共查询到20条相似文献,搜索用时 15 毫秒
1.
F. R. van de Voort K. P. Memon J. Sedman A. A. Ismail 《Journal of the American Oil Chemists' Society》1996,73(4):411-416
A unique and rapid Fourier transform infrared (FTIR) spectroscopic method for the determination of solid fat index (SFI) of
fats and oils was developed, which is capable of predicting the SFI profile of a sample in approximately two minutes, without
the need for tempering. Hydrogenated soybean oil samples (n=72), pre-analyzed for SFI by dilatometry, were melted and their FTIR spectra acquired using a 25 μm NaCl transmission flow
cell maintained at 80°C. Approximately half the samples were used for calibration, with the balance used as validation samples.
Partial least squares (PLS) calibrations were developed from selected spectral regions that are associated with thecis, trans, ester linkage and fingerprint regions of the spectrum and related to the dilatometric SFI values obtained at 50, 70, 80,
and 92°F. The calibrations were initially optimized and cross-validated by using the “leave one out” approach, with the accuracy
and reproducibility of the calibration models assessed by predicting the validation samples. The overall cross validation
accuracy of the PLS calibration models was in the order of ±0.71 SFI units over the four temperatures. Week-to-week validation
accuracy and reproducibility was determined to be ±0.60 and ±0.38 SFI units, respectively, the reproducibility being within
the specifications associated with the dilatometric reference method. To facilitate routine “on-line” FTIR analyses, a Visual
Basic program was written to drive the spectrometer, prompt the user to load the sample, calculate, and print the SFI values
determined from the PLS calibrations. As structured, the FTIR method has the potential to serve as a viable substitute for
the traditional dilatometric SFI method, with the elimination of the tempering step reducing analysis time from hours to minutes.
The FTIR approach should also be applicable to the determination of solid fat content if calibrated against solids data obtained
by nuclear magnetic resonance. 相似文献
2.
Y. B. Che Man G. Setiowaty F. R. van de Voort 《Journal of the American Oil Chemists' Society》1999,76(6):693-699
A rapid method for the quantitative determination of iodine value (IV) of palm oil products by FTIR transmission spectroscopy is described. A calibration standard was developed by blending palm stearin and superolein in specific ratios that covered a range of 27.9 to 65.3 IV units. The spectra of these standards was measured in the range between 3050 and 2984 cm−1, corresponding to the absorption band of=C-H cis stretching vibration. A partial least squares calibration model for the prediction of IV was developed to quantify the IV of palm oil products. A validation approach was used to optimize the calibration with a correlation coefficient of R 2=0.9995 and a standard error of prediction of 0.151. This study concludes that the FTIR transmission approach can be used to determine the IV of palm oil products with a total analysis time per sample of less than 2 min for liquid samples. 相似文献
3.
Hui Li F. R. van de Voort A. A. Ismail R. Cox 《Journal of the American Oil Chemists' Society》2000,77(2):137-142
A Fourier transform-near infrared (FT-NIR) method originally designed to determine the peroxide value (PV) of triacylglycerols
at levels of 10–100 PV was improved upon to allow for the analysis of PV between 0 and 10 PV, a range of interest to the edible
oil industry. The FT-NIR method uses convenient disposable glass vials for sample handling, and PV is determined by spectroscopically
measuring the conversion of triphenylphosphine (TPP) to triphenylphosphine oxide (TPPO) when reacted with hydroperoxides.
A partial-leastsquares calibration was developed for 8 mm o.d. vials by preparing randomized mixtures of TPP and TPPO in a
zero-PV oil. The method was validated with samples prepared by gravimetric dilution of oxidized oil with a zero-PV oil. It
was shown that the American Oil Chemists’ Society primary reference method was quite reproducible (±0.5 PV), but relatively
insensitive to PV differences at lower (0–2) PV. The FT-NIR method on the other hand was shown to be more accurate overall
in tracking PV, but slightly less reproducible (0.9 PV) due to working close to the limit of detection. The sensitivity and
reproducibility of the FT-NIR method could be improved upon through the use of larger-diameter vials combined with a detector
having a wider dynamic range. The proposed FT-NIR PV method is simple to calibrate and implement and can be automated to allow
for routine quality control analysis of edible fats and oils. 相似文献
4.
