1

Gums conditioning and

neutralization of edible oil

and its physicochemical

analysis.

INTERNSHIP PROJECT REPORT

Submitted by:

Rahul Kumar

Rajat Sable

DEPARTMENT OF CHEMICAL

ENGINEERING & TECHNOLOGY

IIT BHU, VARANASI

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BONAFIDE CERTIFICATE

This is to certify that this project report entitled "Gums conditioning

and neutralization of edible oil and its physicochemical analysis "

submitted to B.L. Agro Oils Pvt. Ltd, is a bonafide record of work

done by " Rahul Kumar and Rajat Sable " under my supervision

from " May 16, 2016" to "June 25, 2016 "

Mr. Ajay Singh

Production Manager

B-4 UNIT

B.L.Agro Oils Pvt. Ltd

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Acknowledgement

I wish to express my sincere gratitude to Mr. Ghanshyam Khandelwal,

Managing Director for providing me an opportunity to do my internship and

project work in B.L. Agro Oils Pvt. Ltd.

I sincerely thank Mr. S.P. Singh, Independent Director and Mr. Ajay Singh,

Production Manager (B-4 Unit) for their guidance and encouragement in

carrying out this project work. I also wish to express my gratitude to Mr.

Abhishek Paul, HR Manager and all the officials and other staff members of

B.L. Agro Oils Pvt. Ltd. who rendered their help during the period of project

work.

I also thank Mr. Pradeep Kumar Mishra, Head of the Department, Chemical

Engineering, IIT-BHU for providing me the opportunity to embark on this

project.

Finally, I thank the Almighty God, without whose mercy my training could

never have been accomplished.

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TABLE OF CONTENTS

SR NO. Title Page No.

1. Introduction......................................................... 6

2. Physicochemical properties of oil........................ 7

3. Refinery Section................................................... 8

3.1 Short Mix Section........................................... 8

3.1.1 Degumming......................................... 8

Components Removed....................... 8

Advantages of Degumming................ 8

Types of Degumming......................... 9

Apparatus.......................................... 11

3.1.2 Neutralization.................................... 15

3.1.3 Short Mix Procedure.......................... 17

3.2 Bleaching......................................................... 19

3.2.1 Key Parameters......................................... 19

3.2.2 Components Removed............................ 21

3.3 Dewaxing......................................................... 22

3.4 Deodorization................................................. 23

3.4.1 Operating Variables............................ 23

3.4.2 Components Removed....................... 24

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3.5 Winterization............................................... 26

3.5.1 Winterization Principle........................ 26

3.5.2 Processing Variables............................ 27

4. Treatment of Byproducts....................................... 29

4.1 Gums....................................................... 29

4.2 Soap........................................................ 30

5. References............................................................. 31

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INTRODUCTION

Edible oils are refined to remove impurities which are unfit for consumption.

Also, from the market point of view, imparting proper colour to the oil,

removing its odour etc. are quite essential and greatly affects the brand.

There are majorly three types of oil :

Kolhu Oil:

This is the simplest process to extract the mustard oils from the plant seeds.

This is to be done by compressing the seeds between the two plates, due this

compressive pressure the seed gets break down and the oil gets ripped out.

This is the purest form of oil. This is exclusive for mustard oil.

Expeller Treatment:

Generally this is the second step of extraction of oils from the seeds. In this we

simply increased the compressive force to extract more oils. In this we use

Kolhu’s by-product as a feed. This contents many impurities and need to

refined in many steps to make it edible.

Solvent Extractor:

Here we generally use hexane as a solvent . This process is based on the LLE

(Liquid Liquid Extraction),where the cake with oils is extracted using hexane.

Now the product contains oil and hexane and now hexane is separated out

using distillation. This oil needs to be refined.

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Physicochemical Properties of Oil

The chemical and physical properties are collectively called physicochemical

properties of oil and fats.

The following test are carried out to analyse its properties-

MIV (Moisture Insoluble Volatile)- This is to be done to determine the

moisture and volatile insoluble content in the oil sample.

FFA (Free Fatty Acid)- This is one of the major test of crude oil which

signifies the quality of the crude oil. More FFA content is harmful to

human health and it also decreases the smoke point of the oil.

Colour Determination- It is simply a colour determining process used to

compare with the standard.

