The document discusses the physical refining processes for groundnut oil and coconut oil. It explains that physical refining aims to remove undesirable impurities like free fatty acids and phospholipids from crude oils using physical and chemical processes, while preserving valuable components. The key steps in physical refining include degumming to remove gums, bleaching to reduce color pigments and metals, and deodorization to remove odors and flavors. For groundnut oil specifically, the document outlines that alkali refining is commonly used, which involves gum conditioning, neutralization, bleaching, and deodorization.

1. PHYSICAL REFINING OF OILSEEDS:
GROUNDNUT OIL, COCONUT OIL
TECHNOLOGY OF CEREALS, PULSES AND OILSEEDS
Date of Presentation : 07th December 2022
PRESENTED TO: Dr. Shubham Rohilla
PRESENTED BY: Priyanka
ROLL NO.: 2124612
MSc. Food Technology (3rd semester)
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2. INTRODUCTION: GROUNDNUT OIL
Groundnut oil is a vegetable oil derived from groundnuts/peanuts . The oil
includes strong peanut flavor and aroma. It may be a delicate tasting vegetable
oil expressed from groundnut kernels.
It is widely utilized in American, Chinese, South Asian and Southeast Asian,
each for general preparation and within the case of roasted oil or for added
flavor. It is widely used in preparation as well as cooking, basting and therefore
the manufacture of margarines and shortenings.
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3. Benefits of Groundnut Oil
 Improves insulin sensitivity
 Lowers the risk of cancer
 Great source of vitamin E
 Improves Blood circulation
 Prevents arthritis
 Lowers the signs of ageing
 Characteristic antioxidant content
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4. Introduction: Coconut oil
Coconut oil is one of the most well known and utilized product derived from mature coconut
meat or kernel. It is generally obtained by drying the coconut meat using different methods and
then extracting the oil from granulated dried kernel through use of high pressure mechanical
press or combination of high pressure mechanical press and solvent extraction.
Coconut oil is consumed as food while a significant amount goes into the oleo-chemical industry.
It is also used in food preparation. Additionally, the shell is used for various fibres, charcoal, and
other products not yet fully commercialized.
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5. Benefits of Coconut oil
 Coconut kernel is nutritious and rich in fibre, vitamins and minerals.
 Coconut is a natural anti-bacterial and anti-viral food.
 You can get the benefit of coconut fibre by eating fresh or dried coconut and adding coconut to
recipes.
 A multitude of studies have demonstrated that dietary fibre protects against heart attacks and
strokes.
 Diet rich in coconut kernel prevent digestive disorders and it regulates bowel activity.
 It restores thyroid functions and increases the metabolic rate.
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6. Refining
 Refining is the important processing steps that reduces or removes certain undesirable impurities from the crude
oil. In the refining, physical and chemical processes are combined to remove undesirable components from the
crude oil. The impurities includes major and minor non- triglycerides.
 Crude oil produced by rendering, mechanical extraction or solvent extraction contains variable amount of non-
glyceride impurities. The impurities in high grade animal fat and certain vegetable oils i.e. coconut oil,
groundnut oil, palm kernel oil consists mainly of free fatty acids.
OBJECTIVE: Free fatty acids causes soapy flavor in oil. Thus the main objective is to remove objectionable
impurities present from the oil with least possible damage to either triglycerides, tocopherols or other desirable
impurities.
Term refining refers to any purifying treatment designed to remove the free fatty acids, phosphatides, etc. it excludes
bleaching and deodorization.
Bleaching refers to treatment designed to reduce the color of oil.
Deodorization is term used to treatment intended for removal of traces constituents present which may give rise to
flavors and odors.
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7. Objective of Refining Process
 Removal of undesired products from crude oil
1. Free fatty acids [FFA]
2. Phospholipids [PL]
3. Oxidized products
4. Metal ions
5. Color pigments
6. Other impurities
 Preservation of valuable components
1. Vitamin E or tocopherol : Natural antioxidants
2. Sterols, sterols esters and tocotrienols
 Minimize oil losses
 Protection of oil against degradation
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9. REFINING PROCESS
 There are two primary methods for refining vegetable oils :
o Physical refining
o Chemical [alkali ] refining
✓ Batch refining
✓ Continuous refining
PHYSICAL REFINING: Physical refining helps to reduce the total phospholipids in the oil to a lower
level.
