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1.
Anna-Maija Lampi Leena Kataja Afaf Kamal-Eldin Piironen Vieno 《Journal of the American Oil Chemists' Society》1999,76(6):749-755
Antioxidant properties of 5 to 500 μg/g levels of α-and γ-tocopherols, in the oxidation of rapeseed oil triacylglycerols (RO
TAG), were studied at 40°C in the dark. Each tocopherol alone and in a mixture was studied for its stability in oxidizing
RO TAG. Also the effects of tocopherols on the formation of primary and secondary oxidation products of RO TAG were investigated.
Both tocopherols significantly retarded the oxidation of RO TAG. At low levels (≤50 μg/g), α-tocopherol was more stable and
was a more effective antioxidant than γ-tocopherol. At higher α-tocopherol levels (>100 μg/g), there was a relative increase
in hydroperoxide formation parallel to consumption of α-tocopherol, which was not found with γ-tocopherol. Therefore, γ-tocopherol
was a more effective antioxidant than α-tocopherol at levels above 100 μg/g. As long as there were tocopherols present, the
hydroperoxides were quite stable and no volatile aldehydes were formed. In a mixture, α-tocopherol protected γ-tocopherol
from being oxidized at the addition levels of 5+5 and 10+10 μg/g but no synergism between the tocopherols was found. α-Tocopherol
was less stable in the 500+500 μg/g mixture than when added alone to the RO TAG. No prooxidant activity of either tocopherol
or their mixture was found. 相似文献
2.
In this study, mid-oleic and high-oleic sunflower seeds were developed with high levels of γ- and δ-tocopherols by traditional
breeding techniques. Sunflower seeds containing various profiles of tocopherols, ranging from traditional high α, low γ, low
δ relative to those with high γ, high δ, and low α, were extracted, and the crude oil evaluated for oxidative stability. After
aging at 60 °C, oils were measured for peroxide value and hexanal as indicators of oxidation levels. We found that when the
γ-tocopherol content of mid-oleic sunflower oil (MOSFO) (NuSun) was increased from its regular level of 20 to 300–700 ppm,
the oxidation of the oil was decreased significantly compared to MOSFO with its regular low γ-tocopherol level. The modified
oils had α-tocopherol contents of up to 300 ppm without negatively affecting the stability of the oil. An oil with one of
the best oxidative stabilities had a tocopherol profile of 470 ppm γ, 100 ppm δ, and 300 ppm α, indicating that MOSFO could
be more oxidatively stable and still be a good source of Vitamin E from α-tocopherol.
Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard
of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also
be suitable. 相似文献
3.
The effect of α-tocopherol (αTOH) (50–2000 ppm), γ-tocopherol (γTOH) (100–2000 ppm), and δ-tocopherol (δTOH) (100–2000 ppm)
on the formation and decomposition of hydroperoxides in purified fish oil triacylglycerols (TAG) was studied. The tests were
conducted at 30°C in the dark. Purified fish oil TAG oxidized very rapidly with no apparent induction period. The relative
ability of the tocopherols to retard the formation of hydroperoxides decreased in the order αTOH> γTOH>δTOH at a low level
of addition (100 ppm), but a reverse order of activity was found when the initial tocopherol concentration was 1000 ppm. This
dependence of relative antioxidant activity on tocopherol concentration was caused by the existence of concentrations for
maximal antioxidant activity for αTOH and for γTOH. An inversion of activity, on the basis of hydroperoxide formation, was
observed for αTOH at 100 ppm and for γTOH at 500 ppm, whereas the antioxidant activity of δTOH increased with level of addition
up to 1500–2000 ppm. None of the tocopherols displayed any prooxidant activity. All three tocopherols strongly retarded the
formation of volatile secondary oxidation products in a concentration-dependent manner. At concentrations above about 250
ppm there appeared to be a linear relationship between rate of consumption of αTOH and initial αTOH concentration, in accordance
with the linear relationship observed between the initial rate of formation of hydroperoxides and the initial αTOH concentration.
