Extraction of Essential Oils using Steam Distillation

CHEMICAL ENGINEERING OPERATIONS
PROJECT
ON
EXTRACTION OF ESSENTIAL OIL
FROM CORIANDER USING STEAM
DISTILLATION
13FET1011 PRATHAMESH KUDALKAR

Sr. No. CONTENTS
1.0 Extraction of essential oil from coriander using
steam distillation
1.1 Introduction
1.2 Industry Overview
1.3 Motivation
1.4 Process Flow Chart
1.5 Equipment
1.6 Calculations
1.7 Conclusion

1.1 Introduction
An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds
from plants. They are also known as volatile oils, ethereal oils, aetherolea etc. Essential
oils are made up of highly volatile substances which can be extracted from numerous
plant species. The oil usually bears the name of the plant from which it is extracted and
a host of methods exist for separating these oils from the various plant materials. The
method of extraction is important in that the composition of essential oils is somewhat
dependent on the extraction method employed. Distillation based recovery processes
such as steam and vacuum distillation are preferred for the extraction of essential oils
from plant materials. This is because these processes are flexible, versatile, do not lead
to the decomposition of the essential oils and provide the possibility of operating with
small volumes.
Virtually all naturally occurring essential oils are made up of hydrocarbons such as
camphene, pinene, limonene, phellandrene, cedrene, and oxygenated hydrocarbons
such as alcohols, aldehydes, esters, ethers, ketones, lactones, phenols and organic
acids. The essential oil get their odours from the oxygenated compounds contained in
them and these confer stability on the oil against oxidation. The hydrocarbons are less
stable and they are responsible for thedegradation observed in the oils. The hydrocarbons
contained in the essential oil are often removed so that the oils can be more stable and
still retain their odours and flavours.
Applications
Essential oils have (an unexpectedly) large range of applications finding uses in the food
and beverage industry, the perfume industry, in the production of flavours and spices, in
the soap and detergents industry, in the pharmaceutical industry, and in the plastics
industry to name a few.

1.2 Industry Overview
Oleoresins and spice oils have large domestic as well as export markets. They are
consumed by a broad spectrum of manufacturers like confectionary, noodles, beverages,
sauces, canned meat, soup powders, curries, poultry products and so on. Most of the end
use industries are growing steadily and demand is bound to increase. With increasing
preference for quality products, use of spices is rapidly replaced with oleoresins and spice
oils.
Global essential oil market size was estimated at USD 5.51 billion in 2014. Increasing
essential oil penetration in aromatherapy coupled with rising demand for fragrances and
flavors in food & beverages is expected to remain a key driving factor for the global
market.
The global market can be segmented on the basis of essential oil uses, including aromas
and flavorings in food & beverages, spa & relaxation, cleaning & home, medical, and
others. The Food & Beverages Industry dominated the application market accounting for
over 30% of the overall volume share.
1.2.1 Country-wise Market Overview
Growing demand for high nutrition diet coupled with favorable government initiatives for
promoting industrialization in emerging economies of the BRICS nations is expected to
positively impact food & beverage industry growth. The segment is expected to witness
the highest CAGR of 9.1% from 2015 to 2022 in terms of market volume.
Europe was the largest market owing to rising awareness and growing demand for natural
cosmetics and beauty products, medicines, and nutraceuticals from vast geriatric
population in countries such as France, Germany, the UK, Spain, and Italy. Europe was
valued at over USD 2.40 billion in 2014; however, growth is expected to remain stagnant
owing to the market saturation. Europe was followed by North America. Rising consumer
awareness and high per capita income in countries such as the U.S. and Canada is
expected to foster regional growth over the forecast period.
2.3 The Indian Market
The export of spice oleoresins and essential oils from India amounts to 7,800 tonnes in
volume and US$ 255 million in value.

The industry has witnessed steady growth in volume and value since the beginning. The
post liberalization economic environment in India facilitated the import of raw materials
from Asia-Pacific regions; and the industry leveraged on this to become a processing hub
ensuring competitiveness and managing the supply chain effectively.
The pie-chart shows the relative volumes of product mix from the Indian oleoresin
industry.
Spices are cultivated in a total crop area of 2.94 million hectares that forms only 2% of
the total 142 million hectares of agricultural land in India. The major part of the cropped
land is used for seed spices namely cumin, coriander, celery, fennel, fenugreek, dill and
ajowan. These are concentrated in the northern states of Rajasthan, Uttar Pradesh,
Gujarat, Punjab and Uttaranchal. Chillies being the next major crop are mainly grown in
the southern states of Karnataka and Andhra Pradesh. Essential oil production from these
spices is less than 10%

