Latest Technologies in
Processing of Spices, Plantation
& Medicinal Crops
By
S MUTHU KUMAR
I Ph.D (Horticulture)
Introduction
• For the past 126 years - Soxhlet extraction technique
• lengthy extraction time 8 - 24 hours or more
• Require more time and heat energy
• Labour intensive
• Large amount of organic solvents - detrimental to
environment
• MICROWAVE THEORY
• Microwaves are non-ionizing electromagnetic waves
• Frequency between 300 MHz to 300 GHz
• Positioned between the X- ray and infrared rays in the
electromagnetic spectrum
• Ability to convert a part of the absorbed electromagnetic
energy to heat energy
• Conventional heating - conduction – convection much of the heat energy being lost to the
environment
• MAE - targeted and selective heating
• Practically no heat being lost to the environment
• Unique heating mechanism - reduce the extraction
time (< 30 min) as compared to Soxhlet
• The moisture when heated up inside the plant cell due to
microwave effect, evaporates and generates tremendous
pressure on the cell wall due to swelling of the plant cell
• The pressure pushes the cell wall from inside, stretching
and ultimately rupturing it
• Leaching out of the active constituents from the ruptures
cells
• Higher temperature -microwave radiation - hydrolyze
ether linkages of cellulose
• MAE- enhances the dehydration of cellulose and
reduces its mechanical strength
• Solvent to access easily to compounds inside the cell
• The effect of MAE-strongly dependent on the
dielectric susceptibility of both the solvent and solid
plant matrix
• Most of the time, the sample is immersed in a
single solvent or mixture of solvents that
absorb microwave energy strongly
• There are two types of commercially available
MAE systems
• Closed extraction vessels and focused
microwave ovens
• Closed extraction - performs extraction under
controlled pressure and temperature
• Focused microwave assisted Soxhlet or solvent
extraction - a part of the extraction vessel containing
the sample is irradiated with microwave
Major components
(a) Microwave generator: magnetron, which generates
microwave energy
(b) Wave guide: which is used to propagate the
microwave
from the source to the microwave cavity
(c) The applicator: where the sample is placed and
(d) Circulator: this allows the microwave to move only in the
forward direction.
System types
• Both the above-mentioned systems are available as
multimode and single- mode or focused systems
• A multimode system allows random dispersion of microwave
radiation within the microwave cavity
• So every zone in the cavity and sample it contains is evenly
irradiated
• Single mode or focused systems allows focused microwave
radiation on a restricted zone where the sample is subjected
to a much stronger electric field
Advantages
1) Significant reduction of extraction time.
Extraction time usually ranging from few
seconds to few minutes (15 – 20 min)
2) Reduced solvent usage. In MAE only a few
milliliter of solvent is required
3) Improved extraction yield
4) Automation provides better accuracy and
precision
5) Suitable for thermolabile constituents
Advantages
6) Can even extract minute traces of constituents
including heavy metals and pesticide residue from a
few milligram of plant sample
7) Provides agitation during extraction, which improves
the mass transfer phenomenon.
8) Instrumental set up like Soxwave combines both the
features of Soxhlet and advantages of microwave,
thus making extraction even more attractive.
