• The Korean Journal of Food And Nutrition
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• v.11 no.6
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• pp.635-639
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• 1998

The thermal degradation pattern of $\alpha$-, ${\gamma}$-and $\delta$-tocopherols in glycerol was investigated during heating at 100~25$0^{\circ}C$ for 5-60 min in the absence of oxyge. The tocopherols and thermally decomposed products were separated by HPLC with a reversed phase $\mu$-Bondapak C18-column. The degradation pattern of $\alpha$-tocopherol during the heating in the absence of oxygen was different from those of ${\gamma}$-and $\delta$-tocopherols. But the degradation patterns of ${\gamma}$-and $\delta$-tocopherols were similar to each other. The residual content of $\alpha$-tocopherol during the heating in the absence of oxygen decreased to the range 12~65% and those of ${\gamma}$-and $\delta$-tocopherols decreased to the range 4~96%. The thermal degradation of tocopherols in the absence of oxygen was less than that in the presence of oxygen.

• Preventive Nutrition and Food Science
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• v.12 no.2
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• pp.115-118
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• 2007

Tocopherols are important lipid-phase antioxidants that are subject to heat degradation. Therefore, kinetic analyses for oxidative degradation of tocopherols as a function of temperatures and times were performed. Alpha-, gamma- and delta-tocopherols dissolved in glycerol were heated at 100${\sim}$250$^{\circ}C$ for 5～60 min. Oxidized tocopherols were analyzed by HPLC using a reversed phase ${\mu}$-Bondapak C$_{18}$-column with two kinds of elution solvent systems in a gradient mode. The degradation kinetics for tocopherols followed a first-order kinetic model. The rate of tocopherol degradation was dependent on heating temperatures. The degradation rate constants for ${\gamma}$- and ${\delta}$-tocopherols were higher than those for ${\alpha}$-tocopherol. The experimental activation energies of ${\alpha}$-, ${\gamma}$- and ${\delta}$- tocopherols were 2.51, 6.05 and 5.34 kcal/mole, respectively. The experimental activation energies for the oxidative degradation of ${\gamma}$- and ${\delta}$-tocopherols were higher than that of ${\alpha}$-tocopherol.

• Preventive Nutrition and Food Science
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• v.12 no.3
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• pp.131-134
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• 2007

The kinetic analyses for thermal products of alpha-, gamma- and delta-tocopherols during heating as functions of temperature and time were studied. Alpha-, gamma- and delta-tocopherols dissolved in glycerol were heated at $100{\sim}200^{\circ}C$ for $5{\sim}60$ min. The thermal products were separated by hexane extraction and analyzed by HPLC using a reversed phase ${\mu}-Bondapak$ $C_{18}-column$ with two kinds of elution solvents in a gradient mode. The formation kinetics of thermal products of tocopherols followed a first-order kinetic model. The formation rate of thermal products of tocopherols was dependent on heating temperatures and heating times. The activation energy and enthalpy for the thermal products of ${\gamma}-and$ ${\delta}-tocopherols$ were higher than those for ${\alpha}-tocopherol$ as in the case of the oxidative degradation kinetics of tocopherol. The magnitude order of the activation energy was ${\gamma}->{\delta}->{\alpha}-tocopherol$.

• The Korean Journal of Food And Nutrition
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• v.20 no.2
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• pp.120-124
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• 2007

The thermal degradation kinetics of alpha-, gamma- and delta-tocopherols was studied during heating at 100, 150 200 and 250$^{\circ}C$ for 5, 15, 30 and 60 min in the absence of oxygen. The tocopherols were separated by HPLC using a reversed phase ${\mu}$-Bondapak C$_{18}$-column with two kinds of elution solvent system in a gradient mode. The kinetics for degradation of ${\alpha}$-, ${\gamma}$- and ${\delta}$-tocopherols was analyzed as a function of temperatures and times. The degradation of tocopherols was described by the first-order kinetics in the absence of oxygen. The rate of tocopherols degradation was dependent on heating temperatures. The degradation rate constants for ${\alpha}$-, ${\gamma}$ and ${\delta}$-tocopherols showed an increasing trend as the heating temperature increased. The magnitude order of the experimental activation energy was ${\delta}$->${\gamma}$->${\alpha}$-tocopherol.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.526-532
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• 2009

Quenching mechanisms and kinetics of $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol in photosensitized oxidation of lard were studied. Lard at 0.03, 0.07, 0.11, and 0.3 M in methylene chloride containing $4.4{\times}10^{-6}\;M$ chlorophyll and 0, 0.1, 0.3, and 0.6 mM $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol were stored under light for 4 hr, respectively. Oxidation was determined by headspace oxygen and peroxide value. Tocopherols prevented the photosensitized oxidation of lard (p<0.05). Steady state kinetic study showed that $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol prevented the photosensitized oxidation of lard by quenching singlet oxygen. Singlet oxygen quenching rates of $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol by headspace oxygen depletion were 1.86, 2.39, 2.47, and $2.11{\times}10^7/M/sec$, respectively. The quenching rates of $\alpha$-, $\beta$-, $\gamma$-, and $\delta$-tocopherol by peroxide value were 1.42, 1.11, 0.97, and $0.42{\times}10^7/M/sec$, respectively. The quenching rates of tocopherols were slightly different depending on the measurements of oxidation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48
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• pp.1-12
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• 2003

Vitamin E is a fat-soluble vitamin that exists in eight different forms, which are $\alpha$, $\beta$, $\gamma$, and $\delta$ tocopherol, and $\alpha$, $\beta$, $\gamma$, and $\delta$ tocotrienol. Tocopherols and tocotrienols are important antioxidant in foods, feeds and their raw materials, where they scavenge lipid radicals. Each form has its own biological activity, the measure of potency or functional use in the body. Antioxidants such as vitamin E act to protect cells against the effects of free radicals, which are potentially damaging by-products of the body's metabolism. Free radicals can cause cell dam-age that may contribute to the development of cardiovascular disease and cancer, The content of tocopherols and tocotrienols vary depending on the environmental condition such as growing regions, temperature, crops and varieties. This report deals with chemical and physical properties and extends to their nutritional and health effect on the tocopherols and tocotrienols in cereal grains.

