共查询到20条相似文献,搜索用时 62 毫秒
1.
M. M. Mossoba A. Seiler H. Steinhart J. K. G. Kramer L. Rodrigues-Saona A. P. Griffith R. Pierceall F. R. van de Voort J. Sedman A. A. Ismail D. Barr P. A. Da Costa Filho H. Li Y. Zhang X. Liu M. Bradley 《Journal of the American Oil Chemists' Society》2011,88(1):39-46
Using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, collaborating scientists in ten different laboratories measured (in duplicate) the total trans fat content of ten fat or oil test samples, two of which were blind duplicates. The procedure used entailed measuring the height of the negative second derivative of the IR absorption band at 966 cm?1. This absorption is attributed to the C?CH deformation vibration that is characteristic of isolated (non-conjugated) double bonds with the trans configuration. The precision of ATR-FTIR results in this international collaborative study was satisfactory and led to the approval of this validated procedure as official method AOCS Cd 14e-09 in late 2009. This official method is also suitable for analysis of total isolated trans fat and oil products containing, or supplemented with, trans conjugated linoleic acid (CLA) isomers. Although this method does not require derivatization of the oil or fat test materials, as required for GC, fats and oils in foods must be extracted with organic solvents before analysis. This method is also rapid (5 min) and does not require any weighing or quantitative dilution of unknown neat fat or oil test samples in any solvent. The AOCS Cd 14e-09 method is suitable for determination of test samples with zero trans fat, which is defined according to the US labeling regulations as 0.5 g trans fat per serving or 1.8% trans fat, as a percentage of total fat. 相似文献
2.
M. M. Mossoba J. K. G. Kramer J. Fritsche M. P. Yurawecz K. D. Eulitz Y. Ku J. I. Rader 《Journal of the American Oil Chemists' Society》2001,78(6):631-634
A novel and rapid (5 min) attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic method AOCS Cd 14d-99
for the determination of total isolated trans fatty afids, which absorb at 966 cm‐, was recently developed, collaboratively studied, and applied to food products containing 1–50% rans fat (as percentage of total fat). Attempts to apply the ATR-FTIR method to biological matrices of low trans fat and/or low total fat content, and to dairy and other products were not satisfactory due to interfering IR absorptions
in the trans region. One group of interfering compounds with absorption bands near 985 and 948 cm−1 was the cis/trans positional isomes of conjugated linoleic acid (CLA) found in dairy and meat products from ruminants at levels of <1% (as
percentage of total fat). In the present study, we modified the ATR-FTIR method to overcome matrix interferences. This modification,
which consisted of applying the standard addition technique to the ATR-FTIR determination, was also applied to several food
products, namely, dairy products, infant formula and salad oil dressing, which successfully eliminated interfering absorbances
that impacted on accuracy. The presence of <1% CLA in two butter and two cheese products containing 6.8, 7.5, 8.5, and 10.4%
trans fatty acids (as a percentage of total fat) would have led to errors of −11.6, 10.4, 17.6 and 34.6%, respectively, in trans fat measurements had the standard addition technique not been used. The applicability of ATR-FTIR to the quantitation of
food products is discussed. 相似文献
3.
M. Adam M. M. Mossoba T. Dawson M. Chew S. Wasserman 《Journal of the American Oil Chemists' Society》1999,76(3):375-378
Gas chromatography (GC) has been a standard analytical tool in lipid chemistry. The rapid attenuated total reflection (ATR)
infrared (IR) American Oil Chemists’ Society (AOCS) Recommended Practice (Cd 14d-97) was compared to the capillary GC AOCS Recommended Practice (Ce 1f-97) that was optimized to accurately determine total trans fatty acids on highly polar stationary phases. This comparative evaluation was validated in an independent laboratory. These
procedures were used to quantitate the total trans fatty acid levels in partially hydrogenated vegetable oils, measured as neat (without solvent) triacylglycerols (TAG) by
ATR and as fatty acid methyl ester (FAME) derivatives by capillary GC. Unlike FAME, TAG determination by ATR required no derivatization,
but samples had to be melted prior to measurement. Five blind replicates for each of three accuracy standards and three test
samples were analyzed by each technique. The GC and ATR determinations were in good agreement. Accuracy was generally high.
