CONSTANT FATS AND FIXED OILS

Constants

➢ Value or number of physical and chemical properties ➢ 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

Fats

➢ Compounds consisting of fatty acids combined with glycerol via ester linkages

➢ Contain large amounts of solid glycerides (glyceryl stearate)

➢ Obtained from animals

➢ Solid Glycerides

Fixed Oils

➢ Contain relatively high quantities of liquid glycerides (glyceryl oleate)

➢ Via ester linkages

➢ From Plants

➢ Liquid at room temperature or normal temperature

Waxes

➢ Are esters of high molecular weight monohydric alcohols and high molecular weight fatty acids

➢ Same definition with alcohol and fatty acids

➢ Also known as Lipids

Balsams

➢ Are substances containing benzoic or cinnamic acids

➢ Secondary plant constituent

Resins

➢ Secondary plant constituent

➢ Are 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

Fats

compounds consisting of fatty acids combined with glycerol via ester linkages.

ACID VALUE

# OF mg OF KOH REQUIRED TO NEUTRALIZE THE FREE ACIDS IN 1g OF SUSTANCE

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

# OF mg OF KOH REQUIRED TO SAPONIFY THE ESTERS ON 1g OF THE SUBSTANCE

SAPONIFICATION VALUE (AV + EV)

# OF mg OF KOH REQUIRED TO NEUTRALIZE THE FREE ACIDS AND SAPONIFY THE ESTER IN 1g OF SUSTANCE

HYDROXYL VALUE

# OF mg OF KOH EQUIVALENT TO THE OH CONTENT OF 1g OF THE SUBSTANCE

IODINE VALUE

# OF g OF IODINE ABSORBED BY 100g OF A SUBSTANCE

MEASURE OF UNSATURATION

>120

IODINE VALUE FOR DRYING

<100

IODINE VALUE FOR NON-DRYING

100-120

IODINE VALUE FOR SEMI-DRYING

Linseed, COD

Example of a substance in Drying

Olive, Almond

Example of a substance in Non-Drying

Cotton seed, sesame

Example of a substance in Semi-drying

UNSAPONIFIABLE MATTER

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

PHYTOSTEROL

LIPID OF VEGETABLE ORIGIN

CHOLESTEROL

LIPID OF ANIMAL ORIGIN

Acid value

also called Acid Number or Acidity Index

Alcoholic KOH

is 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

is performed to eliminate errors from all sources like those produced by absorption of C02 by the alkali or by the alkalinity of the glass vessels.

ester value

is important in the analysis of beeswax, which serves to indicate the presence of adulterants like paraffin.

PARAFFIN wax

consist of High MW aliphatic hydrocarbons

Unsaponifiable Matter

These are substances that are not saponified by alkali hydroxides but are soluble in ordinary fat solvents

Unsaponifiable Matter

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

Acetyl Value of Fatty Acids

It is expressed as the number of mg of potassium hydroxide required to neutralize the acetic acid obtained by the saponification of 1 gram of acetylated fatty acids.

Acetyl Value of Fatty Acids

➢ 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.

➢ From the saponification value of acetylated fatty acid and acid value of the original fatty acid, acetyl value is determined

ACETYLATED SAMPLE

The acetyl value is determined by acetylating hydroxy fatty acids e.g. hydroxystearic acid or hydrogenated castor oil and determining the saponification value of the product

Peroxide Value

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

Anisidine Value

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

Total oxidation Value

combined PV and Anisidine value (2PV + AV)

Solidification Temperature of FA

Congealing point