共查询到20条相似文献,搜索用时 78 毫秒
1.
Kangming Ma F. R. van de Voort A. A. Ismail Hualong Zhuo Binjing Cheng 《Journal of the American Oil Chemists' Society》2000,77(6):681-685
A Fourier transform infrared (FTIR) spectrometer equipped with an attenuated total reflectance (ATR) sample handling accessory
was used to rapidly monitor the peroxide value (PV) of oils undergoing catalytic oxidation to produce sulfonated fatliquors
used in the leather industry. PV quantitation was based on the stoichiometric reaction of triphenylphosphosphine (TPP) with
hydroperoxides to produce triphenylphosphine oxide (TPPO). By using a germanium ATR accessory that has a very short effective
pathlength, the spectral contributions of the base oil could be subtracted out, eliminating any oil-dependent intereferences
as well as providing a facile means of observing the spectral changes associated with the TPP/TPPO reaction. A calibration
was devised by adding a constant amount of TPP-saturated chloroform to oils containing varying amounts of tert-butyl hydroperoxide (TBHP) to produce TPPO that had a measurable band at 1118 cm−1. this band was linearly related to TBHP concentration and the calibration devised had an SD of ∼3.4 PV over the range of
0–250 PV. The ATR-PV method was standardized and the spectrometer programmed using Visual Basic to automate the analysis.
the automated FTIR-ATR method was found to be a convenient means of tracking PV of oils undergoing oxidation, and the results
correlated well with the PV values obtained using the AOAC iodometric method (r=0.94). The FTIR-ATR PV methodology provides a simple means of monitoring the PV of oils undergoing rapid oxidation and could serve
as a quality-control tool in the production of sulfonated oils for the leather industry. 相似文献
2.
Supercritical carbon dioxide (SC-CO2) was used to partially defat walnuts, and the oxidative stability of the extracted walnut oils was assessed. The SC-CO2-extracted oils were less stable during accelerated storage in the dark than was pressed walnut oil, as determined by PV,
headspace analysis by solid-phase microextraction, and sensory methods. The SC-CO2-extracted oils, however, exhibited greater photo-oxidative stability than did pressed walnut oil by all of these methods,
possibly because of the presence of chlorophyll in the pressed oil. Oxidative stability indices and tocopherol contents were
significantly lower in the SC-CO2-extracted oils than in pressed oil. 相似文献
3.
Hyun Jung Kim Tae Shik Hahm David B. Min 《Journal of the American Oil Chemists' Society》2007,84(4):349-355
Fifteen milliliters of soybean oil having peroxide value (PV) of 0, 2, 4, 6, 8, or 10 meq/kg oil in a 35 mL serum bottle was
sealed air-tight with a Teflon rubber septum and aluminum cap and was stored in a forced-air oven at 50 °C. The oxidative
stability of soybean oil was evaluated daily for six days by measuring the headspace oxygen content and volatile compounds
in the headspace of a sample bottle by gas chromatography. As the initial PV of the oil increased from 0 to 2, 4, 6, 8 and
10, the headspace oxygen decreased and the volatile compounds increased at p < 0.05. Hydroperoxide accelerated the oxidation of soybean oil. The correlation coefficient (R
2) between the headspace oxygen and the volatile compounds was 0.95. The increase of tertiary butyl hydroquinone (TBHQ) from
0 to 50 ppm for the oil of PV 4 or 8 had a significant effect on the oxidative stability at p < 0.05. The increase from 50 to 100 ppm for the oil of PV 4 or 8 did not significantly increase the stability at p > 0.05. The oxidative stability of PV 8 meq/kg and 50 ppm TBHQ was better than the control with PV 0 and 0 ppm TBHQ at p < 0.05. TBHQ was an effective antioxidant to improve the oxidative stability of soybean oil. 相似文献
4.