OPTIMIZATION OF MICROWAVE ASSISTED EXTRACTION OF
WITHANOLIDES FROM ROOTS
OF ASHWAGANDHA
Dried roots of Withania somnifera were obtained from local market, Bangalore
Department of Pharmacognosy, Al Ameen College of Pharmacy, Bangalore
The factors were microwave power (A), irradiation temperature (B), irradiation
time (C) and particle size (D)
Divya Jyothi, 2010
MICROWAVE ASSISTED EXTRACTION OF
WITHANOLIDES
Effect of microwave power and irradiation
temperature
• Microwave power level was increased from 20% to 100%,
there was 0.15% decrease in amount of withaferin A
• 20% microwave power and irradiation temperature of 50˚C
were ideal to obtain maximum withaferinA content
• MAE offers a rapid delivery of energy to a total volume of the
solid matrix, efficiently and homogenously
• Natural moisture present within the plant absorbs microwave
energy
• Cell disruption – internal superheating & sudden build up of
pressure due to rapid heating of the moisture present in the
plant cells - facilitates desorption of active constituents
Irradiation time
• Max. amount of withaferin A - irradiation time of 2 min and
yield of withaferin A was dropped when irradiation time was
increased to 4min
• Irradiation time of 2min is sufficient to ring about the
extraction of withaferin A
• Reduction in amount of withaferin A may be due to
decomposition of constituent at high temperature for long
period of time
Result
The microwave power‐ 20% + Irradiation temperature ‐50˚C
+ Irradiation time‐ 2min and powder of mesh size‐44
Comparison of MAE with Soxhlation
Conclusion
• MAE - low consumption of organic solvent and, the
rapid extraction (2min)
• Higher amount of withaferin A
• MAE operates through cell bursting where as soxhlet
method operates through cell permeation
Divya Jyothi, 2010
Microencapsulation of black pepper oleoresin
• Solvent-extracted oleoresins exhibit a flavour profile
close to the freshly ground spice
• Acceptable form of natural flavouring ingredient
• Wide spectrum of food applications
• Spice oleoresins exhibit sensitivity to light, heat and
oxygen
• Short storage lives (if not stored properly)
• Black pepper oleoresin, poor storage life is a result of
oxidative and polymeric changes involving the fatty oil
component and monoterpinic hydrocarbons
• Some organoleptic changes can also occur in the oleoresin
during prolonged storage
• Destruction of several pigments occurs under exposure to
oxygen
• Hydroxylic groups  unstable ketones  shorter carbon
skeleton (Colourless compounds)
Microencapsulation
• Protects the oleoresin against such destructive changes
• Protects the flavours from undesirable interaction with food
and minimizes flavour/flavour interaction
• The simplest of the microcapsules - a core surrounded by a
wall or barrier of uniform or non-uniform thickness.
• The core may be composed of just one or several different
types of ingredients and the wall may be single or doublelayered.
Rajesh Bhosale (2010)
• Spray-drying largely dominates the market for encapsulation
of flavours
Carrier materials
• Carbohydrates, such as hydrolyzed starches (SHPs),
emulsifying starches and gums (especially gum acacia)
• Gums - stabilization of emulsion, encapsulation, and film
formation
• Gum arabic - fixative in spray-drying applications where the
gum encapsulates the flavour compound, protecting it from
oxidation and volatilization
Microencapsulation of Black pepper
• Black pepper oleoresin – Ethanolic extraction
• 40 g of gum arabic and modified starch (i.e., Hi-Cap) were
dispersed individually in distilled water at 60–70 C, and final
volume made to 100 ml
• 1 g of oleoresin was then added to the mixture
• This mixture was emulsified (homogenizer for 5 min at 3000
rpm until the oleoresin dispersed completely)
• Two drops of Tween-80 were added (emulsification)
• The resultant slurry was spray-dried
• These powders (microcapsules) were filled in airtight, self-sealable polyethylene pouches and stored
in a dessicator containing calcium chloride
Spray dried microcapsules of
black pepper oleoresin
Modified starch (HiCap-100).
Gum arabic
Microencapsulation of black pepper
Stability of total volatiles (TV) in free and
microencapsulated black pepper oleoresin.
Stability of entrapped piperine (EP) in
microencapsulated black pepper oleoresin
Stability of total volatiles (TV) in free and
microencapsulated black pepper oleoresin
Conclusion
• Gum arabic was found to be a better wall material
for encapsulation of pepper oleoresin than is
modified starch
• The free-flowing nature of all these microcapsules is
of advantage to the food processing industry
Rajesh Bhosale (2010)
Extraction of essential oil using supercritical carbon
dioxide
• Conventional techniques - low extracting power , possibility of
solvent contamination, degradation of thermally labile
product and environmental problems
• Supercritical fluids - fluids in the temperature and pressure
state over their critical point
• They have properties that resemble both a gas and a liquid
• Their gas-like diffusion coefficients allow them to penetrate
solid materials
• Liquid-like densities – high solvating properties
Andri (2009)
• Low viscosity - favorable flow characteristics,
• Good solvents with excellent efficiency and speed
• Carbon dioxide - most commonly used solvent
compared to other solvents such as ammonia, water,
nitrous oxide, and fluoroform
• Other solvents -toxic, reactive, flammable, corrosive,
not readily available and expensive.
