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1.
M. Angiuli C. Ferrari L. Lepori E. Matteoli G. Salvetti E. Tombari A. Banti N. Minnaja 《Journal of Thermal Analysis and Calorimetry》2006,84(1):105-112
Extra Virgin olive oils
(7 samples) originating from different areas of Tuscany, defective olive oils
(5 samples), commercial edible seed oils (4 samples) and two commercial samples
of olive oil (one declared ‘extra virgin olive oil’ and one ‘olive
oil’) were studied by different calorimetric techniques: high sensitivity
isothermal, differential scanning, and modulated scanning calorimetry. The
temperature interval (–60) – (+30)°C was explored for monitoring: i) the main features of the liquid↔solid phase
transitions, ii) the nucleation and growth
rate of the polymorphous crystalline phases of the triacylglicerols, and iii) the melting process. This investigation was
planned for verifying the utility and effectiveness of calorimetry for screening
quality and origin of olive oil. To this end, the main calorimetric operation
modes have been applied, the experimental results reported and their utility
for developing an effective and reliable screening protocol discussed. 相似文献
2.
Nikokavoura A Christodouleas D Yannakopoulou E Papadopoulos K Calokerinos AC 《Talanta》2011,84(3):874-880
A novel fluorimetric method is described for the evaluation of the antioxidant activity of hydrophilic and lipophilic compounds and complex natural products such as edible oils. The method is based on the measurement of fluorescence emission intensity of N-methylacridone produced during the reaction of lucigenin with hydrogen peroxide. The presence of antioxidants in the sample inhibits the concentration of N-methylacridone and reduces the fluorescence intensity. The method was fully validated and applied to a variety of hydrophilic and lipophilic compounds as well as to various types of edible oils and their corresponding hydrophilic and lipophilic extracts. Results were compared to those derived from a lucigenin based chemiluminescent method and the Folin-Ciocalteau method for total phenols. The differences in total antioxidant activity of edible oils of various origins and the effect of heating on total antioxidant activity was further studied and discussed. 相似文献
3.
Paolo Oliveri M. Antonietta Baldo Salvatore Daniele Michele Forina 《Analytical and bioanalytical chemistry》2009,395(4):1135-1143
In this paper, we propose a novel strategy to perform cyclic voltammetric measurements with a platinum microelectrode directly
in edible oil samples. The microelectrode was employed as an electronic tongue that, along with the application of chemometrics
to the current–potential responses, proved useful for discriminating oils on the basis of their quality and geographical origin.
The method proposed here is based on the use of suitable room temperature ionic liquids, added to oils as supporting electrolytes
to provide conductivity to the low-polarity samples. The entire voltammograms, recorded directly on the oil/RTIL mixtures,
were processed via principal component analysis and a classification technique (K nearest neighbors), to extract information on samples characteristics. Data processing showed that oils having different
nature (i.e. maize and olive) or geographical origin (i.e. olive oils coming from different regions) can be distinguished. 相似文献
4.
A. M. T. M. Cordeiro M. L. Medeiros N. A. Santos L. E. B. Soledade L. F. B. L. Pontes A. L. Souza N. Queiroz A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2013,113(2):889-895
The restriction to the use of synthetic antioxidants has fostered the research on natural antioxidants, taking into account that the prolonged usage of these substances can harm seriously the human being provoking degenerative diseases. In the present study, the antioxidant effect of the ethanolic rosemary (Rosmarinus officinalis L.) extract on the oxidative stability of edible vegetable oils was investigated by means of the pressurized differential scanning calorimetry (PDSC) and oven test techniques. The rosemary extract, at the concentration of 2,000 mg kg?1, as well as the synthetic antioxidant tert-butylhydroquinone (TBHQ) at the concentrations of 100 and 200 mg kg?1 were added to samples of sunflower oil, corn oil, and soybean oil. The fatty acid profiles of the vegetable oils were determined by gas chromatography–mass spectrometry confirming the elevated contents of unsaturated fatty acids. The thermogravimetric analysis showed that the rosemary extract is stable at the frying temperature of the oils. The results of the oxidative stability demonstrated that the extract of Rosmarinus officinalis displayed a more effective protective action in the PDSC technique, when compared with the synthetic antioxidant TBHQ, indicating that it is a promising source of natural antioxidants for edible vegetable oils. 相似文献
5.
M. Nasiruddin Khan Anila Sarwar M. Farooq Wahab 《Journal of Thermal Analysis and Calorimetry》2010,102(1):369-374
The effect of microwave heating was studied in six varieties of edible oil. Variations in physicochemical properties were
observed and compared with the data obtained by hot plate heating. Fourier-transform infrared spectra of the oils showed substantial
variations after both types of heating in the region of hydrogen’s stretching (C–H) vibration, region of double bond’s stretching
(C=O), and fingerprint region. The visible spectra of mustard and olive oil showed the reduction in carotenoid, flavonoid,
and chlorophyll pigments after heating. The oil samples were discriminated as saturated, monounsaturated, and polyunsaturated
fats using chemometric techniques on physical and spectroscopic measurements. 相似文献
6.