Bleachability- It measures the ability of the oil to be bleached using

bleaching earth.

Cloud Point- It helps in the determination of maximum temperature at

which crystal of saturated parts starts to form.

Melting point- It is measured to compare with the standard value.

Peroxide Value- It measures the detoriation of oil in meq/kg.

Iodine Value- It is measure of the degree of unsaturation in the oil.

Phosphorous Content- It is one of the important test of crude oil.It helps

in the selection of degumming process which is to be more effective.

Refractive Index- It is carried out for the crude as well as the final

product. It is measured to identify the type of oil.

Saponification Value- It is defined as the milligram of KOH required per

gram of oil. It is used to find out the avg molecular weight of oil.

Determination of Wax- Wax determination gives an idea about the total

percentage of wax in the oil.

The measurements of FFA and Colour are done at every processing step

to determining the effectiveness of the process. These above testing

should be done before refining process to be start.

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REFINARY SECTION

Refinery stages of edible oil

SHORT MIX SECTION:

There are two processes undergoing this section. One is Degumming and

another is neutralization.

Degumming:

The main purpose of the degumming process is to produce an oil that

does not deposit a residue during transportation and storage . It is the

first stage in the refinery process. A degumming process is crucial for

physical refining, but optional for chemical refining. It is used to

separates the gums, Moisture, Trace Metals, Carbohydrates ,proteins etc

that are insoluble in oil when hydrated and treated with acid. The

degumming processes convert the phosphatides to hydrated gums,

which are insoluble in oil and readily separated as sludge by settling,

filtering, or centrifugal action.

Components removed/reduced:

Hydratable non-oil materials, mostly carbohydrates and proteins

partially removed.

Hydratable non-glyceridic lipids such as phospholipids partially

removed.

Chlorophyll (partially removed), especially if phosphoric acid is

employed.

Advantages of Degumming:

It is necessary for lecithin production.

It satisfies export oil requirements for a product free of impurities

that could settle out during shipment.

It reduces the chemical refining neutral oil loss.

It substantially reduces refinery waste load due to the lower neutral

oil losses and the reduction of gums discharged.

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It improves acidulation performance. The soapstock from alkali

refining is easier to acidulate due to lower emulsifier content, and the

acid water has less impact on the wastewater treatment systems.

Types of Degumming (major)-

Water Degumming:

The main purpose of the water degumming process is to produce

an oil that does not deposit a residue during transportation and

storage. There is no chemicals like acids used except water.

Approximately 2% water, by oil volume, is brought into contact

with the crude oil by mechanical agitation in a mix tank. The

proper amount of water is normally about 75% of the phosphatide

content of the oil. Too little water produces dark viscous gums and

a hazy oil, while too much water causes excess oil losses through

hydrolysis.

Temperature is important because degumming is less complete at

higher temperatures due to the increased solubility of the

phosphatides in the oil; also, at lower temperatures the increased

oil viscosity makes separation of the phosphatides more difficult.

Water-degummed oil still contains phosphatides, only the

hydratable phosphatides are removed with water degumming.

The nonhydratable phosphatides, which are the calcium and

magnesium salts of phosphatidic acid and phosphatidyl

ethanolamine, remain in the oil after water degumming.

Acid Degumming:

Acid degumming leads to lower residual phosphorus content than

water degumming and, therefore, is a good alternative. The acid

degumming process might be considered as a variant of the water

degumming process in that it uses a combination of water and

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acid. The nonhydratable gums, consisting mainly of the calcium

and magnesium salts of phosphatidic acid and phosphatidyl

ethanolamine, can be conditioned into hydratable forms with a

degumming acid.

This acid liberates the phosphatidic acid and

phosphatidylethanolamine and forms a binding complex with the

calcium and magnesium divalent metal ions that can be removed

with the aqueous phase.

Phosphoric and citric acids are used because they are food grade,

sufficiently strong, and they bind divalent metal ions.

The reaction takes place during the process-

NPH + H3PO4 -> HP + H2O

Mol Wt. 700 98

Calculation- since 98g of acid required for 700g of NHP.

Therefore 14% of H3PO4 required for the reaction.

Enzymatic Degumming:

The degumming enzyme changes the phospholipids into

lysophospholipids and FFA.

The enzymatic process has three important steps:

(1) adjustment of the pH with a buffer.

