Oils, Fats & Waxes
Contents
1 Oil,
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.14
1.15
1.16
1.17
1.18
1.19
1.20
1.21
1.22
1.23
1.24
1.25
1.26
1.27
1.28
1.29
1.30
1.31
1.32
1.33
1.34
1.35
1.36
1.37
1.38
1.39
Fat & Wax
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . .
Saturated Fatty Acids . . . . . . . . . . . . . . . . . . . .
Unsaturated fatty acids . . . . . . . . . . . . . . . . . . .
Sources of Fat & Oil . . . . . . . . . . . . . . . . . . . . .
Alcohols in Wax . . . . . . . . . . . . . . . . . . . . . . .
Sources of Waxes . . . . . . . . . . . . . . . . . . . . . . .
Classification of Oil . . . . . . . . . . . . . . . . . . . . . .
Properties of Oils and Fats . . . . . . . . . . . . . . . . . .
Uses of oils and fats . . . . . . . . . . . . . . . . . . . . .
Uses of Wax . . . . . . . . . . . . . . . . . . . . . . . . . .
Classification of Wax . . . . . . . . . . . . . . . . . . . . .
Some Common Waxes . . . . . . . . . . . . . . . . . . . .
Differentiate Between Fats, Oils and Waxes . . . . . . . .
Rancidity . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tests for identifying and distinguishing Oil, Fat and Wax .
Distinguish between fat and wax by saponification test . .
Methods of Extraction of Oil . . . . . . . . . . . . . . . .
Purification of Oil Extracted . . . . . . . . . . . . . . . . .
Solvents that are used in the extraction process . . . . . .
Hydrogenation of Oil . . . . . . . . . . . . . . . . . . . . .
Process of Hydrogenation . . . . . . . . . . . . . . . . . .
Chemistry of Hydrogenation . . . . . . . . . . . . . . . . .
Preparation of Ni Catalyst . . . . . . . . . . . . . . . . . .
Purification of Oil . . . . . . . . . . . . . . . . . . . . . . .
How drying Oils are utilized? . . . . . . . . . . . . . . . .
Mechanism of Rancidity with Chemistry . . . . . . . . . .
Advantages and Disadvantages of Mustard Oil . . . . . . .
Canola Oil . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wijs Reagent . . . . . . . . . . . . . . . . . . . . . . . . .
Foots . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Butter & Margarine . . . . . . . . . . . . . . . . . . . . .
What is degumming? Why it is important? . . . . . . . .
What’s Wintering/ Chilling agent? . . . . . . . . . . . . .
What are the purposes of Non-edible Oils? . . . . . . . . .
Why paraffin was is called unsaponifiable wax? . . . . . .
Difference Between Fatty Oil & Mineral Oil . . . . . . . .
Distinguish between Essential Oil and Fatty Oil . . . . . .
Distinguish between Edible Oil and Non-edible Oil . . . .
Which solvent is the best for edible oil extraction purpose?
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1
Oil, Fat & Wax
1.1
Definition
Oils contain a large proportion of high molecular weight unsaturated fatty acid glycerides. Oils are
esters of higher unsaturated fatty acid and other acids with glycerol. The glycerides which are liquid at
20 °C are called oils. Oils contain higher proportion of mixed glycerides than triglycerides.
Fats contain large amount of high molecular weight saturated fatty acid glycerides. Fats are esters of
higher saturated fatty acid and other acids with glycerol. The glycerides which are solid at 20 °C are
called fats. Fats contain higher proportion of triglycerides than mixed glycerides. Example : Lard,
tallow, butter etc.
1.2
Saturated Fatty Acids
Common formula is CnH2n+1COOH. Examples are :
• Stearic Acid : C17H35COOH
• Palmitic Acid : C15H31COOH
• Myristic Acid : C13H27COOH
• Cepric Acid : C9H19COOH
1.3
Unsaturated fatty acids
General formula is CnH2n–1COOH. Examples are :
• Linoleic Acid : C17H31COOH
• Oleic Acid : C17H33COOH
• Uric Acid : C21H41COOH
The unsaturation can be determined by Bromine test (electrophilic addition)
1.4
Sources of Fat & Oil
• Vegetable Source : Linseed oil, palm oil, coconut oil, peanut oil, tung oil, castor oil etc.
• Animal Source : Whale oil, cod-liver oil, shark liver oil, fish oil, lard, tallow or grease etc.
2
Waxes are mixed esters of fatty acid and higher polyhydric alcohol other than glycerol.
Alcohols containing more than three hydroxyl groups attached to an aliphatic carbon chain are called
polyhydric alcohols.
Tung oil or China wood oil is a drying oil obtained by pressing the seed from the nut of the tung tree
(Vernicia fordii).
1.5
Alcohols in Wax
Waxes contain various alcohols, such as :
Aliphatic, General formula CnH2n+1OH
• Cetyl Alcohol : C16H33OH
• Octa Decyl Alcohol : C18H37OH
• Carnaubyl Alcohol : C24H49OH
• Ceryl Alcohol : C26H53OH
• Mericyl Alcohol : C30H61OH
Aromatic Alcohol :
• Cholesterol : C27H45OH
• Lanolin Alcohol : C12H33OH
• Iso Cholesterol : C27H45OH
1.6
Sources of Waxes
• Vegetable Source : Coatings on leaves, stems, flower and seed (e.g Carnauba)
• Animal Source : Secretion from certain insects (e.g bees wax)
• Mineral Waxes : From petroleum
1.7
Classification of Oil
• Depending on source, oils can be classified into :
1. Mineral oil : Oils generally isolated from petroleum. Fractional distillation of crude petroleum.
These are saturated hydrocarbon or paraffin(C5 − C30 ). Example : Kerosene
2. Essential Oil : These oils are volatile in nature with pleasant odour usually obtained from
various plants exudes and flowers. Example : citronella oil, nero, eugenol etc.
