136
use in EAE (Ptichkina et al. 2008; Puri et al. 2012). The former method has been
used to study de-esterification of commercial HM pectin into LM using a synergistic application of high hydrostatic pressure and pectin methyl esterase (PME)
enzyme by Zhao et al. (2015). Similarly, Zykwinska et al. (2008) also reported that
LM pectin can be obtained from HM pectin source by incorporating PME alongside
cellulases and proteases into the Enzyme assisted extraction process.
Electro-Magnetic Field Assisted Extraction (EME)
This technology has been employed to extract pectin from citrange by Zouambia
et al. (2014). In their work, extraction was carried out in magnetizable and enameled
containers that were placed on an induction plate. The apparatus contained 9 levels
where each level provided for a known temperature and power. The time was varied
for 10, 20, 30, 40, 50, 60 and 90 min. The yield of pectin was found to be remarkably high and it was only 2.09 min that gave half the amount of pectin extracted by
conventional heating for 90 min. So a considerable reduction in extraction time is an
added benefit. Hence, this technology can be projected as a novel and promising
method for the extraction of pectin.
Subcritical Water Extraction (SWE)
Subcrtical water extraction involves the use of liquid water at an elevated pressure
which without a change in phase can reach to the temperatures higher than its normal boiling point. It is also known as pressurized hot water extraction (PHWE) and
superheated water extraction (SHWE) (Zakaria and Kamal 2016) and the water may
reach to a temperature of 160 °C which enhances the extraction rate. The high temperature of water can offer a wide range of advantages including low viscosity,
higher rate of mass transfer, low surface tension and high diffusion. It even alters the
physicochemical properties of the subcritical water like dielectric constant and solubility (Azmir et al. 2013). SWE results in reduction of dielectric constant of water
from 79 at 25 °C to 43 at 160 °C and to 33 at temperatures around 200 °C which
enables it to extract both ionic and non-ionic compounds. The solubility of pectin
extracted by solvent having low dielectric constant is enhanced and this in turn
increases the yield (Brunner 2009; Chen et al. 2015). There are certain reports of
low yields at high temperatures, but in case of SWE the yields at 120 °C are high
which highlight the significant increase in mass transfer and prevention of hydrolysis encountered upon conventional extraction. An increase in the yield was observed
by Liu et al. (2016) in case of soy hulls by synergistic application of phosphateassisted subcritical water and ultrasonic treatment. Further at times some other solvent other than water is used and the process is known as accelerated solvent
extraction (ASE). Again the most important property i.e. solubility of water is also
enhanced at subcritical conditions. Further studies in this regard are still needed.
Owing to the higher quality of pectin extracts, short duration of process and acid
N. Noor et al.
use in EAE (Ptichkina et al. 2008; Puri et al. 2012). The former method has been
used to study de-esterification of commercial HM pectin into LM using a synergistic application of high hydrostatic pressure and pectin methyl esterase (PME)
enzyme by Zhao et al. (2015). Similarly, Zykwinska et al. (2008) also reported that
LM pectin can be obtained from HM pectin source by incorporating PME alongside
cellulases and proteases into the Enzyme assisted extraction process.
Electro-Magnetic Field Assisted Extraction (EME)
This technology has been employed to extract pectin from citrange by Zouambia
et al. (2014). In their work, extraction was carried out in magnetizable and enameled
containers that were placed on an induction plate. The apparatus contained 9 levels
where each level provided for a known temperature and power. The time was varied
for 10, 20, 30, 40, 50, 60 and 90 min. The yield of pectin was found to be remarkably high and it was only 2.09 min that gave half the amount of pectin extracted by
conventional heating for 90 min. So a considerable reduction in extraction time is an
added benefit. Hence, this technology can be projected as a novel and promising
method for the extraction of pectin.
Subcritical Water Extraction (SWE)
Subcrtical water extraction involves the use of liquid water at an elevated pressure
which without a change in phase can reach to the temperatures higher than its normal boiling point. It is also known as pressurized hot water extraction (PHWE) and
superheated water extraction (SHWE) (Zakaria and Kamal 2016) and the water may
reach to a temperature of 160 °C which enhances the extraction rate. The high temperature of water can offer a wide range of advantages including low viscosity,
higher rate of mass transfer, low surface tension and high diffusion. It even alters the
physicochemical properties of the subcritical water like dielectric constant and solubility (Azmir et al. 2013). SWE results in reduction of dielectric constant of water
from 79 at 25 °C to 43 at 160 °C and to 33 at temperatures around 200 °C which
enables it to extract both ionic and non-ionic compounds. The solubility of pectin
extracted by solvent having low dielectric constant is enhanced and this in turn
increases the yield (Brunner 2009; Chen et al. 2015). There are certain reports of
low yields at high temperatures, but in case of SWE the yields at 120 °C are high
which highlight the significant increase in mass transfer and prevention of hydrolysis encountered upon conventional extraction. An increase in the yield was observed
by Liu et al. (2016) in case of soy hulls by synergistic application of phosphateassisted subcritical water and ultrasonic treatment. Further at times some other solvent other than water is used and the process is known as accelerated solvent
extraction (ASE). Again the most important property i.e. solubility of water is also
enhanced at subcritical conditions. Further studies in this regard are still needed.
Owing to the higher quality of pectin extracts, short duration of process and acid
N. Noor et al.