Fatty Acids In Edible Oils Research Articles

Occurrence and formation of oxidized fatty acids in edible oils and their use as novel parameters to evaluate oil quality and authenticity

Occurrence and formation of oxidized fatty acids in edible oils and their use as novel parameters to evaluate oil quality and authenticity

1H Nuclear Magnetic Resonance, Infrared, and Chemometrics in Lipid Analysis of Brazilian Edible-Oil-Based Nutraceuticals

Edible oils have commercial and nutritional value due to the presence of essential fatty acids. They can be consumed fresh in the form of capsules known as nutraceuticals. The quality of such products is of interest to the consumer. In this context, this study describes a method based on high-resolution nuclear magnetic resonance (NMR) and Fourier-transform mid-infrared spectroscopic analysis (FTIR), combined with statistical analyses, to differentiate different edible oils used as nutraceuticals in Brazil by fatty acid content. Through the analysis of 1H NMR spectra, the levels of saturated and unsaturated fatty acids in edible oils were characterized and quantified. Statistical analysis of the data confirmed the real distinctions between nutraceutical raw materials, with emphasis on ω-9, ω-6, and ω-3 fatty acids. The analytical approach presented also demonstrates the potential to identify the origin (animal or vegetable) of edible oils used as nutraceuticals.

Targeted quantitation of furan fatty acids in edible oils by gas chromatography/triple quadrupole tandem mass spectrometry (GC-TQ/MS)

Furan fatty acids (FuFAs) have been recognized as beneficial food ingredients to human health. Herein, a targeted quantitation approach by gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-TQ/MS) was developed for the identification of FuFAs in common marine and other edible oils in multiple reaction monitoring (MRM) mode without any isolation and enrichment. The limit-of-quantitation (LOQ, 0.6 pg) was determined under the optimized parameters in MRM mode. Identification of FuFAs in common edible oils demonstrated that marine fish oils were concentrated sources of 9-(3-methyl-5-pentylfuran-2-yl)nonanoic acid (9M5), 11-(3,4-dimethyl-5-propylfuran-2-yl)undecanoic acid (11D3) and 11-(3,4-dimethyl-5-pentylfuran-2-yl)undecanoic acid (11D5). However, FuFAs were not identified in common plant oils. Additionally, 11D5 was identified in the lipids of Schizochytrium limacinum at a comparable level with that in marine fish oil. We believe that this protocol could facilitate the qualitative and quantitative analysis of FuFAs in food and biological samples.

Influence of fatty acids in edible oils on lutein micellization and permeation in a simulated digestion model

Lutein is a nutraceutical compound that promotes human eye health and prevents neurodegenerative diseases. The oral bioavailability of lutein is affected by both extrinsic and intrinsic factors in the host. Although hydrophobicity of the compound is further challenging, its lipophilicity can be utilized to micellize and thereby improve its oral bioavailability. Currently, available data on the effects of dietary fats on lutein micellization and permeation is limited and needs further exploration. In this study, the influence of 17 carrier type edible oils on lutein micellization and permeation, was investigated in a simulated digestion model. The overall effectiveness of these oils to permeate micellized lutein was attributed to its Fatty Acid (FA) profile. While 94% of the edible oils exhibited a positive influence on the permeation of micellized lutein, the micellization and permeation efficiency of these oils were significantly (p ≤ 0.05) modulated by the saturation of FA in the order Saturated (SFA) > Mono-Unsaturated (MUFA) > Poly-Unsaturated (PUFA). The highest apparent permeability coefficient was exhibited by lutein micellized in ghee (3.01 × 10−6 cm/s) and butter (2.93 × 10−6 cm/s), which was 1.28 and 1.24 folds higher than lutein alone (2.35 × 10−6 cm/s) respectively. Exceptionally MUFA rich olive oil and PUFA rich flaxseed oil improved lutein permeation by 1.19 (2.80 × 10−6 cm/s) and 1.14 folds (2.69 × 10−6 cm/s) respectively. This study is the first to report the influence of saturated fatty acids on micellization and permeation of lutein. Furthermore, the outcomes of this study offer the field of lutein delivery systems a fresh perspective.