3. Fatty Oil : Oils which are obtained from vegetable and animal sources. Example : palm oil,
olive oil, coconut oil, codliver oil, whale oil etc.
• Depending on edibility, oils can be classified into :
1. Edible oil : Constitutes 70% of total oil. Animal source : Cod liver oil, fish oil etc. Vegetable
Source : Soyabean oil, cottonseed oil, palm oil etc.
2. Inedible Oil : Around 20% is used for the manufacture of soap, 9% is used for the paint
and varnish, and some oil is used as plasticizers for polymers, synthetic resins and protective
films. It is also used in the manufacture of lubricants, greases, creams and emulsions.
3
• Based on Unsaturation / physical and chemical properties/ Iodine value, oil can be classified into
1. Drying Oil : Contains high proportion of unsaturated acids especially two or three double
bonds, e.g linoleic acid, linolenic acid. Drying oils spread in thin layers over a smooth surface
when exposed to light and air for few hours and set as a hard and firm film. Iodine value is
above 140. Example : Linseed oil, poppy seed oil, tung oil, hemp seed oil. Drying oils are
mainly used for paints and varnishes.
2. Semidrying Oil: Contains intermediate proportion of unsaturated fatty acids with 1 or 2
double bonds, e.g, oleic acid, rincinoleic acid. Semidrying oil have the tendency of becoming
thick in air without actually undergoing drying at ordinary temperatures. Iodine value of
semidrying oil in between 95-140. Example : Maize oil, cottonseed oil rapeseed oil, corn oil,
mustard oil, soyabean oil.
3. Non Drying oil : Contains least proportion of unsaturated fatty acid. They are quite stable
at ordinary temperatures. Iodine value of non drying oil is below 95. Example : Coconut
oil, olive oil, castor oil, palm oil etc.
1.8
Properties of Oils and Fats
• Oils and fats are non volatile organic compounds soluble in organic solvent.
• Oils and fats gradually decompose in light, air and in moisture. They are also decomposed
sometimes by microorganisms.
• They have no taste, odour, color in pure state
• They undergo hydrolysis with acids and alkalies.
• They are the main source of energy.
• When agitated with water in presence of an emulsifying agent, they form an emulsion.
1.9
Uses of oils and fats
• Oils and fats always had an essential role as food for human kind
• Oils and fats used for the production of fatty acid, soap
• Used in paints and varnishes
• Used in the manufacture of lubricants, cream, grease etc
• Used as plasticizer in polymer manufacture.
1.10
Uses of Wax
• Waxes are used in candles, cosmetics polishes and sizing
• They are also found as electrical insulators and lubricants
1.11
Classification of Wax
• Depending on the basis of availability, waxes can be classified into :
1. Natural wax
(a) Animal Source
i. Solid : Bees wax, chinese wax, shellac wax, wool fat wax
4
ii. Liquid: Spermatic wax
2. Vegetable Wax : Carnauba Wax, candelilla wax, sugarcane wax, coffee wax etc.
3. Mineral Wax : Fossil wax, peat wax etc.
• Synthetic Wax : Opal wax, rilan wax, lannette wax
1.12
Some Common Waxes
1. Spermaceti Wax
• Animal Wax
• Major Constituent Cetyl Palmitate (C16H33COOC15H31)
• Insoluble in water
• Uses : Cosmetics
2. Bees Wax
• Insect Wax
• Obtained by melting honey comb
• Honey comb −→ Melt −→ Filter −→ Solidify (Cooling) −→ Bleach (Oxidation in sunlight
in presence of air or H2O)
• Major constituent : Mericyl Palmitate (C30H61COOC15H31)
• Uses : Cosmetics (Nail polish, leather dressing, candle)
3. Chinese Insect Wax
• Yellow color
• Deposited on the branches, trees by Coccus eriferus ; Coccus pela
• Major constituent : Ceryl Acetate (C26H53COOC25H51)
• Uses : Polishing, candles, sizing
4. Carnauba Wax
• Expensive commercial wax
• Obtained from some palm trees in brazil
• Major Constituent : Mericyl cerotate (C30H61COOC25H51)
• Deep yellow or light yellow
• Uses : Constituent of floor material, automobile, carbon paper, candle
5. Paraffin Wax
• Mineral wax from petroleum
• Hydrocarbon (saturated)
• Most cheap
• It’s major constituent is long chain alkanes, such as C36H74 and the general formula is
CnH2n+2
• Unsaponifiable Wax (with NaOH, no soap)
• Uses : Regular candles, waterproof coatings
6. Wool Wax
• Present in sheep wool fibres
• Major constituent : Stearate of cholesterol, and palmitate of iso cholesterol.
5
1.13
Differentiate Between Fats, Oils and Waxes
Physical Appearance
Differentiate Between
Oil
Large portion of high
molecular weight unsaturated fatty acid
glycerides
Liquid at 20 °C
Solubility in Water
Insoluble
Constituent Alcohol
Trihydric
glycerol
Examples
Coconut oil, palm oil,
tung oil etc
Soap making industries, edible purposes,
plasticizers for lacquers and polymers
etc
Property
Constituents
Uses
1.14
Fats, Oils and Waxes
Fat
Large portion of high
molecular weight saturated fatty acid glycerides
Solid at 20 °C
alcohol-
Wax
Esters of fatty acid
and higher polyhydric alcohol other than
glycerol
At room temperature
soft,pilable, adhesive
and plastic solids.
Insoluble
Oil insoluble but water soluble
Trihydric
alcohol- Ester forming alcohol
glycerol
in different waxes may
differ
Lard, tallow, butter Bees wax, carnauba
etc
wax
Soap making indus- Candles,
insulating
tries, edible purposes, and polishing purgreases, paints, var- poses
nishes, plasticizers etc
Rancidity
Rancidity is the phenomenon for which oils and fats develop an offensive odour or off taste after exposing
them to warm moist air for a long time.