1.3 Motivation
The essential oil industry is an agro-based industry, which involves cultivation and
distillation activities. It can involve the rural population by having them produce raw
materials and by creating job opportunities in the processing of the oils (De Silva,
1998).Distillation of essential oil is relatively uncomplicated. It can be done in rural
areas,where the raw materials are produced. Both the technology and the skills required
are not sophisticated. The investment required is also relatively low. As a source of
energy, different materials like fuel wood or fuel oil could be used. Essential oils are
extensively used globally for food flavouring, fragrances, aromatherapy and
pharmaceuticals. Their wide industrial applications make an interlocked connection with
industrial growth vs. essential oil demand.
As mentioned above, there is a huge untapped potential owing to the growing demand
for improved nutritional and dietary needs in developing countries like India. Also the
rapidly growing economy of developing countries presents an opportunity to invest in this
technology of extraction of essential oils. Literature and experience showed that small
scale industries are indispensable for the economic development of India. Promotion and
technology supports are crucial in the development of small-scale industries in the
country. Technology development and adaptation should be based on the resource,
socio–economic condition of the targeted entrepreneur and the end users of the product.
For countries like India where agrarian economy dominates and 85% the population live
in rural, the development of agro-based small scale industries helps to bring a sustainable
development in rural areas. Essential oil industry is one of the potential agro-processing
industries not given adequate attention. Though India favours the cultivation of high
quality aroma plants for essential oil, the benefit of the sector in rural poverty alleviation
is not adequately evaluated by the policy.
1.3.1 Why Coriander?
We focus on essential oil extraction from coriander because coriander seeds have been
used for centuries to aid digestion, and is still used today for this same benefit.* Coriander
has a high linalool content which helps skin maintain complexion. Coriander can be
soothing to the body. Coriander’s sweet, herbaceous aroma is both relaxing and
stimulating, making it a good rotation oil to use in blends to add a fresh, herbaceous note.
The main chemical components of the coriander essential oil are linalool, α-pinene, γ-
terpinene, camphor.
Coriander, although cultivated in large quantities and with relative ease in most parts of
India has a relatively small market share when it comes to essential oils. Coriander
essential oil is amongst the top 15 essential oils by demand in the world market.
The byproduct obtained from the essential oil extraction of coriander is dried and used for
various applications including spice blends after appropriate particle size reduction
making the process economically even more feasible and robust by maximizing output.

In this project, we aim to focus on low cost production of essential oils by using Steam
distillation.
1.3.2 Why Steam Distillation
Steam distillation is the preferred unit operation for essential oil extraction the world over
due to the following reasons.
 The steam pressure helps to vaporize the compound at a lower temperature, which
prevents thermal degradation.
 The simplicity of the method makes it suitable for small-scale distillation of essential
oils.
 The advantages of this type of distillation are that it is relatively rapid and capable
of greater control by the operator. The vessel can be emptied and recharged
quickly and with the immediate reintroduction of steam there is no unnecessary delay
in the commencement of the distillation process.
 Oils produced by this means are more likely to be of acceptable quality as properties
of oil are not altered than those produced using the more direct method.

1.4 PROCESS FLOW CHART
Coriander Seeds (Coriander Sativum)
Sun Drying of Coriander Seeds.
It enhances oil extraction
Steam Distillation
Dried seeds are placed in the Distillation still and steam is
sparged through a sparger. Steam rises through the still
carrying essential oils with it .
Condenser
Steam + Oil system condenses and is passed to the separator
Separator
Separates oil and water on the basis of density difference. Oil is
skimmed from the top periodically

1.5 Equipment
Steam distillation set up consists of four main components:
 Steam generator
 Still
 Condenser
 Separator
1.5.1 Steam Generator
The steam generator of the plant is
responsible for the production of the
required amount of thermal energy
in the form of steam to be fed to the
still.
For steam generation, fire tube
boiler is generally used. In this,
water partially fills a boiler barrel
with a small volume left above to
accommodate the steam (steam
space). This is the type of boiler
used in nearly all steam
locomotives. The heat source is
inside a furnace or firebox that has
to be kept permanently surrounded
by the water in order to maintain the
temperature of the heating
surface below the boiling point. The
furnace can be situated at one end
of a fire-tube which lengthens the
path of the hot gases, thus
augmenting the heating surface
which can be further increased by
making the gases reverse direction
through a second parallel tube or a
bundle of multiple tubes (two-pass or return flue boiler); alternatively the gases may be
taken along the sides and then beneath the boiler through flues (3-pass boiler). In case
of a modified fire tube boiler, a boiler barrel extends from the firebox and the hot gases
pass through a bundle of fire tubes inside the barrel which greatly increases the heating
surface compared to a single tube and further improves heat transfer. Fire-tube boilers
usually have a comparatively low rate of steam production, but high steam storage
capacity. Fire-tube boilers mostly burn solid fuels, but are readily adaptable to those of
the liquid or gas variety.The system can be operated with low technical skill level which