(2) enzymatic reaction in the holding tanks.

(3) separation of the sludge from the oil.

The process advantages include:

Enzymatic reactions are usually carried out under mild

conditions.

The enzymes are highly specific.

The process has acceptable reaction rates.

Only small quantities of the enzyme are required to carry out

the chemical reactions.

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Degummed oils with low phosphorus and iron contents are

produced even with poor-quality starting oils.

Dry Degumming:

In dry degumming, the oil is treated with an acid to decompose

the metal ion/ phosphatide complexes and is then mixed with

bleaching earth. The earth containing the degumming acid,

phosphatides, pigments, and other impurities is then removed by

filtration. Its main advantage is that it does not generate an

aqueous effluent, apart from the water involved in the vacuum

system.

Modified acid degumming

Membrane filter degumming

Apparatus: Centrifuge separator (Model –ALFA LAVAL SRG 610)

SRG 610:

It is the apparatus used as centrifuge separator manufactured

by the company named ALFA LAVAL. It has very complex structure with

high number of conical bawl arranged in manner such that the hole

combined to form a single long hole from which the oil gets out. The

bawls are rotated with very high speed of around 7000 rpm .

Working Principle:

When the oil-water mixture is fed to the separator, the mixture comes

in a contact with the rotating bowls which makes them to centrifuge

with very high speed. The heavier part get ejected radially with very

high velocity and get hit with the wall and comes to rest but the light

part (oil) travelled with relatively low velocity and gets poured in the

holes which are at such a distance such that oils almost comes to rest.

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Now the gums which gets collected at the periphery of separator is over

the top disk and out the discharge port with continuous supply of water

to build a pressure and the lighter phase(oil) moves to the center of the

bowl for discharge from the neck of the top disk.

The major factors to consider for improvement of separation

completeness include:

Greater differences in the specific gravity of each phase.

Lower viscosities.

Higher temperatures.

Shorter travel distance for the heavy particles.

Increased centrifugal forces

longer centrifugal dwell times

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SRG 610 ALFA LAVAL

Centrifuge separator

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Neutralization:

The conventional caustic soda process is the most widely used and best-

known refining system. The addition of an alkali solution to a crude oil

brings about a number of chemical and physical reactions.

The alkali combines with the FFA present to form soaps; the excess

caustic can also bring about the saponification of a portion of the neutral

oil, therefore, selection of the NaOH strength, mixing time, mixing

energy, temperature, and the quantity of excess caustic all have an

important part in making the alkali refining process operate effectively

and efficiently

This is an optional process to many industries as it involves

the neutralization of FFA (Free Fatty Acid) with the sodium hydroxide.

This is majorly done when we go for the refined oil.

This is simply based on the acid base reaction of FFA and NaOH.

The by-product soap which is formed is sent for the further treatments

so that the residue oil is get extracted out.

Selection of the caustic treatment is determined by the type of crude

oil, FFA content, past refining experience with similar oils, and the

refining equipment available. In general, the minimum amount of the

weakest strength necessary to achieve the desired endpoint should be

used to minimize saponification of neutral oil and prevent “three

phasing” or emulsions during separation. Usually, the best results are

obtained with relatively weak caustic solutions or lyes on low FFA oils

and with stronger lyes on high FFA oils.

Comparative studies have shown that more dilute caustic solutions will

remove more phosphorus, therefore, crude oils with high phosphorus

levels are best refined with dilute caustic solutions, but if they become

too diluted then difficult emulsion separation characteristics develop.

For this reason, dilute caustic solutions or low Baume concentrations are

recommended for soybean, peanut, safflower, sunflower, and canola

oils.

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Refining yield efficiency is dependent on the primary separation step.

The light-phase discharge is the neutral oil containing traces of moisture

and soap. The heavy-phase, or soapstock, discharge is primarily insoluble

soap, meal, free caustic, phosphatides, and small quantities of neutral

oil. The flow of material enters the rotating bowl and is forced outward

to a disk stack. The heavier density soap stock is forced to the outside of

the bowl and flows over the top disk and out the discharge port. The

lighter neutral-oil phase moves to the center of the bowl for discharge

from the neck of the top disk.