The ratios of ATR mean trans values (reported as percentage of total TAG) to the true values (based on the amount of trielaidin added gravimetrically)
were 0.89, 0.98, and 1.02 for accuracy standards having about 1, 10, and 40% trans levels. The corresponding GC values, determined as percentage of total FAME, were 0.98, 0.99 and 1.04. The ratios of mean
trans values determined by these techniques were ATR/GC 0.85, 1.04, and 1.01 for test samples having trans levels of about 0.7, 8, and 38%, respectively. The optimized GC procedure also minimzed the expected low bias in trans values due to GC peak overlap found with the GC Official Method Ce 1c-89. Satisfactory repeatability and reproducibility were obtained by both ATR and GC. 相似文献
4.
Magdi M. Mossoba Cynthia Tyburczy Srigley Samantha Farris John K G Kramer Stuart Chirtel Jeanne Rader 《Journal of the American Oil Chemists' Society》2014,91(10):1651-1663
The performance of a novel, transmission‐mode, portable, Fourier transform infrared (FTIR) analyzer was evaluated and compared to that of a benchtop attenuated total reflection (ATR)‐FTIR spectrometer. The total concentration of trans fatty acids in the fat extracted from 19 representative fast foods was rapidly (<5 min) quantified in a single measurement after conversion to fatty acid methyl esters (FAME). While the FTIR determination is rapid, the time required for extraction and derivatization is not. For all extracts, the total trans FAME concentration varied from approximately 0.5 to 11 % (of total FAME) as determined using the portable FTIR analyzer. The trans fat contents (mean ± SD), expressed in grams per serving and calculated on the basis of total fat content and FTIR determination of trans fat content, were found to be 1.00 ± 0.42 for hamburgers, 0.67 ± 0.78 for chicken tenders, 1.00 ± 1.24 for French fries, and 0.27 ± 0.23 for apple pies. Determinations of total trans‐unsaturated FAME were consistent with those obtained by use of ATR‐FTIR and GC official methods (AOCS Cd 14e‐09 and AOCS Ce 1j‐07, respectively). These results indicate that the portable FTIR analyzer is suitable for the rapid and routine quantification of total trans fat measured as FAME prepared from fats extracted from fast foods. 相似文献
5.
W. M. Nimal Ratnayake Steven L. Hansen Michael P. Kennedy 《Journal of the American Oil Chemists' Society》2006,83(6):475-488
The AOCS Official Method Ce 1h-05 was recently approved at the 96th AOCS Annual Meeting (2005) by the Uniform Methods Committee
as the official method for determining cis and trans FA in vegetable or non-ruminant fats and oils. A series of experiments was undertaken using a margarine (hydrogenated soybean
oil) sample containing approximately 34% total trans FA (28% 18∶1 trans, 6% 18∶2 trans, and 0.2% 18∶3 trans), a low-trans oil (ca. 7% total trans FA), and a proposed system suitability mixture (12∶0, 9c−18∶1, 11c−18;1, 9c,12c,15c−18∶3, 11c−20∶1, and 21∶0) in an effort to evaluate and optimize the separation on the 100-m SP-2560 and CP-Sil 88 flexible fused-silica
capillary GC columns recommended for the analysis. Different carrier gases and flow rates were used during the evaluation,
which eventually lead to the final conditions to be used for AOCS Official Method Ce 1h-05. 相似文献
6.