The rate of consumption of γTOH also increased with initial concentration, but to a lesser extent than for αTOH. At high levels
of addition the rate of consumption of δTOH was independent of initial concentration, appearing to reflect the greater stability
of this tocopherol homolog and participation in reactions with lipid peroxyl radicals only.
Presented in part at the AOCS annual meeting in San Diego, California, April 2000. 相似文献
4.
Antioxidant effects of d-tocopherols at different concentrations in oils during microwave heating 总被引:1,自引:0,他引:1
Hiromi Yoshida Goro Kajimoto Shiuji Emura 《Journal of the American Oil Chemists' Society》1993,70(10):989-995
The effects of d-tocopherols at different concentrations (50 to 1000 ppm) on the oxidative stability of ethyl linoleate and
tocopherol-stripped oils were investigated under microwave heating conditions. Purified substrate oils were prepared by aluminum
oxide column chromatography. After the addition of tocopherols (α-, β-, γ- or δ-) to the oils, peroxide, carbonyl andp-anisidine values were measured in the samples after heating in a microwave oven. Further, the residual amount of tocopherol
homologues in the oils after heating was determined by high-performance liquid chromatography for evaluation of their effects
at different concentrations on oxidative deterioration. Microwave heating resulted in some acceleration in the oxidation of
the purified substrate oils. Optimum concentrations of tocopherols required to increase oxidative stability were 100 ppm for
α-, 150–200 ppm for β- or γ- and 500 ppm for δ-tocopherol, respectively. The antioxidant effect of tocopherols decreased in
the order α>β ≒ γ>δ at each level, in all substrates. Therefore, α-tocopherol was consumed first, followed by β- or γ-tocopherol,
and δ-tocopherol was consumed more slowly. The tocopherols had no further significant antioxidant activity (P>0.05) at concentrations higher than 500 ppm. 相似文献
5.
Marjukka M Kinen Afaf Kamal-Eldin Anna-Maija Lampi Anu Hopia 《Journal of the American Oil Chemists' Society》2000,77(8):801-806
The antioxidant effects of α-and γ-tocopherols (at 0, 10, 100, 500, and 1000 ppm) were evaluated in a model system based on
the autoxidation of methyl linoleate in bulk for 4 d at 40°C. Samples were collected every 24 h and analyzed for the 9 cis,trans, 9 trans,trans, 13 cis,trans, and 13 trans,trans isomers of hydroperoxide, hydroxy, and ketodiene oxidation products by high-performance liquid chromatography. Results showed
that both α- and γ-tocopherols are effective hydrogen donors as evidenced by their abilities to inhibit the formation of hydroperoxides,
hydroxy compounds, and ketodienes and the cis,trans to trans,trans isomerization of hydroperoxides. Compared with γ-tocopherol, α-tocopherol was a more efficient antioxidant at very low concentrations
(10 ppm) but a less efficient antioxidant at the high concentrations (100–1000 ppm). This paradoxical behavior is explained
on the basis of differences in ease of hydrogen donation between the two tocopherol homologs. Although α-tocopherol shows
some loss of efficiency with increasing concentration, it is not a prooxidant when compared to the control void of antioxidants. 相似文献
6.
