97
extraction process. Kanauchi and Bamforth (2001) employed a method of β-glucan
extraction which is based on the β-glucan solubilization from cell wall by using
enzymes from outer sources. Lichenase, xylanase, and esterases are some other
enzymes which will improve recovery of β-glucan. To increase the solubilization of
β-glucan, these enzymes are sometimes used as the only treatment, however in
other cases these could also be used along with acid, alkali, or heat treatment.
Skendi et al. (2003) used different varieties of oats for β-glucan extraction by using
heat stable enzyme, termamyl, along with hot water treatment and found greater
recovery of β-glucan by this technique. Additionally, the researchers also used isopropanol and petroleum ether as defatting media that resulted in higher yield.
Soluble and insoluble substances can be separated from each other using highspeed centrifuges during this extraction method. Most of the protein impurities can
become insoluble at their isoelectric point or by use of protein-degrading enzymes
and are excluded during the centrifugation process. After removal of impurities,
solubilized β-glucan was precipitated by either ethanol or calcium sulfate.
Another enzymatic extraction method for β-glucan extraction included boiling
and refluxing of grounded oat powder with ethanol. After defatting, all of the material was suspended in water and heat treated to further deactivate the indigenous
enzymes. α-amylase (termamyl) preparation that is stable at high temperature was
incorporated in this medium to degrade starch impurities. Enzyme pancreatin was
used for removal of protein impurities. Finally, β-glucan was precipitated by slow
addition of ethanol until the concentration reached 50% in the extraction media.
High-speed centrifugation at low temperature was carried out to recover β-glucan
(Dongowski et al. 2005). In a similar study, Papageorgiou et al. (2005) recovered
β-glucan from barley and oats by employing an enzymatic process.
Ultrasound-Assisted Extraction
Ultrasonic-assisted extraction (UAE) is a quick and efficient technique that was
adopted for polysaccharide extraction. The flow diagram for the extraction of
β-glucan from barley by UAE is given in Fig. 1. As is well-known, the application
of UAE may provide several benefits including the reduction of solvents, temperature, and extraction time (Rahmanian et al. 2015). It has been determined that the
extraction rate of UAE is correlated to ultrasound power per unit volume of liquid
(Cheung and Wu 2013), and the kinetics of UAE strongly depend on the fungal
materials, particularly the microstructure and morphology of the fungal cell and
aggregation or dispersion of solid particles in the extracting liquid (Cheung et al.
2013). For example, an optimum UAE extraction condition of polysaccharide from
Ganoderma lucidum (Fr.) Karst was reported to be an ultrasonic frequency of
8 kHz, extraction temperature 95 °C, extraction time 3 h, and the ratio of water to
raw material was 12 (Chen et al. 2010). Similarly, an optimal extraction condition
has been investigated for A. bisporus polysaccharide under the conditions of ultrasonic power 230 W, extraction temperature 70 °C, extraction time 62 min, and
Beta-Glucans
extraction process. Kanauchi and Bamforth (2001) employed a method of β-glucan
extraction which is based on the β-glucan solubilization from cell wall by using
enzymes from outer sources. Lichenase, xylanase, and esterases are some other
enzymes which will improve recovery of β-glucan. To increase the solubilization of
β-glucan, these enzymes are sometimes used as the only treatment, however in
other cases these could also be used along with acid, alkali, or heat treatment.
Skendi et al. (2003) used different varieties of oats for β-glucan extraction by using
heat stable enzyme, termamyl, along with hot water treatment and found greater
recovery of β-glucan by this technique. Additionally, the researchers also used isopropanol and petroleum ether as defatting media that resulted in higher yield.
Soluble and insoluble substances can be separated from each other using highspeed centrifuges during this extraction method. Most of the protein impurities can
become insoluble at their isoelectric point or by use of protein-degrading enzymes
and are excluded during the centrifugation process. After removal of impurities,
solubilized β-glucan was precipitated by either ethanol or calcium sulfate.
Another enzymatic extraction method for β-glucan extraction included boiling
and refluxing of grounded oat powder with ethanol. After defatting, all of the material was suspended in water and heat treated to further deactivate the indigenous
enzymes. α-amylase (termamyl) preparation that is stable at high temperature was
incorporated in this medium to degrade starch impurities. Enzyme pancreatin was
used for removal of protein impurities. Finally, β-glucan was precipitated by slow
addition of ethanol until the concentration reached 50% in the extraction media.
High-speed centrifugation at low temperature was carried out to recover β-glucan
(Dongowski et al. 2005). In a similar study, Papageorgiou et al. (2005) recovered
β-glucan from barley and oats by employing an enzymatic process.
Ultrasound-Assisted Extraction
Ultrasonic-assisted extraction (UAE) is a quick and efficient technique that was
adopted for polysaccharide extraction. The flow diagram for the extraction of
β-glucan from barley by UAE is given in Fig. 1. As is well-known, the application
of UAE may provide several benefits including the reduction of solvents, temperature, and extraction time (Rahmanian et al. 2015). It has been determined that the
extraction rate of UAE is correlated to ultrasound power per unit volume of liquid
(Cheung and Wu 2013), and the kinetics of UAE strongly depend on the fungal
materials, particularly the microstructure and morphology of the fungal cell and
aggregation or dispersion of solid particles in the extracting liquid (Cheung et al.
2013). For example, an optimum UAE extraction condition of polysaccharide from
Ganoderma lucidum (Fr.) Karst was reported to be an ultrasonic frequency of
8 kHz, extraction temperature 95 °C, extraction time 3 h, and the ratio of water to
raw material was 12 (Chen et al. 2010). Similarly, an optimal extraction condition
has been investigated for A. bisporus polysaccharide under the conditions of ultrasonic power 230 W, extraction temperature 70 °C, extraction time 62 min, and
Beta-Glucans