F. R. van de Voort A. A. Ismail J. Sedman J. Dubois T. Nicodemo 《Journal of the American Oil Chemists' Society》1994,71(9):921-926
A rapid method for the quantitative determination of peroxide value (PV) of vegetable oils by Fourier transform infrared (FTIR)
transmission spectroscopy is described. Calibration standards were prepared by the addition oft-butyl hydroperoxide to a series of vegetable oils, along with random amounts of oleic acid and water. Additional standards
were derived through the addition of mono- and diglyceride spectral contributions, as well as zero PV spectra obtained from
deuterated oils. A partial least squares (PLS) calibration model for the prediction of PV was developed based on the spectral
range 3750–3150 cm−1. Validation of the method was carried out by comparing the PV of a series of vegetable oils predicted by the PLS model to
the values obtained by the American Oil Chemists Society iodometric method. The reproducibility of the FTIR method [coefficient
of variation (CV)=5%)] was found to be better than that of the chemical method (CV =9%), although its accuracy was limited
by the reproducibility of the chemical method. The method, as structured, makes use of a 1-mm CaF2 flow cell to allow rapid sample handling by aspiration. The spectrometer was preprogrammed in Visual Basic to guide the operator
in performing the analysis so that no knowledge of FTIR spectroscopy is required to implement the method. The method would
be suitable for PV determinations in the edible oil industry and takes an average of three minutes per sample. 相似文献
5.
Gülgün Yildiz Randy L. Wehling Susan L. Cuppett 《Journal of the American Oil Chemists' Society》2001,78(5):495-502
Use of near-infrared (NIR) transmittance spectroscopy for rapid determination of the oxidation level in soybean oils (SBO)
was investigated, and calibrations were developed for quantitative determination of peroxide value (PV), conjugated diene
value (CD), and anisidine value (AV) of SBO. Partial least squares (PLS) regression and forward stepwise multiple linear regression
were used to develop calibration models from spectral data in log 1/T, first derivative and second derivative of log 1/T formats for both 1- and 2-mm path lengths. The models were validated by comparing NIR results from independent sample sets
to the values obtained by official methods. The spectral region from 1100 to 2200 nm was best for measuring oxidation when
using a 2-mm path length. PLS regression using first-derivative spectra gave the best results for PV. For the validation sets,
linear relationships were obtained for PV (r=0.99), and CD (r=0.95), compared with accepted reference procedures. However, measurement of AV by NIR was less successful than measurement
of the other two indices of oxidation, especially for an external validation sample set. Results obtained in this study indicate
that NIR spectroscopy is a useful technique for measuring oxidation in soybean oil. 相似文献
6.
Jenna C. Sullivan Ritter Suzanne M. Budge Fabiola Jovica Anna‐Jean M. Reid 《Journal of the American Oil Chemists' Society》2015,92(4):561-569
Fish oil is available primarily as triacylglycerols (TAG) or ethyl esters (EE). Anecdotal evidence suggests that TAG have superior bioavailability and oxidative stability compared to EE. In this work, peroxide value (PV) and p‐anisidine value (AV) were used to monitor oxidation in commercially available TAG and EE fish oils incubated at temperatures from 5 to 60 °C. Pseudo first‐order kinetics were assumed and rate constants were calculated for each temperature. At all temperatures, the rates of oxidation were higher for EE oils than TAG oils. For PV and AV measured in both oils, non‐linear Arrhenius models were plotted, generating activation energies that ranged from 7 to 103 and 2 to 159 kJ/mol for PV and AV, respectively. Although TAG were more resistant to oxidation than EE, they had lower activation energies (Ea) at ≤15 °C for reactions measured with PV and AV. The Ea for EE was negative at temperatures ≥45 °C, indicating that reaction rate was influenced by factors in addition to temperature. 相似文献
7.
Stoichiometric determination of hydroperoxides in fats and oils by fourier transform infrared spectroscopy 总被引:1,自引:0,他引:1
K. Ma F. R. van de Voort J. Sedman A. A. Ismail 《Journal of the American Oil Chemists' Society》1997,74(8):897-906
A primary Fourier transform infrared (FTIR) spectroscopic method for the determination of peroxide value (PV) in edible oils
was developed based on the stoichiometric reaction of triphenylphosphine (TPP) with hydroperoxides to produce triphenylphosphine
oxide (TPPO). Accurate quantitation of the TPPO formed in this reaction by measurement of its intense absorption band at 542
cm−1 provides a simple means of determining PV. A calibration was developed with TPPO as the standard; its concentration, expressed
in terms of PV, covered a range of 0–15 PV. The resulting calibration was linear over the analytical range and had a standard
deviation of ±0.05 PV. A standardized analytical protocol was developed, consisting of adding ∼0.2 g of a 33% (w/w) stock
solution of TPP in hexanol to ∼30 g of melted fat or oil, shaking the sample, and scanning it in a 100-μm KCI IR transmission
cell maintained at 80°C. The FTIR spectrometer was programmed in Visual Basic to automate scanning and quantitation, with
the reaction/FTIR analysis taking about 2 min per sample. The method was validated by comparing the analytical results of
the AOCS PV method to those of the automated FTIR procedure by using both oxidized oils and oils spiked with tert-butyl hydroperoxide. The two methods correlated well. The reproducibility of the FTIR method was superior (±0.18) to that
of the standard chemical method (±0.89 PV). The FTIR method is a significant improvement over the standard AOCS method in
terms of analytical time and effort and avoids solvent and reagent disposal problems. Based on its simple stoichiometry, rapid
and complete reaction, and the singular band that characterizes the end product, the TPP/TPPO reaction coupled with a programmable
FTIR spectrometer provides a rapid and efficient means of determining PV that is especially suited for routine quality control
applications in the fats and oils industry. 相似文献
8.
