ESS 3 Lecture Notes - Lecture 4: Lecithin, Trans Fat, Very Low-Density Lipoprotein
Lipids
Include fatty acids, triglycerides, sterols, and phospholipids
➔Structurally diverse group of molecules
➔Insoluble in water
➔Contain carbon, hydrogen, and oxygen
Functions
➔Component of cell membranes
◆Give cell membranes flexibility and integrity
➔Fats supply a concentrated energy source of energy and fat-soluble nutrients
◆9 kcal/g
◆Essential fatty acids
● Broken down into linoleic acid and alpha-linoleic acid
◆Fat-soluble vitamins A, D, E, and K
➔Facilitate the transport and absorption of nutrients
➔Contributes to the sensation of feeling full
◆Fats stay in the stomach longer
◆Absorbed over a longer period of time
➔Increase the flavor and palatability of foods
◆Texture and aroma
➔Primary source of the body’s energy reserves
◆Stored in adipose tissue
● Cushions, protects, and insulates organs
Primary classes of lipids
Fatty acids
➔Major energy source
➔Primary components of triglycerides and phospholipids
◆Consist of a chain of carbon atoms with hydrogen atoms
➔Differ in degree of saturation
◆Saturation = how many hydrogen atoms fill the available carbon bond
◆Saturated fats
● Fully hydrogenated
○ All carbons “saturated” with hydrogen
○ No double bonds
● Food sources
○ Solid at room temperature
◆Animal origin
◆Tropical oils
◆Unsaturated fats
● Liquid at room temperature
●Monounsaturated fats
○ Fewer hydrogen atoms
◆One double bond
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○ Food sources: olives, avocados, nuts, olive oil
●Polyunsaturated fats
○ omega-6 , omega-3
○ More than one point of unsaturation
○ Food sources: vegetable oils
Triglycerides
➔Commonly called “fats”
➔3 carbon glycerol molecules with three fatty acids attached
➔Make up 95% of lipids in our food and 99% of stored fat in our bodies
Sterols
➔Complex lipids
◆4 interconnected carbon rings, with an oxygen and hydrocarbon side chain
➔Cholesterol is a sterol produced by the liver
◆Presence in cell membranes distinguishes between plant and animal cells
● Only found in animal foods
● Not an essential nutrient
○ Liver produces sufficient amounts to meet the body’s needs
● Found in every cell of human bodies
◆Critical component of cell membranes
◆Does not provide calories
◆Precursor for hormone synthesis
Phospholipids
➔Produced by the body
➔3 carbon molecule with two fatty acids and a phosphate group
➔Unlike other lipids, allow phospholipids to suspend fat in water
➔Primary component of cell membranes
◆Component of lipoproteins that transport lipids in the blood
➔Lecithin
◆Found in the body and food products
◆Functions as and lipids from separating
Fat digestion
Occurs in small intestine
➔Facilitated by bile acids, lipases, emulsification
◆Liver produces bile acids from cholesterol
● Bile is stored in the gallbladder
Emulsification
➔Allows fat to mix with water
➔Bile acids help the process
➔Facilitate action of lipases in breaking down molecules
Lipoproteins
Lipids are not soluble and thus require a carrier for transport
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Document Summary
Fats supply a concentrated energy source of energy and fat-soluble nutrients. Broken down into linoleic acid and alpha-linoleic acid. Fat-soluble vitamins a, d, e, and k. Facilitate the transport and absorption of nutrients. Contributes to the sensation of feeling full. Absorbed over a longer period of time. Increase the flavor and palatability of foods. Primary source of the body"s energy reserves. Consist of a chain of carbon atoms with hydrogen atoms. Saturation = how many hydrogen atoms fill the available carbon bond. Food sources: olives, avocados, nuts, olive oil. 3 carbon glycerol molecules with three fatty acids attached. Make up 95% of lipids in our food and 99% of stored fat in our bodies. 4 interconnected carbon rings, with an oxygen and hydrocarbon side chain. Cholesterol is a sterol produced by the liver. Presence in cell membranes distinguishes between plant and animal cells. Liver produces sufficient amounts to meet the body"s needs. Found in every cell of human bodies.
