216
10 Aquatic Plants and Algae Proteins
reported for water fern (Brouwer et al. 2019) and 21.5% for duckweed (AguileraMorales et al. 2018). While there are up to hundreds of thousands of species of algae,
some of which belong to the plant kingdom, there are just about a hundred species
of non-algae aquatic plants. The recent rise in algae bloom incidents in different
parts of the world further eludes to the fast rate of growth of algae. Water hyacinth,
ferns and duckweed are also fast-growing plants which can be explored as abundant
sources of aquatic proteins. Despite the fact that aquatic plants and algae could serve
as an abundant source of proteins, well managed and controlled systems for the
cultivation of aquatic plants and algae is important in order to avoid undesirable
population blooms which could result in devastating environmental impacts.
10.5 Extraction of Proteins from Algae and Aquatic Plants
Protein extraction from aquatic plant could be with different goals. It could be carried
out with the aim of processing the proteins from algae into more digestible or more
appealing forms. Example of such is incorporation of algae proteins into snacks
(Lucas et al. 2018). The proteins could be extracted for their bioactive properties
for use in non-food applications such as cosmetics, pharmaceutical or biotechnology
applications. The latter section of this book will explore some of the applications of
such proteins from aquatic plants and algae.
Conventional extraction processes can be carried out using water, acids or alkali.
Other methods also exist which make use of more advanced techniques, some in
combination with the conventional techniques, to improve ease and effectiveness of
extraction. One of the factors which limit full commercial exploitation of proteins
from algae for processed food is the cost and environmental implications of the
extraction process to prepare them into edible forms. However, when considering
high-value applications such as for use as therapeutic agents, these added costs could
then be compensated.
In algae, proteins are usually present alongside polysaccharides such as cellulose,
alginate, ulvans and carrageenans. The extraction strategy could therefore be to either
break down these polysaccharides in order to free up the proteins, or to break down the
protein into a more soluble form which is then dissolved out of the fibrous structure.
This is then followed by other unit operations such as separation and drying.
10.5.1 Physical Extraction
This process involves the application of mechanical force to the biomass which then
frees up the water-soluble protein from the fiber. This can be achieved by applying
shear through grinding, homogenizing or pressing (Barbarino and Lourenço 2005).
It can also be achieved by applying osmotic pressure through immersion in water
for an extended period of time (Marrion et al. 2003). Ultrapure water is used to have
10 Aquatic Plants and Algae Proteins
reported for water fern (Brouwer et al. 2019) and 21.5% for duckweed (AguileraMorales et al. 2018). While there are up to hundreds of thousands of species of algae,
some of which belong to the plant kingdom, there are just about a hundred species
of non-algae aquatic plants. The recent rise in algae bloom incidents in different
parts of the world further eludes to the fast rate of growth of algae. Water hyacinth,
ferns and duckweed are also fast-growing plants which can be explored as abundant
sources of aquatic proteins. Despite the fact that aquatic plants and algae could serve
as an abundant source of proteins, well managed and controlled systems for the
cultivation of aquatic plants and algae is important in order to avoid undesirable
population blooms which could result in devastating environmental impacts.
10.5 Extraction of Proteins from Algae and Aquatic Plants
Protein extraction from aquatic plant could be with different goals. It could be carried
out with the aim of processing the proteins from algae into more digestible or more
appealing forms. Example of such is incorporation of algae proteins into snacks
(Lucas et al. 2018). The proteins could be extracted for their bioactive properties
for use in non-food applications such as cosmetics, pharmaceutical or biotechnology
applications. The latter section of this book will explore some of the applications of
such proteins from aquatic plants and algae.
Conventional extraction processes can be carried out using water, acids or alkali.
Other methods also exist which make use of more advanced techniques, some in
combination with the conventional techniques, to improve ease and effectiveness of
extraction. One of the factors which limit full commercial exploitation of proteins
from algae for processed food is the cost and environmental implications of the
extraction process to prepare them into edible forms. However, when considering
high-value applications such as for use as therapeutic agents, these added costs could
then be compensated.
In algae, proteins are usually present alongside polysaccharides such as cellulose,
alginate, ulvans and carrageenans. The extraction strategy could therefore be to either
break down these polysaccharides in order to free up the proteins, or to break down the
protein into a more soluble form which is then dissolved out of the fibrous structure.
This is then followed by other unit operations such as separation and drying.
10.5.1 Physical Extraction
This process involves the application of mechanical force to the biomass which then
frees up the water-soluble protein from the fiber. This can be achieved by applying
shear through grinding, homogenizing or pressing (Barbarino and Lourenço 2005).
It can also be achieved by applying osmotic pressure through immersion in water
for an extended period of time (Marrion et al. 2003). Ultrapure water is used to have