Supercritical Algal Extracts: A Source of Biologically Active Compounds from Nature

Table 1

SFE extraction of biomass of microalgae: review of literature reports.

Extraction	Algae	Installation	Temp. [°C]	Pressure [bar]	Extract	Extraction yield	Reference
SFE with CO2	Botryococcus braunii, Chlorella vulgaris, Dunaliella salina, and Arthrospira maxima, whole, crushed, and slightly crushed	Flow	40–60	125, 200, and 300	B. braunii: alkadienes; C. vulgaris: carotenoids (canthaxanthin, astaxanthin); D. salina: β-carotene (trans- and cis-isomer); A. maxima: GLA, C18:3 ω6 (CO2 and CO2 + 10 mol% ethanol) and lipids	Total GLA: 45%: 35.0 MPa, 333.1 K with the mixture (CO2 + 10 mol% ethanol)	[26]
SFE with CO2 and ethanol (9.4% mass)	Haematococcus pluvialis and; Arthrospira maxima (Spirulina)	Column; flow rate: 1 mL/min	60	300	H. pluvialis: astaxanthin,; A. maxima: phycocyanin	Astaxanthin: 1.7% mass (no effect of ethanol); phycocyanin: 1.1% mass (CO2), 1.7% mass (CO2 + ethanol)	[2]
SFE with CO2 and ethanol (9.23 mL/g)	Haematococcus pluvialis	Biomass 6.5 g; CO2 flow rate: 6.0 mL/min; time: 20 min	50	310	Pigment (astaxanthin)	Astaxanthin: 74% (11 mg/g dry cells),; 8 extraction cycles	[5]
SFE with CO2	Chlorella vulgaris	Flow type	40, 55	350	Carotenoids, lipids	Carotenoids and lipids: improved for crushed cells and at higher p	[25]
SFE with CO2	Botryococcus braunii	Flow type	50–85	200–250	Fatty acids	Lipid yield decreased with temperature and increased with pressure	[36]
SFE with CO2	Botryococcus braunii and Chlorella vulgaris	Flow type	40	300 (B. braunii) and; 350 (C. vulgaris)	B. braunii: hydrocarbons; C. vulgaris: carotenoids (canthaxanthin and astaxanthin)	The extraction yield of carotenoids increased with the degree of crushing of the microalga	[37]
SFE with CO2	Arthrospira platensis (Spirulina)	Time: 4 h	48	200	85 g/kg of flavonoids; 78 g/kg of β-carotene; 113 g/kg of vitamin A; 3.4 g/kg of α-tocopherol; fatty acids: palmitic (35%), linolenic (22%), and linoleic (21%)	Yield of the extracts from; S. platensis–10 g/kg	[38]
SFE with CO2 (soybean oil and ethanol as modifier)	Chlorella vulgaris	Flow type	40	300		Carotenoids: 69%, crushing strongly improved extraction recovery	[39]
SFE with CO2	Haematococcus pluvialis	Time: 4 h	70	500	Astaxanthin	The predicted amount of astaxanthin extracted was 23 mg/g	[40]
SFE with CO2 and ethanol (0.856 mL/g of biomass)	Arthrospira platensis (Spirulina)	Time: 1 h	40	400	-linolenic acid	A recovery of 102% GLA	[41]
SFE with CO2 and ethanol	Arthrospira maxima (freeze-dried)	Flow type	50–60	250	γ-linolenic acid and lipids	GLA and lipids: up to 45%	[27, 28]
SFE with CO2	Synechococcus sp.	Flow type	50 (for carotenoids) and; 60 (for chlorophyll)	300 (for carotenoids) and; 500 (for chlorophyll)	Carotenoids and chlorophylls	Carotenoids (1.5 μg/mg dry weight of microalga); chlorophyll a (0.71 μg/mg dry weight of microalga)	[42]
SFE with CO2 and CO2 : ethanol	Arthrospira platensis; (Spirulina)	Pilot-scale plant	75 (CO2); 55 and (CO2 : EtOH)	320 (CO2) and; 78.6 (CO2 : EtOH)	Vitamin E	CO2: yield 0.85%; 16 mg of vitamin E/g of extract; CO2 : ethanol: yield 8.1%; 0.49 mg of vitamin E/g of extract; CO2 (w/w) 69%	[43]
PLE using mixture of ethanol : ethyl lactate	Arthrospira platensis (Spirulina)	Time: 15 min	180	207	-linolenic acid	Total yields up to 21% (w/w), for a solvent composition of ethanol : ethyl lactate (50 : 50, v/v), GLA recovery of 68%	[44]