Previous work in our laboratory demonstrated that soybean oil oxidation, expressed as PV, can be determined using NIR transmission
spectroscopy as an alternative to the official AOCS iodometric titration method. In the present study, a comparison of four
peroxide analytical methods was conducted using oxidized soybean oil. The methods included the official AOCS iodometric titration,
the newly developed NIR method, the PeroxySafe™ kit, and a ferrous xylenol orange (FOX) method, the latter two being colorimetric methods based on oxidation of iron. Five
different commercially available soybean oils were exposed to fluorescent light to obtain PV levels of 0–20 meq/kg; periodic
sampling was done to ensure having representative samples throughout the designated range. A total of 46 oil samples were
analyzed. Statistical analysis of the data showed that the correlation coefficient (r) and standard deviation of differences (SDD) between the standard titration and NIR methods were r=0.991, SDD=0.72 meq/kg; between titration and the PeroxySafe™ kit were r=0.993, SDD=0.56 meq/kg; and between the standard titration and FOX method were r=0.975, SDD=2.3 meq/kg. The high correlations between the titration, NIR, and PeroxySafe™ kit data indicated that these methods were equivalent. 相似文献
9.
This study was conducted to determine the oxidative stability of conjugated linoleic acid rich soy oil (CLARSO) and the effects
of conjugated linoleic acid (CLA) levels on volatile oxidation products formed during CLARSO oxidation. CLARSO oxidative stability
was determined by gravimetric analysis, peroxide value, headspace oxygen analysis and p-anisidine value. Volatile oxidation compounds were analyzed by solid phase microextraction–gas chromatography with a flame
ionization detector and a mass spectrometer. CLA oxidation results were highly dependent on analytical methods used and oxidation
parameters measured. The gravimetric study showed a CLA concentration effect on oxidation, which was not seen in the headspace
oxygen depletion and peroxide value. Volatile oxidation data indicate that CLARSO had significantly higher (p < 0.05) levels of pentanal and trans-2-heptenal than the other oils, but there was no significant difference between the amounts of any volatiles present in 8
and 15% CLARSO. This suggests that oxidation was greater in CLARSO and that CLA concentration did not affect oxidation. 相似文献
10.
Saga LC Rukke EO Liland KH Kirkhus B Egelandsdal B Karlsen J Volden J 《Journal of the American Oil Chemists' Society》2011,88(12):1883-1895
The oxidative stability of mixtures of edible oils containing polyunsaturated fatty acids (PUFA) and microcrystalline cellulose
(MCC) was investigated. The mixtures studied consisted of oils of either camelina (CAM), cod liver (CLO), or salmon (SO) mixed
with either colloidal or powdered MCC. A 50:50 (w/w) ratio of oil:MCC resulted in an applicable mixture containing high levels
of PUFA edible oil and dietary fiber. The oxidative stability of the formulated mixtures and the pure oils was investigated
over a period of 28 days. The peroxide value (PV) was assessed as a parameter for primary oxidation products and dynamic headspace
gas chromatography mass spectrometry (GC/MS) was used to analyze secondary volatile organic compounds (VOC). CAM and the respective
mixtures were oxidatively stable at both 4 and 22 °C during the storage period. The marine oils and the respective mixtures
were stable at 4 °C. At 22 °C, an increase in hydroperoxides was found, but no increase in VOC was detected during the time-frame
investigated. At 42 °C, prominent increases in PV and VOC were found for all oils and mixtures. Hexanal, a common marker for
the degradation of n-6 fatty acids, propanal and 2,4-heptadienal (E,E), common indicators for the degradation of n-3 fatty acids, were among the volatiles detected in the headspace of oils and mixtures. This study showed that a mixture
containing a 50:50 ratio of oil:MCC can be obtained by a low-tech procedure that does not induce oxidation when stored at
low temperatures during a period of 1 month. 相似文献
11.
