ATP + H2O
Glycogens
(Branched polymers
for short-term storage
in liver)

Glucose

(anaerobic)

(monomers)

(soluble)
Pyruvic Acid  CO2 + H20 + ATP
(aerobic)

•Glucose level in blood stream is highly regulated
•Aerobic respiration is releasing 90% of the energy stored in
glucose


Glycogen


Anaerobic
Metabolism

Aerobic
Metabolism

Pyruvic Acid  CO2 + H20 + 32ATP


Molecules of Food: Lipids and Fats
Fats: Large biological molecules, diverse
compositions, insoluble in water (i.e. non-polar in
nature)
Types:
–
–
–
–

Fatty acids (assimilable form)
Triglycerides (in blood)
Phospholipids (cell membranes)
Sterols (e.g. cholesterol)

Roles:
– Source of energy (during sustained activity)
– Structure of cell membrane


Free Fatty Acids (one chain)

• Saturated
• Unsaturated (e.g. Omega-3, Omega-6)


Fatty Acids
• Long-chain fatty acids (12+ carbons) are abundant
in meats and fish
• Short-chain fatty acids (12 carbons or less) are
abundant in dairy products
• Cold-water fish are rich in essential omega fatty
acids
• Unsaturated fatty acids, when cooked, change
conformation to a “trans” shape (which tend to
accumulate in blood vessels)
• Unsaturated fats are more prone to react with
oxygen, causing rancidity (common in stored fish)

Triglycerides


Phospholipids
• Phospholipids are “modified” triglycerides
where one fatty acid chain is replaced by a
phosphate group
• Soluble in water
• Important in cell membrane


Phospholipids


Sterols
• Multiple rings of carbon
• Best-known sterols: cholesterol (the
building block for all other sterols)
• Bile acids, some hormones, Vitamin C


Sterols

Cholesterol

Sitosterol (the most
abundant and common plant
sterol)

Absorption of Lipids
• Fat breakdown occurs in intestines
• Smaller units: fatty acids, glycerol, and
sterols
• Cholesterol and triglycerides are non-polar,
hence need “lipoproteins” to carry them in
the bloodstream


Molecules of Food: Proteins
• Chains of Amino Acids
• Diverse roles: enzymes, hormones,
regulators, molecular transports, antibodies,
building tissue like muscles, and energy
• Made up of C, H, O, N, other ions


Amino Acids
• Four components
around a central
carbon (C)
• One hydrogen
• An amino group (NH2)
• An acid (-COOH)
• A functional group

Glycine

Amino Acids

Essential Amino
Acid: Leucine

Non-essential
Amino Acid:
Asparagine


Molecules of Food: Vitamins
• Essential organic compounds to ensure
proper metabolism
• Little caloric value
• Water-soluble vitamins (enter directly into
bloodstream)
• Fat-soluble vitamins (must be transported
by carrier proteins)
• Several diseases are associated with vitamin
deficiencies



Caloric Contents of Food Molecules
Food Type

Caloric
%
Content (Cal/g) Recommended
Caloric Intake

Fats and Oils

9

30

Carbohydrates

4

58

Proteins

4

10

Vitamins

Trace

Not Applicable


Subsistence Food Provisioning
• Nutrition for indigenous people in the Arctic is
changing rapidly; from 100% to <50% “country
food”.

• Presence of larger communities, presence of “Coop” or “Bay” stores, and an increasing cash
economy contribute to changes in feeding habits.
• Lastly, hunting activities are costly when modern
technologies are used  the “pay off” of
traditional food provisioning is decreasing.


Concepts
Subsistence activities: The hunting, fishing, and
gathering of local foods for consumption, sharing,
and trade or barter.
e.g. caribou, whales, seals, marine birds, waterfowls,
eggs, fruits (largely a carnivore diet)
Note: Commercial trapping or fishing is generally
not viewed as traditional food gathering; although
they could be traditional activities.


Example of Subsistence Food
Economy
Inupiat households in Barrow, Alaska