Supercritical fluid extraction apparatus
• Ground black pepper berries were placed between two layers of
stainless steel balls
• The extraction vessel was immersed in a water
bath controlled by an electrical heater
• When the water bath temperature reached the desired
temperature, CO 2 - continuously delivered at a volumetric flow
rate of 1 mL/min into the system by an HPLC pump until the
system pressure was achieved
• The system pressure was determined by a pressure
transducer
• Oil extracts were collected at one hour intervals
GC-MS Result of Black Pepper Essential Oil (% Area)
Sesquiterpene
Hydrodistillation
SFE
Andri (2009)
• Essential oil obtained by supercritical fluid extraction
(SFE) using carbon dioxide had higher levels of
sequiterpene hydrocarbons,
• Higher sesquiterpene to monoterpene ratios
Effect of pressure on extract yield and extraction rate of
black pepper essential oil
Density of solvent increases with increasing pressure
Temperature
•
•
•
•
Temperature increase from 303
to 313 K at 15 MPa resulted in
the increase of extraction rate
due to the increase of pepper
oil’s vapor pressure
High temperature - higher vapor
pressure of the analytes increasing the analyte solubility
Inversion in extract yield values
as the temperature further
increases from 313 to 323 K
It reduces the pepper oil
solubility from 0.0932 to 0.0858
(g oil/g CO2)
Effect of particle size on extract yield and extraction
rate of black pepper essential oil
• Different sizes of black pepper
particles
• The smaller particle size
generated a higher yield
• Grinding – liberate more pepper
oil by destroying inner structures
of the particles
• Larger particle and whole pepper
berries- intraparticle diffusion
resistance has a significant effect
Conclusion
• The pepper oil extracted using supercritical carbon dioxide
contained more sesquiterpenes (the main components of
perfumes) compared to that obtained from hydrodistillation.
• In general, the extraction rate increased with the increase of
pressure and temperature
• The increase of particle size reduced the extract yield and
extraction rate
Andri (2009)
Freeze drying
• Instant coffee powder - evaporation of coffee extract
upto 40-45% concentration (evaporator) followed by
spray drying at a high temperature (180-220 °C )
• Freeze drying - retains aroma, improves appearance
and taste
• Freeze drying takes place at a low temperature minimizes heat damage and retains volatile
components (aroma)
• Freeze-drying involves dehydration of food
products at low temperature and pressure
• Only the moisture is removed, leaving the
molecular structure intact
Freeze drying of coffee
• Pre-freezing coffee concentrate up to -5 / -10 °C
followed by foaming.
• Freezing of the prefreezed coffee liquor at -50 °C in a
blast freezer.
• Sizing of the freezed coffee particles to a granular
size of 3X3mm.
• Sublimation of the ice in a vacuum freeze dryer (VFD)
under vacuum (0.5 torr) and controlled temperature
Microwave Assisted Extraction of Phenolic
Compounds from
Four Different Spices
• Phenolic compounds in spices - antioxidant activity
• Reducing agents, hydrogen donors and singlet
oxygen quenchers and metal chelation potential
• Ultrasonication and microwave-assisted extractions
• Cinnamomum zeylanicum, Coriandrum sativum,
Cuminum cyminum, Crocus sativus
Monica Gallo, 2010
Extraction methods
Microwave-assisted extraction (MAE)
• Sample (1 g) was extracted with ethanol/water
(50:50 v/v, 20 mL),
• The extractions at 200 W using magnetic stirring at
50% of nominal power and a temperature of 50 ºC
for 18 min
Ultrasound assisted extraction
• Sample (3g) was extracted with ethanol/water (50:50
v/v, 30 mL),
• Ultrasonic bath - frequency of33 KHz
Total phenolic contents of spice extracts
Monica Gallo, 2010
Antioxidant activity of spice extracts obtained with
ultrasound and microwave
assisted extraction
Monica Gallo, 2010
Conclusion
• MAE - more convenient compared to the ultrasound
extraction method especially for Cinnamomum
zeylanicum, Cuminum cyminum, Crocus sativus
• Coriandrum sativum no significative differences
between the two methods
• Extracts obtained using microwaves were richer in
antioxidant metabolites than those obtained by
ultrasonic extraction
Monica Gallo, 2010
Conclusion
• MAE - more convenient compared to the ultrasound
extraction method especially for Cinnamomum
zeylanicum, Cuminum cyminum, Crocus sativus
• Coriandrum sativum no significative differences
between the two methods
• Extracts obtained using microwaves were richer in
antioxidant metabolites than those obtained by
ultrasonic extraction
Monica Gallo, 2010