Determination of cis/trans fatty acid contents in edible oils by 1H NMR spectroscopy in association with multivariate calibration

In this work, cis and trans fatty acid (FA) contents in edible oils was determined using 1H nuclear magnetic resonance (1H NMR) spectroscopy. The comparison of 1H NMR spectra of edible oil and cis-trans isomerized oil showed that they were different in three regions: (1) 2.880 - 2.650 ppm caused by bis-allylic protons; (2) 2.140 - 1.900 ppm due to allylic protons; and (3) 1.030 - 0.930 ppm due to methyl protons of linolenic acyl groups. The 1H NMR signals in these regions were combined with partial least squares method to predict contents of cis/trans fatty acids in edible oils. The results showed that the predicted values were consistent with the gas chromatography-measured values and had a good linear relationship with a correlation coefficient (R2) of above 0.98. This work demonstrates that 1H NMR spectroscopy was successfully used to determine the composition of both cis and trans fatty acids in edible oils.

Rapid Detection of Fatty Acids in Edible Oils Using Vis-NIR Reflectance Spectroscopy with Multivariate Methods.

The composition and content of fatty acids are critical indicators to identify the quality of edible oils. This study was undertaken to establish a rapid determination method for quality detection of edible oils based on quantitative analysis of palmitic acid, stearic acid, arachidic acid, and behenic acid. Seven kinds of oils were measured to obtain Vis-NIR spectra. Multivariate methods combined with pretreatment methods were adopted to establish quantitative analysis models for the four fatty acids. The model of support vector machine (SVM) with standard normal variate (SNV) pretreatment showed the best predictive performance for the four fatty acids. For the palmitic acid, the determination coefficient of prediction () was 0.9504 and the root mean square error of prediction () was 0.8181. For the stearic acid, and were 0.9636 and 0.2965. In the prediction of arachidic acid, and were 0.9576 and 0.0577. In the prediction of behenic acid, the and were 0.9521 and 0.1486. Furthermore, the effective wavelengths selected by successive projections algorithm (SPA) were useful for establishing simplified prediction models. The results demonstrate that Vis-NIR spectroscopy combined with multivariate methods can provide a rapid and accurate approach for fatty acids detection of edible oils.

Monitoring the oxidation state evolution of unsaturated fatty acids in four microwave-treated edible oils by low-field nuclear magnetic resonance and 1H nuclear magnetic resonance

Edible oils oxidize during microwave heating, which may affect their nutritional value and safety. Exploring the oxidation mechanisms of unsaturated fatty acids in edible oils to determine which are suitable for microwave heating is therefore important. We used GC-MS, low-field NMR, and 1H NMR techniques to study functional-group oxidation, the unsaturated fatty acid change law, and the distribution and migration of protons in various functional groups of four common vegetable cooking oils during microwave treatment. We show that the acid values of sunflower, soybean, peanut, and corn oil increased by 14%, 31%, 36%, and 101%, respectively, while the concentrations of malondialdehyde increased by 115%, 664%, 158%, and 333%, respectively, and the peroxide value fluctuated with increasing microwave power. The C16:0 concentrations of all four edible oils increased by more than 50%, and the concentration of polyunsaturated fatty acids decreased by more than 30% during microwave treatment; hence sunflower oil is the most suitable of the above-mentioned oils for daily microwave heating. In addition, we recommend the use of three characteristic functional groups to monitor the oxidative changes undergone by oils: olefinic H (CH = CH), diallyl CH2 (CH = CH–CH2–CH = CH), and allyl CH2 (CH = CH–CH2).

Profiling free fatty acids in edible oils via magnetic dispersive extraction and comprehensive two-dimensional gas chromatography-mass spectrometry

The analysis of free fatty acids (FFAs) in edible oils can provide important information for quality control and oil authentication. Herein, we report the comprehensive profiling of FFAs in edible oils via magnetic dispersive extraction combined with comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC–MS). A magnetic extractant was designed for dispersive extraction of FFAs. The extraction conditions were carefully optimized. To assess the extraction method, we first use the method for analysis of 7 targeted FFAs. The limits of detection range from 5.6 to 25.8 ng g−1, and the recoveries in oil samples are 81%–107%. We then performed comprehensive profiling of untargeted FFAs in oil by combining the extraction method with GC × GC–MS. A total of 64 FFAs were identified positively or putatively. The proposed method can provide FFA fingerprint data to guide the processing, storage and authentication of edible oils.

