M6: LIPIDS

Ester

Lipids that contain an _________ functional group may be hydrolyzed in water.

Hydrolyzable lipids

Waxes, Glycolipids, Phospholipids, Neutral waxes

Non Hydrolyzable lipids

Lack the ester functional group. Includes Steroids and Fat Soluble Vitamins (A,D,E,K)

Energy storage, Cell membrane structural components, Signaling

Functions of Lipids

Solubility Test

Lipids are dissolved in organic solvents like (Ether, Chloroform, Acetone, Benzene) but not in water and other ordinary solvents like (Dilute acids, Dilute alkalies, salt solutions)

[+/-] result in solubility test due to its polar and non polar side

Ethyl Alcohol (CH3CH2-OH)

Distilled Water

A polar solvent, therefore lipids which are non polar solutes, are insoluble with polar H2O

Organic Solvents

Are non polar solvents, therefore can dissolve non polar lipids

5% HCl

some lipids are slightly soluble with __________ because of hydrolysis reactions.

5% NaOH

Some lipids are slightly soluble with __________ because of saponification process.

Coconut oil

White semi-solid fat containing C12 to C15, Slight odor, Soluble in ether, alcohol, and chloroform. Resists oxidative rancidity but is susceptible to that oxidized by molds and other microorganisms.

Oleic Acid

Fatty acid derived from Animal Tallow or Vegetable oils. Yellow to red oily liquid, darkens upon exposure to air.

Butter

Fat derived from Milk

Margarine

Trans fat derived from the Partial Hydrogenation of vegetable oils.

Lanolin

Wax derived from wool

Hydrous and Anhydrous

Two types of Lanolin Wax

Hydrous

Yellow to gray semi solid containing 25-30% H2O, slight odor

Anhydrous

Brownish-yellow semi solid no more than 0.25% H2O but can be mixed about twice its weight of water without separation.

148.5 *C

Melting Point of Cholesterol

360*C

Boiling Point pf Cholesterol (Decomposes)

Tallow

An animal fat containing C16 to C18. Obtained from Beef, Cattle, Sheep and Horses.

27-38*C

Boiling point of Tallow

Lard

A soft, white fat mass of Pork fat with a peculiar faint odor

Canola Oil

It is a semi drying oil that is used as a lubricant, fuel, soap, and synthetic rubber base, as an illuminant for the slick color pages we see in magazines. It is an industrial oil but now used as cooking oil. Was derived from “Canadian Oil Low Acid” in 1978. Derived from rapeseed, once a specialty crop/weed in Canada.

Cooking Oil

Purified fat of plant origin, which is usually liquid at room temperature. Saturated oils such as coconut and palm are more solid at room temperature than other oils.

Vegetable Oils

A generic term used to label cooking oil products. Refers to a blend variety of oils often based on palm, corn, soybean or, sunflower oils.

Bromine Test

[+] Orange Solution; Unsaturated (The more drops, the more unsaturated)

Reaction with Iodine

[+] Red Solution; Unsaturated (The more drops; the more unsaturated)

Hydrolysis of Fats by Dilute Acids

Fat/Oil layer: upper layer contains fatty acids

Acid layer: Lower layer contains glycerol

Simple Lipids + H2O —> 3 Fatty Acids + Glycerol

Equation of Hydrolysis of Fats

Salkowski’s Test

[+] Bluish Red/ Purple Solution; Presence of Cholesterol

Liebermann- Burchard Test

[+] Green Solution; Presence of Cholesterol

Acrolein Test

The General Test for Lipids

Acrolein Test

[+] Pungent/ Irritating odor; Presence of Glycerol

Acrolein

Is responsible for the “Pleasant” Odor associated with the process of barbecuing meat.