Rapid determination of total Trans fat content by attenuated total reflection infrared spectroscopy: An international collaborative study 总被引:2,自引:2,他引:0
Michael Adam Magdi M. Mossoba Theresa Lee 《Journal of the American Oil Chemists' Society》2000,77(5):457-462
Interest in trans fat labeling has prompted efforts to develop new, more efficient methods for rapidly and accurately determining trans fat content in foods. The lower limit of quantitation, 5% trans fat (as percent of total fat), of transmission infrared official methods, such as AOAC 994.14 and 965.34, for total isolated
trans fatty acids is too high to be generally useful for the determination of low levels of trans fats in foods. A novel and rapid (5 min) attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic
procedure was recently developed and applied to food products. This procedure was voted official method AOCS Cd 14d-99 by
the American Oil Chemists' Society in 1999 after testing in a 12-laboratory international collaborative study. The results
of this study are described in this paper. Analytical ATR-FTIR results exhibited high accuracy in the range investigated,
1–40% trans; results tended to have <2% high bias relative to the gravimetrically determined values. The precision of this internal reflection
method was found to be superior to those of transmission infrared official methods. It is recommended that the applicability
of the ATR-FTIR method be limited to trans levels of >1% (as percent of total fat). 相似文献
7.
M. Adam M. Chew S. Wasserman A. McCollum R. E. McDonald M. M. Mossoba 《Journal of the American Oil Chemists' Society》1998,75(3):353-358
An attenuated total reflection infrared spectroscopy procedure was collaboratively studied among two sets of five laboratories
for quantitating the total trans fatty acid levels in neat (without solvent) hydrogenated vegetable oils, measured as triacylglycerols in one study, and as
fatty acid methyl ester derivatives in the other. Unlike the fatty acid methyl esters, the triacylglycerols required no derivatization
but had to be melted prior to measurement. To obtain a symmetric absorption band at 966 cm−1 on a horizontal background, the single-beam spectrum of the trans-containing fat was "ratioed" against that of a refined oil or a reference material that contained only cis double bonds. A single-bounce horizontal attenuated total reflection cell that requires 50 μL of undiluted test samples was
used for oils, melted fats, or their methyl esters. For fatty acid methyl esters, the reproducibility relative standard deviations
were in the range of 0.9 to 18.46% for 39.08 to 3.41% trans, determined as methyl elaidate per total fatty acid methyl esters. For five pairs of triacylglycerol blind duplicates, the
reproducibility and repeatability relative standard deviations were in the ranges of 1.62 to 18.97%, and 1.52 to 13.26%, respectively,
for 39.12 to 1.95% trans, determined as trielaidin per total triacylglycerols. Six pairs of spiked triacylglycerol blind duplicates (quality assurance
standards) exhibited high accuracy in the range of 0.53 to 40.69% trans and averaged a low bias of 1.3%. These statistical analysis results were compared to those collaboratively obtained by the
recently adopted AOCS Cd14-95 and AOAC 994.34 Infrared Official Methods. 相似文献
8.
M. M. Mossoba J. K. G. Kramer V. Milosevic M. Milosevic H. Azizian 《Journal of the American Oil Chemists' Society》2007,84(4):339-342
The mandate to label food products with the content of total trans fatty acids has led to an increase in demand for sensitive and accurate methodologies for the rapid quantitation of trans fats. Unfortunately, the latest official infrared (IR) spectroscopic method lacks the required sensitivity. A more sensitive
IR procedure that requires the measurement of the height of the second derivative (2D) of the trans absorption band at 966 cm−1 was recently proposed; however, a reported inconsistency at low trans levels between GC (0% of total fat) and IR (1.2% of total fat) results for a fully hydrogenated vegetable oil could not be
reconciled, and triggered further investigations. For the first time, we recognize and report the presence of weak interference
bands (962–956 cm−1) attributed to saturated fats in the IR spectra of trans fats; these interference bands have an adverse impact on the sensitivity and accuracy of the IR determination at low trans levels (≤0.5% of total fat). Therefore, weak spectral features observed at energies below the one expected for trans bands (966 cm−1) in test samples high in saturated fat (coconut oil and cocoa butter) must not be mistaken for trans bands. 相似文献
9.