C. Adhikari A. Proctor G. D. Blyholder 《Journal of the American Oil Chemists' Society》1995,72(3):337-341
Diffuse reflectance Fourier transform infrared spectroscopy was used to study the mode of adsorption of phosphatidylcholine
(PC) in hexane onto silicic acid (SA). PC adsorption was mainly through the charged phosphate group with minimal binding through
the ester carbonyl. When the SA surface with adsorbed PC is washed with hexane, containing a small concentration of isopropanol,
the desorbed PC is recovered without structural change, i.e., there is no evidence of PC hydrolysis in the adsorption process.
Adsorbent misture probably promotes PC adsorption due to the increased availability of surface water hydroxyl groups for interaction
with the PC phosphate groups. Isopropanol promoted PC binding by destabilizing PC reverse miscelles in solution, thus promoting
its adsorption. 相似文献
5.
Determination of olive oil free fatty acid by fourier transform infrared spectroscopy 总被引:2,自引:0,他引:2
Enriqueta Bertran Marcelo Blanco Jordi Coello Hortensia Iturriaga Santiago Maspoch Ivan Montoliu 《Journal of the American Oil Chemists' Society》1999,76(5):611-616
A new procedure for determining free fatty acids (FFA) in olive oil based on spectroscopic Fourier transform infrared-attenuated
total reflectance spectroscopy measurements is proposed. The range of FFA contents of samples was extended by adding oleic
acid to several virgin and pure olive oils, from 0.1 to 2.1%. Calibration models were constructed using partial least-squares
regression (PLSR). Two wavenumber ranges (1775–1689 cm−1 and 1480–1050 cm−1) and several pretreatments [first and second derivative; standard normal variate (SNV)] were tested. To obtain good results,
splitting of the calibration range into two concentration intervals (0.1 to 0.5% and 0.5 to 2.1%) was needed. The use of SNV
as a pretreatment allows one to analyze samples of different origins. The best results were those obtained in the 1775–1689
cm−1 range, using 3 PLSR components. In both concentration ranges, at a confidence interval of α = 0.05, no significant differences
between the reference values and the calculated values were observed. Reliability of the calibration vs. stressed oil samples
was tested, obtaining satisfactory results. The developed method was rapid, with a total analysis time of 5 min; it is environment-friendly,
and it is applicable to samples of different categories (extra virgin, virgin, pure, and pomace oil). 相似文献
6.
Fourier transform infrared (FTIR) spectroscopy with transmission cell is described to predict anisidine value of palm olein.
The calibration set was prepared by mixing the thermally oxidized palm olein and the unoxidized palm olein with certain ratios
(w/w) covering a wide range of anisidine values. A partial least square (PLS) regression technique was employed to construct
a calibration model. This model was further accomplished by a validation step. The standard error of prediction found was
0.51. The precision of this method was shown to be comparable to the accuracy of the American Oil Chemists’ Society method
used for measurement of anisidine value, with coefficient of determination (R
2) of 0.99. The study showed that mid-band FTIR spectroscopy combined with a PLS calibration technique is a versatile, efficient,
and accurate technique for the estimation of anisidine value of palm olein within about 2 min with less than 2 mL of sample. 相似文献
7.