☞ The bleaching in addition removes the remaining phospholipids, traces metals, oil decomposition products
and color pigments such as chlorophyll, carotene, etc. from the oil.
☞ Free Fatty acids, mono-glycerides, oil decomposition products are removed in deodorization process
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10. PHYSICAL REFINING PROCESS :
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11. CHEMICAL REFINING:
☞ Chemical refining is widely used for vegetable oils. In this process, the crude oil is pre-treated
with phosphoric acid and then neutralised with caustic solution i.e. Sodium Hydroxide.
☞ The caustics reacts with Free Fatty acid [FFA] in crude oil and produces soap. The soap is
then separated from the refined oil in primary centrifuge; the remaining soap is removed from
the oil via water washing and separating the oil and water in water washing centrifuge.
This method is used in industry for refining of
✓ Crude soybean oil
✓Degummed soybean oil/ canola oil
✓Crude sunflower oil
✓Crude and degummed cottonseed oil
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14. Degumming
Degumming is to reduce the phosphorus content to low as low levels i.e. < 10
ppm as residual gums in oil can get charred during high temperature treatment
and can cause darkening of oil in color.
Aim of Degumming operation :
1. The emulsifying action of phospholipids increases oil losses during alkali
refining.
2. Gums leads brown discoloration of oil after heating during deodorization.
3. Salts may be formed with copper, magnesium, calcium and iron accelerating
oxidative degredation of oil.
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15. GUMS : There are two types of Gums:
o Hydratable Gum
☞ Easy to remove by simple water washing
o Non- Hydratable Gum
☞ Hard to remove from oil
☞ requires the use of acid to convert to hydratable for complete removal.
Degumming Processes
1. Water Degumming
2. Acid Degumming
3. Enzymatic Degumming
4. Membrane Degumming
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16. Water Degumming
 Water degumming is the Hydration process where the oil is heated with about 1% water at 65º C to
hydrate the gums or warm water is added to the crude oil at 80-85º C and the mixture is agitated slowly
for approx. 20 min.
 The water dosage used is usually based on the expected amount of phospholipids in the crude oil.
 The hydratable phospholipids agglomerate at the interface of the oil and water, capturing some non-
hydratable phospholipids with them. This method does not reduce the phospholipids content at desired
amount.
 Oil trapped by phospholipids forming an emulsion
referred to “gums” or “wet gums”.
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17. Acid Degumming
 Acid degumming is particularly suitable for processing oils with low gum contents such as palm
oil, coconut oil or animal fats. Oil is degummed with 0.2% phosphoric acid at 60º C for about 15
min after which gums are removed by centrifugation and oil is water washed to remove residual
acidity.
 STEPs: Acid Degumming
✓ Oil is heated to 60- 70ºC.
✓Acid [0.05-0.2 % Phosphoric acid] is added
and mixed.
✓Allowed hydration mixing time for 30 min.
✓ Centrifugal separation of hydrated gums.
✓ Vacuum drying of degummed oil.
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18. Bleaching
Bleaching is the physical process where the impurities in the oil are removed with help of
absorbent. Degummed oil is then bleached further to reduce phosphorous content and metal ions
in the oil.
☞ oil is heated to about 85 degree Celsius under vaccum to remove entrained moisture and
entrapped air. Then it is mixed with 0.5% bleaching earth and allowed to remain in contact for 15
min. before oil is filtered to remove spent bleaching earth.
☞ After bleaching, phosphorus content of oil is generally reduced to less than 5 ppm which is
required to get good quality de- acidified oil.
☞ Color of oil : RED : Carotenoids
GREEN : Chlorophyll
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19.  Methods of bleaching : There are two different methods of bleaching as
discussed following
1) Batch method: It involves open, cylindrical cone bottom kettle with
mechanical agitators and steam heating coils. The agitators are designed to
maintain the earth in suspension and provide efficient stirring without aeration
at the surface. During this operation, the amount of earth is added to kettle at
70-80º C and oil is continued for 15- 20 min. and oil is pumped through the
filter press.
