Application of response surface methodology  to optimise supercritical carbon dioxide  extraction of volatile compounds from Crocus  sativus.
BACKGROUND
Crocus sativus has been used as a traditional Chinese medicine for a long time. The volatile compounds of C. sativus appear biologically active and may act as antioxidants as well as anticonvulsants, antidepressants and antitumour agents. In order to obtain the highest possible yield of essential oils from C. sativus, response surface methodology was employed to optimise the conditions of supercritical fluid carbon dioxide extraction of the volatile compounds from C. sativus. Four factorswere investigated: temperature, pressure, extraction time and carbon dioxide flow rate. Furthermore, the chemical compositions of the volatile compounds extracted by supercritical fluid extraction were compared with those obtained by hydro-distillation and Soxhlet extraction.


RESULTS
The optimum extraction conditions were found to be: optimised temperature 44.9°C, pressure 34.9 MPa, extraction time 150.2 min and CO₂ flow rate 10.1 L h⁻¹. Under these conditions, the mean extraction yield was 10.94 g kg⁻¹. The volatile compounds extracted by supercritical fluid extraction and Soxhlet extraction contained a large amount of unsaturated fatty acids.


CONCLUSIONS
Response surface methodology was successfully applied for supercritical fluid CO₂ extraction optimisation of the volatile compounds from C. sativus. The study showed that pressure and CO₂ flow rate had significant effect on volatile compounds yield produced by supercritical fluid extraction. This study is beneficial for the further research operating on a large scale.
Qingsong
Q
Shao
Yuqiu
Y
Huang
Aicun
A
Zhou
Haipeng
H
Guo
Ailian
A
Zhang
Yong
Y
Wang
D000927:Anticonvulsants / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D000928:Antidepressive Agents / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D000972:Antineoplastic Agents, Phytogenic / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D002245:Carbon Dioxide / Q000737:chemistry; D002681:China; D025924:Chromatography, Supercritical Fluid; D027622:Crocus / Q000737:chemistry*; D057168:Distillation; D055808:Drug Discovery / Q000379:methods*; D020834:Ethnopharmacology; D035264:Flowers / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D008516:Medicine, Chinese Traditional; D008956:Models, Chemical; D009822:Oils, Volatile / Q000737:chemistry* / Q000302:isolation & purification; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D013223:Statistics as Topic; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000302:isolation & purification
D000927:Anticonvulsants; D000928:Antidepressive Agents; D000972:Antineoplastic Agents, Phytogenic; D000975:Antioxidants; D009822:Oils, Volatile; D012997:Solvents; D055549:Volatile Organic Compounds; D002245:Carbon Dioxide