The Fourier transform infrared (FTIR) technique in combination with multivariate data evaluation was used to analyze a wide variety of cocoa butters (CB), cocoa butter equivalents (CBE), and mixtures thereof. The sample set consisted of 14 CB (10 pure from various geographical origins and 4 commercial mixtures), 18 CBE (12 mixtures and 6 pure CBE from kokum, illipé, and palm midfraction), and 154 mixtures of CB with CBE at various concentrations (ranging from 5 to 20%). A total of 192 samples were analyzed in triplicate. All CB and CBE were shown to have very characteristic FTIR spectra that gave highly reproducible fingerprints. The main vibrational modes were also elucidated. FTIR can easily be employed to distinguish between pure CB and pure CBE. With prior knowledge of which cocoa butter is present in mixtures, FTIR can be applied to distinguish between CB mixed with CBE at the 10 and 20% levels (corresponding to about 2 and 5% of CBE in chocolate). However, the study revealed that a single “global” statistical model (multilayer perceptron, radial basis functions, or partial least square regression) was not able to predict the precise level of addition. The FTIR approach detailed here shows great potential as a rapid screening method for distinguishing between pure vegetable fats and, we believe, could be extended to investigate mixtures of CB and CBE by the establishment of a database. 相似文献
8.
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
9.
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
10.
T. Verleyen R. Verhe A. Cano A. Huyghebaert W. De Greyt 《Journal of the American Oil Chemists' Society》2001,78(10):981-984
A rapid and direct Fourier transform infrared (FTIR) spectroscopic method using a 25-μm NaCl transmission cell was developed
for the determination of free fatty acids (FFA) in six important vegetable oils (corn, soybean, sunflower, palm, palm kernel,
and coconut oils) that differ in fatty acid profile. The calibrations were established by adding either standard FFA (oleic,
lauric acids) or a representative mixture of FFA obtained after saponification of the refined oils. For all oils, up to a
FFA level of 6.5% for coconut oil, the best correlation coefficient was obtained by linear regression of the free carboxyl
absorption at 1711 cm−1. All correlation coefficients were greater than 0.993, and no significant difference between the calibration methods could
be detected. Upon validation of the calibration, no significant difference (α=0.05) between the “actual” and the “FTIR predicted”
FFA values could be observed. The calibration models developed for the six oils differed significantly and indicate the need
to develop a calibration that is specific for each oil. In terms of repeatability and accuracy, the FTIR method developed
was excellent. Because of its simplicity, quick analysis time of less than 2 min, and minimal use of solvents and labor, the
introduction of FTIR spectroscopy into laboratory routine for FFA determination should be considered. 相似文献
11.
12.
J. Sedman F. R. van de Voort A. A. Ismail 《Journal of the American Oil Chemists' Society》1997,74(8):907-913
An automated protocol for the direct, rapid determination of isolated trans content of neat fats and oils by Fourier transform infrared (FTIR) spectroscopy was devised, based on a simple modification
of the standard AOCS trans method, eliminating the use of CS2 and methylation of low trans samples. Through the use of a commercially available, heated transmission flow cell, designed specifically for the analysis
of neat fats and oils, a calibration (0–50%) was devised with trielaidin spiked into a certified, trans-free soybean oil. The single-beam spectra of the calibration standards were ratioed against the single-beam spectrum of the
base oil, eliminating the spectral interference caused by underlying triglyceride absorptions, facilitating direct peak height
measurements as per the AOCS IR trans method. The spectrometer was preprogrammed in Visual Basic to carry out all spectral manipulations, measurements, and calculations
to produce trans results directly as well as to provide the operator with a simple interface to work from. The derived calibration was incorporated
into the software package, obviating the need for further calibration because the program includes an automatic recalibration/standardization
routine that automatically compensates for differences in optical characteristics between instruments, instrument drift over
time, and cell wear. The modified AOCS FTIR analytical package was evaluated with Smalley check samples for repeatability,
reproducibility, and accuracy, producing SD of ± 0.07, 0.13, and 0.70 trans, respectively, the FTIR predictions being linearly related to the Smalley means (r=0.999; SD=± 0.46), and well within one SD of the Smalley sample means. Calibration transfer was assessed by implementing
the calibration on a second instrument and reanalyzing the Smalley check samples in cells of two different pathlengths (25-
and 50-μm). There were no statistically significant differences between the FTIR trans predictions obtained for the Smalley samples from the two instruments and two cells, indicating that the software was able
to adjust the calibrations to compensate for differences in instrument response and cell pathlength. The FTIR isolated trans analysis protocol developed by the McGill IR Group has the benefit of being based on the principles of an AOCS-approved method,
matches its accuracy, and allows the analysis to be performed on both neat fats and oils, producing trans predictions in less than 2 min per sample. It is suggested that this integrated approach to trans analysis, which requires a minimum level of sample manipulation and operator skill, be considered as a modification of the
proposed Recommended Practice CD14b-95. 相似文献
13.