Meghan Allendorf Anand Subramanian Luis Rodriguez-Saona 《Journal of the American Oil Chemists' Society》2012,89(1):79-88
This study evaluated the capabilities of a handheld mid-infrared (MIR) spectrometer combined with multivariate analysis to
characterize oils, monitor chemical processes occurring during oxidation, and to determine fatty acid composition. Vegetable
oils (corn, peanut, sunflower, safflower, cottonseed, and canola) were stored at 65 °C for 30 days to accelerate oxidation
reactions. Aliquots were drawn at 5 day intervals and analyzed by benchtop and portable handheld mid-infrared devices (4,000–700 cm−1) and reference methods (IUPAC 2301 [1], 2302 [1]; AOCS Cd 8-58 [2]; and Shipe 1979 [3]). PLSR and soft independent modeling of class analogy (SIMCA) models were developed for oil classification and estimation
of oil stability parameters. Models developed from MIR spectra obtained with a benchtop spectrometer equipped with a 3-bounce
ATR device resulted in superior discriminative performances for classifying oils as compared to those obtained from handheld
spectra (single-bounce ATR). Models developed from reference tests and handheld spectra showed prediction errors (SECV) of
1 meq/kg for peroxide value, 0.09% for acid value and 2% for determination of unsaturated fatty acids in different oils. Spectral
regions ~3,012–2,850 cm−1 (C–H stretching bands/shoulders of fatty acids), ~1,740 cm−1 (C=O stretching of esters), and ~1,114 cm−1 (–C–O stretching) were found to be important for prediction. Handheld-FTIR instruments combined with multivariate-analysis
showed promise for determination of oil quality parameters. Portability and ease-of-use makes the handheld device a great
alternative to traditional methods. 相似文献
10.
Industrial validation of fourier transform infrared trans and lodine value analyses of fats and oils
J. Sedman F. R. van de Voort A. A. Ismail P. Maes 《Journal of the American Oil Chemists' Society》1998,75(1):33-39
A Fourier transform infrared (FTIR) edible oil analysis package designed to simultaneously analyze for trans content, cis content, iodine value (IV), and saponification number (SN) of neat fats and oils by using calibrations based on pure triglycerides
and derived by application of partial-least-squares (PLS) regression was assessed and validated. More than 100 hydrogenated
rapeseed and soybean samples were analyzed by using the edible oil analysis package as well as the newly proposed modification
of the AOCS IR trans method with trielaidin in a trans-free oil as a basis for calibration. In addition, ∼1/3 of the samples were subsequently reanalyzed by gas chromatography
(GC) for IV and trans content. The PLS approach predicted somewhat higher trans values than the modified AOCS IR method, which was traced to a combination of the inclusion of trilinolelaidin in the calibration
set and the effects of baseline fluctuations. Eliminating trilinolelaidin from the triglyceride standards and the use of second-derivative
spectra to remove baseline fluctuations produced excellent concurrence between the PLS and modified AOCS IR methods (mean
difference of 0.61% trans). Excellent internal consistency was obtained between the IV and cis and trans data provided by the edible oil analysis package, and the relationship was close to that theoretically expected [IV=0.86
(cis + trans)]. The IV data calculated for the GC-analyzed samples matched the PLS IV predictions within 1 IV unit. The trans results obtained by both IR methods were linearly related to the GC data; however, as is commonly observed, the GC values
were significantly lower than the IR values, the GC and IR data being related by a slope factor of ∼0.88, with an SD of ∼0.80.
The concurrence between the trans data obtained by the two FTIR methods, and between the FTIR and GC-IV data, as well as the internal consistency of the IV,
cis and trans FTIR predictions, provides strong experimental evidence that the edible oil analytical package measures all three variables
accurately.
Co-Director, McGill IR Group. 相似文献
11.
