Extraction of Nutraceuticals From Plants_14

8/11/2019 Extraction of Nutraceuticals From Plants_14

1/20

Extraction of Nutraceuticals from

Plants

Nikhil Chipade

11OIL1014


2/20

Introduction

Plant contains broad range of bioactive compoundslike lipids, phytochemicals, pharmaceutics, flavours,

fragrances and pigments.

Bioactive widely used in food, pharmaceutical and

cosmetics industry. Issues for each extraction method is matrix

characteristics, solvent choice, liquid-solid ratio,

temperature, pressure and extraction time.


3/20

Conventional Soxhlet Extraction

Extractor holds plant materialto be extracted.

Solvent from flask evaporates

and condenses in extractor.

Once liquid reaches overflowlevel, it gets siphoned back to

solvent flask.

Solute is separated from

solvent using distillation.

The operation is repeated with

fresh solvent till complete

extraction is achieved.


4/20

Practical issues for Soxhlet Extraction

Solvent Choice: Suitable extracting solvent

NonToxic, Environment Friendly

Low Boiling and Inert

Matrix Characteristics: Depends on particle size; internal diffusion is limiting step.

Operating Condition:

Higher temperature may cause undesirable coloration.


5/20

Advantages: Displacement of transfer equilibrium by repeatedly

bringing fresh solvent in contact with solid.

Maintaining high extraction temperature with heat form

solvent flask.

No filtration required.

Disadvantages:

Long extraction time.

Agitation not possible. Large amount of solvent required.

Possibility of thermal degradation.


6/20

Sonication-assisted Extraction

Sound waves having frequency higher than 20KHzcreate mechanical vibrations.

These mechanical effects induce greater penetration

of solvent into cellular materials thereby improving

mass transfer. Ultrasound also is responsible for efficient cell wall

disruption facilitating release of contents.

Therefore, efficient cell wall disruption and improved

mass transfer are two major factors for enhancementof extraction.


7/20

Practical issues for sonication-assisted

extraction

Efficiency depends on: Moisture Content and Particle Size

Solvent Selection

Ultrasound Frequency

Temperature Sonication Time (Crucial)

Operating Conditions:

Mild temperature (depending on R.M and Extract)

Accurate Temperature Control is necessary


8/20

Advantage: Inexpensive, simple and efficient alternative to soxhlet.

Reduce operating temperature allowing extraction of heat

liable compounds.

Disadvantage: Dispersions may attenuate ultrasound waves.

Restricted to a zone located near ultrasound emitter.


9/20

Microwave-assisted Extraction

Electromagnetic radiation with a frequency from 0.3to 300 GHz.

Generally operated at 2.45 GHz.

Rapid delivery of energy to total volume of solvent

and solid matrix. Cell disruption is promoted by internal superheating,

improving recovery of nutraceutics.


10/20

Microwave-assisted Extraction

Two types of commercially available MAE: Closed Extraction Vessels

Used when high extraction temperature is necessary.

Pressure depends on boiling point of solvent used.

Open Extraction Vessels

Carried out at atmospheric pressure.

Operating temperature depends on boiling point of solvent used.


11/20

Practical issues for MAE

Matrix characteristics: Depends on dielectric susceptibility of solvent and matrix.

Particle size and size distribution influence efficiency of

MAE.

Solvent Choice: Depends on solubility of extracts, interaction with plat

matrix and microwave absorbing properties (dielectric

constant).


12/20

Operating Conditions: Sufficient solvent to immerse solid mass.

Higher solvent volume to solid mass ratio.

Adequate Stirring.

Elevated Temperature (depending on extract)

Advantage: Reduced extraction time and solvent usage.

Improved extraction yield.

Disadvantage: Centrifugation or filtration is necessary.

Efficiency is poor when either target compound or solventis non-polar or volatile.


13/20

Supercritical Fluid Extraction

Supercritical state is achieved when thetemperature and the pressure of substance is raised

over its critical value.

Advantage:

Dissolving power of fluid depends on its density whichcan be adjusted using temperature and pressure.

Supercritical fluid has high diffusion coefficient , lower

viscosity and surface tension than a liquid solvent, leading

to more favourable mass transfer.


14/20


15/20

Practical issues for supercritical fluid

extraction

Fluid Choice: CO2 very popular choice for non-polar extracts.

Freon-22, Nitrous Oxide good for polar extracts but there

are environment and safety issues.

Modifiers are added to CO2 so that it can also extractpolar components.

Methanol is commonly used as its 20% miscible in CO2.

Ethanol may be better choice as its less toxic.


16/20

Preparation of plant materials: High moisture content causes mechanical difficulties such

as clogging due to ice formation.

Water is only about 0.3% soluble in supercritical CO2 but

polar components will prefer aqueous phase more over

CO2.

To avoid this, mix chemicals such as Na2SO4 and silica

gel to absorb moisture from plant materials.

Smaller size, better extraction but too small size may

make CO2 impermissible from particle bed.

Hence some rigid materials, like glass beads and sea

sands are packed with fine plant powder.


17/20

Operating Conditions: Choice of proper density of supercritical fluid such as

CO2 i.e optimum temperature and pressure.

Extraction time also decides extract composition.

Advantage: Unusual possibilities of selective extraction.

Dissolved nutraceutical compound can be recovered by

reducing density of supercritical fluid.

No loss of volatiles while recovering nutraceuticalcompound.

Higher diffusivity of supercritical fluid as compared to any

other liquid, thus rapid mass transfer.


18/20

Advantage: SFE uses moderate temperature for extraction thus

suitable for heat sensitive compounds.

Environmental Friendly process.

SFE can be directly coupled with chromatographicmethod for simultaneous extraction and quantification.

Disadvantage:

High initial cost of investment.


19/20


20/20

Extraction of Nutraceuticals From Plants_14

Documents