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:

𝑙𝑛𝐶

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 (

11 − 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:

𝑚𝐵𝑡 = (𝑃

𝐸𝑃𝐴− 1) (𝑀𝑎𝑖 −𝑀𝑎𝑓) +

𝑃𝑚𝑐

𝐸𝑃𝐴𝑙𝑛

𝑀𝑎𝑖

𝑀𝑎𝑓

𝑚𝐵 =(917.50.7 ∗ 8.8

− 1) (1.9448 − 0.19448) +917.5 ∗ 2.80.7 ∗ 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.