Wheat tocopherol content

Table 9-10 Tocopherol Content of Wheat and Its Milling Products...

Table 2.6 Tocopherol content of crude soybean and wheat germ oils...

Table 10.2. Tocopherol Content and Composition of Crude Soybean and Wheat Germ Oils ...

In similar studies Frazer et al. (1956a, b) noted a drop in the a-tocopherol content of flour from 1.5 mg % to 0.2 mg %. They considered this loss to be of no nutritional import since even whole wheat bread will supply only a small percentage of the 15 mg % of tocopherol required by man daily (Sebrell and Harris, 1954). Mason and Jones (1958) noted that the total tocopherol content of Australian whole wheat dropped from 2.3 to 1.55 mg % in milling, and to 0.72 mg % after chlorine dioxide bleaching. 

Rothe et al. (1958) noted a 50% reduction in the tocopherol content of white and of whole grain flours, and a 25% loss in wheat germ, during... 

That tocopherols are apparently nature s choice of antioxidant is demonstrated in Fig. 4, which is similar to a correlation observed by Hove and Harris (1951). Here the total tocopherol content of oils from babasu (1), beechnut (2), carrot (3), castor bean (4), cacao (5, 6), coconut (7, 8), corn (9, 10), cottonseed (11-13), hazelnut (I4, 15), linseed (16), oat germ (17), okra seed (18, 19), olive (20-25), palm (26-28), peanut (29-33), pecan (34, 35), poppyseed (36), rapeseed (37), rice bran (38), safflower (39), sesame (40, 4I), soybean (42-44), sunflower (45), and wheat germ (46-50), as reported by Lange (1950), have been plotted against their total linoleic plus linolenic acid content as reported by Hilditch (1956). The linoleic, plus linolenic acid content of oils from the same species varies, sometimes threefold. It is unfortunate that the content of tocopherol, linoleic acid, and linolenic acid have seldom been determined on the same sample. If Fig. 4 could have been prepared from such data, the correlation would probably be even more dramatic. 

Gelmez N, Kincal NS, Yener ME (2009) Optimization of supercritical carbon dioxide extraction of antioxidants from roasted wheat germ based on yield, total phenolic and tocopherol contents, and antioxidant activities of the extracts. J Supercrit Fluids 48(3) 217-224... 

The fatty acid composition of the extracts was not affected by temperature, pressure, and the extraction method (Table 4). Supercritical carbon-dioxide-extracted oil samples had similar fatty acid composition to that of the Soxhlet-extracted oil (Table 4). All of the wheat germ extracts consisted of about 56% linoleic acid (18 2 n-6), which is an essential fatty acid (Table 4). The total unsaturated and polyunsaturated fatty acid (PUFA) content of the wheat germ oil was about 81 % and 64%, respectively. The SC-CO2 extraction of wheat germ resulted in extracts with similar tocopherol and tocotrienol compositions to those of the Soxhlet extracts (Table 8) (50). These results indicate that SC-CO2 technology can be used for extraction and fractionation of WGO components to obtain products with high quality. 

Good sources of vitamin E are vegetable oils, such as com, soy, and peanut oii. Animal fats, such as butter and lard, contain lowrer amounts of the vitamin. The content of the most important form of vitamin E, a-tocopherol, in various foods is as follows. Com oil contains about 16 mg of a-tocopherol per 100 g sunflower oil 50 mg/100 g, wheat germ oil 120 mg/100 g and fish, eggs, and beef 0.5 to 2,0 rng/100 g. In plants, a-tocopherol resides in chloroplasts, while other forms of tocopherol ( i-, y-, and 5-tocopherol) occur elsewhere in the plant cell. Tocotrienols, which also have vitamin E activity, are not found in the green parts of plants, but in the bran and germ of seeds... 

Tocopherols are important antioxidants present in relatively high concentration in soybeans. The content of tocopherols in raw soybean is shown in Table 10.1 while the compositional comparison of tocopherols in crude soybean oil and wheat germ oil is shown in Table 10.2. 

The lipid content of total cereal seeds varies considerably. Furthermore the various anatomical parts of seeds contain a very different lipid content. Thus, in wheat seeds the germ contains 25-30% lipid while the endosperm has only 1% lipid. Considerable amounts of wheat germ lipid are lost during milling (Galliard and Barnes, 1980). Cereal germ oils are also a very good source of tocopherols. 

Vitamin D is the most stable of the oil-soluble vitamins, but few extrusion studies have examined this nutrient. Carotenoids and tocopherols are susceptible to oxidation and thermal degradation during extrusion and storage. Although P-carotene is not a vitamin, it has vitamin activity and is an important antioxidant and coloring agent. The content of added all trans P-carotene decreased by more than half when the temperature of wheat flour extrusion was 200 °C compared with 125°C increased levels of the 9-cis and 13-cis... 

About 60-70% of the tocopherols in oilseeds are retained during the oil extraction and refining process (cf. 14.4.1 and Table 3.54). Some oils with very similar fatty acid compositions can be distinguished by their distinct tocopherol spectrum. To illustrate this, two examples are provided. The amount of P-tocopherol in wheat germ oil is quite high (Table 3.54), hence it serves as an indicator of that oil. The blending of soya oil with sunflower oil is detectable by an increase in the content of linolenic acid (cf. 14.5.2.3). However, it is possible to make a final conclusive decision about the presence and quantity of soya oil in sunflower oil only after an analysis of the composition of the tocopherols. 

Carotenoids and tocopherols belong to the minor components of the cereal lipid fraction. Wheat flour has a carotenoid content averaging 5.7 mg/kg. In durum wheats, which have a more intense yellow color, the carotenoids are 7.3 mg/kg of flour. 

Supercritical CO2 has been used to extract oil and tocopherols from wheat germ in several research studies (Ge et al., 2002 Panfili et al., 2003 Eisenmenger et al., 2006 Shao et al., 2008 Piras et al., 2009 Gelmez et al., 2009). These have focused on the effects of extraction parameters (i.e., temperature, pressure, CO2 flow rate, cosolvent flow rate, extraction time) on oil and tocopherol yield and sterol and phospholipid content of the extracted oil. A recent study optimized the SC-CO2 extraction for antioxidant concentration and antioxidant activity of the SC-CO2 extracts rather than simply the oil yield (Gelmez et al., 2009). The effects of pressure (148-602 bar), temperature (40-60°C) and extraction time were modelled. The optimum extraction conditions were 336 bar, 58°C and 10 min, resulting in 5.3% tocopherol yield, 6 mg gallic acid equivalent (GAE) phenolics/g extract, 6.7 mg tocopherol/g extract and 57.3 mg scavenged DPPH/g extract. The tocopherol yield under these conditions corresponded to almost complete recovery. 

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