Current studies on relation of fat to health 总被引:2,自引:0,他引:2
F. A. Kummerow 《Journal of the American Oil Chemists' Society》1974,51(6):255-259
An increase in the linoleic to oleic acid ratio by an increase in the percentage of the polyunsaturated ω6 family of fatty
acids in culinary fats and a decrease in the consumption of cholesterol-rich food were believed necessary as a prerequisite
to early intervention in coronary heart disease. A decrease in total fat consumption also has been recommended. However, a
decrease in the percentage of fat in the diet may not be nutritionally sound, as it may only increase the percentage of carbohydrates
consumed and, thus, the synthesis of the ω9 family of fatty acids from the surfeit calories. It may be more judicious to decrease
the total number of calories through less consumption of a well balanced diet. Furthermore, as thetrans-fatty acids, which are formed during hydrogenation, are not discriminated against completely by acyl-glycerol-3-phosphoryl-choline
transferase or acyl coenzyme A cholesteryl transferase, it would be, from a biological viewpoint, advantageous to eliminatetrans-fatty acids from both stick and tub type margarines.
One of five papers presented at the symposium, “Status of Fat in Food and Nutrition,” AOCS Fall Meeting, Chicago, September
1973. 相似文献
12.
Magdi M. Mossoba A. Seiler J. K. G. Kramer V. Milosevic M. Milosevic H. Azizian H. Steinhart 《Journal of the American Oil Chemists' Society》2009,86(11):1037-1045
In 2006, the US FDA mandated the declaration of the total trans fat content on the Nutrition Fact label of foods including dietary supplements when a product contained 0.5 or more grams
of trans fatty acid per serving; the minimum corresponding trans fat content is estimated to be approximately 2% of total fat. The FDA definition is based on chemical structure and includes
only fatty acids with one or more isolated double bonds in the trans configuration. Several issues negatively impacted the sensitivity of the current official infrared (IR) methods, thus limited
the quantitation of trans fat to 5% of total fat. To improve sensitivity and accuracy and to meet the labeling requirement, a new internal reflection
IR procedure called negative second derivative is described and evaluated for the quantitation of total trans fat in the present study. The enhanced spectral features of a second derivative resolved issues that traditionally limited
the sensitivity of the IR methodology. Calibration standard mixtures starting at approximately 0.5% trielaidin in the total
fat (tripalmitin or triarachidin) were successfully generated and used to determine the trans fat levels for unknown test samples with trans content as low as approximately 1% of total fat. Quantitative IR data were compared to those obtained by gas chromatography
and were found to be in good agreement. 相似文献
13.
Jacqueline Sedman F. R. van de Voort Ashraf A. Ismail 《Journal of the American Oil Chemists' Society》2000,77(4):399-403
A method for the simultaneous determination of iodine value (IV) and trans content from the Fourier transform infrared (FTIR) spectra of neat fats and oils recorded with the use of a heated single-bounce
horizontal attenuated total reflectance (SB-HATR) sampling accessory was developed. Partial least squares (PLS) regression
was employed for the development of the calibration models, and a set of nine pure triacylglycerols served as the calibration
standards. Regression of the FTIR/PLS-predicted IV and trans contents for ten partially hydrogenated oil samples against reference values obtained by gas chromatography yielded slopes
close to unity and SD of <1. Good agreement (SD<0.35) also was obtained between the trans predictions from the PLS calibration model and trans determinations performed by the recently adopted AOCS FTIR/SBHART method for the determination of isolated trans isomers in fats and oils. 相似文献
14.
