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101.
Igor V. Kovalenko Glen R. Rippke Charles R. Hurburgh 《Journal of the American Oil Chemists' Society》2006,83(5):421-427
A key element of successful development of new soybean cultivars is availability of inexpensive and rapid methods for measurement
of FA in seeds. Published research demonstrated applicability of NIR spectroscopy for FA profiling in oilseeds. The objectives
of this study were to investigate the applicability of NIR spectroscopy for measurement of FA in whole soybeans and compare
performance of calibration methods. Equations were developed using partial least squares (PLS), artificial neural networks
(ANN), and support vector machines (SVM) regression methods. Validation results demonstrated that (i) equations for total
saturates had the highest predictive ability (r
2=0.91–0.94) and were usable for quality assurance applications, (ii) palmitic acid models (r
2=0.80–0.84) were usable for certain research applications, and (iii) equations for stearic (r
2=0.49–0.68), oleic (r
2=0.76–0.81), linoleic (r
2=0.73–0.76), and linolenic (r
2=0.67–0.74) acids could be used for sample screening. The SVM models produced significantly more accurate predictions than
those developed with PLS. ANN calibrations were not different from the other two methods. Reduction in the number of calibration
samples reduced predictive ability of all equations. The rate of performance degradation of SVM models with sample reduction
was the lowest. 相似文献
102.
Hydrolysis of olive oil, soybean oil, mink fat, lard, palm oil, coconut oil, and a hydrogenated, hardened oil with lipase
from anAspergillus sp. has been studied. The lipase had high specific activity (60,000 U/g) and did not show any positional specificity. The
lipase proved to be a more effective catalyst than Lipolase fromA. oryzae, with an optimal activity at 37°C and pH 6.5–7.0. It was activated by Ca2+ but inactivated by organic solvents such as isopropanol and propanone. All substrates examined could be hydrolyzed to corresponding
fatty acids with this enzyme at concentrations of 5–30 U/meq with yields of 90–99% in 2–24 h. The degree of hydrolysis was
almost logarithmically linear with reaction time and occurred in two stages. The lipase was stable and could be repeatedly
recycled for hydrolysis. 相似文献
103.
The oxidative stabilities of one canola oil and six soybean oils of various fatty acid compositions were compared in terms
of peroxide values, conjugated dienoic acid values and sensory evaluations. Two of the soybean oils (Hardin and BSR 101) were
from common commercial varieties. The other four soybean oils were from experimental lines developed in a mutation breeding
program at Iowa State University that included A17 with 1.5% linolenate and 15.2% palmitate; A16 with 2% linolenate and 10.8%
palmitate; A87-191039 with 2% linolenate and 29.6% oleate; and A6 with 27.5% stearate. Seed from the soybean genotypes was
cold pressed. Crude canola oil was obtained without additives. All oils were refined, bleached and deodorized under laboratory
conditions with no additives and stored at 60°C for 15 days. The A17, A16, A87-191039 and A6 oils were generally more stable
to oxidation than the commercial soybean varieties and canola oil as evaluated by chemical and sensory tests. Canola oil was
much less stable than Hardin and BSR 101 oils by both chemical and sensory tests. The peroxide values and flavor scores of
oils were highly correlated with the initial amounts of linolenate (r=0.95, P=0.001). Flavor quality and flavor intensity
had negative correlations with linolenate, (r=−0.89, P=0.007) and (r=−0.86, P=0.013), respectively. 相似文献
104.
Characterization of yam bean (Pachyrhizus spp.) Seeds as potential sources of high palmitic acid oil
W. J. Grüneberg F. D. Goffman L. Velasco 《Journal of the American Oil Chemists' Society》1999,76(11):1309-1312
Seeds from 22 accessions of the yam bean species Pachyrhizus ahipa (14 accessions), P. erosus (5), and P. tuberosus (3) were investigated for oil and protein contents, fatty acid composition of the seed oil, and the total tocopherol content
and composition. Plants from the accessions were grown under greenhouse conditions during one (P. erosus and P. tuberosus) or two years (P. ahipa). The pattern of the investigated seed quality traits was very similar in the three species. Yam bean seeds were characterized
by high oil (from about 20 to 28% in one environment) and protein contents (from about 23 to 34%). Seed oil contained high
concentrations of palmitic (from about 25 to 30% of the total fatty acids), oleic (21 to 29%), and linoleic acids (35 to 40%).
Levels of linolenic acid were very low, from about 1.0 to 2.5%. Total tocopherol content was relatively low in P. erosus (from 249 to 585 mg kg−1 oil) and P. tuberosus (from 260 to 312 mg kg−1 oil) compared with the levels found in P. ahipa grown under identical conditions (508 to 858 mg kg−1 oil). In all the samples, γ-tocopherol was predominant, accounting for more than 90% of the total tocopherol content. The
combination of high oil and protein contents, together with high palmitic acid, low linolenic acid, and high γ-tocopherol
concentration, makes these crops an interesting alternative as sources of high palmitic acid oil for the food industry. 相似文献
105.
L.?Alonso M.?J.?Fraga M.?JuárezEmail author P.?Carmona 《Journal of the American Oil Chemists' Society》2002,79(1):1-6
A Fourier transform infrared spectroscopic procedure was used to analyze 34 edible fats (22 shortenings and 12 vegetable margarines)
as neat fats (IRNF) to determine their total trans fatty acid (TFA) content. The sloping baseline was corrected with a reference spectrum based on a nonprocessed olive oil.