can be attained in two-three day trainings. The boiler is a biomass-fired type to use the
wood or any biomass resource available in the rural areas.
1.5.2 Distillation Still
The still is the most important part
of the plant to keep the quality of
oil produced. A still is where oil is
displaced from the biomaterial
placed inside by a steam coming
from the steam generator. In the
design of still, steam injection and
distribution systems, insulation
from the atmospheric condition
plays important role in attaining
the subjected quality and quantity
of oil. Proper material handling
system is also very important for
easy operation and better
efficiency.
Still is made of food grade
stainless steel (SS304 or SS316). It consists of round column. Inside, it has a perforated
grid. A bed of spices, seeds or leaves is stacked upon this perforated grid. Steam is
passed from the bottom of the still through a Sparger . As it goes up, it extracts the
essential oil from the biomass. There is an outlet at the top for steam to pass to the
condenser.
Still is compatible with all types of biomass and doesn’t hold any specificity. Thus different
spices, leaves and seeds can be used with this still.
1.5.3 Condenser
The condenser is responsible in the cooling of oil-
water mixture to separate by density difference in
the separator. The outlet temperature and the
amount of the mixture steam coming from the still
determine the size of the condenser and the
cooling water required.
The main elements of a steam condensing plant
are:
 a condenser in which the exhaust steam in
condensed,
 supply of cooling or injection water, for
condensing exhaust steam,
 a pump to circulate the cooling water in case
of a surface condenser,

 a pump, called the wet air pump, to remove the condensed steam (condensate), the
air, and uncondensed water vapour and gases from the condenser (separate pumps
may be used to remove air and condensed steam),
 a hot-well, where the condensed steam can be discharged and from which the boiler
feed water is taken, and
 an arrangement (cooling pond or cooling tower) for cooling the circulation water when
a surface condenser is used and the supply of water is limited.
1.5.4 Separator
Separator is the smallest but
very important part of the
system. The equipment is
designed based on the
immiscibility of oil and water so
that oil can be separated by
density difference. Usually,
oils have lower density than
water, so it floats on water.
This floating oil can be easily
skimmed off from the top of the
condenser.

1.6 Calculations
1.6.1 Distillation Time
The extraction of essential oils from coriander by steam distillation has been reported to
be a kinetic process. This means that the rate at which oil is removed from the plant
material is entirely dependent on the average quantity of essential oil present in the grass
at any time. For the modeling exercise done in this work, the diffusion of the oil from the
tissues within the seed to their surface was not considered. The modeling effort is only
focused on the transport of oil from the surface of the leaves into the vapor phase. The
rate at which oil is extracted from coriander seeds is directly proportional to the amount
of oil present in the plant material at any time t.
This was expressed mathematically in the form of a first order ordinary differential
equation (ODE).
𝑑𝐶
𝑑𝑡
= −𝑘𝐶
Where, C= average quantity of essential oil in the grass at any time t
k= first order rate constant
t= time of distillation
This ordinary differential equation was solved using the variable separable method of
solving first order ODE,
By separating variables, we arrive at:
𝑑𝐶
𝐶
= −𝑘𝑑𝑡
Both sides of this equation were integrated within limits Co to C for the left-hand-side and
0 to t for the right-hand-side to obtain:
𝑙𝑛
𝐶
𝐶𝑜
= −𝑘𝑡
Where, Co = initial quantity of essential oil.
The initial quantity was approximated to be a function of the cumulative volume of oil
extracted from the lemon grass.
A new variable y(t) representing the time dependent fractional extraction yield was
defined as follows:
𝑦( 𝑡) =
𝐶𝑜 − 𝐶
𝐶𝑜
This equation was rewritten in favour of y(t) to obtain:
ln (
1
1 − 𝑦( 𝑡)
) = 𝑘𝑡