Effect of natural antioxidants in virgin olive oil on oxidative stability of refined,bleached, and deodorized olive oil 总被引:1,自引:0,他引:1
M. Teresa Satue Shu-Wen Huang Edwin N. Frankel 《Journal of the American Oil Chemists' Society》1995,72(10):1131-1137
The factors influencing the oxidative stability of different commercial olive oils were evaluated. Comparisons were made of
(i) the oxidative stability of commercial olive oils with that of a refined, bleached, and deodorized (RBD) olive oil, and
(ii) the antioxidant activity of a mixture of phenolic compounds extracted from virgin olive oil with that of pure compounds
andα-tocopherol added to RBD olive oil. The progress of oxidation at 60°C was followed by measuring both the formation (peroxide
value, PV) and the decomposition (hexanal and volatiles) of hydroperoxides. The trends in antioxidant activity were different
according to whether PV or hexanal were measured. Although the virgin olive oils contained higher levels of phenolic compounds
than did the refined and RBD oils, their oxidative stability was significantly decreased by their high initial PV. Phenolic
compounds extracted from virgin olive oils increased the oxidative stability of RBD olive oil. On the basis of PV, the phenol
extract had the best antioxidant activity at 50 ppm, as gallic acid equivalents, but on the basis of hexanal formation, better
antioxidant activity was observed at 100 and 200 ppm.α-Tocopherol behaved as a prooxidant at high concentrations (>250 ppm) on the basis of PV, but was more effective than the
other antioxidants in inhibiting hexanal formation in RBD olive oil.o-Diphenols (caffeic acid) and, to a lesser extent, substitutedo-diphenols (ferulic and vanillic acids), showed better antioxidant activity than monophenols (p- ando-coumaric), based on both PV and hexanal formation. This study emphasizes the need to measure at least two oxidation parameters
to better evaluate antioxidants and the oxidative stability of olive oils. The antioxidant effectiveness of phenolic compounds
in virgin olive oils can be significantly diminished in oils if their initial PV are too high. 相似文献
12.
Abderrahmane Aït Kaddour Evane Grand Nathalie Barouh Bruno Bara Pierre Villeneuve Bernard Cuq 《European Journal of Lipid Science and Technology》2006,108(12):1037-1046
The present study was aimed at determining the ability of near‐infrared (NIR) spectroscopy to in situ describe fat oxidation kinetics in three different cereal‐based products: salted crackers (20% saturated palm oil and lauric oil, sprayed on surface); healthy crackers (10% unsaturated rapeseed oil, homogeneously distributed inside the product matrix); and moist pasteurised Asian noodles (1.5% unsaturated rapeseed oil, sprayed on surface). Products were stored under accelerated oxidation conditions at 40 °C. Lipid oxidation rates were determined from peroxide value (PV) measurements. We observed no significant changes in PV for the dry crackers (3 meq/kg after 60 days), a slight linear increase in PV for the healthy crackers (40 meq/kg after 60 days), and a rapid increase for the Asian noodles (80 meq/kg after 20 days). The NIR spectra were recorded between 1000 and 2500 nm by using a Fourier Transform NIR spectrometer, using an external probe. Measurements were done directly in situ on the product, on the ground samples, and on the extracted fat phase. The analysis of NIR spectral data by PLS statistical methods demonstrated some correlation trends (R2 = 0.575–0.897; RMSEC = 17–55%) for the products having a significant increase in PV. It was not possible to propose predictive models to calculate the oxidation rate. 相似文献
13.
Arkadiusz Szterk M. Roszko E. Sosińska D. Derewiaka P. P. Lewicki 《Journal of the American Oil Chemists' Society》2010,87(6):637-645
Scientific data on the oxidative stability of borage oil, Camelina sativa oil, linseed oil, evening primrose oil and pumpkin seed oil are scarce. Chemiluminescence (CL) methods most commonly used
to determine the oxidative stability of oils include measurement of hydroperoxide, intensity of light emitted during the accelerated
oxidation process performed at high (>100 °C) temperatures or assisted by forced flow of air/oxygen through the sample. The
aim of this study was to investigate the chemical composition and oxidative stability of selected vegetable oils available
on the Polish market. Oxidative stability was determined using a fast, novel chemiluminescence-based method, in which light
emitted during oxidation process conducted at 70 °C in the presence of some catalyzing Fe2+ ions is measured. A reaction of the applied type has not been reported so far. High contents of tocopherols and phytosterols
were found in the analyzed oil samples. Oxidative stability of the samples was in most cases higher than the stability of
refined rapeseed oil, a relatively stable substance from the oxidation point of view. 相似文献
14.
