Tocopherol extraction

Tocopherols consist of a, (3, y, and 8 isomers and are effective antioxidants. Oomah et al. (1997a) observed that y-tocopherol (9.04 mg/100 g seed) was the predominant isomer of Canadian flaxseed cultivars. Total tocopherol ( r = 0.42) and y-tocopherol (r = 0.41) values were correlated with seed oil content. Kamm et al. (2001) reported the distribution of tocopherols and tocotrienols in high and low linolenic flaxseed. Results were similar to the findings of Oomah et al. (1997a) in which y-tocopherol content was greater (430-575 mg/kg oil) in high ALA flaxseeds, whereas low linolenic flaxseed exhibited lower (170 mg/kg oil) values. Bozan and Temelli (2002) compared tocopherol levels in oil extracted by supercritical C02 fluid and soxhlet (Table XI). Soxhlet-extracted oil had greater tocopherol levels (76.4 mg/100 g oil). These authors speculated that the temperature-pressure combination may have influenced the tocopherol extraction by supercritical C02 fluid. 

Miraliakbari and Shahidi, 2008). It has been suggested that the extraction of tocols from plasma samples is improved by deproteiniza-tion of the sample with ethanol before solvent extraction (Lee et ah, 2003 Chauveau-Durio et ah, 2010). Ethanol treatment was also used in oc-tocopherol extraction and the analysis of pharmaceutical preparations and milk (Kadioglu et ah, 2009). 

M. oleifera seed oil is high in the natural antioxidants - tocopherols (128) with homologues (a- P, y-, and 8-tocopherol) (42). Extraction methods influence the quantities of tocopherols extracted (2). a-Tocopherol is the primary vitamer with biological activity, while the other vitamers have been shown to have decreased activity, y-tocopherol has 10% of the activity of a-tocopherol, and 5-tocopherol has 1% of the activity of a-tocopherol (38,115). a-tocopherol content of M. oleifera leaves averages 90.0 mg/kg. However, a-, y- and 5-tocopherols are detected up to levels of 105.0, 39.5 and 77.6 mg/kg of oil, respectively as shown in Table VII (2,82). 

Fig. 4. H NMR spectra of tocopherols, extracted from the contour plot of the continuous-flow measurement (Fig. 4) at each peak maximum.

The most popular natural antioxidants on the market are rosemary extracts and tocopherols. Natural antioxidants have several drawbacks which limit use. Tocopherols are not as effective ia vegetable fats and oils as they are ia animal fats. Herb extracts often impart undesirable colors or flavors ia the products where used. In addition, natural antioxidants cost considerably more than synthetic ones. Despite this, the pubHc s uncertainty of the safety of synthetic antioxidants continues to fuel the demand for natural ones (21). 

Inhibition of nitrosation is generally accompHshed by substances that compete effectively for the active nitrosating iatermediate. /V-Nitrosamine formation in vitro can be inhibited by ascorbic acid [50-81-7] (vitamin C) and a-tocopherol [59-02-9] (vitamin E) (61,62), as well as by several other classes of compounds including pyrroles, phenols, and a2iridines (63—65). Inhibition of iatragastric nitrosation ia humans by ascorbic acid and by foods such as fmit and vegetable juices or food extracts has been reported ia several instances (26,66,67). 

Numerous high pressure Hquid chromatographic techniques have been reported for specific sample forms vegetable oHs (55,56), animal feeds (57,58), seta (59,60), plasma (61,62), foods (63,64), and tissues (63). Some of the methods requite a saponification step to remove fats, to release tocopherols from ceHs, and/or to free tocopherols from their esters. AH requite an extraction step to remove the tocopherols from the sample matrix. The methods include both normal and reverse-phase hplc with either uv absorbance or fluorescence detection. AppHcation of supercritical fluid (qv) chromatography has been reported for analysis of tocopherols in marine oHs (65). 

E. Ibanez, J. Palacios and G. Reglero, Analysis of tocopherols by on-line coupling supercritical fluid extraction-superaitical fluid chromatography , ]. Microcolumn Sep. 11 605-611 (1999). 

TROJAKOVA L, REBLOVA z and poKORNY J (2000) Degradation of tocopherols in rapeseed oil with rosemary extract under different conditions , Czech J Food Sci, 18 (Spec) 175-6. 

Gnayfeed, M.H. et ah. Supercritical COj and subcritical propane extraction of pungent paprika and quantification of carotenoids, tocopherols, and capsaicinoids, J. Agric. Food Chem., 49, 2761, 2001. 

Wise JA, Morin RJ, Sanderson R and Blum K. (1996). Changes in plasma carotenoid, alpha-tocopherol, and lipid peroxide levels in response to supplementation with concentrated fruit and vegetable extracts a pilot study. Curr Ther Res 57(6) 445 t61. 

Basic procedure (ACL kit) Mix 2400 pL of ACL reagent 1 (diluter) with 100 pL of ACL reagent 2 (buffer) and 25 pL of photosensitizer reagent (luminol based). Start measurement after brief vortexing. Assayed solution (lipid extract) is added before addition of photosensitizer reagent. Volume of ACL reagent 1 is reduced by the volume of assayed solution. Standard substance a-tocopherol or Trolox. Duration of measurement 1 min. Measured parameter integral (area under the kinetic curve of PCL). 

E 306 tocopherol-rich extract biscuits, rusks, and baby individually... 

Synthetic analogues or derivatives of a-tocopherol which have better antioxidant properties can be introduced. Many natural antioxidants such as flavonols, flavones, tea leaf catechins, rosemary antioxidants and spice extracts have been reported to be more active than BHA, BHT or the tocopherols in model systems. The food applications of these compounds need to be explored further. 

The effect of vitamin E supplementation on a-tocopherol and /(-carotene concentrations in tissues from pasture- and grain-fed cattle was also elucidated with HPLC analysis. The investigation was motivated by the fact that a-tocopherol influences beneficially meat colour and stability [53], and the presence of /(-carotene can modify the amount of a-tocopherol in tissues [54], Samples were extracted with hexane and the concentration of /(-carotene was assessed by HPLC. Some data are listed in Table 2.20. It was concluded from the data that... 

Another fat-soluble vitamin, E, was found by Evans and Bishop in 1923. Pregnant rats on a defined diet (alcohol-extracted casein, cornstarch, and lard) supplemented with butter (vitamins A and D) and yeast extract (vitamin B group) produced few young because of fetal resorption. Male rats on the same diet were sterile. The disorders, which have not been identified in man, were corrected by wheat-germ oil, from which tocopherol, the active ingredient, was isolated in 1936. In spite of intensive investigations and a recognition that the vitamin is an antioxidant and destroyer of free radicals, the function of vitamin E remains obscure. 

FIGURE 7.6 Extracted NMR spectra (600 MHz, 1.5 xL solenoidal microprobe) of the tocopherol homologues at the corresponding peak maxima residual solvent signals. (Reproduced with permission from Ref. 30. Copyright (2004) American Chemical Society.)... 

The main problem in the vitamin E analysis is that it is easily oxidized, thereby an antioxidant, such as butyl hydroxy toluene (BHT) or ascorbic acid, is added to prevent degradation during the extraction step. The traditional method for extraction of tocopherols and tocotrienols in foods is solvent extraction (like soxhlet) and saponification with KOH [457,458]. Some authors have recently proved that saponification is not necessary [459-462], nevertheless, it has been widely applied until the present day. 

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