Profile of trans fatty acids (FAs) including trans polyunsaturated FAs in representative fast food samples

Fatty acid isomerism: analysis and selected biological functions

The biological functions of fatty acids and the lipids in which they are esterified are determined by their chain length, double bond position and geometry and other structural motifs such as the presence of methyl branches. Unusual isomeric features in fatty acids of human foods such as conjugated double bonds or chain branching found in dairy products, some seeds and nuts, and marine foods potentially have important effects on human health. Recent advancements in identifying fatty acids with unusual double bond positions and pinpointing the position of methyl branches have empowered the study of their biological functions. We present recent advances in fatty acid structural elucidation by mass spectrometry in comparison with the more traditional methods. The double bond position can be determined by purely instrumental methods, specifically solvent-mediated covalent adduct chemical ionization (SM-CACI) and ozone induced dissociation (OzID), with charge inversion methods showing promise. Prior derivatization using the Paternò-Büchi (PB) reaction to yield stable structures that, upon collisional activation, yield the double bond position has emerged. The chemical ionization (CI) based three ion monitoring (MRM) method has been developed to simultaneously identify and quantify low-level branched chain fatty acids (BCFAs), unattainable by electron ionization (EI) based methods. Accurate identification and quantification of unusual fatty acid isomers has led to research progress in the discovery of biomarkers for cancer, diabetes, nonalcoholic fatty liver disease (NAFLD) and atherosclerosis. Modulation of eicosanoids, weight loss and the health significance of BCFAs are also presented. This review clearly shows that the improvement of analytical capacity is critical in the study of fatty acid biological functions, and stronger coupling of the methods discussed here with fatty acid mechanistic research is promising in generating more refined outcomes.

Unusual polymethylene-interrupted, Δ5 monounsaturated and omega-3 fatty acids in sea urchin (Arbacia punctulata) from the Gulf of Mexico identified by solvent mediated covalent adduct chemical ionization mass spectrometry

Sea urchin (class Echinoidea) gonads are a prized delicacy in Japan and many other world cultures. The complexity of its fatty acid (FA) profile, particularly minor FA, presents a formidable analytical challenge. We applied solvent mediated (SM) covalent adduct chemical ionization (CACI) tandem mass spectrometry to comprehensive de novo structural and quantitative characterization of the FA profile of Gulf of Mexico Atlantic sea urchin (Arbacia punctulata). >100 FA were detected including many with unusual double bond structure. Gulf sea urchin gonad lipids are rich in Δ5 monounsaturated FA 20:1(5Z) at 2.7% and the polymethylene-interrupted (PMI) diene 20:2(5Z,11Z) at 4.9%, as well as common omega-3 eicosapentaenoic acid (EPA; 5Z, 8Z, 11Z, 14Z, 17Z) at 9.8%±3.1% and arachidonic acid (AA; 5Z, 8Z, 11Z, 14Z) at 6.1%±2.1%. We propose plausible desaturation/elongation-based biochemical pathways for the endogenous production of unusual unsaturates. Unusual unsaturates may modify mammalian signaling and present novel bioactivities.

Tutorial for the Characterization of Fatty Acid Methyl Esters by Gas Chromatography with Highly Polar Capillary Columns

The fatty acid composition of fats and oils is commonly determined by gas chromatography after preparing fatty acid methyl esters (FAME). Capillary columns coated with polyethylene glycol emerged as the preferred separation tool for the quantification of the polyunsaturated fatty acids contained primarily in marine oils. However, their selectivity is inadequate for measuring the trans fatty acids (TFA) contained in refined vegetable oils, dairy fats, and marine oils. Highly polar 100% poly(biscyanopropyl siloxane) capillary columns provide the necessary selectivity, but small differences in the phase polarity caused by column age, conditioning, or manufacturing variations affect the reproducibility of their separations of these complex samples. In this study, a simple procedure is described to compensate for small variations in column selectivity by adjusting the elution temperature. The balance between the dipole-induced dipole interactions and dispersive interactions was determined by measuring selectivity factors [SF(i)] corresponding to the elution of an unsaturated FAME such as 18:3n-3 relative to two saturated FAME such as 20:0 and 22:0. Knowing the SF(i) provided by the installed capillary column at a given elution temperature, and the SF(i) of the target separation, we propose a simple calculation to determine the necessary elution temperature adjustment to achieve (or restore) the desired separation. After determining the SF(i) which provides the optimal separation of TFA, the novel methodology was applied to the separation of refined vegetable oils, butter fats, and marine oils.

