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1.
Anacardic acids, 6-pentadec(en)ylsalicylic acids isolated from the cashew Anacardium occidentale L. (Anacardiaceae) nut and apple, were found to possess preventive antioxidant activity while salicylic acid did not show this activity. These anacardic acids prevent generation of superoxide radicals by inhibiting xanthine oxidase (EC 1.1.3.22, Grade IV) without radical-scavenging activity. Notably, the inhibition kinetics of anacardic acids do not follow hyperbolic dependence of enzyme inhibition on inhibitor contents (Michaelis–Menten equation) but follow the Hill equation instead. Anacardic acid (C15:1) inhibited the soybean lipoxygenase-1 (EC 1.13.11.12, Type 1) catalyzed oxidation of linoleic acid with an IC50 of 6.8 μM. The inhibition is a slow and reversible reaction without residual enzyme activity. The inhibition kinetics indicate that anacardic acid (C15:1) is a competitive inhibitor and the inhibition constant, KI, was 2.8 μM. Anacardic acids act as antioxidants in a variety ways, including inhibition of various prooxidant enzymes involved in the production of the reactive oxygen species and chelate divalent metal ions such as Fe2+ or Cu2+, but do not quench reactive oxygen species. The C15-alkenyl side chain is largely associated with the activity. 相似文献
2.
3.
用于氢化的铜铬氧化物催化剂的研究 总被引:4,自引:0,他引:4
通过铜铬氧化物催化剂用于豆油的选择氢化,研究了制备方法及氢化条件对催化剂活性的影响.在所用的五种催化剂中,以Adkins法制备的催化剂活性最好,碳酸氢铵法次之.文中还对催化剂焙烧气氛、焙烧温度、焙烧时间、铜铬原子比对催化剂活性的影响以及氢化温度、催化剂用量、搅拌速度、氢流速等对反应的影响进行了较详细的讨论. 相似文献
4.
5.
A. C. Lanser G. R. List R. K. Holloway T. L. Mounts 《Journal of the American Oil Chemists' Society》1991,68(6):448-449
A user-interactive computer-assisted Fourier transform infrared (FTIR) method has been developed for estimation of free fatty
acids (FFA) in vegetable oil samples by deconvolution of the infrared (IR) absorbances corresponding to the triglyceride ester
and FFA carbonyl bonds. Peak areas were used to determine FFA as a percentage of the total carbonyl areas in weighed standards
of refined, bleached, deodorized soybean oil containing from 0 to 5% added oleic acid. These data for percent FFA by FTIR
were compared to corresponding FFA data obtained by two titration methods-the AOCS Official Method Ca 5a-40 and the Official
Method with a slight modification. Correlation coefficients were 0.999 for the Ca 5a-40, 0.999 for the modified and 0.989
for the FTIR methods. FFA in samples of crude soybean oils extracted from damaged beans (0.5 to 2.1% FFA) were measured by
FTIR and compared to data obtained by titration of the same samples (correlation coefficient, 0.869).
To whom correspondence should be addressed at National Center for Agricultural Utilization Research, Agriculture Research
Service, U.S. Department of Agriculture, 1815 North University Street, Peoria, IL 61604.
1The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of
Agriculture over other firms or similar products not mentioned. 相似文献
6.
The amounts of isoflavones extracted from Korean soybean by various ultrasonic waves were compared using 60% aqueous ethanol
solution. The effect on extraction yield of variations in solvent composition, temperature, and extraction time was investigated.
The experimental results confirmed that ultrasonic waves are a desirable method to extract isoflavones from Korean soybean.
The highest yield of aglycone isoflavones was obtained by ultrasonic waves with a frequency of 20 KHz and an extraction time
of 10 min, which produced yields of glycoside and aglycone isoflavones three-fold greater than those by dipping method. 相似文献
7.