J. P. Koskas J. Cillard P. Cillard 《Journal of the American Oil Chemists' Society》1984,61(9):1466-1469
The autoxidation of linoleic acid dispersed in an aqueous media and the effect of α-, γ- and δ-tocopherols were studied. The
quantitative analysis of the hydroperoxide isomers (13-cis,trans; 13-trans,trans; 9-trans,cis; 9-trans,trans) by direct high-performance liquid chromatography exhibited a prooxidant activity of α-tocopherol at high concentration (3.8%
by weight of linoleic acid). On the other hand, α-tocopherol at lower concentrations (0.38 and 0.038%) and γ- and δ-tocopherols
at high concentration (3.8%) were antioxidant. Furthermore, the addition of tocopherols modified the distribution of the geometrical
isomers. The formation of thetrans,trans hydroperoxide isomers was completely inhibited by the highest concentration of the three tocopherols independently of their
antioxidant or prooxidant activity and only delayed by the lower concentrations of α-tocopherol. The addition of tocopherols
to hydroperoxide isomers reduced the decomposition rate of these isomers in the order α-tocopherol < γ-tocopherol < δ-tocopherol
for thecis,trans hydroperoxide isomer and α-tocopherol ≪ γ-tocopherol ⋍ δ-tocopherol for thetrans,trans hydroperoxide isomer. With these hydroperoxides, as during linoleic acid autoxidation, α-tocopherol was completely oxidized
whatever its initial concentration, while γ-tocopherol underwent partial oxidation and δ-tocopherol was practically unchanged. 相似文献
7.
Anita Rani Vineet Kumar Sandeep K. Verma Arvind K. Shakya G. S. Chauhan 《Journal of the American Oil Chemists' Society》2007,84(4):377-383
Plant seed oils, including soybean seed oil, represent the major source of naturally derived tocopherols, the antioxidant
molecules that act as free radical quenchers preventing lipid peroxidation in biological systems and vegetable oil products.
All four isomers of tocopherols, i.e. α, β, γ, δ tocopherols that exist in nature are found in soybean seeds. The biological
activity and the contribution of these isomers in improving the oxidative stability of vegetable oil are in reverse order.
Because of the nutritive value and the importance for oil stability, enhancement of tocopherol content, through breeding programs,
in soybean seeds has become a new and an important objective. Genotypic variability, which is the basis of every breeding
program, is scarcely reported for tocopherol content and profile in soybean seeds. In the present investigation, the tocopherol
content and profile in seed samples of 66 genotypes of Indian soybean were determined. The ratios observed between the lowest
and the highest values for α, β, γ, δ, total tocopherol content were 1:13.6, 1:10.4, 1:7.5, 1:9.1, 1:7.9, respectively. The
mean contents for α, β, γ, δ and total tocopherols were 269, 40, 855, 241 and 1,405 μg/g of oil, respectively. Total tocopherol
content was the highest in ‘Co Soya2’ followed by ‘Ankur’. Concentration of α-tocopherol was the highest (27%) in ‘Ankur’
followed by ‘MACS124’ (26%) whereas gamma tocopherol concentration was the highest (69%) in ‘VLS1’ and ‘PK327’ followed by
‘MACS13’ (67%). In view of the fact that levels of unsaturated fatty acids, apart from tocopherols, also determine the oxidative
stability of vegetable oils, the relationship of four isomers of tocopherols with each other as well as with different unsaturated
fatty acids and oil content was also investigated in the present study. All the four isomers of tocopherols exhibited highly
significant correlations with each other (p < 0.001) whereas γ-tocopherol and total tocopherol content showed a significant relationship with linoleic acid (p < 0.05). 相似文献
8.
Tocopherols can exhibit opposite effects in aqueous media on linoleic acid autoxidation rate. The effect which was observed
depended on tocopherol concentration and on the tocopherol itself. At 0.05 mole of tocopherol per mole of linoleic acid, α-tocopherol
was prooxidant while in similar conditions, δ-tocopherol was anti-oxidant as well as γ-tocopherol. However, this latter one
exhibited a slight antioxidant activity. When tocopherol concentration decreased (twice as weak), α-tocopherol still exhibited
the same pro-oxidant activity, while the antioxidant effect of γ and δ tocopherols was increased. The study of tocopherol
stability by HPLC has shown that tocopherol oxidation increased in order δ < γ < α. There was a relationship between the ability
for a tocopherol to be easily oxidized by air and its prooxidant activity. Tocopherol oxidation would enhance the formation
of a perhydroxyl radical ([·OOH] or one of this type [O20=, ·OH]) which was responsible for the prooxidant effect. 相似文献
9.