Laila H. Ali Gerald Angyal Carol M. Weaver Jeanne I. Rader Magdi M. Mossoba 《Journal of the American Oil Chemists' Society》1996,73(12):1699-1705
The totaltrans fatty acid content of 18 food products was determined, after acid hydrolysis, extraction and methylation of fatty acids,
by gas chromatography with a polar 100% cyanopropylsiloxane capillary column and by single-bounce horizontal attenuated total
reflection spectroscopy (SB-HATR). Thetrans fatty acid methyl esters (FAME) of 9-hexadecenoate (9t-16:1), 9-octadecenoate (9t-18:1), and 9,12-octadecadienoate (9t,12t-18:2) were identified by comparison of their retention times with those of known standards and quantitated. The isomersc,t- andt,c-18:2 were identified from their published retention times and included in the quantitation oftrans FAME. Neat 50-μL portions of the FAME that were used for gas-chromatographic analysis also were analyzed by SB-HATR. This
technique requires neither weighing nor quantitative dilution of test portions prior to spectroscopic quantitation of isolated
double bonds oftrans configuration. A symmetric 966-cm−1 absorption band on a horizontal background was obtained from unhydrogenated soybean oil FAME as the reference material. For
9 of 11 products withtrans fat content>5% of total fat, results obtained by SB-HATR were higher than those obtained by gas chromatography. Results obtained
by the gaschromatographic procedure were slightly to significantly higher than those obtained by SB-HATR for the six foods
in whichtrans fat content was <5% of total fat. 相似文献
15.
Assessment of Trans Fatty Acid Level in French Fries from Various Fast Food Outlets in Karachi,Pakistan 总被引:1,自引:0,他引:1
Zahida Karim Khalid Mohammed Khan Shakeel Ahmed Aneela Karim 《Journal of the American Oil Chemists' Society》2014,91(11):1831-1836
The purpose of this study is to determine the trans fat level in French fries sold in different fast food outlets in Karachi. In the present study, attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy was used for the quantification of trans fatty acid (TFA). A number of studies have been reported on trans fat in different regions of the world, but no categorical study has yet discussed the trans fat in fast food products in Karachi. Amongst the samples examined, the total trans fatty acid content was in the range of 0.11 ± 0.01–24.00 ± 0.25 %. Most of the samples contain a high percentage of TFA. There is an urgent need to monitor and regulate the level of trans fat in order to reduce the health risk to the consumers of fast food items in Karachi, Pakistan. 相似文献
16.
A computer-assisted method has been developed for estimation of isolatedtrans unsaturation using the peak area of thetrans absorbance band at 966 cm-1from FTIR spectra of fatty acid methyl esters. Peak areas were used to determine thetrans content of weighed standards containing from 0 to 100% methyl elaidate and of hydrogenated soybean oil samples containing
up to 36%trans unsaturation. These data for percenttrans by FTIR were compared to corresponding data obtained by capillary gas chromatography and the AOCS Official Method 14-61.
Determination of isolatedtrans composition in oils using peak areas gave values with the smallest standard deviation for weighed standards and values within
4% of those obtained by capillary gas chromatography and the AOCS Official Method for hydrogenated samples.
Presented at the AOCS meeting in Phoenix, AZ in May 1988.
To whom correspondence should be addressed. 相似文献
17.
A rapid method for analysis of trans and cis FA in hydrogenated fats has been developed. The method is based on a single anlaysis by CG with IR detection. Multivariate
partial least squares regression is applied on the IR spectra to predict the number of cis and trans double bonds. For each chain length the method provides information about the amount of the saturated FA, the amount of trans monoenes, the amount of cis monoenes, the amount of PUFA, and the average number of cis and trans double bonds in PUFA. The method has been validated by summing the values to a total trans value and total unsaturation. These sum values were compared with total trans unsaturation, as determined by AOCS method Cd 14-95, and iodine value, as determined by AOCS Cd 1d-92. 相似文献
18.
