以液相層析串聯質譜法分析糙米與條類米製品之植物固醇含量

Separation and determination of phytosterols in brown rice and rice vermicelli using UPLC-APCI-MS/MS

許芸華(Yun-Hua Hsu)

指導教授 ： 呂廷璋

國立臺灣大學/生物資源暨農學院/食品科技研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.10836

摘要

植物體中之植物固醇，有以下幾種主要型態，包含自由態(Sterols)、以及酯化態(Steryl Esters, SE)、Steryl Ferulate (SF)、醣苷態(Steryl Glycoside, SG)與酯化醣苷態(Acylated Steryl Glycoside, ASG)等結合態。傳統的植物固醇分析採用水解法，用皂化後產生的自由態固醇進行總固醇定量，缺點是方法繁瑣且無法測得不同結合型態之植物固醇；本研究目的為建立同步分析自然存在不同型態植物固醇之分析方法，進一步了解糙米、發芽糙米與米製加工品之植物固醇含量。樣品前處理以Folch法萃取總脂質，以酸水解鹼皂化方式取得總植物固醇含量，而萃取液以NH2固相萃取管淨化可去除三酸甘油酯及酯化態固醇，獲得完整結合態植物固醇。儀器檢測以Diol正相液相層析管柱搭配蒸發光散射偵檢器(ELSD)可檢測不同型態植物固醇總量，而逆相液相層析採用BEH Shield RP18管柱串聯質譜儀，以大氣壓化學游離法(Atmospheric Pressure Chemical Ionization, APCI)游離後，固醇基團脫去一分子水為植物固醇之特徵離子訊號，自由態固醇偵測極限介於4.5-51.7 ppb。利用建立之方法分析台南11號與台稉2號之糙米與發芽糙米，植物固醇以自由態β-sitosterol、campesterol、stigmasterol為主，並含有相當含量之米糠醇(γ-oryzanol)32.94-105.17 mg/100 g與少量之醣苷態與酯化醣苷態固醇；經熱加工蒸煮後之糙米與發芽糙米，總植物固醇含量為50.95-147.37 mg/100 g；市售條類米製品之植物固醇含量標示100%純米製造者檢測出米糠醇植物固醇含量為0.77-2.89 mg/100 g，而稻米含量占成品比例少於50%或原物料非以稻米為主之樣品，米糠醇含量為未檢出。

關鍵字

植物固醇 ； 米糠醇 ； 糙米 ； 發芽糙米 ； 液相層析串聯質譜儀 ； 蒸發光散射偵檢器

並列摘要

Phytosterol has been proved to have biological activities of reducing blood LDL-cholesterol, anti-cancer activity and anti-inflammatory activity. Phytosterols can be separated into free form sterols, and conjugated sterols, including steryl esters, steryl ferulates, steryl glycoside and acylated steryl glycoside. It is well known that the analysis of phytosterols to use acid hydrolysis, basic saponification and purification to release free form sterols. The aim of this study is to separate and detemine the diversiform phytosterols in brown rice andgerminated brown rice. Sample preparation includes the extraction of lipids by Folch method, saponification or acid hydrolysis, extraction of unsaponification matter and NH2 solid phase extraciton to partial purification of sterols. Sterols were separated by normal or reverse phase liquid chromatography and determinated and quantified by evaprated light scattering detector (ELSD) or mass sepctrometry in positve atmospheric pressure chemical ionization (APCI). We found almost all phytosterols to have the most abundant signal corresponding to a protonated fragment ion [M+H-H2O]+, which was chosen for the identification. The limit of detection (LOD) for free sterols was 4.5-51.7 ppb. It is found that the main free form phytosterols in two cultivars of brown rice and germinated brown rice including β-sitosterol, campesterol and stigmasterol, the content of γ-oryzanol ranges from 32.94 to 105.17 mg/100 g, and trace amount of steryl glycoside and aclyated steryl glycoside were also be detected. The total phytosterol contents in porridge and steamed brown rice were 50.95-147.37 mg/100 g. The content of γ-oryzanol were found to have 0.77-2.89 mg/100 g in commercial rice products made of 100% rice material, and others were made no more than 50% of rice material were not detected.

並列關鍵字

phytosterol ； γ-oryzanol ； brown rice ； germinated brown rice, ； liquid chromatography-tandem mass spectrometry ； evaporative light scattering detector

參考文獻

蘇鼎元。2012。糙米及豆類中不同型態植物固醇同步分析方法之建立。國立台灣大學食品科技研究所碩士論文。台北，台灣。

戴慧玲。2012。以靈芝菌絲進行西洋蔘生物轉化過程固醇類化合物之組成變化。國立台灣大學食品科技研究所碩士論文。台北，台灣。

林毓之。2003。山藥塊莖中植物固醇之分析及其受加工之影響。國立灣大學食品科技研究所碩士論文。台北，台灣。

Abidi, S. L.; List, G. R.; Rennick, K. A. Effect of genetic modification on the distribution of minor constituents in canola oil. J. Am. Oil Chem. Soc. 1999, 76, 463-467.

Abidi, S.L., Chromatographic analysis of plant sterols in foods and vegetable oils. J. Chromatogr. A 2001, 935, 173-201.