Anna-Maija Lampi Afaf Kamal-Eldin 《Journal of the American Oil Chemists' Society》1998,75(12):1699-1703
The antipolymerization effects of α- and γ-tocopherols were compared in model systems composed of purified high-oleic sunflower
triacylglycerols at 180°C. γ-Tocopherol was much more effective as an antipolymerization inhibitor than α-tocopherol, partly
due to lower oxidizability/disappearance. Purified triacylglycerols of sunflower, rapeseed, and high-oleic sunflower oils
were less stable than their nonpurified forms containing tocopherols. Results confirmed that tocopherols per se can act as antipolymerization agents in high-oleic oils at frying temperatures. No synergism was observed when α- and γ-tocopherols
were present together although larger amounts of residuals were left for both tocols. Results suggested that high-oleic/high-γ-tocopherol
oils (such as high-oleic canola and high-oleic soybean oils) may provide better frying oils than high-oleic/high-α-tocopherol
oils (such as high-oleic sunflower oil). 相似文献
10.
The intake of γ-tocopherol by North Americans is generally higher than that of α-tocopherol. However, the levels of α-tocopherol
in human blood have consistently been shown to be higher than those of γ-tocopherol suggesting differential cellular retention
of the two tocopherol forms. We sought to resolve this question by studying tocopherol metabolism by human endothelial cells
in culture. The time- and dose-dependent uptake of γ-tocopherol by endothelial cells was similar to that of α-tocopherol.
To determine the comparative uptake between α- and γ-tocopherol, we adopted two approaches in which cells were enriched with
either increasing concentrations of an equimolar mixture of α- and γ-tocopherol; or cells were enriched with a fixed concentration
of tocopherols in which the α to γ ratio was varied. Our results indicated that there was a preferential uptake of γ-tocopherol
by the cells. When cells were enriched with either α- or γ-tocopherol and the disappearance of individual tocopherols was
monitored over time, γ-tocopherol exhibited a faster rate of disappearance. The faster turnover of γ-tocopherol can explain
the discrepancy between high intake and low retention of γ-tocopherol in man. 相似文献
11.
Temperature effects on tocopherol composition in soybeans with genetically improved oil quality 总被引:7,自引:5,他引:2
G. O. Almonor G. P. Fenner R. F. Wilson 《Journal of the American Oil Chemists' Society》1998,75(5):591-596
Tocopherol, a natural antioxidant, typically accounts for a small percentage of soybean (Glycine max L. Merr.) oil. Alleles that govern the expression of polyunsaturated fatty acids in soybean germplasm are influenced by temperature.
However, little is known about the environmental influences on tocopherol expression. The objective of this study was to assess
the influence of temperature on tocopherol composition in soybean germplasm that exhibit homozygous recessive and dominant
alleles that govern the predominant ω-6 and ω-3 desaturases. The control cv. Dare and three low-18:3 genotypes (N78-2245,
PI-123440, N85-2176) were grown under controlled-temperature environments during reproductive growth. Analysis of crude oil
composition at various stages of seed development revealed a strong negative correlation between total tocopherol content
and growth temperature. The relative strength of this correlation was greater in the germplasm that exhibited homozygous alleles
governing the ω-6 desaturase than those governing the ω-3 desaturase. The decline in total tocopherol with reduced temperature
was attributed predominantly to loss of γ-tocopherol. However, γ-tocopherol concentration also was directly related to 18:3
concentration in all genotypes. Thus, low-18:3 oils contained both a lower content and a lower concentration of γ-tocopherol.
Although the biochemical basis for this observation is unknown, the antioxidant capacity of γ-tocopherol appeared to be directly
associated with changes in oil quality that were mediated more by genetic than by environmental influences on 18:3 concentration.