This is the solution of the ODE presented and this was fitted to the results obtained from
experiments to determine its validity.
1.6.1.1 Time Calculations:
Assumptions from the literature:
 Value of k was obtained experimentally to be 0.007962 min-1
 Average essential oil content in coriander seeds 0.96ml/100g
 Average yield of essential oil obtained after steam distillation is 0.5ml/100g
Therefore,
Co=0.96
C =0.96-0.5
=0.46
𝑦( 𝑡) =
𝐶𝑜 − 𝐶
𝐶𝑜
=
0.96−0.46
0.96
=0.5208
ln (
1
1 − 𝑦( 𝑡)
) = 𝑘𝑡
ln (
1
1 − 0.5208
) = 0.007962𝑡
∴ 𝑡 =
ln (
1
1 − 0.5208
)
0.007962
∴ 𝒕 = 𝟗𝟐. 𝟑𝟗𝒎𝒊𝒏
Thus, it will take approximately an hour and half for steam distillation.
For a 20kg batch size:
Batch Size= 20kg
Yield = 0.5ml/100g
Therefore, yield per batch=0.5*200= 100ml
1.6.1.2 Factors affecting kinetics of essential oil extraction are as
follows:
i. Structure of the biomass: The rate of oil vaporization from the plant material is not
affected by the relative volatility of the chemical components that make up the oil;

rather it is influenced by their solubility in the vapour phase which in this case is steam.
Therefore it is reasonable to conclude that some of the oil could still be trapped within
the tissues of the plant inaccessible to the vapor phase. It is also the reason for low
yield of essential oils.
ii. Packing of the materials: Tight packing of the plant material results in reduced oil
extraction while loose packing improves extraction by offering less resistance to
upward flow of the oil-steam mixture.
iii. Wetting: Vapourisation of the oil does not start immediately steam is injected into the
still. Plant material needs to be wetted by steam before oil extraction begins. Wetting
actually helps the oil to diffuse from within the leaves to the surface and once it is on
the surface, it is available for stripping by steam. Wetting time of 10-15 minutes is
generally observed.
iv. Steam Flow Rate: Increasing the steam flow rate led to the acceleration of essential
oil extraction until a certain limiting value. Once this value is reached, there is no
further increase in extraction rates whatsoever.
1.6.2 Purification Calculations
Linalool is a major component of essential oils extracted from coriander. It has a high
demand in the market due to its unique flavor- floral, with a touch of spiciness. Thus it
becomes imperative to separate Linalool from other components due to its high value.
Purification of Linalool can be achieved by steam distillation.
Consider 1kg of crude Coriander essential oil has to be purified to separate Linalool (C10
H18O) having molar mass 154.25g/mol. The material contains 30 mass % of required
essential oil and rest are non-volatile impurities with average mol. Wt. 250. Batch time is
0.5hr. Operating temperature is taken as 105 degree Celcius and vapourization efficiency
of 70%. Recovery required is 90%.
As the vapour pressure of Linalool is not available, we will use the equation available for
Citranellol: ln PA(mm Hg)=21.33-7241/T
Steam Rate Calculations:
Vapour pressure at 105 degree Celcius using above equation(PA)=e^(21.33- 7241/105)
=8.8mm Hg
Linalool content= 0.3kg
Mai=300/154.25
=1.9448mol
Mass of impurities= 1000-300= 700g
Mci=700/250
=2.8mol
90% of the oil is recovered.

Moles of oil left Maf=1.9448*0.10
=0.19948
Vapour Pressure of water PB=908.7 mmHg
Efficiency= 0.7
Total Pressure P= 908.7+8.8= 917.5mm Hg
Total steam required is given by:
𝑚 𝐵 𝑡 = (
𝑃
𝐸𝑃𝐴
− 1) (𝑀 𝑎𝑖 − 𝑀 𝑎𝑓) +
𝑃𝑚𝑐
𝐸𝑃𝐴
𝑙𝑛
𝑀 𝑎𝑖
𝑀 𝑎𝑓
𝑚 𝐵 =
(
917.5
0.7 ∗ 8.8
− 1) (1.9448 − 0.19448) +
917.5 ∗ 2.8
0.7 ∗ 8.8
𝑙𝑛10
0.5
Therefore, mB=2438 mol/hr
=2438*18g/hr
=43884g/hr
=43.88 kg
For the required purification, steam rate should be 43.88kg/hr for batch time 0.5hr.
1.7 Conclusion
The above unit operation in which steam distillation has been proposed for extraction of
essential oil from coriander requires close to 22 kg of steam for a batch time of 30
minutes for a yield of 0.5 ml/100g coriander, Extraction time for a batch size of 20 kg is
92 minutes 24 seconds.
The byproducts are further used for production of spice blends which further contributes
to making the extraction process even more economically viable.

Extraction of Essential Oils using Steam Distillation

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