15.5 Extraction of Cutin
339
15.5 Extraction of Cutin
A few methods have been presented for extraction of cutin from plants such as
tomatoes and fewer on aquatic plants. The extraction methods presented either make
use of various solvents or acid or alkali for extraction of cutin from parts of the plants
such as the leaves and peels (Borisjuk et al. 2018; Cifarelli et al. 2016; Cigognini
et al. 2015). The cuticle is separated from the plant epidermal wall by either mild
chemical treatment or enzyme treatment. Ammonium oxalate is often used in the
chemical treatment, and pectinases are used in the enzyme method to degrade the
pectinaceous layer which serves as a “glue” to adhere the cuticle to the epidermal
wall.
Extraction of cutin from duckweed as presented by Borisjuk et al. (2018) is used
to extract cutin from the cuticle of aquatic plant for the main purpose of studying
the biochemistry of cutin from species of aquatic plants. This was therefore not
presented as a commercial process for cutin extraction; rather, it was the mildest
means to obtain cuticle components for analysis. In the said process, the first step
was to remove the wax fraction of the cutin matrix. The duckweed fronds were
lyophilized and immersed in 2 ml chloroform in two consecutive processes. The
first process involves a 60 s chloroform treatment of the lyophilized fronds twice
then followed by another chloroform treatment for 30 s. This is then followed by
treatment with alkane at a concentration of 10 mg/50 ml. The wax residue is separated
at this point. This wax residue can also be a source of other useful compounds
such as squalene. The extract is then dried under a stream of nitrogen. This was
then followed by further exhaustive extraction with a mixture of chloroform and
methanol at equal volume ratios for 2 weeks with the solvent changed daily. The
residue is then transesterified with 1 N methanolic HCL for 2 h at 80 °C. Following
transesterification-saturated sodium chloride and dotriacontane were added followed
by subsequent triple extraction with hexane (Borisjuk et al. 2018).
In a method patented in 2015 (Cigognini et al. 2015), used for extraction of cutin
from tomato peels, a less laborious process using much less solvent is presented.
However, no work is yet presented which uses this method for cutin extraction from
aquatic plants. It is assumed that the same method is applicable to extract cutin from
aquatic plant leaves. The extraction is achieved with sodium hydroxide, heating and
centrifugation as follows. It can be assumed that since the cutin from both aquatic
and terrestrial plants has the same chemical components, similar methods can be
employed in their extraction since the general goal of the extraction is the isolation
of cutin from the other components of the cuticle through dissolution and partial
degradation followed by precipitation.
In the said method, tomato peels are treated in sodium hydroxide at a concentration
of 0.75 M (patent claim states that anywhere between 0.5 and 6 M can be used) and
a temperature of 100 °C or anywhere between 65 and 130 °C for a period of 2 h with
an acceptable time period range between 15 min and 6 h. The liquid alkali solution is
added at a solid to liquid alkali ratio of 1:100 tomato peels: liquid. The mass is then
filtered with sieve, and the solid residue is discarded while the brown liquid fraction
339
15.5 Extraction of Cutin
A few methods have been presented for extraction of cutin from plants such as
tomatoes and fewer on aquatic plants. The extraction methods presented either make
use of various solvents or acid or alkali for extraction of cutin from parts of the plants
such as the leaves and peels (Borisjuk et al. 2018; Cifarelli et al. 2016; Cigognini
et al. 2015). The cuticle is separated from the plant epidermal wall by either mild
chemical treatment or enzyme treatment. Ammonium oxalate is often used in the
chemical treatment, and pectinases are used in the enzyme method to degrade the
pectinaceous layer which serves as a “glue” to adhere the cuticle to the epidermal
wall.
Extraction of cutin from duckweed as presented by Borisjuk et al. (2018) is used
to extract cutin from the cuticle of aquatic plant for the main purpose of studying
the biochemistry of cutin from species of aquatic plants. This was therefore not
presented as a commercial process for cutin extraction; rather, it was the mildest
means to obtain cuticle components for analysis. In the said process, the first step
was to remove the wax fraction of the cutin matrix. The duckweed fronds were
lyophilized and immersed in 2 ml chloroform in two consecutive processes. The
first process involves a 60 s chloroform treatment of the lyophilized fronds twice
then followed by another chloroform treatment for 30 s. This is then followed by
treatment with alkane at a concentration of 10 mg/50 ml. The wax residue is separated
at this point. This wax residue can also be a source of other useful compounds
such as squalene. The extract is then dried under a stream of nitrogen. This was
then followed by further exhaustive extraction with a mixture of chloroform and
methanol at equal volume ratios for 2 weeks with the solvent changed daily. The
residue is then transesterified with 1 N methanolic HCL for 2 h at 80 °C. Following
transesterification-saturated sodium chloride and dotriacontane were added followed
by subsequent triple extraction with hexane (Borisjuk et al. 2018).
In a method patented in 2015 (Cigognini et al. 2015), used for extraction of cutin
from tomato peels, a less laborious process using much less solvent is presented.
However, no work is yet presented which uses this method for cutin extraction from
aquatic plants. It is assumed that the same method is applicable to extract cutin from
aquatic plant leaves. The extraction is achieved with sodium hydroxide, heating and
centrifugation as follows. It can be assumed that since the cutin from both aquatic
and terrestrial plants has the same chemical components, similar methods can be
employed in their extraction since the general goal of the extraction is the isolation
of cutin from the other components of the cuticle through dissolution and partial
degradation followed by precipitation.
In the said method, tomato peels are treated in sodium hydroxide at a concentration
of 0.75 M (patent claim states that anywhere between 0.5 and 6 M can be used) and
a temperature of 100 °C or anywhere between 65 and 130 °C for a period of 2 h with
an acceptable time period range between 15 min and 6 h. The liquid alkali solution is
added at a solid to liquid alkali ratio of 1:100 tomato peels: liquid. The mass is then
filtered with sieve, and the solid residue is discarded while the brown liquid fraction