ANALYSIS OF FATS AND FIXED OILS AND FATTY SUBSTANCES

Constant

value or number of physical and chemical properties.

Fats

compounds consisting of fatty acids combined with glycerol via ester linkages

specific gravity

melting point

congealing point

refractive index

optical activity

acid value, saponification value, ester value, iodine value, acetyl value, hydroxyl value, unsaponifiable matter, water and sediment

Examples of Constants

Fixed oils

contain relatively high quantities of liquid glycerides

glyceryl oleate

Other term of liquid glyceride

Fats

contain large amounts of solid glycerides

Glyceryl Streate

Other term for solid glycerides

Wax

esters of high molecular weight monohydric alcohols and high molecular weight fatty acids.

high molecular weight monohydric alcohols and high molecular weight fatty acids.

Was are esters of _____

Balsams

substances containing benzoic or cinnamic acids

Resins

natural or induced solid or semi-solid exudates from plants characterized by being insoluble in water, soluble in alcohol and ether, crystallizable and softening or melting at a moderate heat.

by determination of constants

The purity of fixed oils, fats, waxes, resins, etc. cannot be ascertained by the usual methods based on gravimetric or volumetric processes à therefore it is by?

color, odor, taste and special identity tests

The determination of these constants are made in conjunction with the study of ___________ for the substance analyzed and for the presence of adulterants serve as a basis of the purity and quality of such substances.

Butyric - 4C chain

Caproic – 6C chain

Caprylic – 8C chain

Capric – 10C chain

Names of some common fatty acids

Fixed oils and fats

mixture of glyceryl esters of high molecular weight fatty acids

Palmitic (16)

Stearic (18)

Oleic (18)

Fixed oils and fats like

Fats

• Mainly animals

• Saturated (no double bond)

• Solid

• High melting point

Oils

• Mainly plants

• Unsaturated (double bond)

• Liquid

• Low melting point

Comparison between Fats and Fixed oils

Plants (soybean, carnauba)

Animals (spermaceti, Ambergris)

Example of some waxes

Wax

Low melting point solids and have long alcohol chains

Fat and oils

Made from glycerol and three fatty acids joined by dehydration synthesis

Either aqueous or alcoholic alkali

Fats and oils is saponified by mean of

Alcoholic alkali

Waxes are saponified by

separation of stearin

The fats and oils to be employed in the determination of their chemical constants should undergo preliminary treatment if they are turbid due to_____

hot water jacket

If warming the oil fails to clarify, it should be filtered through a dry filter paper in a funnel held in a ____

Acid Value

This is the number of miligrams of KOH required to neutralized the free acids in 1 g of substance

Acid Value

It may be expressed as the number of milliliters of 0.1-N sodium hydroxide required to neutralize the free acids in 10 grams of sample

Ester value

Number of miligrams of KOH required to saponify the esters on 1 g of the substances

Saponification value

Number of miligram of KOH required to neutralized the free acid and saponify the ester in 1g of substance

Hydroxyl Value

Number of miligram of KOH equivalent to the OH content of 1g of the substance

Iodine value

Number of miligram of iodine absorbed by 100 g of a substance

Iodine value

Measure of unsaturation

Hanu

Wij

Hubl - unofficial method

Official method for iodine value determination

Iodobromide

Test solution of Hanu’s method iodine value determination

Iodochloride

Test solution of Wij’s method iodine value determination

Startch TS

The indicator of Hanu and Wij’s for Iodine value determination

Chloroform

Solvent of Hanu’s method for iodine value detemination

CCl4

Solvent of Wij’s method for iodine value detemination

0.1 N Na2S2O3

Hanu’s method titrant

0.1 N Na2S2O3

Wij’s method titrant

Drying

• >120

• Linseed, COD

Semi-drying

• 100-120

• Cotton seed, Sesame

Non-drying

• <100

• Olive, Almond

Types of fixed oils based on iodine value

Vegetable origin

Phytosterol origin

Animal origin

Cholesterol origin

Unsaponifiable matter

PRESENT IN OILS/FATS THAT ARE NOT SAPONIFIED BY ALAKALI OH BUT SOLUBLE IN ORDINARY FAT SOLVENTS

Acid Number or Acidity Index

Acid Value is also called

Free acid

due to hydrolysis of the esters that compose them.

