Tocol levels in milling fractions of some cereal grains and soybean

Abstract

Tocol levels in the milling fractions of rice, barley, corn, wheat, and soybeans were analyzed by HPLC with a fluorescence detector. Among all milling fractions tested in this study, rice germ had the highest total tocol levels. In the four milling fractions of barley, except pearling flour, all eight tocol isomers were detected, and they were more uniformly distributed than in any other cereal grains measured in this study. The total tocol and α-tocopherol levels of wheat germ were significantly (P < 0.05) higher than the other wheat milling fractions. A significantly (P < 0.05) higher proportion of γ-tocopherol was obtained from corn germ (71.5%) and endosperm (50.3%) than from corn hulls. Only four tocol isomers (α-, β-, γ-, and δ-tocopherol) were detected in soybean milling fractions; no tocotrienol isomers were detected. The δ-tocopherol level of soybean endosperm, although minor, was significantly higher than those in milling fractions of other cereal grains in this study.Paper no. J10476 in JAOCS 80, 585-589 (June 2003).a Results (mg/kg of fraction) are expressed on a dry weight basis, and means within columns followed by the same letter are not significantly different P < 0.05). Values in parentheses are the percent distribution of each tocol. For abbreviations see Table 1.

Changes in lipid substances in rice during grain development

“…isomers, a-(21), c-(23), and d-tocotrienol (24), were detected but no b-tocotrienol (22) was detectable in this study. This result was similar to that in rice bran lipid extract as reported by Ko et al (2003). A marked decrease in the total tocopherol (17-20) level was observed while the total tocotrienol (21, 23, 24) level steadily increased during rice seed development.…”

Vitamin E Homologs and γ‐Oryzanol Levels in Rice (Oryza sativa L.) During Seed Development

“…These phytochemicals are known to be synthesized in the bran and germ, which accounts for approximately 7% by weight of the whole grain (i.e., including the hull) at maturity (Ko et al 2003). These phytochemicals are known to be synthesized in the bran and germ, which accounts for approximately 7% by weight of the whole grain (i.e., including the hull) at maturity (Ko et al 2003).…”

“…The present study adds to our understanding of the biosynthetic pathways of the tocopherols, tocotrienols, and g-oryzanol and the concentration of these compounds found during kernel development. These phytochemicals are known to be synthesized in the bran and germ, which accounts for approximately 7% by weight of the whole grain (i.e., including the hull) at maturity (Ko et al 2003). In the present study, the starch concentration in the endosperm was low at early developmental stages and accumulated rapidly from the milky to soft dough stages.…”

Tocopherol and Tocotrienol Content in Commercial Wheat Mill Streams

“…It has previously been reported that the bran and feed (middlings and tailings) fractions of wheat have the highest antioxidant capacity, followed by shorts and flour fractions, but that the germ fraction has the highest concentration of α-T (Ko et al 2003;Liyana-Pathirana and Shahidi 2007). The higher content of tocotrienols in the bran fractions might contribute to the higher antioxidant properties of these fractions.…”

“…Because wheat is normally used as straight-grade flour or patent flour without bran and germ fractions, only few studies have been made to investigate the content of vitamin E in different fractions from wheat milling. The total vitamin E content of several products includes wheat germ oil 3,121 µg/g; wheat germ 152-252 µg/g; wheat bran 14-75 µg/g; whole meal flour 76 µg/g, and white wheat flour 9-32 µg/g (Barnes and Taylor 1980;Morrison et al 1982;Piironen et al 1986;Håkansson and Jägerstad 1990;Wennermark and Jagerstad 1992;Ko et al 2003;Leenhardt et al 2006). The distribution of the different isomers of vitamin E has hardly been investigated in different milling fractions of wheat.…”