The calibration was done using seven partially hydrogenated fats with an individual TFA content previously determined by the
combination of gas chromatography (GC) with argentation thin-layer chromatography. Taking into account the different absorptivities
of various trans isomers, different correction factors were calculated using the calibration standards (0.83 and 1.71 for single trans bonds in both diethylene and triethylene and for trans, trans-diethylene fatty acids, respectively) and applied to calculate the total TFA of samples. Moreover, the samples were converted
to their methyl esters and reanalyzed following the same procedure (IRFAME). Differences in TFA content of fats were not found when a t-test was used to compare the results obtained by IRNF vs. either IRFAME or GC, suggesting that IR of neat fats could be used, thus avoiding the need to prepare sample solutions in organic solvents
and to prepare fatty acid methyl esters. The mean TFA content (determined by IRNF) of a representative group of Spanish shortenings (22 samples) that varied widely in terms of fat sources, processes, and
purposes (bakery, sandwiches, ice cream, coatings, chocolate coverings) was 6.55±11.40%, although more than 54% contained
<3% of TFA. Fatty acid composition of shortenings by direct GC using a 100-m polar cyanopolysiloxane capillary column indicated
that the mean trans-18∶2 isomer content was 0.58%, ranging from 0.9 to 3.4%. Small amounts of trans-18∶3 isomers (<0.3%) were observed in 18 of the 22 shortenings studied; the maximal value was <2%. The mean value of the
fraction saturated+TFA of shortenings was high (59.95±12.73%), including two values higher than 83%. 相似文献
106.
A fast and cost-effective procedure to quantitate epoxidized soybean oil by means of an external standard method is reported.
This procedure is applicable to commercial epoxidized oils, polymer additive packages and polymers—polyvinyl chloride (PVC)—containing
epoxidized oils. The epoxidized soybean oil is converted into fatty acid methyl esters with tetramethylammonium hydroxide,
and analyzed by capillary gas chromatography with flame-ionization detection. In PVC samples, the epoxidized soybean oil was
extracted with toluene and followed by derivatization prior to analysis. The methyl esters of monoepoxyoctadecanoic, diepoxyoctadecanoic
and triepoxyoctadecanoic acid were separated with a short capillary column. 相似文献
107.
制备皮胶原纤维固载Zr(IV)吸附剂(ZLCF),并考察ZLCF对水体中苯甲酸(BA)、邻苯二甲酸(o-PA)、对苯二甲酸(p-PA)和间苯二甲酸(m-PA)的吸附特性.研究表明:这4种苯羧酸的吸附平衡同时符合Langmuir和Freundlich方程,但随着它们的羧基数量和位置的不同,其吸附容量也随之变化.总体看,ZLCF对所研究的苯羧酸均具有较大的吸附容量.当苯羧酸溶液(10 m1)的初始浓度为6 mmol/L、吸附温度为293 K时,ZLCF(0.05 g)对BA、o-PA、m-PA和p-PA的吸附容量分别达0.4616、0.5892、0.4912和0.3138 mmol/g.吸附动力学研究表明:BA的吸附符合拟一级速率方程,边界层扩散为主控步骤;而o一PA、m-PA和p-PA的吸附符合拟二级速率方程,化学吸附为主控步骤. 相似文献
108.
109.
A new technology was developed to couple the anaerobic digestion of food wastes with production of polyhydroxyalkanoates (PHAs). Acetic, propionic, butyric and lactic acids were produced during food wastes anaerobic digestion and their concentrations reached 5.5, 1.8, 27.4 and 32.7 g/L, respectively under appropriate digestion conditions. The fermentative acids were transferred through a dialysis membrane to an air-lift reactor for PHA synthesis by Ralstonia eutropha. Dry cell concentration and PHA content reached 22.7 g/L and 72.6%, respectively. The obtained PHA was a copolymer of b-hydroxybutyrate (HB) and b-hydroxyvalerate (HV) with 2.8% (mole ratio) of HV units in polymer. 相似文献
110.
P. Larry Phelan Caryn J. Roelofs Roger R. Youngman Thomas C. Baker 《Journal of chemical ecology》1991,17(3):599-613
Ovipositional host-finding in the navel orangeworm,Amyelois transitella (Walker), is brought about by an in-flight response to host odors. Wind-tunnel studies of the response of gravid females to almonds showed that this response is mediated primarily by long-chain fatty acids, particularly oleic acid and linoleic acid. Evidence for the behavioral activity of fatty acids is based on the fact that: (1) behavioral activity of almond oil was concentrated in a single liquid chromatographic fraction whose composition was predominantly long-chain fatty acids, (2) behavioral activity was lost when either almond oil or the active fraction of that oil was treated with diazomethane, (3) full activity was elicited by a selective extraction of free fatty acids from crude almond oil, and (4) upwind response by females was elicited by a blend of synthetic oleic and linoleic acids, albeit at a level less than that elicited by almond oil. Five fatty acids identified from the almond oil were: myristic acid (1%), palmitic acid (16%), stearic acid (3%), oleic acid (58%), and linoleic (22%). Attraction to various combinations of synthetic acids was observed only when oleic acid was present, and oleic acid elicited upwind flights to the source when presented alone; however, short-range responses were enhanced by the addition of linoleic acid, which elicited no long-range orientation by itself. Despite significant levels of attraction to synthetic blends, the percentage of females flying to the source was lower than that flying to acidulated almond oil, the best natural attractant tested. Thus, although longrange response may be mediated primarily by a blend of oleic and linoleic acids, additional and as yet unidentified components must also play an important role. Long-range chemically modulated host finding in this and other generalist plant feeders is discussed with respect to current models of the evolution of host finding, and it is argued that suggestions that long-range host finding should be correlated with narrowness of host utilization are logically flawed and are not supported by our current understanding of specific examples of host finding. 相似文献