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
14.
K. Ma F. R. van de Voort A. A. Ismail J. Sedman 《Journal of the American Oil Chemists' Society》1998,75(12):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
15.
A simple, rapid, and direct Fourier transform infrared (FTIR) spectroscopic method was developed for the determination of
moisture content of crude palm oil (CPO). The calibration set was prepared by adding double-distilled water to dried CPO in
ratios (w/w) between 0 and 13% moisture. A partial least squares (PLS) regression technique was employed to construct a calibration
model followed by cross-validation step. The accuracy of this method was comparable to the accuracy of the American Oil Chemists'
Society's vacuum oven method, which is used for determination of moisture and volatile matter, with mean difference (MDa) of 0.0105, a coefficient of determination (R
2) and a standard error of calibration (SEC) of 0.9781 and 0.91, respectively. It is also comparable to the accuracy of the
International Union of Pure and Applied Chemistry's distillation method with MDa, R
2, and SEC of 0.0695, 0.9701, and 0.65, respectively. The study showed that midband FTIR spectroscopy combined with the PLS
regression calibration technique is rapid and accurate for determination of moisture content of CPO samples with a total analysis
time of less than 2 min and less than 2 mL of sample. 相似文献
16.
W. De Greyt A. Kint M. Kellens A. Huyghebaert 《Journal of the American Oil Chemists' Society》1998,75(2):115-118
A Nicolet 410 Fourier (FTIR) spectrophotometer, equipped with a DGTS detector and a sample cell with NaCl windows (nominal pathlength=50 μm), was used for the development of an FTIR method for routine analysis of low trans levels in physically refined oils. The approach of the study differed from those previously described in that a separate calibration curve was established for each type of oil. Quantitation was established by use of Basic Quant Software® and by measuring the peak height at 967 cm?1 relative to a baseline drawn between 1002 and 932 cm?1. The slope of the different calibration curves established in six vegetable oils (soybean, corn, sunflower, high-oleic sunflower, low-erucic rapeseed, and high-erucic rapeseed) was close to 1 (0.9942–1.0041), and correlation coefficients (r 2) were rather good (0.9990–0.9999). FTIR spectra of 20 soybean oil samples were collected and quantitated with the different calibrations. Compared to previous reported literature data, increased accuracy (mean difference=0.05%; standard deviation of difference=0.11%) and reproducibility (r 2=0.09–0.12%) were obtained when the FTIR spectra were quantitated with a calibration curve based on 10 physically refined soybean oil samples. 相似文献
17.
A. A. Ismail F. R. van de Voort G. Emo J. Sedman 《Journal of the American Oil Chemists' Society》1993,70(4):335-341
Rapid direct and indirect Fourier transform infrared (FTIR) spectroscopic methods were developed for the determination of
free fatty acids (FFA) in fats and oils based on both transmission and attenuated total reflectance approaches, covering an
analytical range of 0.2–8% FFA. Calibration curves were prepared by adding oleic acid to the oil chosen for analysis and measuring
the C=O band @ 1711 cm–1 after ratioing the sample spectrum against that of the same oil free of fatty acids. For fats and oils that may have undergone
significant thermal stress or extensive oxidation, an indirect method was developed in which 1% KOH/methanol is used to extract
the FFAs and convert them to their potassium salts. The carboxylate anion absorbs @ 1570 cm–1, well away from interfering absorptions of carbonyl-containing oxidation end products that are commonly present in oxidized
oils. Both approaches gave results comparable in precision and accuracy to that of the American Oil Chemists’ Society reference
titration method. Through macroprogramming, the FFA analysis procedure was completely automated, making it suitable for routine
quality control applications. As such, the method requires no knowledge of FTIR spectroscopy on the part of the operator,
and an analysis takes less than 2 min. 相似文献
18.
