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41.
L. Ambrosone R. Angelico G. Cinelli V. Di Lorenzo A. Ceglie 《Journal of the American Oil Chemists' Society》2002,79(6):577-582
Different emulsifying techniques were used to study the influence of water on the oxidative degradation of extra virgin olive
oil. The emulsions of water/extra virgin olive oil, oxidized with O2, UV radiation, and Air, were prepared by dispersing water under different conditions. Oil oxidation, monitored by measuring
the PV and polyphenolic content, was greater for emulsions obtained with low dispersing power. A linear model was used to
correlate the PV and the polyphenolic content with dispersing energy. An important result was that the dispersed water exerted
a positive antioxidant effect on the oil. 相似文献
42.
Rana M. Tubaileh Antonio Garrido-Fernández M. Victoria Ruiz-Méndez Manuel León-Camacho Enrique Graciani-Constante 《Journal of the American Oil Chemists' Society》2002,79(1):101-104
Changes in the contents of waxes and fatty alcohols during deodorization/physical refining of bleached olive oil were studied.
Experiments were carried out with 1.85% acidity oil, which was physically refined in a discontinuous deodorizer of 250-kg
maximum capacity using nitrogen as stripping gas instead of steam. The variables studied were load and temperature of oil
in the deodorizer as well as N2 flow. Analyses of waxes and alcohols were carried out at different operation times. The maximum content of wax was always
observed when the oil reached the deodorization temperature. The variation in the wax content depended on temperature and
N2 flow. Wax decomposition started and continued during the operating time, and a progressive decrease, which was pronounced
between 3 and 4 h, was observed. Small changes in waxes were observed between 4 and 5 h. Total content of fatty alcohols diminished
throughout the operating time, and changes did not depend on the variables studied. 相似文献
43.
Lourdes?Gallardo-Guerrero María?Roca M?Isabel Mínguez-MosqueraEmail author 《Journal of the American Oil Chemists' Society》2002,79(1):105-109
The present work has studied the content and type of pigments present in olive fruits and the respective oils and alperujos.
The concentration of isochromic pigment fractions—chlorophylls and carotenoids—decreased with fruit ripening, more markedly
in the former than in the latter. This implied that the ratio between the two pigment fractions also decreased in parallel
in the three products studied. However, the value in the oil was lower than in the fruit, and that in the alperujo was much
higher. During the extraction process, the release of acids may have caused pheophytinization reactions in the chlorophyll
fraction, increasing pheophytin content in alperujos and oils, whereas the carotenoid fraction was affected only in the alperujo.
Chlorophyll b derivatives were destroyed in greater proportion than chlorophyll a derivatives during transfer to the oil. During processing the destruction of lutein was greater than that of β-carotene.
The balance of matter between fruit, alperujo, and oil indicated that not all the fruit pigmentation was released from the
structures, and most remained occluded in the alperujo. The rest of the pigmentation, and particularly the chlorophyll fraction,
was partly destroyed during its transfer to the oil. 相似文献
44.
Rosario?Zamora Gemma?Gómez Francisco?J.?HidalgoEmail author 《Journal of the American Oil Chemists' Society》2002,79(3):267-272
13C NMR spectra of oil fractions obtained chromatographically from 109 vegetable oils were obtained and analyzed to evaluate
the potential use of those fractions in the classification of vegetable oils and to compare the results with the NMR analysis
of complete oils. The oils included the following: virgin olive oils from different cultivars and regions of Europe and north
Africa; “lampante” olive, refined olive, refined olive pomace, hazelnut, rapeseed, high-oleic sunflower, corn, grapeseed,
soybean, and sunflower oils; and mixtures of virgin olive oils from different geographical origins. Oils were divided into
two sets of samples. The training set (98 samples) was employed to select the variables that resulted in significant discrimination
among the different oil classes. By using stepwise discriminant analysis, more than 98% of correct validated assignments were
obtained; these results were confirmed when applied to the test set (11 blind samples). Results suggest that the use of oil
fractions considerably increases the discriminating power of NMR in the analysis of vegetable oils. 相似文献
45.
Francisco J. Hidalgo Manuel Alaiz Rosario Zamora 《Journal of the American Oil Chemists' Society》2002,79(7):685-689
Twenty-eight virgin olive oils—from different regions of Spain and prepared from olive drupes of different varieties—and six
refined olive oils were analyzed to determine the presence of proteins in these oils. All oils studied showed the presence
of proteins in the range of 7–51 μ/100 g of oil. There were no significant differences in protein content in oils from different
varieties or between virgin or refined oils. In addition, all oils exhibited analogous amino acid patterns, suggesting a similarity
among protein fractions obtained from different oils. A polypeptide with an apparent M.W. of 4600 Da was common to the isolated
protein fractions. These results suggest that this polypeptide is a previously unknown minor component in olive oils. No clear
influence of this component on oil stability was observed when oil stabilities were estimated as a function of phenol, tocopherol,
phosphorus, and protein contents of the oils. 相似文献
46.