The Role of Ionic Liquid Interaction in the Separation of Fatty Acid Methyl Esters—Polyunsaturated Geometric Isomers in GC–MS

Knowledge of the type and level of saturated and unsaturated fatty acids in food and clinical matrices is of practical importance, but the wide variety of fatty acids makes analyses very complex. The discrimination of the geometric isomers of fatty acid needs proper and effective separation conditions. The efficiency of three different stationary phases was evaluated by GC–MS methods in the separation of fatty acids in their methyl ester forms. Significant differences were observed in the efficiencies of polysiloxane-based (non-polar HP-5MS and medium/high polarity DB-225MS) and ionic liquid-based (SLB-IL111) columns. Baseline separation of the geometric isomers of linoleic acid methyl ester was obtained by the extremely polar SLB-IL111 column, showing a preference over the other two columns. The optimization of the experimental conditions (response linearity, limit of detection, limit of quantification, system suitability, intraday and interday repeatability and accuracy) showed the separation power of the ionic liquid interaction in the analyses by using short (25–30 m long) columns. By deducting the general principles of the interaction, predictions can be made for the separation of other isomers. The results facilitate the precise identification of various types of fatty acids in real samples for nutritional information.

Characterization and Semiquantitative Analysis of Novel Ultratrace C10-24 Monounsaturated Fatty Acid in Bovine Milkfat by Solvent-Mediated Covalent Adduct Chemical Ionization (CACI) MS/MS

The net action of ruminal bacteria and endogenous bovine enzymes are responsible for cow's milk having the most complex fatty acid profiles among common foods. About 40 monounsaturated fatty acids below 1.5% w/w are known. Analysis of trace and ultratrace fatty acids is a challenge to the highest resolution chromatography even with prior fractionation. We employ solvent-mediated covalent adduct chemical ionization (CACI) tandem mass spectrometry (MS/MS) to enable rapid, unambiguous identification of unsaturated fatty acid methyl esters (FAME) at high sensitivity. Fifty-four monounsaturated fatty acids (C_10-24) were completely characterized, with the discovery of 15 novel fatty acids including nine at ultratrace levels 10-100 ppm, g/10⁶ g fatty acids (lowest concentration 19:1n-6 (10 ± 11 ppm, w/w (0.001%, w/w))). Ultratrace monoenes were typically odd chain lengths and all analyzed in a single 20 min analysis. These data establish the abundance of 15 new monoene fatty acids in bovine milkfat and a strategy for rapid unambiguous analysis of ultratrace monounsaturated fatty acids.

Gas Chromatography Chemical Ionization Mass Spectrometry and Tandem Mass Spectrometry for Identification and Straightforward Quantification of Branched Chain Fatty Acids in Foods

Fatty acid analysis of food lipids containing branched chain fatty acids (BCFAs) are complex because of unavoidable gas chromatography (GC) co-elution. We demonstrate a method for convenient quantitative GC coupled to novel solvent-mediated chemical ionization (CI) mass spectrometry (MS) that enables resolution of co-eluting peaks by mass. The relevant masses yield uniform responses for C_14-20 normal fatty acids and BCFAs, eliminating the need for rare purified BCFA standards essential for unpredictable responses, as for electron ionization (EI). CI-tandem mass spectrometry analysis of MH⁺ yields fragments characteristic of the branch position. Application of the measurement to BCFAs in salami samples demonstrates consistent results for the novel method and EI-MS. A higher proportion of C_17-18 BCFAs was found in beef compared to milkfat, possibly indicative of fatty acid elongation, endogenous in the beef animal. This method enables straightforward structure elucidation and quantification of food BCFAs and similar chain length normal fatty acids without purified standards.