Quantification and monitoring the heat-induced formation of trans fatty acids in edible oils by Raman Spectroscopy

Trans fatty acids (TFAs), a type of unsaturated fatty acids, has been linked to increased risks of coronary heart disease and other health problems. Thus, efficient and reliable detection methods for TFAs are of great importance for both industrial applications and research purposes. In this study, a rapid and pretreatment-free quantification approach was developed for TFAs in 13 edible oils (including 2 soybean oils, 2 peanut oils, 2 rapeseed oils, blend oil, oleum camelliae, sunflower oil, rice oil, sesame oil, olive oil and corn oil) with Raman spectroscopy and chemometric methods. The commercial oils contained 0–0.397% (w/w) of trielaidin and each of the oils were further added with 0.1–5% of trielaidin, resulting in a total of 130 samples. Results show that the concentration of TFAs in various oils can be well-predicted based on the Raman spectral features in the region of 1640–1680 cm−1 (characteristic to C=C stretching modes), yielding a residual predictive deviation (RPD) of 4.639. This approach exhibits high sensitivity in quantification, and TFAs added in different kinds of edible oils combined with their initial levels can be successfully quantified with good descriptive statistics (Rc = 0.9657, Rcv = 0.9598, Rp = 0.9634, RMSEC = 0.351, RMSECV = 0.391 and RMSEP = 0.302). Furthermore, in order to understand the heat-induced formation of TFAs during food preparation, the TFA concentrations of the oil heated under different temperatures was investigated based on the above predication model. The results indicate that the concentration of TFAs increased sharply when the oils were heated at 169–250 °C for 10 min.

A multichannel Au nanosensor for visual and pattern inspection of fatty acids

Fatty acids (FAs) are important dietary sources of fuel for animals and structural components for cells. The number, position and configuration of olefins in the alkyl chains play important roles in the impacts of FAs on human health. Currently, structural profiling of FAs in edible oils and fats is an important issue in nutrition industries and food safety. Due to the lack of distinct functional groups, it is extremely difficult to discriminate FAs with structural differences by facile and in situ sensing methods. A few chemosensors have been developed for shape selective sensing of FAs, but their capability and performance were still limited. Herein, for the first time, we proposed a multichannel Au nanosensor for visual and pattern-generating inspection of FAs based on the highly selective binding ability of Ag+ to olefinic bonds and Ag+ regulable color variation of Au nanoparticles. As a result, the nanosensor showed good selectivity for five FAs with subtle structural difference as low as 5 nM. By further deriving three channel signals in respect of color and color depth, a signature-like signal pattern could be generated by principal component analysis for each FA and even different FA mixtures such as edible oils. Hence, structural variation of FAs in edible hot pot oils with heat treatment was successfully monitored by this Au nanosensor over time. This sensor holds great promise in point-of-care inspection of edible oils and fats.

Computational and experimental research on mechanism of cis/trans isomerization of oleic acid

The harm of trans-fatty acids to health has aroused public concern. It is believed that the main source of trans-fatty acids in diets is the isomerization of unsaturated fatty acids in edible oils during cooking. However, the information on the isomerization mechanism is very limited. In this paper, we used oleic acid, an unsaturated fatty acid, as a simplified model for edible oil and investigated the mechanism of cis/trans isomerization by computation and experiments. The computational results show that Rc-O-O-H is a very important intermediate, and the cleavage of O-O bond in Rc-O-O-H is the rate-controlling step during the cis/trans isomerization. Using the ATR-FTIR measurements, the contents of elaidic acid were measured quantitatively in sites. The experimental results indicate that the cis/trans isomerization of oleic acid can occur obviously only under oxidizing condition when the temperature is higher than 120 °C.

<em>Cis-trans</em> isomerization of unsaturated fatty acids in edible oils to prepare <em>trans</em> fat

Trans fats, unsaturated fatty acids with at least one double bond in the trans configuration, have received a great amount of attention in the field of oleo chemistry and safety. In this work, the cis-trans isomerization of unsaturated fatty acids in edible oils has been successfully developed using simple and cheap p-toluenesulfinic acid as catalyst. The effects of reaction time, temperature, catalyst loading, and the amounts of water and antioxidants on the cis-trans isomerization have been systematically investigated. The results indicate that the amount of water (0–20 wt %) and antioxidants (0–200 mg/kg) had no significant effect on this cis-trans isomerization of unsaturated fatty acids in edible oils. The final products (trans fats) from the cis-trans isomerization reaction were characterized by both GC and React IR. The yield of trans double bonds from the isomerized fat can reach 79.6% after heating at 100 oC for 90 min without changing either the location of the double bonds or the degree of unsaturation. In addition, this convenient method has been applied to various vegetable oils (e.g., olive oil, camellia seed oil, corn oil, sesame oil, sunflower oil and soybean oil) and nearly 80.0% yields of TFA were generated, which shows a promising method to provide trans-fat products for research related to oleo and food chemistry.