H. J. Dutton 《Journal of the American Oil Chemists' Society》1974,51(9):407-409
Attenuated total reflectance for IR determination oftrans-isomers in fats appears to have distinct advantages over procedures currently used. The AOCS standard method CD 14-61 requires
weighing and quantitative dilution of a sample with carbon disulfide before spectrophotometric analysis at 10.3 μm. In contrast,
according to the attenuated total reflectance analytical procedure, one neither weighs nor dilutes but merely fills the cell
with oil and reads at 10.3 μm. In addition to analyses fortrans-isomers in liquid oils, margarines and shortenings, attenuated total reflectance enables one to monitortrans-development continuously during hydrogenation. The presence of catalyst in unfiltered hydrogenated oils does not interfere
with attenuated total reflectance measurements in contrast to classical transmission measurements. Unfiltered oil from the
hydrogenator can be circulated through the attenuated total reflectance cell to recordtrans-isomerization during the reaction.
ARS, USDA. 相似文献
19.
Variations of <Emphasis Type="Italic">trans</Emphasis> octadecenoic acid in milk fat induced by feeding different starch-based diets to cows 总被引:1,自引:1,他引:1
The impact of starch sources differing in their velocities of ruminal degradation on the milk fat of dairy cows was studied.
The animals received diets containing a slowly degradable (potatoes) or rapidly degradable (wheat) starch concentrate (40%
of the dry matter) in a total mixed diet. Milk fat was the only animal performance factor affected: Cows produced significantly
less milk fat when fed the wheat diet than the potato diet (−3.3 g/kg, −122 g/d; P<0.05). With the wheat diet, milk fat was poorer in short-chain FA and richer in unsaturated longchain FA, especially in trans octadecenoic acid (4.4 vs. 2.7% of the total FA, P<0.05). A very large increase in the isomer trans-10 18∶1 (+1.46% of the total FA) was observed. Because no difference in volatile FA concentrations in the rumen was revealed,
the increase in trans octadecenoic acids, and particularly the isomer trans-10 18∶1, was associated with the larger postprandial drop in ruminal pH with wheat. Similar concentrate levels and FA profiles
in both diets indicated that the decrease in milk fat was due to changes in the ruminal environment. Quicker degradation of
wheat starch, and hence a greater drop in pH with this diet associated with the absence of any effect on volatile FA, strengthen
the hypothesis developed in the literature of enzyme inhibition via increased levels of trans octadecenoic acids, especially the trans-10 isomer. Hence, milk fat can be decreased with rapidly degradable starch sources and not only with high levels of concentrates
in the diet or added fat. More detailed work is necessary to elucidate the microorganisms involved and to determine whether
metabolic pathways similar to those reported for high-concentrate diets are involved. 相似文献
20.
On July 11, 2003, the U.S. Food and Drug Administration published a final rule amending its food-labeling regulations to require
that trans FA be declared in the nutrition label of conventional foods and dietary supplements. The effective date of this final rule
is January 1, 2006. This places some urgency on increasing the number and types of currently available foods for which there
are trans-fat data. Compositional databases on trans fat content of food are currently limited. The purpose of this study was to determine the trans-fat content of a wide range of foods prior to the effective date of the new regulation. AOAC Official Method of Analysis
996.01 was modified for the analysis of trans fat in noncereal products. Food products for analysis were selected on the basis of market share and data from the USDA's
1994–1996 Continuing Survey of Food Intake by Individuals. Foods were purchased from local supermarkets, weighed, hydrolyzed,
converted to FAME, and analyzed by GC. The results showed that trans fat (g/100 g fat) ranged from 0.0 to 48.8 in bread, cake, and related products; from 14.9 to 27.7 in margarines; from 7.7
to 35.3 in cookies and crackers; from 24.7 to 38.2 in frozen potatoes; from 0.0 to 17.1 in salty snacks; from 0.0 to 13.2
in vegetable oils and shortenings; from 0.0 to 2.2 in salad dressings and mayonnaises; and from 0.0 to 2.0 in dry breakfast
cereals. Serving sizes for the foods included in this survey ranged from 12 to 161 g, and trans-fat levels ranged from 0.0 to 7.2 g/serving. The significant differences in trans-fat content in products within each food category are due to differences in the type of fats and oils used in the manufacturing
processes. 相似文献