A Comparative Study of the Properties of Selected Melon Seed Oils as Potential Candidates for Development into Commercial Edible Vegetable Oils 总被引:1,自引:0,他引:1
M. B. Mabaleha Y. C. Mitei S. O. Yeboah 《Journal of the American Oil Chemists' Society》2007,84(1):31-36
A comprehensive compositional and characterization study was carried out on five seed oils from varieties of the melons Citrullus lanatus and C. colocynth in order to evaluate their suitability for large-scale exploitation as edible vegetable oils. The oils were extracted by
Soxhlet with a 3:1 mixture of n-hexane/2-propanol with yields that ranged from 24.8 to 30.0% (wt/wt). The refractive indices and relative densities of the
oils fell within the narrow ranges of 1.465–1.469 and 0.874–0.954 g/cm3, respectively. Saponification values ranged between 182.1 and 193.8 mg KOH/g, whilst iodine values (IV) ranged from 95.8
to 124.0 (Wijs). The ranges of the values for free fatty acid (AV), 1.2–4.0 mg KOH/g, peroxide (PV), 1.1–10.9 meq/kg and p-anisidine (p-AV), 0.2–9.0, indicated that secondary oxidation products were barely present. GC analysis gave total unsaturation contents
of 67.93–82.36%, with linoleic acid (18:2) being the dominant fatty acid (55.21–66.85%). The GC results agreed closely with
those from proton NMR analysis of the fatty acid classes. The physicochemical and compositional properties determined in this
study show that the qualities of the test Cucurbitacea seed oils are highly comparable to those of soybean, sunflower and
groundnut seed oils. Therefore, the test melon seed oils could be developed into commercial products to serve as alternate
vegetable oils in Southern and West Africa, the regions where these melons grow. 相似文献
15.
Dámaso Hornero-Méndez Antonio Pérez-Gálvez Ma Isabel Mínguez-Mosquera 《Journal of the American Oil Chemists' Society》2001,78(11):1151-1155
A rapid and sensitive ultraviolet-visible spectrophotometric method for determination of peroxide value (PV) in foods with
high carotenoid content (e.g., paprika oleoresin, paprika powder, red palm oil) has been developed. The proposed protocol
[modified International Dairy Federation (IDF) method] was established from the IDF Fe(II)-oxidation-based spectrophotometric
method, and the main one of the introduced modifications consisted of a clean-up extraction step of pigments before determining
the PV by complexing Fe(III) ions with thiocyanate. Fe(II) oxidation time, reaction medium, and Fe(III)-thiocyanate complex
formation time were optimized. The modified IDF method was compared with and was validated by iodometric AOAC official method
with a good correlation (R
2=0.957) between data obtained by both analytical methods. The high sensitivity of the method allows the use of only about
0.010–0.015 g of sample, with a detection limit of 0.044 mequiv peroxide/kg of sample. Therefore, an improved spectrophotometric
method for assessing PV in food lipids with high carotenoid content is now available and can be applied to any kind of sample,
independent of oil and pigment content. 相似文献
16.