Types of Rancidity :
1. Oxidative Rancidity : It occurs due to the oxidation of oil due to presence of air of atmosphere.
It occurs in triglycerides containing unsaturated acid components. By using antioxidants like
Vitamin E, ascorbic acid etc, oxidative rancidity can be prevented.
2. Hydrolytic Rancidity : It occurs due to the temperature and moisture from atmosphere. The
reason for this type of rancidity is the liberation of lower fatty acids by hydrolysis of ester links
of triglycerides. Hydrolytic rancidity is prevented by persuing oil or fat in refrigerator so that it
can’t come in contact with high temperature and moisture.
1.15
Tests for identifying and distinguishing Oil, Fat and Wax
1. Saponification Value : It is the measure of average molecular weight of fat or oil. Saponification
value is defined as number of milligrams of KOH required to saponify completely 1 gm of fat or
oil. Saponification value gives us information whether :
(a) An oil or fat contains higher or lower proportion of same fatty acids
(b) An oil or fat contains higher proportion of higher or lower fatty acids
(c) Saponification value determines both the free fatty acid and combined fatty acid in oil or
fat
Saponification value of castor oil, palm oil, linseed oil is 180, 200, 192 respectively.
2. Acid Value : Acid value determines the proportion of free fatty acids in oil or fat. Acid value is
defined as number of milligrams of KOH required to neutralize the total amount of free fatty acid
in one gm of fat or oil. NaOH is not preferred over KOH because NaOH is a strong base.
6
Acid Value = Theoretical Saponification Value - Actual Saponification Value
Acid value of castor oil, cottonseed oil and linseed oil is 0.7, 2.2 and 8.0 respectively.
Importance: The lower value of acid value indicates the freshness of fat or oil. Rancid oil contains
higher amount of free fatty acids giving out bad odour and is not used for edible purposes.
Determination of Acid Value:
Procedure : The sample is dissvoled in a solvent (alcohol : benzene = 1:1). Then it is titrated
against standard 0.1M KOH solution in presence of phenolphthalein indicator. Acid value is
calculated using the following equation :
X = V ×MW×56.1
Where, V = Volume (in cm3 ) of KOH
M = Molarity of KOH
W = Weight of sample (in gm)
X = Acid Value
3. Iodine Value : Iodine value shows the degree of unsaturation of the constituent fatty acids of oil
or fat. Iodine value is defined as the number of grams of iodine absorbed by 100 gms of oil or fat.
For one double bond in fatty acid 1 mole of oil or fat, one mole of I2 (254 gms) absorbed.
Non drying oil having one double bond, iodine value is below 90
Semi drying oil having 2 double bond, iodine value is 95-140
Drying oil having 3 double bond, iodine value is above 140.
Iodine value is expressed in terms of % basis. Iodine value of castor oil, palm oil and linseed oil
is 85%, 52% & 190% respectively.
Importance:
a) Number of double bonds present can be found
b) We can also classify oil according to their iodine value.
Determination of Iodine Value:
Procedure : The sample is dissolved in 10 ml of CCl4 and exactly 25 ml of Hanus solution is
added from a burette and is allowed to stand for half an hour with occasional shaking. 100 ml of
water is added at the end of the period followed by 10 ml of 12% KI solution. The iodine left is
titrated with standard M/10 Na2SO3 solution using starch indicator.
Under identical conditions, a blank experiment is performed with the omission of oil. The differemce between the volumes of Na2SO3 required in the above two experiments will correspond to
the amount of I2 absorbed by the oil or fat.
4. Reichert- Miesel Value (RM Value): This value represents the amount of volatile and water soluble fatty acid present in oil or fat. It is expressed in terms of volume in cm3 of decinormal solution
of NaOH required to neutralize the distillate obtained from exactly 5 gms of saponified material
(oil/ fat). Generally, RM value of an oil or fat is 3-4%
Procedure : 5 gm of oil or fat first taken in a 300 cm3 flask and then added 2cm3 of 50% NaOH
and 10 cm3 of 92% ethanol. Then the solution is boiled under reflux condition for 1 hour for
saponifying the material. The resultant solution is then heated on water bath to remove alcohol
and dry soap is obtained. Dry soap is dissolved in 100 cm3 of distilled water and thus soap solution is obtained. Then 50cm3 of 1 N H2SO4 is added to the soap solution. Soap is converted to
Na2SO4 and fatty acid. This solution is distilled in polenske’s apparatus and 110 cm3 of distillate
is collected in 30 minutes. Distillate is filtered and 100 cm3 of the filtrate is titrated against 0.1N
NaOH solution using phenolphthalein indicator. Run a blank test without the fat but using same
quantities of reagents.
Calculation : Let V cm3 the volume of 0.1 N NaOH required to neutralize 100 cm3 of filtrate,
so for 110 cm3 filtrate required (V × 1.1) cm3 0.1N NaOH.
RM value = (A-B) ×N × 11 = V × 0.1 × 11 = (V × 1.1)
7
Where, A = Volume of standard NaOH required for sample titration
B = Volume of standard NaOH required for blank titration
N = Strength of NaOH
Importance: RM value determines have been used principally for analysis of butter and margarines. Butter fat contains mainly butyric acid glycerides, and therefore the RM value of butter
fat is higher than any other fat. Coconut oil, palm oil contain appreciable quantities of caprylic
capric and lauric acid glycerides. These fatty acids are steam volatile but not soluble in water
and hence give high polenske value.
5. Hehner Value : Hehner value is the measure of the water insoluble fatty acids present in the oil
or fat. It is expressed as percentage of the oil or fat. Usually henher value is 95-96%.
Procedure : The material left in the flasks after removing the distillate during the determination
of RM value is vigorously shaken with water to dissvole the soluble matter and then filtered. The
residue is dried & weighed.
calculation : Let the weight of the residue be w gm then,
Henher value =
W
5
× 100
Importance: The modified Hehner’s test (MHT) was applied to detect the formalin in experimentally contaminated and collected commercial cheeses and fish.