trans Fatty Acids in Polish Pastry

HIGHLIGHTS

Determination of Iodine Value in Hydrogenated Oils: Comparison of Titration and Gas Chromatography with Flame-Ionization Detection Methodologies

The United States Food and Drug Administration (FDA) recently issued its final determination that partially hydrogenated oils (PHO) are no longer generally recognized as safe (GRAS) for any use in human food. Consequently, the discrimination between PHO and fully hydrogenated oils (FHO), which is achieved by the iodine value (IV), has become an important regulatory issue. This study compared American Oil Chemists' Society (AOCS) and International Organization for Standardization (ISO) titration and gas chromatography with flame-ionization detection (GC-FID) methodologies for the determination of IV in seven samples of hydrogenated oil, namely coconut, cottonseed (n = 2), palm kernel, palm stearine, and soybean (n = 2) oils. Titrations produced statistically higher IV determinations than those achieved by GC-FID, for all samples except the FH coconut oil. The unsaponifiable matter content of the hydrogenated oils, which varied from 0.15% to 0.47% of total fat, likely contributed modest increases to the IV by titration. Both methodologies were prone to issues at low IV (~4), with titrations showing greater variability, and GC-FID being susceptible to incomplete separation, identification, and quantification of all unsaturated fatty acids. The variability observed with titrations could be minimized by careful execution of the titration protocol. Although both approaches successfully discriminated PHO and FHO in the test materials, at low IV (~4), titration is the most accurate method for determining the IV, and the only approach that has been validated in oils with a very low IV (<1).

Neighborhood food environment, dietary fatty acid biomarkers, and cardiac arrest risk

We explored links between food environments, dietary intake biomarkers, and sudden cardiac arrest in a population-based longitudinal study using cases and controls accruing between 1990 and 2010 in King County, WA. Surprisingly, presence of more unhealthy food sources near home was associated with a lower 18:1 trans-fatty acid concentration (-0.05% per standard deviation higher count of unhealthy food sources, 95% Confidence Interval [CI]: 0.01, 0.09). However, presence of more unhealthy food sources was associated with higher odds of cardiac arrest (Odds Ratio [OR]: 2.29, 95% CI: 1.19, 4.41 per standard deviation in unhealthy food outlets). While unhealthy food outlets were associated with higher cardiac arrest risk, circulating 18:1 trans fats did not explain the association.

Rapid Prediction of Low (<1%) trans Fat Content in Edible Oils and Fast Food Lipid Extracts by Infrared Spectroscopy and Partial Least Squares Regression

The United States Food and Drug Administration (FDA) ruled that partially hydrogenated oils (PHO), the major dietary source of industrially produced trans fat (TF), were no longer "generally recognized as safe (GRAS)" for any use in human food. Consequently, the objective of this study was to develop a rapid screening procedure using attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy in conjunction with partial least squares regression (PLSR) for the quantitative and accurate prediction of low concentrations of trans fatty acid (TFAs) (<1% of total fatty acids (FAs)). Broad-based calibration models were developed for a combined set of samples consisting of edible oils and fast food lipid extracts. Predicted concentrations of TFAs in the two matrices showed good correlation with the primary reference data generated by gas chromatography (GC) (R² > 0.99) and high accuracy as evidenced by low root-mean-square error of cross-validation (RMSECV) values. The lowest TFA concentration, determined by GC to be 0.13% of total FAs, was accurately predicted by ATR-FTIR/PLSR as 0.18% of total FAs. This simple, rapid ATR-FTIR/PLSR methodology has the potential for use as a screening alternative to conventional gas chromatographic methods for predicting the TFA content of edible oils and food lipid extracts for regulatory purposes and quality control of raw material and processed food.

PRACTICAL APPLICATIONS

FDA ruled that partially hydrogenated oils were no longer "generally recognized as safe (GRAS)" for any use in human food. Consequently, we have proposed a rapid screening procedure, based on infrared spectroscopy and chemometrics, to rapidly and accurately predict low concentrations of trans fatty acids (<1% of total fatty acids) in edible oils and food lipid extracts.