A new FTIR approach was investigated for assessing edible oil oxidative stability with the use of polymer IR (PIR) cards as
sample holders. This approach allows oil oxidation to be monitored at moderate temperatures owing to the fairly rapid rate
at which unsaturated oils oxidize on the PIR cards. To assess the FTIR/PIR card method, pure TAG—triolein, trilinolein, and
trilinolenin—were loaded onto cards and placed in a chamber where warm air (55°C) flowed over them continuously to facilitate
oxidation. At periodic intervals, individual cards were removed and their FTIR spectra scanned, after which they were replaced
in the aeration chamber. All spectra were normalized to compensate for variations in PIR card path lengths or oil loadings,
and for each card the initial spectrum recorded (t=0) was subtracted from all subsequent spectra taken over time to produce differential spectra. With the use of a peak-find
algorithm, the absorbance minimum in the cis region (3017–3000 cm−1) and the absorbance maxima in the hydroperoxide (3550–3200 cm−1), isolated trans (977–957 cm−1), and conjugated trans regions (995–983 cm−1) were measured in the differential spectra and plotted as a function of time. For all three TAG, the loss of cis double bonds was linearly related to the development of hydroperoxides and isolated trans bonds for much of the oxidation process, whereas for the polyunsaturated TAG a similar relationship also existed for conjugated
trans species. Based on experimentally determined hydroperoxide (ROOH) absorbance slope factor (0.06 mAbs/PV), ROOH absorbance
changes were converted to PV, allowing direct PV monitoring as a function of time using the PIR cards. Trilinolenin, trilinolein,
and triolein attained a PV of 100 mequiv/kg oil after, 43,98, and 2889 min, respectively, their relative reaction rates being
similar to ratios published in the literature. The assessment of the FTIR/PIR card method using TAG indicates that it may
be a practical and rapid means of oxidizing lipids and tracking their oxidative state in terms of PV so as to provide a measure
of their oxidative stability. 相似文献
17.
Muhammad Ahmad Khan Fereidoon Shahidi 《Journal of the American Oil Chemists' Society》2000,77(9):963-969
Oxidative stability of stripped and nonstripped borage and evening primrose oils and their emulsions in water was evaluated.
The results indicated that column chromatographic techniques provide an effective means for stripping vegetable oils of their
minor components. However, some minor components may be retained in the stripped oils. The minor components in borage and
evening primrose oils significantly (P<0.05) influenced their oxidative stability in the dark. In contrast, the behavior of endogenous antioxidants in borage and
evening primrose oil-in-water emulsions, according to the “polar paradox” theory, was difficult to evaluate. Correlations
existed between peroxide value (PV) and conjugated dienes (CD) (P<0.05) as well as 2-thiobarbituric acid-reactive substances (TBARS) and hexanal content (P<0.01) for most oils and emulsion systems. Therefore, CD and TBARS may generally be used to assess the oxidative stability
of borage and evening primrose oils and their oil-in-water emulsions in addition to or in place of PV and headspace volatiles,
respectively. 相似文献
18.
A flow injection analysis (FIA) system coupled with a fluorescence detection system using diphenyl-1-pyrenylphosphine (DPPP)
was developed as a highly sensitive and reproducible quantitative method of total lipid hydroperoxide analysis. Fluorescence
analysis of DPPP oxide generated by the reaction of lipid hydroperoxides with DPPP enabled a quantitative determination of
the total amount of lipid hydroperoxides. Use of 1-myristoyl-2-(12-((7-nitro-2-1,3-benzoxadiazol-4-yl)amino) dodecanoyl)-sn-glycero-3-phosphocholine as the internal standard improved the sensitivity and reproducibility of the analysis. Several commercially
available edible oils, including soybean oil, rapeseed oil, olive oil, corn oil, canola oil, safflower oil, mixed vegetable
oils, cod liver oil, and sardine oil were analyzed by the FIA system for the quantitative determination of total lipid hydroperoxides.
The minimal amounts of sample oils required were 50 μg of soybean oil (PV=2.71 meq/kg) and 3 mg of sardine oil (PV=0.38 meq/kg)
for a single injection. Thus, sensitivity was sufficient for the detection of a small amount and/or low concentration of hydroperoxides
in common edible oils. The recovery of sample oils for the FIA system ranged between 87.2±2.6% and 102±5.1% when PV ranged
between 0.38 and 58.8 meq/kg. The CV in the analyses of soybean oil (PV=3.25 meq/kg), cod liver oil (PV=6.71 meq/kg), rapeseed
oil (PV=12.3 meq/kg), and sardine oil (PV=63.8 meq/kg) were 4.31, 5.66, 8.27, and 11.2%, respectively, demonstrating sufficient
reproducibility of the FIA system for the determination of lipid hydroperoxides. The squared correlation (r
2) between the FIA system and the official AOCS iodometric titration method in a linear regression analysis was estimated at
0.9976 within the range of 0.35−77.8 meq/kg of PV (n=42). Thus, the FIA system provided satisfactory detection limits, recovery, and reproducibility. The FIA system was further
applied to evaluate changes in the total amounts of lipid hydroperoxides in fish muscle stored on ice. 相似文献
19.