Damage to soybeans due to pre-harvest stress, storage, and export shipment has been related to an increase in the nonhydratable
phospholipid content of crude oil. Phospholipids in crude soybean oil extracted from such distressed soybeans have been analyzed
by gradient high-performance liquid chromatography. Crude oil was fractionated by solid phase extraction using sequential
elution for recovery of phosphatides. High-performance liquid chromatography of the concentrated phospholipids was accomplished
on a Lichrosorb Si-60 10 μ column, 250×4.6 mm with ultraviolet detection at 206 nm. A 20-min solvent gradient of 2-propanol/hexane/water
(42∶56∶2, 51∶38∶11) gave retention profiles of phospholipid distribution (major subclasses) that changed with impact of stress
applied to plant or seed. Soybeans stored at high moisture levels (16% and 20% moisture) for up to 28 days yielded oils having
phosphorus contents which decreased in direct relationship to days of storage. Retention profiles were unusable for fractions
isolated from oils with phosphorus content below 100 ppm. Data show that during progressive damage, the content of phosphatidylcholine
and phosphatidylinositol decreased while the phosphatidic acid content increased.
Presented at the Annual American Oil Chemists' Society meeting, May 8–12, 1988, Phoenix, AZ. 相似文献
19.
J. M. Whittinghill J. Norton A. Proctor 《Journal of the American Oil Chemists' Society》1999,76(12):1393-1398
The effect of temperature on soy lecithin-stabilized emulsions was studied using Fourier transform infrared spectroscopy (FTIR).
Oil-in-water (o/w) 4% (wt/vol) soy lecithin emulsions were prepared in 6% (vol/vol) medium-chain triglycerides and 94% (vol/vol)
water using a two-stage homogenizer set at a pressure of 3000 psig. Three types of emulsions were used in this study: emulsions
containing Lecigran and Lecimulthin as emulsifiers and a control emulsion, with no emulsifier added. After preparation, the
emulsions were cooled to 4°C, held at this temperature, and spectra were collected after 1 h. The emulsions and reference
water were raised to room temperature (22°C) and held at that temperature for 1 h and the spectra collected. The temperature
was raised 15°C over the temperature range of 22 to 82°C, and spectral data were collected similarly. The four regions used
for this determination in the subtracted spectra of the emulsion were those contributing to -OH vibration, -CH2 stretching, H-O-H bending vibrations, and P=O, C-O-C, and P-O-C vibrations. The control emulsion was greatly affected at
temperatures other than room temperature. This was due to the lack of lecithin as an emulsifier, resulting in a destabilization
of the emulsion with temperature increases. The vibrational peaks for the emulsion containing Lecimulthin were found to be
lower than those for the emulsion made with Lecigran due to greater water bonding. The control had the highest peaks at the
-OH regions because of reduced interaction at the oil-water interface. Both of the emulsions with phospholipids remained stable
throughout the temperature range. FTIR is a potentially powerful tool that could be used in the rapid determination of emulsion
stability in food systems by measuring emulsifier-water interactions. 相似文献
20.
Characterization of semisolid fats and edible oils by Fourier transform infrared photoacoustic spectroscopy 总被引:2,自引:0,他引:2
The potential of Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) for the analysis of semisolid fat and edible oil was demonstrated with butter, soybean oil, and lard as representative materials. Results of Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy analysis was compared with FTIR-PAS results. The PAS technique is simple and requires no sample preparation unlike ATR. Optimal PAS instrumental parameters for obtaining quality spectra are a scanning speed of 5 kHz, number of scans of 256 scans/sample, and a resolution of 4 cm−1. The PAS spectra of soybean oil and lard are similar because they have similar functional groups. Results for soybean oil compare well with those available in the literature. The ATR spectra of butter were better than those from its PAS counterpart. Functional groups corresponding to vibration mode and intensity are provided for soybean oil and lard. 相似文献