Hydrolysis

caused by the catalytic action of light and heat, by bacterial action and by chemical treatment.

rancidity but hydrolytic decomposition

If a substance has a high acid value, it does not indicate ____ but ____ during their preparation, purification or storage.

Rancidity

Bacterial action on free acids

Also known as the Saponification Number or Koettsdorfer Number

Saponification Value is also known as

Saponification value

Determination of this constant helps in the detection of the presence of glycerides of fatty acids which contain less than 16 or more than 18 carbon atoms

less than 16 or more than 18 carbon atoms

Saponification value determination of this constant helps in the detection of the presence of glycerides of fatty acids which contain _______

average of the molecular weights of the fatty acids

saponification value is inversely proportional to the __________ found in the sample.

H2SO4

HCl cannot be substituted with

HCl cannot be substituted with H2SO4 because K2SO4 which would be the product of the neutralization will not dissolve in the alcoholic solution and interfere with the observation of the endpoint.

Why si HCl cannot be substituted with H2SO4?

Alcoholic KOH

more advantageous than the aqueous solution because the alcohol acts as a solvent for the oil and the products of saponification which are insoluble in water.

Blank test

performed to eliminate errors from all sources like those produced by absorption of CO2 by the alkali or by the alkalinity of the glass vessels

Ester number

Ester value is also known as

ester and saponification values

Substances, which do not contain free acids, have equal______

acid value and saponification value.

Substances containing free acids have their ester values equal to the difference between the _______

beeswax

paraffin

The ester value is important in the analysis of ____, which serves to indicate the presence of adulterants like_____

rosin

stearic acid

The determination of ester value of waxes is made in conjunction with the determination of the acid value will show the presence of such adulterants as ______ or a mixture of them.

abnormally increase the acid values and lowers the ester value.

Adulterants in Ester value will abnormally effect acid value in what way?

Paraffin

consists of High MW aliphatic hydrocarbons

Unsaponifiable matter

Determination of this constant will indicate the presence of unsaponifiable adulterants such as petroleum oil added to linseed oil.

petroleum oil added to linseed oil.

Unsaponifiable matter in determination of this constant will indicate the presence of unsaponifiable adulterants such as _____

unsaturated fatty acids present

This value is a quantitative measure of the proportion of _______ both free and combined as esters that have the property of absorbing iodine

Determination of Iodine Value

important since it indicates whether they are pure or a mixture.

Iodine number

Iodine value is also known as

Iodine value

not only serves to help in the identification of known oils but also to indicate the class to which an unknown fat or oil belongs.

iodine value

In conjunction with the saponification value of a fat or oil, _____ also serves as a means of detecting adulteration.

Iodine flask

used to prevent other side reaction from taking place in which iodine monochloride is consumed.

excess iodine

The sodium thiosulfate reacts with the ______

Hydroxyl number

Hydroxyl value is also known as

alcoholic hydroxyl groups.

Hydroxyl value constant gives an indication of the identity and purity of fatty substances possessing

higher molecular weight alcohols or with non-alcoholic fatty substances

An abnormally low hydroxyl value is indicative of adulteration with _____________

Acetyl Value

corresponds closely to the hydroxyl value of fatty alcohol and the two constants have much the same significance with respect to identity and purity of substances.

Acetyl Value

saponification value of acetylated fatty acid and acid value of the original fatty acid

acetylating hydroxy fatty acids

saponification value of the product

The acetyl value is determined by ______ (e.g hydroxystearic acid or hydrogenated castor oil) and determining the _____

Peroxide value

the number , in mEq of oxygen, of peroxides in 1 gram sample

Peroxide value

This is important for determining the extent of primary oxidation

Antisidine Value

Defined as 100 times the absorbance (at 350nm) of a solution resulting from reaction of 1g of fat in 100mL of solven

Total oxidation Value

combined PV and Anisidine value (2PV + AV)

Solidification Temperature of FA

Congealing point