6. Elaiden Test : This is a very good test to distinguish non drying oils, semidrying oils, & drying
oils
Procedure : Freshly prepared mercuric nitrate solution is required for this test. It is prepared by
dissolving 13 gm of Hg in 12 cm3 of concentrated HNO3. The solution is kept cold. 50 cm3 of
the oil is taken in 100 cm3 wide mouth stoppered bottle and 2 cm3 of mercuric nitrate solution
is added to it. The bottle is shaken well and placed in an oven at 25 °C. The bottle is allowed to
stand for 24 hours and shaken occasionally.
Observation:
1 ) If the oil remains fluid after one day
Drying Oil
2) If the oil assumes a treacle like consistency,
Semi Drying Oil
3) If the oil becomes thick solid,
Non drying oil.
Importance : It is an important test to determine which oil can be used as a lubricant or not.
We cannot use drying oil as lubricant as it will get sticked to the equipment and thus destroy it’s
functionality.
1.16
Distinguish between fat and wax by saponification test
• In case of Wax (More alcohol, less acid)
C16H33COOC15H31 (cetyl palmitate) + NaOH
C16H33OH (cetyl alcohol, 55% insoluble) +
C15H31COONa (Sodium Palmitate, 45% soluble)
In this case, while wax reacts with NaOH, acid remains in the solution (as a salt) and alcohol
(cetyl alcohol) remains insoluble
• In case of fat (more acid compared to alcohol, both soluble)
8
10% Glycerol is produced.
When oil or fat is saponified, both glycerine and sodium salt is soluble, thus oil and wax can be
distinguished by the amount of alcohol produced.
1.17
Methods of Extraction of Oil
1. Mechanical Extraction Method or expression
In this process, seeds are cleaned and dehulled, steared and cooked at 220 °F- 250 °F for 15-20
minutes. Then they are pressed in continuous screw extruder/ expeller or Batch hydraulic press.
Normally continuous press is applied in most of the industry for higher yield. Expeller is used for
edible purposes. By mechanical method, about 80-82% oil can be extracted and used for edible
purposes.
2. Solvent Extraction Method
It maybe used alone or in combination with mechanical extraction. Solvent extraction gives 9899% oil which cannot be used for edible purposes. It is only used in industrial purpose because
dark color, odour and high content of free fatty acid (FFA) are obtained.
3. Combined Method
Both mechanical and solvent extraction methods are used. As the demand of oil increases, and
the oil bearing seed decrases, so maximum oil is to be extracted from oil seeds. By mechanical
method, only 81-82% oil can be extracted from seeds and used for edible purpose. On the other
hand, solvent extraction gives 98-99% oil which cannot be used for edible purpose. It is only used
in industrial purpose.
So, a combination of both mechanical and solvent extraction method is being widely used by
which we get 81-82% edible oil in mechanical method and the rest of the 18-19% oil is being
extracted by solvent extraction method and used for industrial processes.
9
(a) The seeds are cleaned and dehulled mechanically and the clean seeds are passed through then
cracking to convert it into thin flakes to make them easily permeable to steam in solvent
extraction.
(b) The flakes are sent directly into extractor for direct extraction and in case of combined
process they are fed to the screw-conveyed miscella for cooking.
(c) The cooked flakes are fed into the expeller and most of the oil is extracted at a pressure of
20000- 40000 psi.
(d) Solvent extraction is carried out in a countercurrent manner through a series of extraction
stages by circulating solvent over the flakes.
(e) The extraction oil with solvent is passed through a steam heater and then a flash film
evaporator.
(f) In the flash film evaporator (at low pressure and high temperature), the oil seperated from
solvent is recycled to the extractor
(g) The oil is further passed through the vacuum stripping column. The trace amount of solvent
is removed here as overhead product and the bottom product is finished solvent extracted
oil.
(h) The wet meal from the extractor is passed through the solvent recovery system and the
recovered solvent is recycled to the extractor.
(i) Finally the oil from the expeller and from solvent extraction system is passed through a
purification process.
10
1.18
Purification of Oil Extracted
Alkali such as NaOH or Na2CO3 is added to remove free fatty acids as foots by centrifugation. Foots
are used for manufacturing low quality soap such as washing soap. Bleaching is done in a purification
tank with adsorbent clays, filter air or fuller earth carbon. Bleaching removes most of the color and
odour present in oil. Traces of color and odour still present are removed by filtration.
Why purification is necessary?
1. For the removal of suspended or dissolved matter or colloidal dispersion
There’re three processes that are available for removal of suspended or colloidal material:
(a) Settling Process : The oil is taken to conical bottomed flask and the particles of higher density
than oil are allowed to settle down. Sometimes, the coagulation of dispersed materials is
facilitated by heating with open steam
(b) Degumming Process: This is done for sufficient removal of colloidal particles of oils especially
in case of soyabean oil. Oil is heated up to 200 °C for several hours in presence or absence
of absorbants (conc HNO3)
(c) Acid Wash: Crude oil may contain trace amount of foreign matters including heavy metals.
These are eliminated by acid washing in case of non edible oils. Oil is taken into a tank, 60
°Be H2SO4 is added with constant agitation & heating to 100 °C.
2. For the removal of free fatty acid
Free fatty acids are usually removed by adding an aqeous solution of NaOH (1%) or Na2CO3 to
the oil.
3. For the removal of bad odour
Adsorbent bleaching remove some of the odourizing constituents of treated oils but usually not
to a satisfactory degree. Steam vacuum deodorization is much more efficient and is carried out
at 130-230 °C and 28 mm Hg pressure. Superheated steam is used to remove odorous substances.
