antioxidants are Chlamydomonas nivalis [33], Chlorella spp. [34, 35], Botryococcus
braunii [36], and Scenedesmus spp. [34].
2.4 Lipids
Algae are a valuable source of a variety of lipids. The lipid fraction of microalgae
primarily consists of polyunsaturated fatty acids (PUFA) like omega 3 fatty acids,
omega 6 fatty acids, arachidonic acids, eicosapentaenoic acid, etc. Due to their
antibacterial, antifungal, and antioxidative properties, PUFAs are considered of
immense importance for proper functioning of the human body [8, 37]. Essential
polyunsaturated fatty acids especially omega-3 and omega-6 are well-known to have
several positive effects on human health such as in the prevention of hypertension,
type 2 diabetes, coronary heart disease, pulmonary disease, etc. [38]. Microalgal
polyunsaturated fatty acids are extracted through novel extraction techniques such as
supercritical fluid extraction, microwave-assisted extraction, pressurized liquid
extraction, ultrasound assisted extraction, and enzyme assisted extraction
[23, 24]. Out of these, carbon dioxide lipid extraction method offers high rate, is
non-toxic, produces solvent-free lipids, and has high selectivity towards
acylglycerols, and therefore, it is a promising technique for large-scale extraction
of lipid from microalgae. It is disadvantageous in the fact that it requires high cost
and energy for supercritical fluid compression [23, 24]. Sterols are also a type of
lipids extracted from micro- and macroalgae, having applications in pharmaceuticals
production by steroidal therapeutics, nutrition as anticholesterol additives in food,
nutraceuticals, and cosmetics [39]. Another promising use of lipids from algae is in
biodiesel production since it promises reduction in dependence on petro fuels,
thereby lowering greenhouse gas emission. Extraction of lipid from algae has a
great potential for an impressive future market accompanied with simultaneous
production of value-added co-products [40]. The current obstruction in large-scale
biodiesel production from algae is cultivation and efficient lipid extraction methods.
However, methods such as UAE, MAE, and SFE are being utilized for the extraction
of lipids, but none of these methods have been exploited at a large scale [41, 42].
2.5 Proteins
Microalgae are contemplated as a potential source of proteins and essential amino
acids. Comprehensive and nutritional analysis has revealed that the proteins derived
from algae are of high standards and very much similar to the regular vegetable
proteins [43]. Due to their high digestibility, nutritional value, and protein content,
microalgae like Spirulina, Arthrospira, Chlorella, and many more are considered
currently as green food. Recently, algal proteins are receiving a lot of attention on
grounds of bioactive and functional properties like anti-inflammatory, anticancerous,
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S. Sinha et al.
braunii [36], and Scenedesmus spp. [34].
2.4 Lipids
Algae are a valuable source of a variety of lipids. The lipid fraction of microalgae
primarily consists of polyunsaturated fatty acids (PUFA) like omega 3 fatty acids,
omega 6 fatty acids, arachidonic acids, eicosapentaenoic acid, etc. Due to their
antibacterial, antifungal, and antioxidative properties, PUFAs are considered of
immense importance for proper functioning of the human body [8, 37]. Essential
polyunsaturated fatty acids especially omega-3 and omega-6 are well-known to have
several positive effects on human health such as in the prevention of hypertension,
type 2 diabetes, coronary heart disease, pulmonary disease, etc. [38]. Microalgal
polyunsaturated fatty acids are extracted through novel extraction techniques such as
supercritical fluid extraction, microwave-assisted extraction, pressurized liquid
extraction, ultrasound assisted extraction, and enzyme assisted extraction
[23, 24]. Out of these, carbon dioxide lipid extraction method offers high rate, is
non-toxic, produces solvent-free lipids, and has high selectivity towards
acylglycerols, and therefore, it is a promising technique for large-scale extraction
of lipid from microalgae. It is disadvantageous in the fact that it requires high cost
and energy for supercritical fluid compression [23, 24]. Sterols are also a type of
lipids extracted from micro- and macroalgae, having applications in pharmaceuticals
production by steroidal therapeutics, nutrition as anticholesterol additives in food,
nutraceuticals, and cosmetics [39]. Another promising use of lipids from algae is in
biodiesel production since it promises reduction in dependence on petro fuels,
thereby lowering greenhouse gas emission. Extraction of lipid from algae has a
great potential for an impressive future market accompanied with simultaneous
production of value-added co-products [40]. The current obstruction in large-scale
biodiesel production from algae is cultivation and efficient lipid extraction methods.
However, methods such as UAE, MAE, and SFE are being utilized for the extraction
of lipids, but none of these methods have been exploited at a large scale [41, 42].
2.5 Proteins
Microalgae are contemplated as a potential source of proteins and essential amino
acids. Comprehensive and nutritional analysis has revealed that the proteins derived
from algae are of high standards and very much similar to the regular vegetable
proteins [43]. Due to their high digestibility, nutritional value, and protein content,
microalgae like Spirulina, Arthrospira, Chlorella, and many more are considered
currently as green food. Recently, algal proteins are receiving a lot of attention on
grounds of bioactive and functional properties like anti-inflammatory, anticancerous,
166
S. Sinha et al.