Another aspect of this work showed that low-18:3 soybean varieties should be expected to contain more α-tocopherol, especially
when grown under normal commercial production environments. This condition should be regarded as another beneficial aspect
of plant breeding approaches to the improvement of soybean oil quality. 相似文献
12.
The antioxidant effects of α- and γ-tocopherols were evaluated in a model system based on the autooxidation of purified sunflower
oil (p-SFO) triacylglycerols at 55°C for 7 d. Both tocopherols were found to cause more than 90% reduction in peroxide value
when present at concentrations >20 ppm. α-Tocopherol was a better antioxidant than γ-tocopherol at concentrations ≤40 ppm
but a worse antioxidant at concentrations >200 ppm. Neither α- nor γ-tocopherol showed a prooxidant effect at concentrations
as high as 2000 ppm. The amount of tocopherols consumed during the course of oxidation was positively correlated to the initial
concentration of tocopherols, and the correlation was stronger for α- than for γ-tocopherol. This correlation suggested that,
besides reactions with peroxyl radicals, destruction of tocopherols may be attributed to unknown side reactions. Addition
of FeSO4, as a prooxidant, caused a 12% increase in the peroxide value of p-SFO in the absence of tocopherols. When tocopherols were
added together with FeSO4, some increase in peroxide value was observed for samples containing 200, 600 or 1000 ppm of α- but not γ-tocopherol. The
addition of FeSO4, however, caused an increase in the amount of α- and γ-tocopherols destroyed and led to stronger positive correlations between
the amount of tocopherols destroyed during oxidation and initial concentration of tocopherols. No synergistic or antagonistic
interaction was observed when α- and γ-tocopherols were added together to autooxidizing p-SFO. 相似文献
13.
To determine the effects of the addition of pure tocopherols to triacylglycerols, α, γ, and δ tocopherols were added singly
and in various combinations to stripped mid-oleic sunflower oil (SMOSUN). Tortilla chips were fried in the treated oils and
then aged at ambient temperature to determine storage stability of the fried food. Frying oils were evaluated for total polar
compounds (TPC) as an indicator of oil deterioration, and they were also analyzed for retention of tocopherols. To determine
effects of tocopherols on fried-food stability, chips were evaluated for hexanal as an indicator of oxidative stability and
for odor characteristics by a trained, experienced analytical sensory panel. Oils extracted from the tortilla chips were also
analyzed for residual tocopherols. TPC were highest in the SMOSUN control with no additives followed by the SMOSUN containing
only α tocopherol. The SMOSUN oil containing γ tocopherol had the best fry life as indicated by the lowest TPC. Hexanal content
and rancid odor intensity were highest in the chips fried in the SMOSUN control and in the SMOSUN containing only α tocopherol.
The most stable tortilla chips were fried in SMOSUN containing all three (α, γ, and δ) tocopherols; however, the lowest hexanal
levels were measured when γ and δ tocopherols were added at their highest concentrations. 相似文献
14.
During national and regional health surveys, done from 1984–1995 in Germany, consumption data for all drugs used by the participants—approximately
18,000 persons—in the last 7 d before the examination were monitored with a detailed drug-usage questionnaire. The groups
examined are representative for the national and regional German inhabitant population aged 25–69 yr. In serum samples of
subsamples of the study participants, all tocopherols were measured by isocratic high-performance liquid chromatography (Si
60 column, fluorescence detection). Consumption data for tocopherol-containing drugs showed that up to 5% of females and up
to 3% of males of the study population used those drugs. During the study period, the serum content of α-tocopherol (mean
values ± SD) rose from 7.5 ± 2.6 mg/L serum to 11.8 ± 2.8 mg/L serum for nonusers and from 11.9 ± 4.3 mg/L serum to 15.3 ±
4.9 mg/L serum in tocopherol-drug users. Throughout all studies, it could be shown that β- and γ-tocopherol were heavily reduced
in those persons taking daily doses ≥50 mg α-tocopherol. The reduction of the two tocopherols is dose-dependent and especially
pronounced in females using high-dose α-tocopherol drugs. Owing to the emerging evidence of the physiological importance concerning
the balance of the different tocopherols in biological systems, the possible benefits of using natural tocopherol mixtures
from plant origin instead of pure RRR-α-tocopherol, gained from permethylation procedures, as vitamin supplements in human nutrition should be considered. 相似文献
15.
