Oils tocopherols

Reversed-phase high-performance liquid chromatography (RP-HPLC), cholesterol measurement, 456-458 Rhamnogalacturonanas, 735 Rice bran oil, tocopherols/tocotrienols in, 488 (figs.)... 

FIGURE 5-52. Examples of normal phase separations, (a) Corn-oil tocopherols. Sample 10 /xL of corn oil in 100 /xL of mobile phase. Column Nova Pak Silica (4 jam), 3.9 mm ID x 150 mm. Mobile phase 0.3% isopropyl alcohol in isooctane. Flow rate 1.0 mL/min. Detection fluorescence 290 nm excitation and 335 nm emission. (b) Separation of vitamin E from vitamin A. Mobile phase 0.5% isopropyl alcohol in isooctane. Other conditions are the same as those in a with the exception that retinol was detected with 365 nm excitation and 510 nm emission, (c) Structures of compounds. 

Olive oil contains a-tocopherol in the range of 12-190 mg/kg. According to one report (43), olive oil tocopherols were found to consist of 88.5% a-tocopherol, 9.9% (3--f y-tocopherol, and 1.6% 8-tocopherol. Tocopherol content can be used to detect adulteration of olive oil with seed oils. 

Unsaponifiable Components Wheat germ oil is quite rich in unsaponi-fiable compounds, in particular phytosterols and tocopherols (Table 7). Small quantities of triterpenols, n-alkanols, carotenoids, and hydrocarbons are also present in the unsaponifiable fraction of the oil. Tocopherols and n-alkanols are commercially the most important unsaponifiable components in WGO. 

The effect of carotenoids is mostly cosmetic in nature high levels of carotenoids cause the oil to be too reddish or yellowish for present-day consumers who prefer lightly colored oils. Tocopherols and tocotrienols are natural antioxidants it is desirable that they be left in the oil to the maximum extent possible during processing. 

The main components of unsaponifiables in vegetable oils are tocopherols and sterols, present in different amounts in vegetable oils. Tocopherols are known to be very efficient natural antioxidants. Their amount in the plant is probably... 

Sea buckthorn (soft part) oil is also rich in carotenoids (up to 1 %, w/w of oil), tocopherols (0.3-0.5%), and phytosterols (2-3%) (Yang, 2001) and the benefits observed with sea buckthorn oil are probably the result of a synergy between fatty acids and other bioactive components. 

The antioxidant activity is affected by the antioxidant stracture (Lien et al., 1999), temperature (Reblova, 2006), light, relative humidity (Kimet al., 2015), oil physical state and presence of other compounds. Anyway, lipophilic antioxidants such as a-tocopherol were more effective in a heterogeneous system (Frankel et al., 1994 Losada-Barreiro et al., 2013a Schwarz et al., 2000). In com oil, tocopherol emulsion is localized toward oil-interfacial regions and for this reason it manifests a good efficiency in the inhibition of lipid oxidation (Losada-Barreiro et al., 2013b). 

Lecithin and cephalin are common phosphatides found in edible oils. Soybean, canola/rapeseed, com, and cottonseed are the major oils that contain significant quantities of phosphatides. Alkaline treatment used for FFA reduction is also capable of removing most of the phosphatides from these crade oils. Tocopherols are important minor constituents of vegetable oils, which are natural antioxidant that retard the development of rancidity. 

Another kind of d. is steam distillation steam is blown into the material with or without vacuum being applied. Some, especially neutral and nonpolar substances (-> essential oils, - tocopherol), will distill together with the steam and thus can be separated from the nonvolatile material. The distillate separates into two layers upon cooling or is extracted with proper organic solvents. Because steam d. is a gentle procedure, it is used frequently in the isolation of -> fragrance raw materials and in oil refining (- fats and oils). 

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