NMR spectroscopy in conjugation with multivariate statistical analysis for distinguishing plant origin of edible oils

NMR spectroscopy in combination with multivariate statistical analysis provides the promising feasibility for discriminating food origins. In this study, this technique was successfully employed to analyze various refined edible oils from seven plant-origins including sunflower seed, rapeseed, sesame, soybean, peanut, corn and olive oils. A variety of fatty acids in edible oils including oleic acid, linoleic acid, linolenic acid, saturated fatty acids and the corresponding iodine values were quantified via a single NMR measurement, and principal component analysis was used to distinguish their plant origins. The compositional differences both in major and minor components were derived from the pair-wise orthogonal partial least squares discriminant analysis models between the other edible oils and olive oil with highest nutritional value and favorable flavor. The results suggested that olive oil and rapeseed oil seem to provide the more nutritional benefit to human, and the minor components such as terpenes and tyrosol also induce health benefits and desirable flavor. The further analysis of different-producing-region sesame oils indicated that the altitude gives the great contribution to their compositional differences, and the climatic conditions also cause the compositional variations.

Rapid and sensitive detection of free fatty acids in edible oils based on chemical derivatization coupled with electrospray ionization tandem mass spectrometry

In this study, a strategy based on chemical derivatization coupled with electrospray ionizationtandem quadrupole mass spectrometry (ESI-MS/MS) for rapid and sensitive detection of FFAs in edible oils was developed. A derivative reagent (N,N-diethyl-1,2-ethanediamine, DEEA) was employed to selectively label carboxyl groups of FFAs to form an amino compound with a tertiary amino group. The DEEA derivative products could lose a characteristic neutral loss fragment of 73Da in collision-induced dissociation (CID), which enabled to discriminate and analyze the DEEA derived FFAs with neutral loss scan (NLS 73Da)under the positive ion mode of mass spectrometry. The assay was linear over the concentration range 0.5–200nmol/L with satisfactory correlation coefficients (R2≥0.9942), whilst the limit of detection and quantitation were 0.1–0.3nmol/L and 0.3–1.0nmol/L, respectively. Finally, the established method was applied to determine dynamic FFA formation in seven types of edible oils subjected to a microwave heating treatment test.

Prediction of the acid value, peroxide value and the percentage of some fatty acids in edible oils during long heating time by chemometrics analysis of FTIR-ATR spectra

Edible oils are used in the preparation of foods as a part of their recipe or for frying. So to ensure of food safety, checking the quality of the oils before and after usage is an important subject in food control laboratories. In this study, edible oils from four different sources (canola, corn, sunflower and frying) were heated for 36 h at 170 °C and sampling was done every 6 h. The free fatty acid, peroxide value and the content of some fatty acids (C16:0, C18:0, C18:1, C18:2, C18:3) of the oil samples were determined by standard methods. Then, the ATR-FTIR spectra of the samples were collected. The partial least squares (PLS) regression combined with genetic algorithm was performed on the spectroscopic data to obtain the appropriate predictive models for the simultaneous estimation of acid value, peroxide value and the percentage of five kinds of fatty acids. The effect of some preprocessing methods on these models was also investigated. Preprocessing of data by orthogonal signal correction (OSC) resulted in the best predictive models for all oil properties. The correlation coefficients of calibration set (>0.99) and validation set (>0.86 and in most case >0.94) of the OSC–PLS model suggested suitable predictive modeling for all studied parameters in the oil samples. This method could be suggested as a rapid, economical and environmental friendly technique for simultaneous determination of seven noted parameters in the edible oils.

Direct FTIR analysis of isolated trans fatty acids in edible oils using disposable polyethylene film

A new transmission-based Fourier transform infrared (FTIR) spectroscopy method has been developed to determine trans fatty acids (TFA) content in edible oils using disposable polyethylene (PE) film as a spectral acquisition accessory. Calibration standards were devised by gravimetrically adding TFA to TFA-free oil. The response was measured at 990–945cm−1 against the baseline. A linear relationship between the areas in the spectral regions 1670–1625cm−1 and 990–945cm−1 in TFA-free oil samples was established to compensate for interference due to underlying triacylglycerol absorptions in the trans measurement region (990–945cm−1). Subsequently, the area measured at 990–945cm−1 was corrected for interference, using the linear equation obtained, to determine TFA content. Results indicated that the PE film-based FTIR method for analyzing TFA content in edible oils was simple and rapid, and could be used effectively as an alternative to gas chromatography and mass spectrometry methods.