Refined oil from the primary centrifuge is washed with hot softened

water. Softened water must be used to avoid the formation of insoluble

soaps. Sodium soaps remaining from the primary centrifugation phase

are readily washable and easily removed from the oil with either a single

or double wash. A single wash is usually sufficient; however, two washes

may provide savings in bleaching earth and hydrogenation catalyst usage

as well as a reduction in wash water volume.The things that water

washing will not do are remove phosphatides left in the oil after the

primary centrifuge and remove unwashable soaps related to the calcium

and magnesium content of the crude oil.

Reaction involves during the neutralization-

RCOOH + NaOH RCOONa + H2O

Mol Wt 282 40 304 18

Calculation: It is required to calculate the amount of NaOH.

Since, for 282g of fatty 40g of NaOH required

So, 14.1% (by Weight)of caustic required for 1 mol of fatty.

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Following procedure is employed in short-mix section for the degumming and

neutralization process-

Raw oil from the storage tank is drawn into the neutralization tank called

the NTR (capacity-20 tons) at about 60-65°C,where it is dozed with 0.1%

H3PO4 solution. As a result, a heterogeneous mixture of oil and gums is

formed.

This oil is then taken into the Hydration Tank(HT). The purpose of HT is

to increase the retention time of the mixture so that maximum

formation of gums may take place.

Oil then goes into the High Speed Centrifuge Separator(SRG 610), which

separates the 2 phases, namely oil and gums. This separation is caused

due to the difference in specific gravities of the 2 phases (oil being

lighter). Gums being heavier are forced outwards in the larger radii zone

and are removed from the top.

Oil is pumped from the centrifuge into the mixer (80-85°C)where it is

dozed with caustic soda (NaOH) solution. Retention time here is just 2-3

seconds to prevent oil loss due to saponification. Rise in temperature is

obtained by a Plate Heat Exchanger(PHE). Purpose of dozing is to

neutralize fatty acids present in the oil which are thereby converted into

soaps.

The resulting mixture is then pumped into 2nd centrifuge which

separates the soap solution from oil. Other impurities like pigments are

also removed in the process.

The resulting oil is raised to about 85-95°C trough a PHE and is passed

into a mixer where it mixed with water and citric acid solution(optional).

The solution is pumped again into 3rd centrifuge to wash off the

remaining soap present in the oil, reducing its concentration to less than

30 ppm. However, in this process some oil loss (0.2%) is also observed

so this process is sometimes omitted, instead soap-up agents are used

which absorb the soap and get removed in the bleaching section.

Oil is then pumped into the Vacuum Dryer (VD), where the remaining

moisture is absorbed from the oil. This completes the refining process in

the short mix section.

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Flow chart of short mix section for RBO

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Bleaching:

The purpose of bleaching is not only to provide lighter colored oil, but

also to purify it in preparation for further processing. In many cases, the

bleaching process is performed more for the removal of the nonpigment

materials, such as soap, gums, and prooxidant metals, which hinder

filtration, poison hydrogenation catalyst, darken the oils, and affect

finished oil flavor.

The key parameters for the bleaching process are:

Procedure:

Here are the flow charts of the process-

Bleaching agents:

There are different types of bleaching earths are used according

to the requirements. Bleaching are acts absorber as well as

adsorbent.

The different types of bleaching agents used in BL Agro are shown

in figure below-

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Bleaching Earth dosage:

The amount of bleaching earth used depends on the type of

absorbent used and the type of refined oil, as well as the

adsorption of color bodies and other impurities required. The

percentage of clays used varies in a wide range from 0.15 to 3.0%,

and only in extreme cases are higher quantities used.

Temperature:

Bleaching clay activity increases as the temperature is increased

by reducing the viscosity of the oil, but decoloration declines after

the optimum temperature has been reached and color fixation

occurs. The optimum earth–oil contact temperature is dependent

on the oil type and the type of bleaching system. Temperature

requirements for vacuum bleaching systems are normally lower

than those for atmospheric bleaching to reach optimum color

removal. Temperature also affects other properties of the oil, so it

should be kept as low as possible to minimize product damage,

but high enough for adequate adsorbance of the impurities and

color pigments.

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Time:

In theory, adsorption should be practically instantaneous;

however, in practice, this is not the case. The rate of color

decrease is very rapid during the first few minutes that the

adsorbent is in contact with the oil and then decreases to a point

where equilibrium is reached and no more color is removed.