4. For the removal of colour
Decolourization can be done :
(a) By using an effective absorbant, e.g, charcoal, activated carbon, fuller earth carbon
(b) By using chemical agents like oxidizing and reducing agents. H2O2, Chromic Acid, Cl2, ClO2,
benzoic acid are commonly used as oxidizing agent. Chemical bleacing is done only for non
edible purposes.
11
(c) By exposing them to chemically active agents like ligands. Ligands absorb odour from oil.
(d) By solvent extraction process which only removes odour.
5. For the removal of saturated glycerides
Wintering/Chilling is carried out for the partial removal of saturated glycerides. Before making
oil or fat, they are cooled to about 5 °C and are kept at this temperature for a considerable time.
By cooling saturated glycerides (stearins) get solidified and can be filtered easily and the oil or
fat donot freeze easily.
1.19
Solvents that are used in the extraction process
• Carbon disulphide (CS2) : Boiling point 46 °C. Used in cold solvent extraction process (< 70 °C)
1. Advantages :
1) It can be completely removed from oil or fat
2) Oil or fat extracted by using CS2 is odourless
2. Disadvantages :
1) CS2 contains impurities which need to be removed
2) It is very inflammable and may cause serious explosion easily.
• Petroleum Ether : Boiling point 80-120 °C. It is also used for painting and other purposes.
1. Advantages
1) Not so inflammable and has no poisonous effect
2. Disadvantages:
1) Oil or fat extracted by this process is not completely odourless & cannot be used as edible
oil
• Carbon Tetrachloride (CCl4) : Boiling point 76.5 °C.
1. Advantages :
1) Very volatile and not inflammable
2) It leaves odourless extract
2. Disadvantages:
1) It attacks metals and has poisonous effect
2) Costly solvent
• Trichloro Ethylene : Have toxic effect and costly
• Ether : Have toxic effect and costly
• Chloroform : Costly Solvent
1.20
Hydrogenation of Oil
Hydrogenation or hardening as applied to fats and oils may be defined as the conversion of various
unsaturated radicals of fatty glycerides into more highly or completely saturated glycerides by the
addition of hydrogen in presence of a catalyst.
12
Why is Oil Hydrogenated?
1. Some oil such as whale oil, cottonseed oil donot have wide use. After hydrogenation, they can be
used in the manufacture of good hard soap.
2. Whale oil, peanut oil, cottonseed oil, linseed oil etc donot keep well. Moreover, some of them
such as whale oil, linseed oil cannot be used for edible purposes because of their bad odour and
taste. On hydrogenation to proper degree, these oils can be converted into edible fats.
3. Margarine or artificial butter can be obtained from hydrogenated oils.
1.21
Process of Hydrogenation
The process of hydrogenation is carried out by passing H2 gas through the oil kept at about 140-180
°C and containing finely divided Ni in suspension, until the absorption of H2 takes place to the proper
degree indicated by the determination of iodine value.
Optimum Conditions for the process
1. The hydrogen gas must be pure, if it contains trace impurities such as P, S, Ar, Cl then these
impurities react with Ni catalyst and thus destroy the activity of the catalyst.
2. Oil must be pure, it must be free from free fatty acid (FFA). FFA reacts with Ni to form Ni soap
which is soluble in the oil and can act as poison.
3. In order to prevent Ni from catching fire, it is carefully transferred to the oil out of the contact
of air.
4. In order to keep the Ni particles in free suspension and and to bring oil in close contact with H2,
the mixture of oil, H2 gas and catalyst is agitated.
5. The process of hydrogenation is an exothermic process. According to the Le-chateliers principle,
the reaction is favoured by low temperature but the reaction rate decreases with decrease in
temperature. Hence, it is necessary to select an optimum temperature at which yield is maximum
in minimum time. In this case, optimum temperature is between 140-180 °C.
6. Catalyst must be in the form of Ni oxide or Ni formate.
13
1.22
Chemistry of Hydrogenation
Ni Catalyst
(C17 H31 COO)3 C3 H5 + 3 H2 −−−−−−→ (C17 H33 COO)3 C3 H5
190 °C
Ni(HCOO)2 · 2 H2 O −−−→ Ni + 2 CO2 + 2 H2 O + H2
Ni(OH)2 + H2 −−→ Ni + 2 H2 O
NiCO3 + H2 −−→ Ni + CO2 + H2 O
2 Ni – Al + 6 NaOH −−→ Ni + 2 NaAlO3 + 3 H2
Total Hydrogenation Can be Divided into three process: Impure Hydrogen
Impregnated
with electrolytic H2 and O2
Mixture is then heated over Pt catalyst
Mixture is passed over
quick lime
Pure H2
The main impurities of H2 are CO, H2S, PH3 which are impregnated with electrolytic H2 and O2. The
mixture is then heated over Pt gauge catalyst. The impurities burn along with some H2 and form CO2,
P2O5, SO2 etc. The resultant gas mixture is passed over quicklime where moisture and acidic oxides
are absorbed and very pure H2 is obtained.
1.23
Preparation of Ni Catalyst
• From decomposition of nickel formate,
190 °C
Ni(HCOO)2 · 2 H2 O −−−→ Ni + 2 CO2 + 2 H2 O + H2
• From precipitating Ni salts and then reducing it at high temperature in current of H2 gas
Ni(OH)2 + H2 −−→ Ni + 2 H2 O
NiCO3 + H2 −−→ Ni + CO2 + H2 O
• Raney Ni is obtained by treating a powdered alloy of Ni & Al with caustic soda.
2 Ni – Al + 6 NaOH −−→ Ni + 2 NaAlO3 + 3 H2
1.24
Purification of Oil
Oil contains some free fatty acids (FFA) which hampers the total oil quality and must be removed by
purification. Oil is taken in a tank and heated to 30 °C by steam and oil purified by the given procedure
14
:
Oil
Agitation with NaOH
Mixed with water to remove excess NaOH solution
The
moisture is removed by heating the oil at about 50 °C and agitating the oil with compressed air
The last traces of moisture are removed by further heating under vacuum
Pure Oil
Moisture must be removed completely from oil as it may hydrolyze the oil at high temperature and
pressure to form fatty acid.