Direct detection of free fatty acids in edible oils using supercritical fluid chromatography coupled with mass spectrometry

Determination of free fatty acids (FFAs) in food products is of enormous interest mainly because they are related to the quality and authenticity of the oils. In this study, supercritical fluid chromatography (SFC), followed by an electrospray ionisation triple–quadrupole mass spectrometry (ESI-MS), is shown to provide a novel method for the separation and detection of FFAs in edible oils without any pretreatment. Eight FFAs were separated on a HSS C18 SB column with gradient elution within 3min. Effects of different columns, modifiers and column temperature changes were evaluated. The results indicated the feasibility of this method for the high-throughput determination of individual FFAs with satisfactory correlation coefficients (R2>0.994) and good reproducibility of RSD<13.5% (intraday) and <15.0% (interday). By combined with principal component analysis (PCA), different types of edible oil were successfully distinguished into several categories, showing a potential application for the determination of oil quality or authenticity.

Direct FTIR Analysis of Free Fatty Acids in Edible Oils Using Disposable Polyethylene Films

To simplify a previously reported Fourier transform infrared (FTIR) method for the direct determination of free fatty acid (FFA), a new technique was designed to facilitate mid-FTIR transmission analysis of viscous edible oil samples using disposable polyethylene (PE) films as a spectral acquisition accessory. In the PE-film-based procedures, the viscosities of oil samples were reduced by mixing hexane for allowing the samples to readily deposit onto PE films to form oil films when the solvent evaporated (PE film as spectral background), and the path length of each oil film was normalized to a fixed path length of 0.15 mm. The relationship between FFA content (expressed as percentage of oleic acid) and the absorbance of FFA at 1711 cm−1 relative to a baseline at 1600 cm−1 (baseline was 1600 cm−1) in thenormalized spectra was expressed by a linear calibration equation. To remit the interference from the absorbance due to triglyceride esters (approximately 1,746 cm−1) in the wave numbers used in FFA determination (1,711 cm−1), the intensity of the first overtone of the ester vibration (3,471 cm−1/3,527 cm−1) in FFA-free oil samples was used to determine the intensity of the interfering signal at 1,711 cm−1. Moreover, a linear relationship between the two absorbances was established. Consequently, the absorbance measured at 1,711 cm−1/1,600 cm−1 by FFA determination in the oil samples was corrected for the linear equation. FFA determination in oil samples with known FFA content (0 to 3 %) was carried out in parallel by using the American Oil Chemists’ Society titrimetric method and the PE-film-based FTIR procedures. A comparison indicated that the PE-film-based FTIR method can be used to determine FFA content in different kinds of edible oils.

Determination of free fatty acids in edible oils by 1H NMR spectroscopy

AbstractHere we describe a novel 1H NMR assay for the determination of FFAs in edible oils. The analytical performance of the NMR assay is similar to that of the commonly used acid value (AV) method. A total of 120 edible oil samples were analysed by both approaches. Except for pumpkin seed oil, showing slight deviations, there was a good compliance between the results obtained from the two methods.

Fatty Acid Composition Including Trans‐Fatty Acids in Edible Oils and Fats: Probable Intake in Indian Population

The susceptibility of trans-fat to the human health risk prompted the Food and Agriculture Organization (FAO) and World Health Organization (WHO) to prepare regulations or compulsory claims for trans-fatty acids (TFA) in edible oils and fats. In this study, analysis of fatty acid composition and TFA content in edible oils and fats along with the possible intake of trans-fat in Indian population was carried out. The analysis was carried out as per the Assn. of Official Analytical Chemists (AOAC) methodology and the results were statistically analyzed. The average TFA content in nonrefined mustard and refined soybean oils exceeded by 1.16- to 1.64-fold as compared to the Denmark limit of 2% TFA in fats and oils destined for human consumption. In branded/nonbranded butter and butter oil samples, average TFA limit exceeded by 4.2- to 9.5-fold whereas hydrogenated vegetable oil (HVO) samples exceeded the limit by 9.8-fold, when compared to Denmark standards. The probable TFA intake per day through different oils in Indian population were found to be less than WHO recommendation. However Punjab having highest consumption of HVO (-15 g/d) showed 1.09-fold higher TFA intake than the WHO recommendation, which is alarming and may be one of the factors for high cardiovascular disease mortality rate that needs further elucidation. Thus there is a need to prescribe TFA limit for edible oil, butter, and butter oil in India and to reduce the already proposed TFA levels in HVO to safeguard the health of consumers. The probable daily intake of trans-fatty acid (TFA) especially through hydrogenated vegetable oil (HVO) was assessed. In absence of any specification for TFA and fatty acid composition for edible oils, butter, and butter samples, a pressing need was felt to prescribe TFA limit in India. The study indicates that TFA intake through HVO consumption is higher in States like Punjab than the recommended daily intake prescribed by WHO. Hence, strategies should be adopted to either decrease the consumption of HVO or to modify the industrial processing method of HVO with less content of TFA to safeguard the health of consumers.