Table 7.
The extraction parameters of Crocus sativus stigmas, as recorder from the extensive review of literature.
| Solvent | Method | Measured Parameters | Main Results | Reference |
|---|---|---|---|---|
| Water (solid/liquid 1/2000, w/v) | CSE with magnetic stirring at 1000 rpm for 1 h under dark (ISO 3632-2:2010) |
UV–vis spectrophotometry | picrocrocin, safranal and crocins are expressed as direct reading of the absorbances produced by the 1:10 dilution of the extract at 257, 330 and 440 nm | [192] |
| Methanol, ethanol, propanol, acetone, ethyl acetate and petroleum ether (solid/liquid 1/50, w/v) |
Soxhlet Cold percolation |
UV–vis spectrophotometry, HPLC-UV | Soxhlet (overnight): acetone recovered picrocrocin in the highest yield, while methanol was more effective for the extraction of safranal and crocins. Cold percolation (overnight): the safranal content of oleoresin remain more intact in this method |
[193] |
| Ethanol–water mixtures (solid/liquid 1/10–1/40, w/v) | CSE (agitation at 200 rpm for up to 60 min, at 25 °C, and protected from light |
HPLC-DAD, TPC | Optimization for crocins: ethanol 50% (v/v), temperature 25 °C, solid/solvent 1/20; recovery 77% of theoretical | [194] |
| Distilled water (DW), ethanol/DW, methanol/DW, propylene glycol/DW, heptane/DW and hexane/DW (solid/liquid 1/30, w/v) |
Maceration (72 h, 25 °C) | UV–vis spectrophotometry | Ethanol–water was the most efficient solvent for the extraction of crocin and safranal, while methanol–water was the most efficient for picrocrocin | [195] |
| Ethanol in water 50% (solid/liquid 1/10, 1/20 w/v) |
MAE: 200 W (under magnetic stirring, 50 °C, 18 min) UAE: (33 KHz, room temperature, 30 min) |
ABTS, DPPH, FRAP, TPC | The MAE method was more effective compared to the UAE method, with six fold higher yield. | [196] |
| Methanol in water 50% (solid/liquid 1/180–1/1800, w/v) |
UAE. Amplitude setting range, 10–100 in 1% increments; frequency, 20 kHz and output, 70 W; 100% amplitude; temperature: 15 ± 0.5 °C |
HPLC-DAD, Optical Microscopy | Optimal conditions for crocins recovery: solid/liquid 1/180 w/v; sonication time: 29 min; yield 627 mg/g saffron | [197] |
| Ethanol in water 50% (solid/liquid 1/20, w/v) |
UAE. frequency 25 kHz; power: 100 W; sonication time 1–10 min; temperature 25 °C | UV–vis spectrophotometry | Optimal time to extract crocin, picrocrocin and safranal was 10 min. The yield was higher than with maceration for 72 h. | [198] |
| Water (solid/liquid 1/100, w/v) |
Hydration of the ground material for 2 h at 4 °C, and then application of high hydrostatic pressure | UV–vis spectrophotometry (ISO method), HPLC-DAD | Optimal conditions for maximum extraction of safranal, picrocrocin and crocin: 5800 atm and 50 °C. Total yield of crocins more than 250 mg/g | [199] |
| CO2 | SFE 200 atm, 100 °C |
Safranal GC-FID, HPLC-DAD |
0.476 g/mL fluid density (200 atm and 100 °C); total extraction of safranal within 30 min | [200] |
| Supercritical CO2 (solid/S. Fluid 1/3755, w/v) |
SFE Extraction between 30 and 190 min |
GC-MS | Optimal conditions: temperature 44.9 °C; pressure 349 atm; extraction time 150.2 min; CO2 flow rate 10.1 L h−1; yield 10.94 mg/g from the non-polar fraction | [201] |
| CO2 and CO2-methanol (solid/S. Fluid 1/73, w/v) |
SFE | HPLC-UV/vis detector | Optimal recovery of crocin (32.67% w/w): 44 °C, 193 atm, 1.0 cm3/min, 110 min Safranal (recovery 91.8% w/w): 92 °C, 213 atm, 0.9 cm3 min, 122 min |
[202] |
| CO2 (solid/S. Fluid 1/1440; solid/liquid methanol or water as modifier, 1/96 /V) |
SFE; duration 240 min; CO2 pump flow rate 3 mL/min; modifier flow rate of 0.2 mL/min. | HPLC-UV/vis detector | Crocin was optimally extracted at 80 °C and 300 atm using water as a modifier. Optimal conditions for safranal: 80 °C and 400 atm using methanol as a modifier |
[203] |
ABTS: 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical, CSE: conventional solvent extraction, DPPH: 1,1-diphenyl-2-picrylhydrazyl radical, FRAP: ferric reducing antioxidant power, MAE: microwave assisted extraction, SFE: supercritical fluid extraction, TPC: total phenolic content, UAE: ultrasound assisted extraction.