1.25
How drying Oils are utilized?
Linseed Oil : Paints, varnishes, floor coverings, lubricants and greases
Tung Oil : Paints and Varnishes
1.26
Mechanism of Rancidity with Chemistry
Rancidity is the condition in which incomplete oxidation or hydrolysis of fats and oils takes place that
spoils the food. Rancidity occurs when food is exposed to light, air, moisture or to any bacterial action.
• Unsaturated fats that are exposed to air convert into hydroperoxide.
• This forms volatile aldehydes, hydrocarbons, esters, alcohol, etc which results in an unpleasant
odour and taste.
• Rancidity or Rancidificiation is produced by the aerial oxidation of unsaturated fat in foods and
other products leading to unpleasant flavours or odours.
• Rancidity can be classified into 2 types such as hydrolytic rancidity and oxidative rancidity.
Rancidity refers to the oxidation of unsaturated fats or oils that results in a bad smell and taste. When
oxygen molecules interact with oil or fat, the normal composition of the oil/fat is damaged which causes
a change in taste and smell, and thus the oil/fat is not recommended to be consumed.
• Rancidity leads to Rancidification.
• Rancidification is a condition produced by the aerial oxidation of unsaturated fatty acid glycerides
present in oil and fat that are noticeable by their rotten smell or taste.
• When unsaturated fatty acid glycerides are exposed to sunlight, it converts to hydroperoxide and
breaks down into volatile aldehydes, esters, alcohols, hydrocarbons, ketones, etc., some of which
have an unpleasant odour.
Examples of Rancidity : Oil becomes rancid due to the decomposition of triglycerides it contains and
sometimes milk turns rancid due to not heating it in the humid atmosphere.
Butter changes its smell and taste when it is kept in an open atmosphere for a longer duration.
Rancidity Process : Rancidity happens in food products that have oil and fatty acids in them. Fatty
acids are mainly formed of fats, steroids, and cholesterol. These are saturated or unsaturated carboxylic
acids with a long aliphatic chain. Any substance turns rancid in basically three steps:
• Initiation Reaction: Initiation reaction leads to the formation of radicals on the food substances
because of external factors like heat and air that stimulates this reaction. A radical is an atom
molecule or ion that has an unpaired electron. These unpaired electrons make radicals very
reactive chemical substances.
RH −−→ R – + H+
• Propagation Reaction: In this step, oxygen present in the atmosphere gives rise to peroxides.
These peroxides react further with unsaturated fatty acids and then produce new radicals.
15
R – + O2 −−→ ROO – (peroxide)
• Termination Reaction: In the third stage, two radicals combine together to form a new single
bond.
ROO – + ROO – −−→ End Products
• Fats, Lipids and other compounds are decomposed at the end of the rancidification. The process
leads to the formation of highly reactive molecules. Thus, food starts smelling unpleasant and
tastes bad after rancidity.
Types of Rancidity:
• Hydrolytic Rancidity
Hydrolytic Rancidity refers to the smell or odour that occurs when free fatty acids are released
and triglycerides are hydrolyzed.
– Triglyceride is a combination of three fatty acids present in oily food.
– Hydrolytic Rancidity occurs more quickly in the presence of enzymes like lipase and with
moisture and heat.
– It results in the hydrolysis of the fats with the liberation of either one or more volatile fatty
acids.
• Oxidative Rancidity
Oxidative Rancidity causes oxygen damage to a food substance. It occurs with unsaturated fats.
– The natural oil structure is damaged and interrupted by oxygen molecules in such a way
that it changes its colour, taste, and smell.
– It leads to the formation of toxic compounds like peroxides that damage Vitamins A and E
in foods.
– In Oxidative Rancidity, unsaturated fatty acids of glycerides are oxidized at their double
bonds.
– Thus, this reaction causes the release of ketones, volatile aldehydes, and acids.
– It can be prevented by an oxygen-free atmosphere, light-proof packaging, and the addition
of antioxidants.
16
Prevention of Rancidity : There are many possible ways to prevent Rancidity. Some of them are:
• Antioxidants can be added to foods that contain oils and fats to slow down oxidative deterioration.
• To slow down the process of rancidification, food can be stored in airtight containers.
• Vacuum packing can be done to keep oxygen out.
• By adding inert gas such as nitrogen to the bag to replace oxygen.
• Food items can be kept in the refrigerator. It will reduce the rate of most reactions that take
part in rancidity.
• By storing food in dark places.
Factors affecting Rancidity : There are various factors that affect rancidity. Some of the factors
are discussed below:
• Oxygen: The primary cause of rancidity is exposure to oxygen. Oxygen is more soluble in fats,
which leads to food damage and oxidation by releasing free radicals.
• Microorganisms: Many microorganisms release an enzyme known as lipase which leads to the
hydrolysis of lipids. These microorganisms use their enzyme on food materials and destroy their
chemical composition.
• Physical factors: Physical factors like Heat, light, and temperature plays an important role in
rancidification. Heat and light stimulate the process of oxidation and are the main source for the
production of free radicals. Light promotes the decomposition of unsaturated fatty acids.
• Trace elements: The rate of rancidity can be increased by trace elements like Fe and Zn. This is
another important factor that affects rancidity.
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1.27
Advantages and Disadvantages of Mustard Oil
Mustard oil has about 60% monounsaturated fatty acids(MUFA)(42% erucic acid and 12% oleic acid);
it has about 21% polyunsaturated fats(PUFA) (6% the omega-3 alpha-linolenic acid(ALA) and 15%
omega-6 linoleic acid(LA)) and it has about 12% saturated fats.
This optimum ratio of omega-3 and omega-6 fatty acids and low content of saturated fats makes
mustard oil more beneficial and preferred over several other oils available in the market.
