探討不同萃取方法對黑芝麻籽的芝麻油回收與品質之影響

黑芝麻籽為傳統食用油重要來源之一，其榨油之技術主要來自民間流傳的技藝，雖然具有文化傳承之意義，但是缺少科學探討與認證。黑芝麻油壓榨之前，需進行加熱焙炒，以去除水分、產生香氣與色澤，不過高溫通常造成油脂氧化，而本研究最主要之目的為了解不同萃取油之方式及高溫焙炒黑芝麻籽對壓榨油所產生的影響及其因應之道。黑芝麻籽先以冷凍乾燥以及焙炒100℃、150℃、200℃、250℃等方式進行去水處理。接著分別再以低溫壓榨、有機溶劑提取及超臨界流體萃取等方法，萃取初榨的芝麻油，置於4℃冷藏48小時沉澱雜質，過濾後，裝瓶密封，待測。經檢測分析後，發現機器壓榨、索氏萃取和超臨界萃取的萃油效率分別為39.5%、48.5% 和53.5%，進行游離脂肪酸氣相層析時，炒焙組的機器壓榨亞麻油酸為871 ppm、油酸為904 ppm、棕櫚酸為151 ppm、硬脂酸為158 ppm，相較其他萃取方式有較低趨勢，而經由在未精鍊、精鍊、未油炸、油炸過程，可以發現炒焙組機器壓榨的未做任何加工處理之油脂酸價為1.27 mg KOH/g 油，發煙點為180℃，色澤部份L*為47.37，a*為0.59，b*為13.61，相較於其他萃取方式有較佳現象，而在過氧化價分析中，炒焙組精製組別裡其機器壓榨為1.20 meq/1000g 油，也可以發現有較低趨勢。藉由這些品質檢測，比較其油脂酸敗變化之情形，以作為傳統黑芝麻油生產之科學依據。本研究所得結果將可應用在低溫壓榨黑芝麻油的焙炒溫度、焙炒時間、萃油率、品質穩定性上。

關鍵字

低溫壓榨；黑芝麻油；焙炒溫度；食用油萃取

並列摘要

Black sesame seeds is one of the important sources of traditional edible oil. The technique of oil extraction is mainly from local traditional folk practices. Although such folk technique could be a significant cultural inheritance, it is lack of scientific investigation and evaluation. Before cold pressed, black sesame seeds have to be roasted at high temperatures in order to remove moisture, and generate aroma and color. The heating process usually causes lipid oxidation. The main purpose of this study is to investigate the effect of different roasting temperatures and different extraction on production of black sesame seed oil, and also look for an optimal solution to produce a high quality oil. In this study, black sesame seeds were dehydrated by freeze-drying, heating at 100℃, 150℃, 200℃, 250℃ and followed by cold-pressed extraction oil. The optimal roasted temperature is 200℃, compare with unroasted sesame seeds on the low temperature mechanical extraction, organic solvent extraction, and supercritical extraction on black sesame oil. The oils were stored at 4℃ for 48 hours for precipitation of impurities. The oils were then filtered, bottled, and kept at 4℃ for further studies. It is found the extraction oil rate of mechanical pressing, organic solvent extraction, and supercritical extraction is 39.5%, 48.5%, and 53.5%. After free fatty acid of gas chromatography analysis, the content that the linoleic acid, oleic acid, palmitic acid, stearic acid of mechanical pressing oil without processing is 871 ppm, 904 ppm, 151 ppm, and 158 ppm in the roasting group, which show lower trend than other extraction methods. Through the process of un-refining, refining, non-fried and deep-fried, the acid value of mechanical pressing oil without processing is 1.27 mg KOH/g oil, the smoking point is 180℃, and the L. a. b. of color analysis is 47.37, 0.59, and 13.61 in the roasting group, which is better than other extraction methods. In the peroxide value analysis, the mechanical pressing is 1.20 meq/1000g oil in the refining group, and it can also be showed lower trend than other extraction methods. Through these quality tests, and compare with the rancidity of the oil, the research results may be useful for application on the improvement of roasting temperature, roasting time, extraction oil rate, quality, and stability on cold-pressed black sesame oil technology.