Calvano CD Aresta A Palmisano F Zambonin CG 《Analytical and bioanalytical chemistry》2007,389(7-8):2075-2084
Laser desorption ionization time-of-flight mass spectrometry (LDI–TOF MS) was used to characterize olive and sunflower oils
before and after thermally assisted oxidation in order to develop a rapid fingerprinting method for oil that contains unchanged
and oxidized components. No matrix was used to assist laser desorption, and simplified mass spectra were obtained in the mass
range of interest (m/z 500–1000), where triacyl- and diacylglycerol ions were observed. Sample preparation was reduced to dissolving oil in chloroform
saturated with NaCl. Sodiated triacylglycerols (TAGs), their epoxy/hydroxy and hydroperoxy derivatives, as well as TAGs with
shortened chain fatty acids (β-scission products) were clearly observed in the spectra. LDI–TOF MS rapidly provides semiquantitative information about the
oxidation level of edible oil, and thus represents a very useful quality control tool.
Dedicated to Professor Pier Giorgio Zambonin on the occasion of his 72nd birthday. 相似文献
7.
Biodiesel comprises of fatty acid alkyl esters prepared from vegetable oils or animal fat by esterification/transesterification
with short-chain alcohols (methanol or ethanol, for example). It is a biodegradable renewable fuel. Its production is growing
exponentially due to greater concerns about environmental protection and depletion of fossil fuel resources. Further, its
production from non-edible oils and animal fat is more desirable than from edible oils due to lower cost of non-edible feedstocks
and elimination of food verses fuel issues. Solid acid catalysts are ideal for conversion of such low-grade oils to biodiesel. Biodiesel from non-edible
oils can be produced by two methods: (1) simultaneous esterification of fatty acids and transesterification of fatty acid
glycerides and (2) hydrolysis of glycerides followed by esterification. This account reports the catalytic performance of
solid, Fe–Zn double-metal cyanide (DMC) complexes and other acid catalysts in these transformations for biodiesel production.
The factors influencing the catalytic performance of the solid acid catalysts in biodiesel production are discussed. 相似文献
8.
This work proposes a new method for determination of the oxidative stability of edible oils at frying temperatures using near infrared emission spectroscopy (NIRES). The method is based on heating an oil sample at a fixed temperature, followed by the acquisition of the emission spectra with time using a home-made spectrometer with an acousto-optical tunable filter (AOTF) as monochromator. The induction time, related to the oxidative stability, is determined by means of the emission band at 2900 nm and its increase and broadening during the heating time. After the induction period, this band also provides information related to the oxidation rate of the sample. Twelve samples of edible oils, of different types and from different manufacturers, were analyzed for oxidative stability with mean repetitivity of 3.7%. The effects of nitrogen insertion, heating temperature and the presence of antioxidant compounds on the oxidative stability were evaluated. 相似文献
9.
O. T. Kasaikina V. D. Kortenska E. M. Marinova I. F. Rusina N. V. Yanishlieva 《Russian Chemical Bulletin》1997,46(6):1070-1073
The suppression of the oxidation of triglyceride and methyl esters of lard and olive and sunflower oils by additives of natural
phenolic acids (hydroxy and methoxy derivatives ofpara-hydroxybenzoic and cinnamic acids) at 100 °C was studied. The rate constants of the interaction of these acids with peroxyl
radicals in the oxidation of cumene at 60 °C were determined by the chemiluminescence method. Caffeic acid is the most efficient
lipid antioxidant, exceeding ionol and α-tocopherol.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1119–1122, June, 1997. 相似文献
10.
Physicochemical properties and fatty acid composition of Juglans regia cultivars grown in Serbia 总被引:1,自引:0,他引:1
Tree cultivars (Jupiter, Sejnov, and Elit) of walnut (Juglans regia L.) were collected during the 2004 harvest from Cacak, Central Serbia. The chemical composition, including moisture, total
oil content, crude protein, ash, and carbohydrates, was determined. Afterwards, two techniques of oil extraction were implemented:
cold pressing extraction and organic solvent extraction. Iodine value, saponification value, acid value, and peroxide value
of obtained walnut oils were analyzed. The fatty acid composition of the walnut oils was determined using gas chromatography
with flame ionization detector. The oleic acid content of the oils ranged from 15.9–23.7% of the total acids, while linoleic
acid content ranged from 57.2–65.1% and the linolenic acid from 9.1–13.6%. The process of oil extraction had no significant
effect on content and composition of fatty acids.
Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 118–120, March–April, 2008. 相似文献
11.
Bin Zhu Qingbiao Wang Esben F. Roge Peng Nan Zhijun Liu Yang Zhong 《Chemistry of Natural Compounds》2006,42(4):422-425
Hydrodistilled leaf oils of Pistacia chinensis Bunge from five locations in China were analyzed using GC/MS. A total of 58
compounds was identified in the oils, and a relatively high variation in their contents was found. The major compounds include
β-phellandrene (0.54–53.86%), α-pinene (4.74–54.44%), β-pinene (0.49–42.90%), caryophyllene (5.64–20.01%), cis-ocimene (tr−43.93%), eudesmadiene (0–15.06%), and camphene (tr−20.57%). Cluster analysis classified the leaf oils into two
chemotypes: one rich in α-pinene and β-pinene, and the other rich in β-phellandrene.
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 341–343, July–August, 2006. 相似文献
12.
Li Wang Shuguang Jian Peng Nan Jimei Liu Yang Zhong 《Chemistry of Natural Compounds》2005,41(5):491-493
The chemical constituents of leaf oils of Elephantopus scaber L. from 12 locations in Southern China, including three provinces and Hong Kong, were investigated using GC/MS. A total of
24 compounds were detected, of which 20 were identified by their mass spectra fragmentation patterns. The major compounds
include hexadecanoic acid (8.19–39.22%), octadecadienoic acid (trace - 29.22%), five alkane homologues, i.e., n-tetradecane
(1.19–5.26%), n-pentadecane (3.22–12.05%), n-hexadecane (2.38–16.26%), n-heptadecane (2.48–15.32%), and n-octadecane (1.39–9.59%),
as well as tetramethylhexadecenol (2.06–4.31%). Hierarchical cluster analysis classified the leaf oils into two groups. Two
main chemotypes of leaf oils in E. scaber were thus identified, one rich in hexadecanoic acid and octadecadienoic acid, and the other rich in the five alkane homologues.
__________
Published in Kimiya Prirodnikh Soedinenii No. 5, pp. 403–404, September–October, 2005. 相似文献
13.
P. S. Epaminondas K. L. G. V. Araújo J. A. Nascimento M. C. D. Silva R. Rosenhaim L. E. B. Soledade N. Queiroz A. L. Souza I. M. G. Santos A. G. Souza 《Journal of Thermal Analysis and Calorimetry》2011,106(2):545-550
Physico-chemical properties, spectroscopy, and thermal analyses were used aiming at evaluating the influence of toasting and
of the flaxseed variety on thermo-oxidative behavior of flaxseed oils. Thermogravimetry (TG) and differential scanning calorimetry
(DSC) were associated to gas chromatography, infrared spectroscopy and UV–Vis spectroscopy, as well as to physico-chemical
analyses to characterize the oils obtained from raw and toasted flaxseeds. No meaningful differences in the thermal and oxidative
stabilities were noticed comparing oils obtained from the brown and the golden flaxseeds. Nevertheless, the UV–Vis spectra
indicated that both flaxseed oils were at the beginning of the oxidation process. The previous toasting of the seeds led to
a higher oxidation for both varieties being harmful to the flaxseed oil quality. 相似文献
14.
C. Tănase Lucia Odochian N. Apostolescu A. Pui 《Journal of Thermal Analysis and Calorimetry》2011,103(3):1079-1085
The article is devoted to the study on the thermal behaviour of three species of edible mushrooms: Boletus edulis (foot and cap), Pleurotus ostreatus (foot and cap), Lactarius deterrimus (cap) by the TG–FTIR-coupled technique, in air, over the 30–900 °C temperature range. The analysis of the TG–DTG–DTA curves
reveals the thermal degradation mechanism to be complex and specific to every species under the recording conditions applied.
A similar degradation mechanism is noticed for the foot and cap of Pleurotus ostreatus in comparison with the Boletus edulis and Lactarius deterrimus species where the mechanisms are different. The TG–FTIR analysis, combustion heats and IR spectra of the starting samples
also support these results. The initial degradation temperatures from TG–DTG indicate the temperature range where these species
are thermally stable and their nutrient features maintained making them proper for food. The TG–FTIR analysis gives information
on the gaseous species evolved by the thermal degradation bringing thus a contribution to the elucidation of the changes developing
by processing the edible mushrooms (industrialization, conservation, culinary preparations, etc.) at temperatures above the
initial degradation temperature. At the same time, the environmental impact, when the mushroom failed cultures are burned,
is also important. 相似文献
15.