Mustard oil is reddish-brown or amber in colour and is known for its strong smell and pungent
sharp flavour. The pungency of mustard oil is due to the presence of allyl isothiocyanate. This fatty
vegetable oil is obtained by pressing mustard seeds.
Advantages:
• Cardioprotective Effects
Mustard oil is healthy edible oil it is low in Saturated fatty acid (SFA), high in MUFA and PUFA,
especially alpha-linolenic acid and has a good LA: ALA ratio (6:5).
• Reduces Cough, Colds
Since ancient times, mustard oil is used to soothe colds, coughs and other respiratory illnesses
and allergies.
• Anti-bacterial, Anti-fungal Anti-carcinogenic Properties
Glucosinolate, available in mustard oil which accounts for antibiotic, fungicidal and cancer prevention qualities, serves as a therapeutic for human health. Ally Isothiocyanate serves as an
anti-fungal agent, which protects food from fungal growth and reduces infection.
• Strengthens Red Blood Cells
Mustard oil reduces cholesterol and improves the membrane structure of red blood cells (RBC)
• Acts as a Stimulant
Mustard oil is a natural stimulant that is known to stimulate our sweat glands, thereby improving
blood circulation throughout the body.
• Relief from Joint Pain Arthritis
Omega-3 fatty acids help to ease stiffness and pain caused due to arthritis. A regular massage
with mustard oil helps in relieving aching joints and muscles.
• Immunity Booster
The optimum range of omega-3 and omega-6 fatty acids and vitamin E provides the required
nutritive value and boosts our immune system.
• Reduces Diabetic Hazards
The amount of vitamin E in the alpha-tocopherol present in mustard oil has beneficial effects to
control diabetic hazards.
• Boosts Appetite
Mustard oil is extremely useful and can be consumed by people who are underweight. It makes
you want to eat more by pumping your stomach and facilitates the secretion of gastric juices and
bile which is known to create the feeling of hunger.
• May slow the growth of cancer cells
Research suggests that mustard oil may also help in slowing down the growth and spread of
certain types of cancer cells in your body.
• Trans fat is the major cause of insulin failure and high oxidation of fat. The absence of trans fat
in mustard oil thus helps maintain insulin levels, which in turn regulates our blood sugar levels.
18
Disadvantages
• Mustard oil contains Erucic acid. As per research in the United States, Erucic acid has toxic
effects on the heart at high enough doses. Consumption of mustard oil is thereby banned in the
U.S.A.
• Long-term topical application of mustard oil can have harmful effects on the skin. It can even
cause minor to major skin blisters.
• Excessive consumption of mustard oil can cause rhinitis in which the mucous membrane tends to
get inflamed.
• Pregnant women should avoid the consumption of mustard oil as it contains a few chemical
compounds that are harmful to them as well as the growing foetus.
• Too much mustard oil causes anaemia or diarrhoea.
1.28
Canola Oil
Canola oil is oil made from crushed canola seeds.
Benefits of Canola Oil
• Canola oil is generally considered a “healthy” oil because it is very low in saturated fat (7%).
Like olive oil it is high in monounsaturated fat (63%)
• Canola oil also contains a significant level of polyunsaturated omega-3 (ω-3) fat (9-11%)
• In addition, canola oil contains significant amounts of phytosterols (about 0.9% by weight) that
reduce the absorption of cholesterol into the body.
• Because of its light flavor, high smoke point, and smooth texture, canola oil is one of the most
versatile cooking oils.
Canola Oil Disadvantages
• There were concern that most canola is chemically extracted using a solvent called hexane, and
heat is often applied which can affect the stability of the oil’s molecules, turn it rancid, destroy
the omega-3s in it, and can even create trans fats. There is no evidence to substantiate any
risk or danger to consumer health when foods containing trace residual concentrations of hexane
are ingested. It has been estimated that refined vegetable oils extracted with hexane contain
approximately 0.8 milligrams of residual hexane per kilogram of oil (0.8 ppm). There appears
to be very little reason for concern about the trace levels of hexane in canola oil. Also, canola
oil does contain very low levels of trans-fat, as do all oils that have been deodorized. When
canola oil is deodorized it is subjected to temperatures above 200ºC (as high as 235ºC, 455°F)
under vacuum for various lengths time to remove volatile components such as free fatty acids and
phospholipids. During exposure to these high temperatures a small amount of the unsaturated
fatty acids, especially the essential ω-6-linoleic and ω-3–linolenic acid, are transformed into transfatty acid isomers. Because of earlier studies showing that even quite low levels of trans isomers
of ω-3–linolenic can have adverse effects of blood cholesterol fractions, the processes used for
deodorization have been modified to limit the production of these compounds. Thus the amount
of conversion of ω-3–linolenic acid is negligible.
Thus it can be stated that, despite a risk of trans fat production in canola oil by the cost of necessary
ω-3–linolenic acid, still canola oil is the safest oil now and discussed worldwide.
19
1.29
Wijs Reagent
Wijs reagent is basically solution of iodine monochloride in glacial acetic acid. Wijs method is a
method for determining the iodine number (as of an oil or fat) that consists in adding a solution of
iodine monochloride in glacial acetic acid and estimating the excess of unused halogen by titration with
sodium thiosulfate.
1.30
Foots
The product obtained from the neutralization reaction between free fatty acids(FFA) and alkali like
NaOH or Na2CO3 (During purification of extracted oil) is referred to as foots. Foots are used to produce
low quality soap, such as wash soap.
1.31
Butter & Margarine
Butter
• Butter is a dairy product made by churning cream. Conversely, margarine is a product designed
to imitate butter. While butter is mainly composed of dairy fat, margarine is typically produced
from vegetable oils.
• Butter has a large proportion of lower fatty acid than lard and tallow. Thus butter has a high
saponification.
– Volatile acids in butter
1.
2.
3.
4.
