Presence of Phytosterol Oxides in Crude Vegetable Oils and Their Fate during Refining

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• 作者：Renzo Bortolomeazzi ; Francesca Cordaro ; Lorena Pizzale ; and Lanfranco S. Conte
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2003
• 出版时间：April 9, 2003
• 年：2003
• 卷：51
• 期：8
• 页码：2394 - 2401
• 全文大小：108K
• 年卷期：v.51,no.8(April 9, 2003)
• ISSN：1520-5118

文摘

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 notfor direct consumption. The 7s/gifchars/alpha.gif" BORDER=0>- and 7s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-hydroxy derivatives of s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-sitosterol, stigmasterol, andcampesterol and the 7-keto-s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-sitosterol were the principal phytosterol oxides found in almost all ofthe oils analyzed. In some oils, the epoxy and dihydroxy derivatives of s/gifchars/beta2.gif" BORDER=0 ALIGN="middle">-sitosterol were also foundat very low levels. The highest total concentrations of phytosterol oxides, ranging from 4.5 to 67.5and from 4.1 to 60.1 ppm, were found in sunflower and maize oils, respectively. Lower concentrationswere present in the peanut oils, 2.7-9.6 ppm, and in the palm nut oil, 5.5 ppm, whereas in the lampanteolive oils, only three samples of the six analyzed contained a low concentration (1.5-2.5 ppm) ofoxyphytosterols. No detectable levels of phytosterol oxides were found in the samples of palm andcoconut oils. Bleaching experiments were carried out on a sample of sunflower oil at 80 s/entities/deg.gif">C for 1 hwith 1 and 2% of both acidic and neutral earths. The bleaching caused a reduction of thehydroxyphytosterol with partial formation of steroidal hydrocarbons with three double bonds in thering system at the 2-, 4-, and 6-positions (steratrienes). The same sunflower oil was deodorized at180 s/entities/deg.gif">C under vacuum for 1 h, and no dehydration products were formed with a complete recoveryof the hydroxyphytosterols. A bleaching test with acidic earths was carried out also with an extravirgin olive oil fortified with 7-keto-cholesterol, dihydroxycholesterol, and s/gifchars/alpha.gif" BORDER=0>-epoxy-cholesterol. Therewas no formation of steratrienes from these compounds, but dihydroxycholesterol underwentconsiderable decomposition and s/gifchars/alpha.gif" BORDER=0>-epoxycholesterol underwent ring opening with formation of thedihydroxy derivative, whereas 7-ketocholesterol was rather stableKeywords: Phytosterol oxides; cholesterol oxides; vegetable oils; steroidal hydrocarbons; steradienes;steratrienes; refined oils; bleaching; deodorization; gas chromatography-mass spectrometry