Optimization of extraction process parameters of caffeic acid from microalgae by supercritical carbon dioxide green technology

Table 1 Phytochemical properties of obtained SFE extract by SC-CO₂ extraction

Extraction pressure (bar)	Extraction temperature (°C)	Yield of extract (mg/gdw)	TPC (µg GAE/g dw)	Reducing power (µg BHT equivalent/g dw)	FRAP value (mM FeSO₄ equivalent/g dw)	IC₅₀ (µg/mL)
200	30.00	20.06 ± 0.75^a	65.23 ± 3.44^c	456.32 ± 12.01^h	1.21 ± 1.25^h	100.87 ± 4.25^h
200	40.00	15.98 ± 0.27^g	26.29 ± 1.57ⁱ	153.23 ± 7.10^k	0.4 ± 0.14ⁱ	180.10 ± 9.58^d
200	40.00	8.74 ± 0.34^j	20.99 ± 4.69^j	199.68 ± 5.16^j	3.22 ± 0.32^d	140.45 ± 4.21^g
200	50.00	11.56 ± 0.29^d	41.25 ± 2.21^f	214.56 ± 10.09 ⁱ	1.14 ± 0.47^h	100.24 ± 9.54^h
350	30.00	17.81 ± 0.98^f	60.49 ± 3.05^d	179.02 ± 10.72^k	1.27 ± 0.14^h	90.25 ± 2.14ⁱ
350	30.00	2.22 ± 0.37ⁱ	110.45 ± 3.58^a	1124.25 ± 6.58^b	2.35 ± 0.23^f	105.89 ± 8.58^h
350	40.00	12.57 ± 0.22^d	76.87 ± 1.89^b	2278.46 ± 8.03^a	4.19 ± 0.89^a	89.28 ± 10.09^h
350	50.00	1.21 ± 0.72^ij	16.08 ± 4.11^k	947.89 ± 4.81^e	3.31 ± 0.81^c	200.17 ± 7.14^c
350	50.00	2.09 ± 0.07ⁱ	28.11 ± 1.79ⁱ	89.29 ± 7.04^l	3.29 ± 0.47^c	204.83 ± 4.78^c
500	30.00	10.22 ± 0.92^b	42.56 ± 2.14^f	700.13 ± 10.01^f	4.09 ± 0.87^b	211.52 ± 2.10^b
500	40.00	4.80 ± 0.07^h	33.74 ± 1.89^h	579.73 ± 9.14^g	2.58 ± 0.56^e	219.17 ± 6.45^a
500	40.00	9.25 ± 0.22^e	50.89 ± 3.58^e	1068.29 ± 8.47^d	2.25 ± 0.23^f	157.22 ± 11.49^f
500	50.00	4.57 ± 1.46^c	38.24 ± 2.17^g	1155.21 ± 7.09^c	2.17 ± 0.18^g	174.96 ± 7.28e

dw: Dry weight of sample; TPC: Total phenolic content (µg gallic acid equivalent (GAE)/g of dry weight (dw) of microalgae sample); IC₅₀: IC₅₀ value of DPPH radical scavenging activity
Different letters in a column indicate significant differences at p < 0.05 level

ISSN: 2661-801X