The relative stabilities of selected individual tocols and tocotrienols and of equimolar mixtures of either α- plus γ- or
α- plus δ- tocopherols were determined in methyl myristate and methyl linoleate during autoxidation and photolysis. Solutions
containing 0.05% of the appropriate tocopherol(s) or tocotrienols were subjected to UV light (254 nm) or to a flow of 4.3
ml/min of oxygen, both at 70 C. Tocopherols (T) and tocotrienols (T−3) were determined by gas chromatography without preliminary
separation or purification. Under photolytic conditions, stabilities in increasing order in methyl myristate were γ-T−3<α-T−3<δ-T<α-T
<γ-T<5,7-T<β-T and in methyl linoleate were α-T<α-T−3≤γ-T−3≤β-T≤5,7-T <γ-T<δ-T. A solvent effect on the initial rate of photolysis
was observed for 5-methyl substituted tocols but not for the tocols with an unsubstituted 5-position or for the tocotrienols.
Under autoxidative conditions, stabilities in increasing order in methyl myristate were α-T=α-T−3 <β-T−3<γ-T−3<δ-T−3<γ-T<δ-T=β-T
and in methyl linoleate were α-T<α-T−3 <γ-T−3<β-T<γ-T<δ-T. Tocopherols were much more stable during autoxidation in methyl
myristate than they were in methyl linoleate. In mixtures, there was no significant protection of α-tocopherol by either γ-
or δ-tocopherol under any of the conditions used. However, α-tocopherol was highly effective in protecting γ- and δ-tocopherols
in methyl myristate during both photolysis and autoxidation and in methyl linoleate during photolysis. During autoxidation
in methyl linoleate, α-tocopherol protection of γ- and δ- tocopherols after 24 hr was slight tough measurable. 相似文献
16.
The main biochemical function of the tocopherols is believed to be the protection of polyunsaturated fatty acids (PUFA) against
peroxidation. A critical question that must be asked in reference to this is whether there is a biochemical link between the
tocopherol levels and the degree of unsaturation in vegetable oils, the main source of dietary PUFA and vitamin E. We used
a mathematical approach in an effort to highlight some facts that might help address this question. Literature data on the
relative composition of fatty acids (16:0, 16:1, 18:0, 18:1, 18:2, and 18:3) and the contents of tocopherols (α-, β-, δ-,
and γ-tocopherol) in 101 oil samples, including 14 different botanical species, were analyzed by principal-component analysis
and linear regression. There was a negative correlation between α- and γ-tocopherols (r=0.633, P<0.05). Results also showed a positive correlation between linoleic acid (18:2) and α-tocopherol (r=0.549, P<0.05) and suggested a positive correlation between linolenic acid (18:3) and γ-tocopherol. 相似文献
17.
O. Podlaha Å. Eriksson B. Toregård 《Journal of the American Oil Chemists' Society》1978,55(6):530-532
The polarographic behavior of α-, γ-, and δ-tocopherols was studied according to the proposed official IUPAC method for tocopherol
determination in vegetable oils and fats. Each of the tocopherols had a different polarographic response; however, the tocotrienols
had the same half-wave potentials and probably also the same polarographic response as the corresponding tocopherols. Additives
previously investigated plus several others were examined for possible interference. The results by polarography and a new
high performance liquid chromatography (HPLC) method were compared. The analysis by t-test at 99% significance level showed
no differences for the determinations of α-tocopherol, but the results for three of the γ-tocopherol results were less consistent
under the same conditions. The results for the determination of δ-tocopherol were below the detection limit for polarography
and could not be statistically evaluated. The polarographic method investigated was found to be uncomplicated and therefore
suitable for routine work. However, when using the method, one has to take into account possible interference by additives
and the limitations due to the lack of separation of β- from γ-tocopherol and/or the interference of tocotrienols with the corresponding tocopherol peaks. From this aspect the HPLC
method gives better resolution. 相似文献
18.
