Lipids

SOLUBILITY TEST

 The principle of "like dissolves like" applies, implying

that polar solvents effectively dissolve polar

substances, whereas nonpolar solvents dissolve

nonpolar substances well.

 This test is preliminary and detects the presence of

all lipids

translucent spot test

is also a preliminary test for

the lipids, which is characterized by a translucent

and greasy spot.

 The lipids will form a greasy or translucent spot due

to their greasy texture and penetrate the filter paper.

Unlike lipids, the spot of water will disappear from

the paper.

 To identify the presence of double or triple bonds

present in fatty acids.

 The lipids will form a greasy or translucent spot due

to their greasy texture and penetrate the filter paper.

Unlike lipids, the spot of water will disappear from

the paper

Bromine Test, orange color, white fumes

- Dissolkve a given test sample in carbon

tetrachloride and add bromine in CCl4 drop

wise with constant shaking.

- The disappearance of ______ indicates

saturation.

- When all the bonds are broken then the color

brown persists.

- If the color of bromine persists then the given

test sample is saturated.

- Blow across the mouth of the test tube or bring

a rod dipped in ammonium hydroxide. Absence

of _____ confirms unsaturation.

- In the context of experiment: oleic acid and

linoleicacid are unsaturated; while lauric,

myristic, palmitic, stearic, and arachidic are

saturated.

Hanus Iodine Test (Iodine number), iodine value, unsaturation, choloroform

Determines the amount of unsaturation

contained in the fatty acids that make up oils.

- The unsaturation is in the form of double bonds

which react with iodine compounds.

- The higher the ______ the greater the

______ present in the fatty acid.

- The addition of ______ into the oil will

make the oil penetrated into the solution.

ACROLEIN TEST, fat, dehydrating agent, glycerol portion, acrolein

 To detect the presence of glycerol or fat

 Principles:

- When ____ is treated strongly in the presence of

______ like potassium bisulphate

(KHSO4), the _______ of the molecule is

dehydrated to form an unsaturated aldehyde,

______ that has a pungent irritating odor.

TEST FOR RANCIDITY, unpleasant smells, aerial oxidation of

unsaturated fat

 Development of _____ in fats and oils,

which are accompanied by changes in their texture

and appearance.

 A condition produced by _______ present in foods and other products,

maked by unpleasant odor or flavor.

pH Difference, rancidity, acid

- Mas acidic and rancid over fresh oils or fats.

- As _____ increases in the

fermented/uncooked and unfermented/cooked

samples ______ increases seen as a drop in pH

values generally, ranging from pH 7.2 (in the

fresh state) and pH 4.5 (in sample 8) the worst

sample.

Saponification, triglycerides, fatty acid

metal salts, fatty

acids, white precipitate

 is the process in which ____

are combined with strong base to form ______ during the soap-making process. The

distribution of unsaturated and saturated fatty acid

determines the hardness, aroma, cleansing, lather,

and moisturizing abilities of soaps.

 Principles:

- Treatment of soap solution with diluted

hydrochloric acid produces a mixture of _____

- Fatty acids are long-chain carboxylic acids (C10

to C18 which may be saturated or unsaturated .

The_____ formed is a positive result

indicating a formation of fatty acids.

PROPERTIES OF SOAP (INSOLUBLE SOAPS), calcium, magnesium, lead or iron ions, insoluble, white precipitate

 To investigate the effect of different cations on soap

solubility.

 Principles:

- Working ________

to the deposition of soap and make it _____

in water, where solve these ions replace the

sodium or potassium ions are present in soap.

- Due to the hard water contain significant

quantities of Ca2+, Mg2+ and some Fe3+ that

react with the charged ends of the soaps to form

insoluble salts of fatty acid. The insoluble salts of

fatty acid that Ca2+ and Mg2+ form with soap

anions cause ______ to form which is

from calcium stearate or oleate.

LIEBERMANN-BURCHARD TEST FOR CHOLESTEROL, colored

subtances

 To detect the presence of cholesterol.

 Also called as acetic anhydride tests.

 A chemical estimation of cholesterol, the cholesterol

reacts as a typical alcohol with a strong

concentrated acids and the product are ______

Liebermann-Burchard, sulfucric acid and acetic anhydride, pink color, light green , dark green, hydroxyl group

_______ is a reagent mixture of

_______. Take note to

dissolve the cholesterol first in a chloroform.

- The color begins as a purplish, _______ and

progresses through to a _____ then very

____ color when cholesterol is detected.

- The colour is due to the ______ (-OH) of

cholesterol reacting with the reagents and

increasing the conjugation of the un-saturation

in the adjacent fused ring

EMULSIFYING ACTION OF LECITHIN, interfacial

surface tension, Emulsification

 ? is most often used as amphoteric

emulsifiers.

 They promote a stable formation of oil-in-water and

water-in-oil emulsions by reducing the ____ between immiscible liquids.

 ________ is the formation of emulsions from

two immiscible liquid phases is probably the most

versatile property of surface-active agents.

- Egg yolk – contains the emulsifying agent

lecithin.

- Butter – water in the fat emulsion.

- Oil and water mixture.

- Mayonnaise – an emulsion of oil in water.

- Crema on espresso – an emulsion of water and

coffee oil.

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