Jose Gerde Connie Hardy Walter Fehr Pamela J. White 《Journal of the American Oil Chemists' Society》2007,84(6):557-563
Two extruded-expelled physically refined soybean oils with reduced contents of linolenic acid, ultra-low- linolenic acid (ULL,
1.5%) and low-linolenic acid (LL, 2.6%), and a extruded-expelled physically refined control oil (control, 5.3% linolenic acid)
were evaluated by frying French fries in a commercial-like setting for 6 h day−1 during 23 days. The oils became darker, increased in yellow color at the beginning, and became redder and less green throughout
the process. Free fatty acids levels were not different among the oils until day 14, after which, ULL was different from the
control for the remainder of frying. The conjugated dienoic acid values were greatest in the control. Generally, ULL and LL
oils had lower percentages of polar compounds than did the control, providing a frying life 2 days longer than the control
and ~30% increase in frying time. A trained sensory panel evaluated the French fries on days 2, 5, and 6. Buttery and potato
flavors decreased, and rancid and painty flavors increased over frying time for all products. Rancid flavor was highest in
the fries from the control oil. Overall, the ULL and LL oils performed better than did the control oil and ULL tended to perform
better than the LL. 相似文献
8.
Nitrous oxide emission from upland crops and crop-soil systems in northeastern China 总被引:2,自引:0,他引:2
X. Chen M.L. Cabrera L. Zhang J. Wu Y. Shi W.T. Yu S.M. Shen 《Nutrient Cycling in Agroecosystems》2002,62(3):241-247
Although it is known that crops can directly emit N2O, their contribution to the total N2O emission from crop-soil systems under field conditions is not well understood. This study was conducted to study the contribution
of crops to total N2O emission from soybean-soil and maize-soil systems in northeastern China. The effects of N fertilization on N2O emission and NO
3
−
-N concentration in plants were also studied. The emission from crop-soil systems was measured with the closed chamber method,
whereas the direct emission from crops was measured with the soil surface-sealed method. The addition of fertilizer N significantly
increased the NO
3
−
-N concentration in crops and enhanced the N2O emission from crop-soil systems and from crops alone. The amount of N2O emitted directly from soybean plants accounted for 6 to 11% of the total soybean-soil emission. Similarly, the amount of
N2O emitted directly from maize plants accounted for 8.5 to 16% of the total maize-soil emission. The proportion of the applied
N lost through direct N2O emission from plants ranged from 0.19 to 0.34%, whereas the proportion of the applied N lost through N2O emission from the crop-soil system ranged from 1.1 to1.9%. These results suggest that the use of chambers that do not include
plants may lead to an underestimation of the total N2O emission from crop-soil systems.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
9.
超临界CO_2萃取大豆油的实验研究 总被引:11,自引:0,他引:11
采用超临界CO2 萃取技术进行了大豆油的萃取实验。在压力为 2 0~ 30MPa、温度为 30 8~ 32 3K的范围内 ,考察了萃取压力、萃取温度、流体流量和物料预处理方式等条件对出油率的影响。在本文实验范围内 ,大豆油的最佳萃取工艺条件为 :压力 30MPa ,温度 313K ,物料状态为约 0 .4mm厚的大豆片。流体流量只影响萃取速率 ,而不影响最终的出油率 相似文献
10.
Late season nitrogen fertilization of soybeans: effects on leaf senescence, yield and environment 总被引:3,自引:0,他引:3
Flavio H. Gutiérrez-Boem Javier D. Scheiner Helena Rimski-Korsakov Raúl S. Lavado 《Nutrient Cycling in Agroecosystems》2004,68(2):109-115
Nitrogen demand from soybean seeds during seed filling is very high and has been proposed as the cause of nitrogen remobilization and leaf senescence. Previous research has not shown consistent effects of late season fertilization on seed yield, while its effects on leaf senescence have not been evaluated. Two field experiments were performed to determine the effects of a late season N fertilization on leaf senescence and fall, seed yield and its components, and residual soil nitrate, and to evaluate the potential risk of groundwater contamination. Two rates of nitrogen (50 and 100 kg N ha–1) were applied at the R3 and R5 development stages. Nitrogen fertilization, either at R3 or R5, increased soil nitrate availability during the seed-filling period. Seed yield, seed number and protein content were not affected by N fertilization. The addition of 100 kg N ha–1 produced a small delay of 1–2 days in the leaf fall, and slightly increased seed size (3.6%). Our results suggest that increasing soil N availability during the seed-filling period is not an effective way to delay leaf senescence or to increase seed growth and yield of soybean. Nitrogen fertilization increased the level of residual nitrate in the top soil at one site (the one with lowest seed yield), increasing the risk of nitrate leaching during subsequent fallow. 相似文献