R. J. Hamilton C. Kalu G. P. McNeill F. B. Padley J. H. Pierce 《Journal of the American Oil Chemists' Society》1998,75(7):813-822
The effects of α-, γ/δ, and δ-tocopherol concentrates (0.2–2.0%) alone and in combination with ascorbyl palmitate (0.1%) and
lecithin (0.5%) on oxidative stability and flavor of fish oil were studied. Stability was assessed on oil stored in air at
20°C by peroxide value (PV) and off-flavor formation. Polymer content, para-anisidine value, and conjugation were used to characterize selected samples. When used alone, the protective effect of the
tocopherols, as measured by PV, was δ≫γ/δ≫α, especially at the 2% concentration. Binary systems of ascorbyl palmitate-lecithin
and lecithin-γ/δ or-δ-tocopherol were strongly synergistic in delaying peroxidation. The ternary blends provided the greatest
protection against autoxidation. Refined fish oil with 2% δ-tocopherol, 0.1% ascorbyl palmitate, and 0.5% lecithin showed
no significant peroxidation at 20°C over a period of 6 mon. The original antioxidant effect noted for the ternary systems
in delaying peroxidation was not reflected in improved flavor stability. Off-flavors developed within 3 wk, making the oils
unsuitable for use at high concentrations in ambient products that are unprotected from air. 相似文献
19.
Amy Richards Chakra Wijesundera Phil Salisbury 《Journal of the American Oil Chemists' Society》2008,85(2):159-168
The effects of genotype and growing environment on the tocopherols and fatty acids (FA) of experimental Brassica juncea and B. napus breeding lines were investigated. For both species, with the exception of a few genotypes, the concentration ratio of γ-tocopherols
to α-tocopherol was practically constant. The genotype influenced the tocopherol concentration in B. napus, and to a lesser degree, B. juncea. The environment also had a similar effect, and a positive correlation existed between the daily maximum temperature and
the α-tocopherol concentration in B. napus. Genotype effects on the FA composition were significant for the conventional but not for Clearfield or triazine tolerant
traits of B. napus. The genotype had no effect on the FA of the B. juncea genotypes. In contrast, the growing environment had a significant influence on the FA composition of both species with apparent
influence from temperature and rainfall. For both species, the concentration of γ-tocopherol as well as total tocopherols
was inversely related to the 18:3 concentration, which could have resulted from opposite and independent effects of temperature
on the two variables. No relationship existed between the concentrations of tocopherol and the remaining unsaturated FA 18:1
and 18:2. The positional distribution of unsaturated FA within the oil triacylglycerol was a function of their total concentration. 相似文献
20.
S. Chevolleau J. F. Mallet A. Debal E. Ucciani 《Journal of the American Oil Chemists' Society》1993,70(8):807-809
α-Tocopherol was identified as the main antioxidant in hexane extracts of leaves of sixteen Mediterranean plant species. The
α-tocopherol content was determined by a two-step procedure involving column and gas chromatography with α-tocopherol acetate
as internal standard. The tocopherol content of the extracts was in the range of 0.0–4.7%, and that of the dry leaves was
0–846 ppm. The highest α-tocopherol content was found in the leaves of a Mediterranean oak,Quercus ilex. The antioxidative activity, which was previously investigated, was correlated with the α-tocopherol content. Correlation
coefficients were 0.947 and 0.904 for extracts and leaves, respectively. 相似文献