13.6 Extraction Process
299
13.6.2 Extraction of Starch from Duckweed
Removal of lignin is carried out by treating the biomass with 25 mM of sodium acetate
at a pH of 5.5 and autoclaving at 121 °C for 20 min. The residue from this is the starch
and cellulose component of the biomass. The starch can then be separated from the
cellulose by methods such as hydrolysis whereby the starch is removed as soluble
sugar. This can be enzymatic hydrolysis with amylase or amyloglucosidase. In this
process, 500 and 50 µL of alpha-amylase and alpha-amyloglucosidase, respectively,
are added per gram of dried biomass and heated under continuous agitation of 250 rpm
for a duration of 5 h after in which hydrolysis is completed. The hydrolyzed starch in
the form of glucose can then be separated from the cellulosic residue. This method of
the extraction of saccharified starch is used, for example, as stage in the conversion
of aquatic plant biomass for bioethanol production. This particular method has been
adapted for use in the extraction of starch for use in the production of biofuel from
duckweed (Miranda et al. 2016). The starch can also be extracted in the whole form.
13.6.3 Extraction of Starch from Macroalgae
Extraction yield from algae varies depending on the type of algae and efficiency of
the process. Here, we review a typical method used for extraction of starch from the
green macroalgae U. ohnoi. Extraction yield of 50.37% has been reported for the
green macroalgae U. ohnoi. The starch extract had 75.45% starch content per extract
mass.
In the method reported for extraction of starch from the green seaweed, U. ohnoi,
the cultivated seaweed was washed and added to distilled water in the ratio 1:20 dry
weight of biomass to water volume. The mixture of water and seaweed was then
homogenized until it forms a fine suspension. This was then followed by filtration
using nylon filters with pore sizes of 100 µm and then through 50 µm and finally
through 10 µm filters. This allowed for more effective filtration. The filtrate obtained
was then centrifuged at 4000 rpm for 6 min. The solid fraction from the centrifugation
contains mainly starch. The residual pigments and lipids are removed by washing
three times with absolute ethanol.
The extraction process can be scaled up for mass production. The process does not
deviate much from the typical process used for industrial production of starch from
terrestrial sources. Extraction yield of 50.37% has been reported for starch from the
green algae U. ohnoi. The purity obtained using this particular method was 75.45%
(Prabhu et al. 2019). This is similar to the purity of other non-aquatic starches such
as cassava, rice and potato which are 80, 75–86.8 and 78.6%, respectively (Bhat and
Riar 2016; Sjöö and Nilson 2018).
299
13.6.2 Extraction of Starch from Duckweed
Removal of lignin is carried out by treating the biomass with 25 mM of sodium acetate
at a pH of 5.5 and autoclaving at 121 °C for 20 min. The residue from this is the starch
and cellulose component of the biomass. The starch can then be separated from the
cellulose by methods such as hydrolysis whereby the starch is removed as soluble
sugar. This can be enzymatic hydrolysis with amylase or amyloglucosidase. In this
process, 500 and 50 µL of alpha-amylase and alpha-amyloglucosidase, respectively,
are added per gram of dried biomass and heated under continuous agitation of 250 rpm
for a duration of 5 h after in which hydrolysis is completed. The hydrolyzed starch in
the form of glucose can then be separated from the cellulosic residue. This method of
the extraction of saccharified starch is used, for example, as stage in the conversion
of aquatic plant biomass for bioethanol production. This particular method has been
adapted for use in the extraction of starch for use in the production of biofuel from
duckweed (Miranda et al. 2016). The starch can also be extracted in the whole form.
13.6.3 Extraction of Starch from Macroalgae
Extraction yield from algae varies depending on the type of algae and efficiency of
the process. Here, we review a typical method used for extraction of starch from the
green macroalgae U. ohnoi. Extraction yield of 50.37% has been reported for the
green macroalgae U. ohnoi. The starch extract had 75.45% starch content per extract
mass.
In the method reported for extraction of starch from the green seaweed, U. ohnoi,
the cultivated seaweed was washed and added to distilled water in the ratio 1:20 dry
weight of biomass to water volume. The mixture of water and seaweed was then
homogenized until it forms a fine suspension. This was then followed by filtration
using nylon filters with pore sizes of 100 µm and then through 50 µm and finally
through 10 µm filters. This allowed for more effective filtration. The filtrate obtained
was then centrifuged at 4000 rpm for 6 min. The solid fraction from the centrifugation
contains mainly starch. The residual pigments and lipids are removed by washing
three times with absolute ethanol.
The extraction process can be scaled up for mass production. The process does not
deviate much from the typical process used for industrial production of starch from
terrestrial sources. Extraction yield of 50.37% has been reported for starch from the
green algae U. ohnoi. The purity obtained using this particular method was 75.45%
(Prabhu et al. 2019). This is similar to the purity of other non-aquatic starches such
as cassava, rice and potato which are 80, 75–86.8 and 78.6%, respectively (Bhat and
Riar 2016; Sjöö and Nilson 2018).