Daniel Escolar María R. Haro Jesús Ayuso 《Journal of the American Oil Chemists' Society》2002,79(8):769-774
Four polynomial expressions are obtained that provide a good approximation and an easy, rapid calculation of the chromatic
coordinates and the chroma—L
*, a
*, b
*, and C—for the illuminant C and the standard observer, for a virgin or extra virgin olive oil; absorbance is measured at only 480
and 670 nm. These are as follows: L
*=0.556458(A480)2−2.51145A480+0.55504(A670)2−8.53016A670+98.4089; a
*=0.177372(A480)2+2.1363A480+1.43254(A670)2−0.789231A670−13.9246; b
*=−16.0277(A480)2+79.8932A480−5.06558(A670)2+3.36169A670+31.9405; C=−15.8439(A480)2+78.9312A480−5.26784(A670)2+3.56917A670+33.3927. These give acceptable results, making the method a practical alternative to the extremely laborious Commission Internationale
d’Eclairage (CIE) L
*
a
*
b
*
system, by which 391 absorbance values must be measured individually, nanometer by nanometer, before applying more complex
equations. The validity of the proposed method has been confirmed by comparison, using a set of 20 sample oils different from
the set of 25 oils used to generate the order of the equations. The variations between the values provided by the proposed
and standard methods, respectively, had a mean of 0.00 for each of the chromatic variables—L
*
, a
*
, b
*
, and C; SD were moderate (0.71, 0.52, 1.22, and 1.22, respectively); the root mean square and the R
2-terms also confirmed the validity of the method. 相似文献
47.
蔗渣浆低浓黑液多聚物粘度对温度依赖性的关联模型 总被引:3,自引:1,他引:3
利用聚合物自由体积理论模拟了蔗渣浆低浓黑液对粘度对温度的依赖性的数学模型,最终得出黑液多聚物粘度与温度的相关式:η=A1exp[B1/(T-T0)]。利用示差扫描量热分析技术(DSC)得出了蔗渣黑液多聚物中连续相与分散相的转变曲线,并获得了表观温度T0的平均值为255K;通过实验数据拟合可回归出蔗渣黑液多聚物在不同浓度时的系数A1和B1值。因此,使用该粘度的数学模型可估算蔗渣低浓(接近40%固含量)黑液多聚物在操作温度范围内(20-100℃)的粘度值。 相似文献
48.
The objective of this study was to explore the use of reversed-phase high-performance liquid chromatography (RP-HPLC) as a
means to detect adulteration of olive oil with less expensive canola oil. Previously this method has been shown to be useful
in the detection of some other added seed oils; however, the detection of adulteration with canola oil might be more difficult
due to similarities in fatty acid composition between canola oil and olive oil. Various mixtures of canola oil with olive
oils were prepared, and RP-HPLC profiles were obtained. Adulteration of olive oil samples with less than 7.5% (w/w) canola
oil could not be detected. 相似文献
49.
W. Dennis Pocklington 《Journal of the American Oil Chemists' Society》1992,69(8):789-793
The development, by collaborative study, of a standardized method for the determination of tetrachloroethylene in olive oils
is described. The results of the study, which was carried out in 1989 under the direction of the International Olive Oil Council
(IOOC), are presented and show that tetrachloroethylene can be readily determined, to an acceptable degree of precision, by
gas-liquid chromatography with electron capture detection. A limited number of results obtained for the determination of trichloroethylene
and chloroform by the same method indicate that a similar precision could be obtained with the method when determining these
solvents also. 相似文献
50.
F. Gutiérrez Rosales S. Perdiguero R. Gutiérrez J. M. Olias 《Journal of the American Oil Chemists' Society》1992,69(4):394-395
An analytical method has been developed to evaluate the intensity of the bitter taste in virgin olive oil. Results from the
proposed method, based on extraction of the bitter constituents of virgin olive oil with methanol/water and measurement of
the absorbance at 225 nm, show a significant correlation with the intensity of bitterness that had been evaluated in a sensorial
manner by a panel. The developed method, therefore, offers a real alternative to the panel test for the evaluation of this
attribute. 相似文献