Filtration:

After an adsorbent has selectively captured the impurities, it must

be removed from the oil before it becomes a catalyst for color

development or other undesirable reactions. Filtration, the

separation method most often used for spent bleaching earth

removal, is the process of passing a fluid through PLF(Pressure

Leaf Filter).

Components removed/reduced:

Carotenoids removed.

Chlorophyll and its decomposition products removed.

Gossypol-like pigments removed.

Toxic agents, such as polycyclic aromatic hydrocarbons removed

(if carbon is used in quantity).

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Dewaxing-

Wax- Waxes are esters of long chain aliphatic alcohols and fatty

acids with low solubility in oils.

An increased demand for salad oils high in unsaturates has

resulted in the marketing of source oils that must be dewaxed to

maintain clarity during storage, on the retail store shelf, and at

refrigerator temperatures. Many vegetable oils have small

quantities of waxes that solidify and cause cloudy oil. These waxes

solidify after a period of time to give the oil a cloudy appearance,

an unsightly thread, or a layer of solidified material.

Dewaxing is basically based on the principle of crystallization. As

we lowers the temperature the wax part in the oils gets solidify

and we filtered it out by frame and plate filter. In this process we

basically focus on the rate of cooling that should not be so rapid.

We cool it with very slowly so that there should be the time

crystal growth. The temperature should be maintained at 25⁰-

30⁰C.

Flow chart of Dewaxing Section-

Bleached Oil

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Deodorization-

Deodorization is a vacuum-steam distillation process of an oil at an

elevated temperature during which FFA and minute levels of odoriferous

materials are removed to obtain a bland and odorless oil.

The odoriferous substances are FFA, aldehydes, ketones, peroxides,

alcohols, and other organic compounds. Efficient removal of these

substances depends on their vapor pressure, for a given constituent is a

function of the temperature and increases with the temperature. The

process is operated at 240⁰-260⁰C and of 2mm Hg vacuum.

The four interrelated operating variables that influence deodorized oil

quality are –

Vacuum:

The low absolute pressure necessary for low-temperature

distillation of the odoriferous substances is affected by the

vacuum system. The boiling point of the fatty acids and the vapor

pressure of the odoriferous materials decrease as the absolute

pressures decreases. The required low absolute pressure, usually

between 2 and 4 mbar, is commonly generated by vacuum

systems consisting of a combination of steam jet ejectors, vapor

condensers, and Boosters.

Temperature:

Deodorization temperatures must be high enough to make the

vapor pressure of the volatile impurities in the oil conveniently

high. The vapor pressure of the odoriferous materials increases

rapidly as the temperature of the fat is increased. For example,

the vapor pressure of palmitic fatty acid is 1.8 mm at 350°F

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(176.7°C), 7.4 mm at 400°F (204.4°C), 25.0 mm at 450°F (232.2°C),

and 72 mm at 500° F (260°C).

Higher deodorizer temperatures definitely provide shorter

deodorization times. Deodorizer operation at elevated

temperatures can also promote thermal decomposition of some

constituents naturally present in oils, such as pigments and some

trace metal–prooxidant complexes.

Stripping Steam:

Adequate stripping steam, consistent with the temperature and

pressure in the deodorizer, is required. The amount of stripping

steam required is a function of both the absolute operating

pressure and the mixing efficiency of the equipment design.

Agitation of the oil, necessary to constantly expose new oil

surfaces to the low absolute pressure, is accomplished by the use

of carefully distributed stripping steam.

Retention Time:

Deodorizer holding time is the period during which the fat or oil is

at deodorizing temperature and subjected to stripping steam.

Stripping time for efficient deodorization has to be long enough to

reduce the odoriferous components of the fats and oils products

to the required level. This time will vary with the equipment

design.

Components removed/reduced:

Free fatty acids, peroxide decomposition products, colour bodies

and their decomposition products eliminated.

Sterols and sterol esters reduced.

Tocopherols reduced.

Pesticide residues and mycotoxins removed totally.

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Flow diagram of Deo – section-

Dewaxed Oil

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Winterization-

The descriptive term of winterization evolved from the observation that

refined cottonseed oil stored in outside tanks during the winter months

physically separated into a hard and clear fraction. Topping or decanting

the clear oil from the top of the tanks provided oil that remained liquid

without clouding for long periods at cool temperatures. The clear oil

portion became known as winterized oil. The hard fraction from the

bottom of the tanks was identified as stearine, which is the solid portion

of any fat.