• Food Science of Animal Resources
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• v.18 no.1
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• pp.1-8
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• 1998

This study was conducted to investigate the effects of $\alpha$-, ${\gamma}$-, $\delta$-Tocopherols on oxidative stability of lipid in hamburger patties during frozen storage. Hamburger patty samples were prepared with the addition of tocopherol by fat basis: control, treat 1 (control+0.02% $\alpha$-tocopherol), treat 2 (control+ 0.02% ${\gamma}$-tocopherol were cooked at 85$^{\circ}C$ for 3 minutes and the stored at -1$0^{\circ}C$ or 3$0^{\circ}C$). The fatty acids composition of the hamburger samples were analyzed during the storage periods (1, 20, 40, 60 and 80 days). there was no difference in the fatty acids composition among control and treatment groups in early storage time; however, content of unsaturated fatty acid was decreased in control group and slightly decreased or almost not changed in treatment groups as the storage period passed. No difference in the ratio of saturated fatty acid : unsaturated fatty acid (SFA : USFA) and saturated fatty acid : monounsaturated fatty acid : unsaturated fatty acid (SFA : MUFA : PUFA) between control and treatment groups at early storage time. However, SFA : USFA and SFA : MUFA : PUFA was decreased in control and slightly decreased or not changed in all treatment groups as the storage period passed.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.1-5
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• 1992

The concentrations of tocopherols and lipids, and compositions of fatty acids in the seeds of thirteen pulse plants, which are used for the raw materials of our traditional food as well as for the typical nutrients in Korea, were analyzed by HPLC and GC. The beans showed great differences of the tocopherol concentrations from 4.74 to 44.05 mg/100g, which were in the order of ${\gamma}->{\delta}->{\alpha}-tocopherol$ with the exception of the order of ${\delta}->{\gamma}->{\alpha}-tocopherol$ in jeock sodu and gal sodu of azuki bean. The contents of lipids were also remarkably different as 0.53 to 20.96%. Especially, the beans having from 15.78 to 20.96% of lipid contents showed high composition ratios of unsaturated fatty acid between 85.6 to 88.2%, of which the contents of linoleic acid were the highest as 56.0 to 58.6% of the total fatty acids, and also showed comparatively high concentrations of tocopherols as 23.2 to 44.05 mg/100g. There were significantly positive correlation between ${\gamma}-tocopherol$ and unsaturated fatty acids.

• Analytical Science and Technology
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• v.15 no.3
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• pp.248-255
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• 2002

The contents of ${\alpha}$-, ${\beta}$-, ${\gamma}$-, and $\delta$-tocopherols in sesame oils were determined by high performance liquid chromatography with UV detection. ${\alpha}$-Tocopherol contents ranged from 10.28 to 19.79 mg/g oil, ${\beta}$-tocopherol contents from 8.22 to 20.10 mg/g. However, both ${\gamma}$- and $\delta$-tocopherol were less than 1.49 mg/g or not detected. ${\gamma}$-Tocopherol was not detected from both unroasted white and black sesame seed oils. Significantly higher level of tocopherol in sesame oil than other oils is an evidence of the reason why it is highly stable and prevents oxidation. The tocopherol composition for twenty sesame oils was classified by using principal component analysis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.25 no.3
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• pp.441-452
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• 1996

The effects of chlorophyll, tocopherols($\alpha$-tocopherol, ${\gamma}$-tocopherol and $\delta$-tocopherol), carotenoids ($\beta$-carotene and lutein), light sources, light intensities and strage temperatures on the photooxidative stability of soymilk were studied by measuring TBA value and depleted headspace oxygen(DHO) of soymilk. The samples were stored in the light storage box for 6 days and evaluated for the photooxidative stabilities. As the concentrations of chlorophyll increased, TBA value and DHO of the sample increased significantly(p<0.05), indicating chlorophyll acting as a photosensitizer. However, as the concentrations of tocopherols ($\alpha$-tocopherol, ${\gamma}$-tocopherol and $\delta$-tocopherol) and carotenoids ($\beta$-carotene and lutein) increased, TBA values and DHO of the samples decreased significantly(p<0.05). The light screening effects of carotenoids on DHO in the samples were not significantly different from the control at p>0.05. Therefore, there was no light screening effects of carotenoids on the oxidative stability of soymilk. The results indicate that tocopherols and carotenoids reduce the photooxidative stability of soymilk. $\delta$-Tocopherol was the most effective in photosensitized oxidation followed by ${\gamma}$-and $\alpha$-tocopherols in the order of increasing stability. $\beta$-Carotene was significantly(p<0.05) more effective than lutein in minimizing the chlorophyll-sensitized photooxidation of soymilk. Visible light was more effective than UV light in decreasing the photooxidative stability of soymilk. Therefore, photooxidation of soymilk containing chlorophyll is mainly due to photosensitized oxidation rather than photolysis reaction. As the intensities of fluorescence light increased, TBA values and DHO of the samples increased significantly at P<0.05. However, as the storage temperatures increased, TBA values and DHO of soymilk did not change significantly at p>0.05.