Presence of phytosterol oxides in crude vegetable oils and their fate during refining
Presence of phytosterol oxides in crude vegetable oils and their fate during refining
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DOI：
10.1021/jf026063d
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发表时间：
2003-04-09
影响因子：
6.1
通讯作者：
Conte, LS
中科院分区：
文献类型：
--
作者：
Bortolomeazzi, R;Cordaro, F;Conte, LS
植物甾醇氧化产物的含量是在粗植物油样品中测定的：花生油、向日葵油、玉米油、棕榈仁油和灯油橄榄油，这些油是用于精炼而不是直接食用的。 β-谷甾醇、豆甾醇和菜油甾醇的 7α-和 7β-羟基衍生物以及 7-酮-β-谷甾醇是几乎所有分析的油中发现的主要植物甾醇氧化物。在一些油中，β-谷甾醇的环氧和二羟基衍生物的含量也非常低。向日葵油和玉米油中的植物甾醇氧化物总浓度最高，分别为 4.5 至 67.5 ppm 和 4.1 至 60.1 ppm。花生油中的氧化植物甾醇浓度较低，为 2.7-9.6 ppm，棕榈仁油中的氧化植物甾醇浓度为 5.5 ppm，而在灯油橄榄油中，分析的 6 个样品中只有 3 个样品含有低浓度（1.5-2.5 ppm）的氧化植物甾醇。棕榈油和椰子油样品中未发现可检测到的植物甾醇氧化物。使用 1% 和 2% 的酸性土和中性土对葵花籽油样品进行 80 ℃ 1 小时的漂白实验。漂白导致羟基植物甾醇减少，并部分形成在环系统中的 2-、4-和 6-位具有三个双键的甾体烃（甾体三烯）。同样的葵花籽油在180℃真空脱臭1小时，没有形成脱水产物，羟基植物甾醇完全回收。还用7-酮胆固醇、二羟基胆固醇和(x-环氧胆固醇)强化的特级初榨橄榄油进行了酸土漂白试验。这些化合物没有形成硬脂三烯，但二羟基胆固醇经历了相当多的分解，α-环氧胆固醇经历了开环，形成了二羟基衍生物，而7-酮胆固醇相当稳定。
The content of phytosterol oxidation products was determined in samples of crude vegetable oils: peanut, sunflower, maize, palm nut, and lampante olive oils that were intended for refining and not for direct consumption. The 7alpha- and 7beta-hydroxy derivatives of beta-sitosterol, stigmasterol, and campesterol and the 7-keto-beta-sitosterol were the principal phytosterol oxides found in almost all of the oils analyzed. In some oils, the epoxy and dihydroxy derivatives of beta-sitosterol were also found at very low levels. The highest total concentrations of phytosterol oxides, ranging from 4.5 to 67.5 and from 4.1 to 60.1 ppm, were found in sunflower and maize oils, respectively. Lower concentrations were present in the peanut oils, 2.7-9.6 ppm, and in the palm nut oil, 5.5 ppm, whereas in the lampante olive oils, only three samples of the six analyzed contained a low concentration (1.5-2.5 ppm) of oxyphytosterols. No detectable levels of phytosterol oxides were found in the samples of palm and coconut oils. Bleaching experiments were carried out on a sample of sunflower oil at 80 degreesC for 1 h with 1 and 2% of both acidic and neutral earths. The bleaching caused a reduction of the hydroxyphytosterol with partial formation of steroidal hydrocarbons with three double bonds in the ring system at the 2-, 4-, and 6-positions (steratrienes). The same sunflower oil was deodorized at 180 degreesC under vacuum for 1 h, and no dehydration products were formed with a complete recovery of the hydroxyphytosterols. A bleaching test with acidic earths was carried out also with an extra virgin olive oil fortified with 7-keto-cholesterol, dihydroxycholesterol, and (x-epoxy-cholesterol. There was no formation of steratrienes from these compounds, but dihydroxycholesterol underwent considerable decomposition and a-epoxycholesterol underwent ring opening with formation of the dihydroxy derivative, whereas 7-ketocholesterol was rather stable.