Winterized oil became known as salad oil. Summer oils, or oils that had

not been subjected to winterization, became known as cooking oils.

Winterization Principle:

Winterization is a thermomechanical separation process where

component triglycerides of fats and oils are crystallized from a melt.

The two-component fractional crystallization is accomplished with

partial solidification and separation of the higher melting triglyceride

components. The complex triglycerides may have different fatty acids

compositions depending on the source oil and prior processing.

Fat crystallization occurs in two steps: nucleation, and crystal growth.

The rate of nucleation depends on the triglyceride composition of the

oil being winterized, the cooling rate of the oil, the temperature of the

nucleation, and the mechanical power input or agitation. Growth rate is

dependent on the crystallization temperature, time, and mechanical

input or agitation.

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The effect of the major processing variables upon winterization

performance is discussed below-

Source Oil Composition:

Nucleation and crystal growth depend on the composition of the

oil being winterized. The various triglycerides in a particular oil

will fractionate in the following order: (1) trisaturate, S3; (2)

disaturate monounsaturate, S2U; (3) monosaturate diunsaturate,

SU2; and (4) triunsaturate, U3.

Cooling Rate:

An essential requirement of the winterization process is a slow

rate of chilling. Rapid cooling of the oil results in

(1) Mass of very small α-crystals

(2) High nucleation rate that increases the viscosity, which, in

turn, restricts crystal growth.

Crystallization Temperature:

The crystal growth rate is affected by the temperature of

crystallization. A high viscosity resulting from too low a

temperature reduces the crystal growth rate. A temperature

differential between the coolant and the oil must be maintained

to avoid shock chilling. If the coolant is allowed to become too

cold in relation to the oil, a heavy layer of stearine will build up

on the surfaces and insulate the oil from the coolant.

Agitation Rate:

Crystal formation is hastened by stirring to bring the first crystals

into contact with more of the liquid; however, mild agitation

rates are recommended because high shear rates fragment the

crystal during the growth stage, thus producing smaller crystals

instead of the desirable large crystal.

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Crystallization Time:

Crystallization is inseparably linked to two elements of time:

(1) The time it takes to lower the temperature of the material to

the point where crystallization will occur.

(2) The time for the crystal to become fully grown.

Flow diagram of winterisation-

Deo Oil

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TREATMENT OF BYPRODUCTS

Treatment of byproduct for any industries is compulsory. This is not only

because to maintain the balance in ecosystem but also the for the benefits for

the companies. This may also counts in the total worth of the industry. A

industry’s profit or loss also depends on the marketing of these byproducts.

Gums: It is one of the most important byproduct , which is separated

out during the degumming process can be treated further to use as

lecithin for the chocolate industries.

The gums are processed through the following stages:

The gums is stored in a tank where it is treated with

H3PO4,casein,salts and heated to 80⁰C.

Now it is again heated to 95⁰C at a pressure of 4 Kg/cm2 (heating is

to be done by steam).

At 95⁰C we further add salt and left the tank to settle down.

The solution of the tank is separated into three layers of oil,gums

and water.

By gravity the water and gums are pulled out and oil is sent to the

refinery section and the gums supplied to chocolate industries.

Note: Lecithin is formed only in case water and enzymatic degumming.

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Soap:

Soap is formed in the neutralization process, when degummed oil is

treated with NaOH. Soap is further treated to extract the residue oil

which get associated with the oil.

Soap undergoes these processes:

Stored in a tank where it is mixed with H2SO4(1.5-2%) and heated

to 65⁰-70⁰C.

Salt is added(optional).

The solution is settled down and separated into two

layers(oil+Water).

Oil(60-70% FFA) is used in soap industries and water is sent for the

treatment at ETP.

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References :

1. Bailey’s Industrial Oil And Fat Products , Sixth Edition , A John Wiley &

Sons, Inc., Publication.

2. Richard D. O’Brien , Fats and Oils Formulating and Processing for

Applications , Third Edition.

3. Manual of methods of analysis of foods , Oils and fat , Food Safety and

Standards Authority Of India .

4. Wikipedia.