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Plants as Food 2
What Are Lipids?
These are a group of diverse molecules that are
grouped together because they share the
characteristic that do not mix with water.
They comprise Oils, Fats, Waxes, Phospholipids
and Steroids.
Lipids are classified into two groups
1. Lipids with fatty acids: Triglycerides
Phospholipids
2. Lipids without fatty acids: Steroids.
Triglycerides
Commonly known as fats oils and waxes.
Most plants contain unsaturated fats
which are made with unsaturated fatty
acids. Examples are olive oil, peanut oil
corn oil, soybean and canola oil.
Some plant oils such as coconut oil,
cocoa butter and palm oil contain
saturated fatty acids.
Functions of Lipids
What Are Proteins?
Proteins are biomolecules that are made
of C, O, H, N and S.
The building blocks of proteins are amino
acids.
What are amino acids?
An amino acid is a molecule
that has an carboxyl group
(COOH-) and an amino group
(NH2). R represents the radical or rest
of the molecule.
There are 20 different amino acids. Out of the 20, 8
are called essential.
Essential amino acids are amino acids that the
human body cannot make (we do not have the
enzymes to produce them, thus we have to ingest
them as part of our food). Why? Because we need
them to make our own proteins.
Cells link amino acids together by dehydration
synthesis
The bonds between amino acid monomers are called
peptide bonds
Amino Acids
Essential and Non-essential Amino Acids
Functions
Proteins are involved in
enzymes
cellular structure
movement
defense
transport
Communication
Regulation.
Structure
15% of your cell membranes are made of
proteins.
Mammals hair and nails is made of protein
Spider webs are made of protein.
Movement
Muscle cells
involved in the
formation of
muscles are
made
of pure protein:
actin and
myosin. Muscles
are responsible
for movement.
Defense
All antibodies produced
by your white blood cells
are proteins!
Venom produced by
poisonous
snakes and other
poisonous
animals are made
of proteins.
Transport
Hemoglobin in your
red blood cells transports
oxygen and carbon
dioxide.
Regulators
Some hormones, such as insulin and
glucagon that regulate the glucose
levels in the blood stream are
proteins.
The human growth hormone that
regulates growth is a protein.
So…Is all protein the same?
The quality of a protein is evaluated in 2 areas:
1. Does it provide all essential AA?
2. Can it be broken down completely by the digestive
system (can it free all the AA to be used by the organism?)
Protein Digestibility Corrected Amino Acid Score (PDCAAS)
This is a rating adopted by the US Food and Drug
Administration (FDA) and the Food and Agricultural
Organization of the United Nations/World Health
Organization (FAO/WHO) in 1993 as "the preferred 'best'"
method to determine protein quality.
So…Is all protein the same?
Complete proteins are proteins that can provide all the
essential AA. Animal proteins are usually complete
proteins.
Incomplete proteins are proteins that are deficient in one
essential AA. Plant proteins are usually incomplete.
However a complete protein diet can be achieved by
combining two different incomplete plant protein sources.
For example Native Americans (as well as ancient and many
modern day Mesoamerican cultures) combine beans (low
in methionine but high in lysine and tryptophan) and corn
(high in methionine but low in the other two).
So…Is all protein the same?
2. Digestibility: Some
proteins cannot be
broken down
completely. For example
when digestibility is
taken into account, even
egg albumin (egg white)
which is considered an
excellent proteins based
on its essential AA
content is not
completely digestible.
Rating of Protein “Quality”
1.00 casein (milk protein)
1.00 egg white
1.00 soy protein
1.00 whey (milk protein)
0.99 mycoprotein
0.92 beef
0.91 soybeans
0.78chickpeas
0.76 fruits
0.75 black beans
0.73vegetables
0.70 Other legumes
Protein
Content
of
Some
Common
Food
Items
Protein Content of Some Common Food items
Micronutrients
These are required in small amounts
and it makes only 1 to 2% of dry
weight.
There are two categories of
micronutrients:
Vitamins
Minerals
Vitamins
Vitamins are classified according to their
solubility:
Fat soluble vitamins (do not disolve in
water and store in fat tissue): Vitamin A,
D, E and K.
Water soluble vitamins (do not store):
eight B-complex and C.
Fat Soluble Vitamins
Water Soluble Vitamins