乾燥溫度-時間條件對荔枝花萃出物成分之影響

Effect of drying temperature – time condition on the composition of litchi（Litchi chinensis Sonn.）flower extract

陳志永(Chin-Yung Chen)

指導教授 ： 劉世詮

中山醫學大學/健康管理學院/健康產業科技管理學系/碩士(2012年)

https://doi.org/10.6834/CSMU.2012.00167

摘要

荔枝（Litchi chinensis Sonn.）為無患子科（Sapindaceae fimily）荔枝屬（Litchi）植物，於春季開花，花的外觀為白綠色、淡黃色小花。通常被作為栽作的副產物，但近年來研究指出荔枝花本身具有豐富的酚類化合物與清除DPPH自由基能力和抑制以銅離子誘導人類LDL氧化效果。本研究以不同乾燥溫度-時間條件（50℃ 24h、50℃48h、75℃ 24h及100℃ 24h）乾燥荔枝花，並以冷凍乾燥處理之荔枝花作為實驗對照組，再以不同極性溶劑（水、乙醇、丙酮、乙酸乙酯及正己烷）萃取，經由不同抗氧化活性檢測法（清除DPPH自由基能力、清除ABTS+自由基能力、還原能力及抑制以銅離子誘導人類LDL氧化）探討不同熱風溫度乾燥對荔枝花品質的影響，並進一步使用高效能液相層析檢測其組成變化，盼能建立乾燥荔枝花相關資訊，提供相關研究及產品研發之參考。實驗結果顯示如下：在抗氧化能力測定方面，荔枝花冷水萃取物的清除DPPH自由基能力、清除ABTS+自由基能力及還原能力之EC50值，隨著乾燥溫度升高其EC50值下降，其EC50值下降率皆超過25%以上，然丙酮、乙酸乙酯和正己烷荔枝花萃取物者則為乾燥溫度上升，其抗氧化效果降低。此外，丙酮、乙酸乙酯正己烷荔枝花萃取物皆具延緩LDL氧化之能力，其中發現乙醇、丙酮及乙酸乙酯荔枝花萃取物，其氧化遲滯時間隨熱風乾燥上升，有延緩的趨勢。分析不同溫度乾燥-時間條件對不同溶劑之荔枝花萃取物中酚酸與類黃酮含量之變化，發現冷水荔枝花萃取物中rutin、gallic acid含量隨熱風乾燥溫度增加而上升；乙醇荔枝花萃取物中以gallic acid、rutin及p-coumic acid含量與加熱溫度上升呈現正相關性；丙酮及乙酸乙酯荔枝花萃取物中，隨乾燥溫度上升，其gallic acid與p-coumic acid含量則增加。經本研究結果顯示，不同熱風乾燥溫度-時間條件影響荔枝花之組成分，整體上以75-100 ℃熱風乾燥24小時或50℃熱風乾燥48小時，可增加冷水、乙醇荔枝花萃取物的抗氧化能力，而乙醇、丙酮及乙酸乙酯荔枝花萃取物亦可增加其抑制LDL氧化之能力。欲開發健康食品則建議可選擇以75℃- 100℃的溫度為乾燥溫度，如欲大量萃取荔枝花的機能成分，可選擇乙醇或水作為萃取溶劑。

關鍵字

荔枝花 ； 乾燥溫度 ； 溶劑萃取 ； 抗氧化活性 ； LDL

並列摘要

Litchi (Litchi chinensis Sonn.) is the plant of the genus Litchi in the soapberry family, Sapindaceae. Litchi (Litchi chinensis Sonn.) flowers blossom in spring. The color of litchi flowers is white-green to canary yellow. Litchi flowers are regarded as agricultural by-product, but in recent years it had been found that litchi flowers are rich in polyphenol content and good antioxidant effects, such as scavenging 1.1-Diphenyl-2-picrylhydrazyl hydrate (DPPH) radical effect and inhibiting the copper ion (Cu2+)-induced oxidation of human low-density lipoprotein (LDL) effect. In this study, litchi flower were dried at 50℃, 24h; 50℃, 48h; 75℃, 24h; 100℃, 24h; and the freeze-dried flower as the control. These samples were extracted by different polar and non-polar solvents (i.e. cold water, 95% ethanol, acetone, ethyl acetate and n-hexane) to study the effect of drying temperature on quality of the processed litchi flowers, using various antioxidative assays, such as DPPH free radical scavenging effect, ABTS+ free radical scavenging effect, reducing power and Cu2+-induced oxidation of human LDL. The changes of compositions were determined by high performance liquid chromatographic assay. We hope to establish the data base and information of dried litchi flowers, which may further provide reference for research and new product development. The results were demonstrated as following: Antioxidative activities of litchi flower cold water extracts: the EC50 values of extracts determined by DPPH scavenging, ABTS+. scavenging and reducing power methods decreased as the drying temperature increasing. The EC50 values decreased percentage were more than 25%. However, the antioxidative activities of acetone, ethyl acetate and n-hexane litchi flower extracts decreased as drying temperature increased. The acetone, ethyl acetate and n-hexane litchi flower extracts can delay the oxidation of LDL. The oxidation lag time of cold water, ethanol, acetone and ethyl acetate litchi flower extracts by various drying treatments increased as drying temperature increased. However, the lag time of cold water extracts were shorter than the control. In analyzing the changes in phenolic acids and flavonoids of various solvents by various drying treatments, the rutin and gallic acid contents of cold water litchi flower extract increased as the drying temperature increased. It was found that positive correlation existed between the gallic acid, rutin and p-coumic acid contents of ethanol litchi flower extracts and the drying temperatures. The gallic acid and p-coumic acid contents of acetone and ethyl acetate litchi flower extracts increased as the drying temperature increased. In this study, the compositions of treated litchi flower may be affected by drying temperatures. For developing new functional food, we suggest that litchi flower can be dried at 75-100oC, and be extracted by cold water or ethanol to obtain more functional contents than the other solvents extracted.

並列關鍵字

litchi flower ； dried temperatures ； solvent extracts ； antioxidative activities ； LDL

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