Aerial parts of Sideritis cilicica Boiss. & Bal. and Sideritis bilgerana P.H. Davis (Lamiaceae) were hydrodistilled to obtain essential oils that were then analyzed by GC and GC/MS. β-Pinene (39%),
α-pinene (28%), and β-phellandrene (20%) were the main components in the oil of S. cilicica, while β-pinene (48%), and α-pinene (32%) were the major constituents in the oil of S. bilgerana. The antimicrobial activities of the oils were evaluated by using the microdilution broth method. Both of the oils showed
good inhibitory effects on C. albicans.
__________
Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 559–561, November–December, 2005. 相似文献
16.
The composition of the hydrodistilled essential oils obtained from dried leaves and fruits of Grammosciadium platycarpum Boiss. & Hausskn. were determined by GC and GC/MS. Twenty-five compounds (87.0%) and sixteen constituents (96.2%) were identified
in the leaf and fruit oils, respectively. Linalool (26.1 and 53.9%), (E,E)-α-farnesene (24.1 and 20.4% ) and (Z)-β-santalol (10.6 and 10.9%) were the major components in the leaf and fruit oils.
Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 559–560, November–December, 2006. 相似文献
17.
The present study was conducted to determine and compare the oxidative stability of soybean and sunflower oils using differential scanning calorimetry (DSC). These edible oils were enriched with marjoram (Origanum majorana L.), thyme (Thymus vulgaris L.), and oregano (Origanum vulgare L.) extracts at three different concentrations and synthetic antioxidant (BHA). The fatty acid composition of studied oils was determined by gas chromatography mass spectrometry to evaluate the content of unsaturated fatty acids that are sensitive to oxidation process. Oil samples were heated in the DSC at different heating rates (4.0, 7.5, 10.0, 12.5, and 15.0 °C min?1) and oxidation kinetic parameters (activation energy, pre-exponential factor, and oxidation rate constant) were calculated. The results showed that the oxidative stability of sunflower oil samples enriched with oregano extracts and soybean oil supplemented with thyme extracts was improved compared to samples without the addition of herbal plant extracts and the synthetic antioxidant. 相似文献
18.
Farid Benkaci-Ali Aoumeur Baaliouamer Jean Paul Wathelet Michel Marlier 《Chemistry of Natural Compounds》2012,47(6):925-931
The fatty acids, sterols, and polyphenols from the fixed oils of Nigella sativa seeds originating from four locations were determined. The seeds contained respectively 30.63–34.27% and 25.66–32.77% of
fixed oils using hexane and isopropyl alcohol in solvent extraction. Linoleic, oleic, and palmitic acids formed the main proportion
using the two solvents, respectively: hexane 54.47–61.28%, isopropanol 56.98–67.30%; hexane 19.62–22.94%, isopropanol 18.85–21.96%,
and hexane 11.17–13.60%, isopropanol 9.20–14.18%. Other minor unsaturated fatty acids were identified. Eight phytosterols
were isolated and identified in the fixed oils by GC and GC/MS analysis, wherein β-sitosterol was the dominating compound that inhibits the absorption of dietary cholesterol, followed by stigmasterol, campesterol,
and Δ5-avenasterol. 相似文献
19.
Martin Adam Petr Dobiáš Petra Pavlíková Karel Ventura 《Central European Journal of Chemistry》2009,7(3):303-311
The analytical microextraction methods of gas chromatography coupled with flame ionisation detector (GC-FID) for determination
of selected essential oils in herbs were proposed. Two microextraction methods for the isolation of essential oils from plants
such as Lavandula spica L., Melissa officinalis L., Mentha piperita L. and Salvia officinalis L. were used. The methods of solid-phase and single-drop microextractions, were optimised and compared. The obtained LOD
values for all studied essential oils were found to be within 2.5–20.5 μg for SDME and 57.0–139.8 μg for SPME method per 100
g of dried sample leaves. The appropriate LOQ values were then 8.4–68.4 μg for SDME and 189.8–466.1 μg for SPME of target
analytes per 100 g of dried sample leaves.
相似文献
20.
I. A. Dzhafarov E. G. Mamedbeili T. G. Kyazimova Kh. I. Gasanov E. I. Suleimanova 《Russian Journal of Applied Chemistry》2010,83(5):854-857
New 2-aminomethyloxy derivatives of 1-(propylsulfanyl)pentane were prepared by condensation of 1-(propylsulfanyl)pentan-2-ol
with formaldehyde and secondary amines. The starting 1-(propylsulfanyl)pentan-2–ol was synthesized by the reaction of 1–propanethiol
with 1–bromopentan–2–ol. The structures of the products were proved by elemental analysis, IR and 1H NMR spectroscopy, and mass spectrometry. The compounds were tested as antimicrobial additives to lubricating oils and as
antiseptics against bacteria and fungi. 相似文献