超臨界二氧化碳法與二種水蒸汽蒸餾法對檜木萃取效率之研究

本研究係以超臨界二氧化碳(Supercritical carbon dioxide)、傳統水蒸汽蒸餾及新型雙重冷卻蒸餾三種方法萃取檜木(Chamaecyparis formosensis Matsum)，再比較其色澤、氣味以及萃取率，並使用反應曲面法(Response surface methodology；RSM)探討超臨界萃取的適當條件。試驗結果顯示：以超臨界二氧化碳的萃取物，最接近檜木粒片的天然香氣；而使用新型雙重冷卻裝置者，由於蒸餾過程經過雙重冷卻，將餾出的精油保持在低溫狀態，因此，檜木香氣的成份得以保留；而使用傳統水蒸汽抽提之精油氣味，較不似天然香氣。以超臨界二氧化碳萃取之萃取率則依操控條件之不同而異，最高可達15.65%，較水蒸汽蒸餾者，增加了3倍；將水蒸汽蒸餾後之檜木粒片，再以超臨界二氧化碳法，仍可再萃取出約9.0%，可知以水蒸汽蒸餾只萃取出全量的1/3。經反應曲面法解析使用超臨界二氧化碳由壓力(10-20MPa)、溫度(40-60℃)及時間(1.5-2.5hr)組成17項條件之萃取結果，顯示壓力最具效應，其次為作業時間，操作溫度的影響則最小。

This study adopted three extraction methods, namely supercritical carbon dioxide, traditional steam distillation, and novel dual-cooling distillation, to extract essential oil from Chamaecyparis formosensis Matsum. Subsequently, the color, odor and extraction yield of the obtained extracts were compared, and Response Surface Methodology (RSM) was used to investigate the optimal operating conditions for supercritical extraction. The experimental results demonstrated that the extract obtained via supercritical carbon dioxide extraction exhibited an aroma closest to the natural scent of cypress wood chips. For the product from the novel dual-cooling distillation, as the distillation process adopted dual cooling, the distilled essential oil was maintained at low temperatures, thus retaining the characteristic odor components of the cypress wood. By contrast, the essential oil extracted via traditional steam distillation had an odor that was less similar to the natural scent. The extraction yield of supercritical carbon dioxide extraction varied with operating parameters, with a maximum value of 15.65%, which was 3 times higher than that of traditional steam distillation. Moreover, approximately 9.0% of essential oil could still be extracted from the cypress wood chips that had undergone steam distillation using supercritical carbon dioxide, revealing that traditional steam distillation only extracted about one-third of the total essential oil. Through RSM analysis of the extraction results under 17 operating conditions consisting of pressure (10-20 MPa), temperature (40-60 ℃) and extraction time (1.5-2.5 hr), it was found that pressure exerted the most significant effect, followed by operating time, while operating temperature had the minimal impact.