2) Continuous method: Continuous vaccum bleaching protects the oil from
harmful effects of oxidation even more effectively than batch vaccum
bleaching since better de-aeration is affected by spraying the oil into vaccum
that can ordinarily be obtained by agitating a large batch under vaccum.
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20. Benefits of Bleaching
o Reduces the chlorophyll and some of the other color pigments i.e. Carotenoids present in
the oil.
o Reduces trace metals such as Ca++, Mg++, Fe++, Na+, etc.
o Reduces the level of non hydratable PL in the refined oil.
o Remove decomposition products such as aldehydes, ketones, polymers, non- triglycerides
production from oil oxidation.
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21. Filtration
Because of the continuous nature of the refining plants the bleacher is normally supplied with two
filters. The oil supply to the filter and operating cycles of the filter can then be automated.
It is utmost important that the oil obtained form the bleaching earth filtration should be clear, bright
and free from the clay/ earth particle.
The filters used in this process are:
o Plate and Frame filter
o Vertical leaf tank or pressure leaf filter
o Centrifugal self cleaning filter
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Figure: Plate and frame filter
Figure : Centrifugal self
cleansing filter
Figure: Vertical leaf tank

23. Deodorization
Deodorization is usually the last stage of refining process of edible oils. It is the process in which the
odors and flavors od fats and oils are removed. Natural oils and fats contain significant amount of
odors which renders them unacceptable for use in food products.
The flavoring compounds can be boiled out of non- distillable oil to produce a bland product.
Deodorization of refined and bleached oil is carried out under vaccum and at absolute pressure of 1-
6 mm of mercury.
Processing steps:
1. Deaeration: To remove dissolved oxygen [ to prevent oxidation] and moisture from oil.
2. Heating: To a temperature of 240-260 ºC under vaccum.
3. Steam distillation : Steam blowing through the oil at 260º C under high vaccum.
4. Citric acid treatment: As chealting agent for trace metals.
5. Cooling: Cool to room temperature for storage.
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24. Functions of Deodorisation:
 Reduces free fatty acid [FFA] to <0.05%, preferably < 0.03%.
 Removes the odoriferous compounds such as aldehydes, ketones, hydrocarbons, alcohol etc.
produced from decomposition of the oils.
 Any residual traces metals, picked by the oil after bleaching are reduced via citric acid
treatment.
 There is some increase in the amount of polymers, conjugated dienes and other oil
decomposition products.
 There can be a very small but detectable increase in the trans fatty acids content in the oil ,
depending on the deodorizer temperature.
Factors affecting Deodorisation process:
 Deaeration
 Operating temperature and pressure
 Cooling of oil
 Citric acid content
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25. Groundnut oil Refining
Groundnut oil is usually refined by alkali neutralization process. For alkali refining following
processing step takes place:
o Gums conditioning & Neutralization
o Bleaching
o Deodorization
Gums conditioning & Neutralization: Groundnut oil first treated with citric acid and followed by
caustic soda lye to neutralize the fatty acids and conditioning of phospholipids. Neutralization
reaction produced the sodium salt of fatty acids which removed through centrifugal separator and
clean oil washed by hot water to remove the traces of soap.
Washing: Neutralized oil treated with hot water and separated through centrifugal separator to
remove the traces of soaps from neutral oil.
Drying: Removal of moisture under vacuum.
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26. Figure: Degumming process
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27. “Bleaching” is a process of selective removal of pigments and impurities by the physical and
chemical interaction of an adsorbent with an oil or fat to improve its quality.
This process refers to the art of removing:
 Color pigments
 Dirt, Trace metals
 Removal of polycyclic Aromatic compounds
 Phospholipids
Deodorization of Groundnut oil is a vacuum stripping process in which a given amount of a
stripping steam is passed for a given period of time through hot oil at a low pressure which
removes various volatile components and fatty acids to increase the self-life, and maintained the
good odor free test of product.
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28. Figure: Bleaching process
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29. Figure: De-odorisation process
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30. QUIZ ?
o Which acid is present in groundnut oil?
o What is the color of groundnut oil?
o Why degumming of oil done?
o What is removed during oil refining?
o Which part of groundnut contain oil?
o Difference between physical and chemical refining?
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