Mengzhu Wang Jia Chen Bingyu Jing Lingyan Zhang Yaoyao Dong Xiuzhu Yu 《European Journal of Lipid Science and Technology》2020,122(6)
Edible oils are studied to analyze their reaction kinetics during oxidation and predict shelf life at ambient temperature. Rapeseed oil (RO), soybean oil (SO), linseed oil (LO), and peanut oil (PO) are detected via Fourier transform infrared spectroscopy with a mesh cell as spectral acquisition accessory. The reaction kinetics of ROOH bonds, C═O bonds, trans double bonds (TDBs), and carbon chain skeletons (CCSs) are determined by absorbance changes in their characteristic absorption peaks. Prediction models for shelf life based on various characteristic absorption peaks are converted via the reaction kinetics equations of the oils. Results show that first‐order reaction kinetics are used to describe absorbance changes of ROOH bonds in PO, SO, and LO, while zero‐order reaction kinetics are used to describe the absorbance changes in RO. Both C═O bonds and CCS absorbance changes in the four oils satisfy first‐order reaction kinetics. TDBs absorbance changes in PO, SO, and LO are in accordance with zero‐order reaction kinetics. The regression equations of reaction kinetics exhibit good fitting degree (coefficient of determination, R2 > 0.9000) and statistical significance (p < 0.001), indicating that the proposed method can be used to analyze the reaction kinetics of oil oxidation and predict shelf life. Practical Applications: The reaction kinetics of RO, SO, LO, and PO are studied at ambient temperature and the shelf life is predicted by using FTIR spectroscopy based on the absorbance changes of ROOH bonds, C═O bonds, TDB bonds, and CCS in the oils. The shelf life of edible oils can be more effectively predicted in this case and provide a practical reference for food industries. Furthermore, the proposed technique is rapid, green, and accurate, and allows real‐time characterization of absorbance changes in various characteristic absorption peaks, which corresponded to different oxidation products. By this method, it is possible to reflect real‐time information for different quality indices (such as peroxides and acid values) of oil oxidation simultaneously, and unnecessary to measure these indices directly one by one, saving manpower and material resources. Therefore, FTIR spectroscopy is convenient for the rapid evaluation of oxidation stability and shelf life of edible oils under ambient temperature. 相似文献
20.
K. Ma F. R. van de Voort A. A. Ismail J. Sedman 《Journal of the American Oil Chemists' Society》1998,75(9):1095-1101
Disposable polyethylene infrared cards (3M IR cards) were investigated for their suitability for the quantitative determination
of peroxide value (PV) in edible oils relative to a conventional transmission flow cell. The analysis is based on the stoichiometric
reaction of triphenylphosphine (TPP) with hydroperoxides to produce triphenylphosphine oxide (TPPO). Preliminary work indicated
that the cards, although relatively consistent in their pathlength (±1%), had an overall effective pathlength variation of
±∼5%, caused by variability in loading of the oil onto the cards. This loading variability was reduced to <0.5% by developing
a normalization protocol that is based on the peak height of the ester linkage carbonyl overtone band at 3475 cm−1, which allowed one to obtain consistent and reproducible spectra. The standard PV calibration approach, based on the TPPO
peak height at 542 cm−1, failed because of unanticipated card fringing in the region where the measurements were being made. However, the development
of a partial-least-squares (PLS) calibration provided a means of eliminating the interfering effect of the fringes and allowed
the TPPO band to be measured accurately. An alternate approach to the standardized addition of TPP reagent to the oil was
also investigated by impregnating the 3M IR cards with TPP, thus allowing the reaction to take place in situ. The spectral analysis protocols developed (normalization/calibration) were programmed to automate the PV analysis completely.
The 3M card-based Fourier transform infrared PV methods developed were validated by analyzing oxidized oils and comparing
the PV predictions obtained to those obtained in a 100-μm KCI flow cell. Both card methods performed well in their ability
to predict PV. The TPP-impregnated 3M card method reproduced the flow cell PV data to within ±1.12 PV, whereas the method
with an unimpregnated card was accurate to ±0.92 PV over the calibrated range (0–25 PV). Our results indicate that, with spectral
normalization and the use of a PLS calibration, quantitative PV data, comparable to those obtained with a flow cell, can be
provided by the 3M IR card. With the analytical protocol preprogrammed, the disposable 3M card provides a simple, rapid and
convenient means of carrying out PV analyses, suitable for quality control laboratories, taking about 2–3 min per analysis. 相似文献