Butyric Acid : C3H7COOH
Caporic Acid : C5H11COOH
Caprylic Acid : C7H15COOH
Capric Acid : C9H19COOH
– Non- Volatile acids in Butter
1. Lauric Acid : C11H23COOH
2. Myristic Acid : C13H27COOH
3. Stearic Acid : C17H35COOH
• Butter has short chain acids, small chain acid are volatile, so butter has scent.
• Butter from grass-fed cows contains much greater amounts of heart-healthy nutrients than butter
from grain-fed cows. Butter from Grass-Fed cows contain Vitamin K2, Conjugated Linoleic Acid,
Butyrate, Omega-3 which are health beneficial nutrients.
• Risk of taking butter is it containts high amount of saturated fat which causes heart disease.
• Butter is also high in cholesterols.
Margarine
• Margarine is often rich in polyunsaturated fat. Studies show that eating polyunsaturated fat
instead of saturated fat may reduce the risk of heart problems.
• Vegetable oil-based margarine is often rich in phytosterols. While phytosterols may reduce the
levels of LDL cholesterol, they don’t seem to affect heart disease risk.
• Many margarines are high in trans fat, which is linked to an increased risk of chronic disease.
However, because of negative publicity and new laws, trans-fat-free margarines are becoming
increasingly common.
20
• Margarine is often very high in polyunsaturated omega-6 fatty acids. Some scientists believe
excessive omega-6 intake may promote inflammation, but controlled studies do not support this
theory.
• Margarine smells faintly, not strong smell like butter, due to absence of volatile acids as in butter
1.32
What is degumming? Why it is important?
Degumming means the removal of phospholipids, proteins and carbohydrates, vegetable gums and
colloidal components that negatively impact the keepability of an oil, irrespective of whether they are
really gums or not.
Importance of degumming:
• Non degummed oil easily forms an emulsion during alkaline refining process which increases the
difficulty in operation, oil refining loss and auxiliary material consumption. This is one of the
primary reason why degumming is done.
• Non degummed oil will increase the consumption of adsorbent and reduce discoloring effectiveness.
So, degumming is a must.
• The gum impurities will impact the stability of oil, through decomposition it may darken the oil,
so removal of it is necessary.
• The gums will spray on the meal if the oil is not degummed, so it is important.
1.33
What’s Wintering/ Chilling agent?
Wintering agent is a solvent that is used to carry out the unwanted saturated glycerides out of the oil/
fat, cold temperature is maintained, the oil gets solidified slowly, and when the oil is partially solidified,
the saturated glycerides along with the solvent which have become fully solid can be filtered or scooped
out. The saturated glycerides are responsible for the oil to freeze at moderately cold temperatures.
When these are removed, the oil doesn’t freeze easily anymore.
1.34
What are the purposes of Non-edible Oils?
• Used as fuel and biofuel
• Producing good soap
• Producing detergent
• Paints and varnishes
• Rubber and plastic industry
• Manufacturing of candles
• Oleo Chemical Industries
1.35
Why paraffin was is called unsaponifiable wax?
As it’s constituents are mainly long chain alkanes with the general formula CnH2n+2, they are chemically
inert in nature and doesn’t form soap with NaOH or KOH. That’s why they are called unsaponifiable
wax.
21
1.36
Difference Between Fatty Oil & Mineral Oil
Distinguish Fatty Oil & Mineral Oil
Fatty Oil
Mineral Oil
These are derived from animal and vegetable They are derived from fractional distillation
sources like palm oil, olive oil, codliver oil etc of crude petroleum. Used to make gasoline
They contain fatty acids, so these are actual They don’t contain fatty acids, they are not
fat
true fat.
They are bio-degradable organic compounds These are also organic compounds but barely
bio-degradable
Can spoil naturally with time
Shows low spoilage rate
Less impact toward environment pollution
They cause environment pollution
They are nutrient rich and edible
They are not meant for eating
It can reproduce easily
It takes millions of years to reproduce
Not costly
Very costly
Not odourless and colorless
Odourless and colorless
1.37
Distinguish between Essential Oil and Fatty Oil
Distinguish between Essential oil & Fatty Oil
Essential Oil
Fatty Oil
They are distilled from plant parts
They are pressed from seeds
Not involved with seed germination and early Necessary food for seeds to germinate
growth
Essential to the life processes of the plant
Not essential to the life processes of the plant.
Tiny molecules
Large Molecules
Molecules built from rings and short chain
Molecules built from long chain
Aromatic and volatile
Non aromatic and non volatile
Not greasy to touch
Greasy to touch
Do not spoil or turn rancid
Can spoil and turn rancid
Pleasant odour
Non pleasant odour
Anti bacterial, antiseptic
Not anti bacterial or antiseptic
1.38
Distinguish between Edible Oil and Non-edible Oil
Distinguish between Edible Oil and Non-edible Oil
Edible Oil
Non-edible Oil
They are based on vegetable sources (oil seed These can be extracted from vegetable
grains and plant fruits)
sources, petroleum oils or animal fat
These are mainly used for direct human con- They have industrial usages such as fuel and
sumption as food intake
bio-fuel, producing soap, paintings
Contains various nutritional elements and They are toxic for health
thus are healthy
They donot need chemical processing
Different chemical processing are desired.
They are more expensive
They are comparatively of lower price
1.39
Which solvent is the best for edible oil extraction purpose?
Hexane is the best solvent for edible oil extraction purposes, it has the following properties that make
it a very good solvent :
• Easy oil recovery
• Narrow boiling point ((63–69 °C))
22
• Excellent solubilizing ability
• It is considered non toxic. It has been observed that vegetable oils obtained using hexane solvent
contains 0.8 milligrams of residual hexane per kilogram of oil (0.8 ppm). Intake of hexane in this
little amount has no proven detrimental affect to the human health.
• It is both colorless and odourless liquid, which is a pre-requisite for being solvent of edible oil
extraction.
• It releases no poisonous chemicals into oil during operation.
23