Study of Trans Fatty Acid Formation in Oil by Heating Using Model Compounds

The intake of trans fatty acids (TFAs) in foods changes the ratio of low density lipoprotein (LDL) to high density lipoprotein (HDL) cholesterol in blood, which causes cardiovascular disease. TFAs are formed by trans isomerization of unsaturated fatty acids (UFAs). The most recognized formation mechanisms of TFAs are hydrogenation of liquid oil to form partially hydrogenated oil (PHO,) and biohydrogenation of UFAs to form TFA in ruminants. Heating oil also forms TFAs; however, the mechanism of formation, and the TFA isomers formed have not been well investigated. In this study, the trans isomerization mechanism of unsaturated fatty acid formation by heating was examined using the model compounds oleic acid, trioleate, linoleic acid, and trilinoleate for liquid plant oil. The formation of TFAs was found to be suppressed by the addition of an antioxidant and argon gas. Furthermore, the quantity of formed TFAs correlated with the quantity of formed polymer in trioleate heated with air and oxygen. These results suggest that radical reactions form TFAs from UFAs by heating. Furthermore, trans isomerization by heating oleic acid and linoleic acid did not change the original double bond positions. Therefore, the distribution of TFA isomers formed was very simple. In contrast, the mixtures of TFA isomers formed from PHO and ruminant UFAs are complicated because migration of double bonds occurs during hydrogenation and biohydrogenation. These findings suggest that trans isomerization by heating is executed by a completely different mechanism than in hydrogenation and biohydrogenation.

Comparison of the Effect of trans Fatty Acid Isomers on Apolipoprotein A1 and B Secretion in HepG2 Cells

Intake of trans fatty acid (TFA) is believed to change the ratio of low-density lipoprotein (LDL) to high density lipoprotein (HDL) cholesterol in blood, which leads to cardiovascular disease. In this study, thirteen types of TFA including monoene type TFA (trans-octadecenoic fatty acid isomers, t-18:1 isomers), diene type TFA (t9,t12-18:2), and triene type TFA (t-18:3) were added to cultured HepG2 cells to compare the amount of apolipoprotein A1 and B (those relating to levels of HDL and LDL cholesterol in blood, respectively) being secreted. We found that trans-5-18:1 increased the secretion of apolipoprotein B relative to oleic acid (cis-9-18:1, control). Secretion of apolipoprotein B was also increased by t-18:3; however, the amount was not significant compared with that observed in the control. The secretion amount of apolipoprotein B tended to increase with the number of double bonds in TFA among trans-9-18:1, t9,t12-18:2, and t-18:3. The secretion amount of apolipoprotein A1 after TFA treatment was also measured. No significant difference was detected among t-18:1 groups; however, t-18:3 increased the amount significantly compared to that in the control. These results suggest that the effect of TFA isomers on the ratio of LDL to HDL cholesterol in the blood follows a mechanism different from that in cultured cells.

Margarines and Fast-Food French Fries: Low Content of trans Fatty Acids

The lipid fraction of margarines and fast food French fries, two types of foods traditionally high in trans fatty acids (TFA), is assessed. TFA data reported worldwide during the last 20 years have been gathered and show that some countries still report high TFA amounts in these products. The content of TFA was analysed in margarines (two store and four premium brands) and French-fries from fast-food restaurants (five chains). All samples were collected in Pamplona (Navarra, Spain). The margarines showed mean values of 0.68% and 0.43% (g TFA/100 g fat) for the store and premium brands, respectively. The French fries’ values ranged from 0.49% to 0.89%. All samples were lower than the 2% set by some European countries as the maximum legal content of TFA in fats, and contained less than 0.5 g/serving, so they could also be considered “trans free products”. This work confirmed that the presence of TFA is not significant in the two analysed products and contributes updated food composition tables, key tools for epidemiological and nutrition studies.

Ionic liquids as stationary phases for fatty acid analysis by gas chromatography

The present paper provides an overview of the application of ionic liquid (IL) columns for GC analysis of fatty acid methyl esters (FAMEs).

Changes in mean intake of fatty acids and intake of saturated and trans fats from potatoes: NHANES 2005-2006, 2007-2008, and 2009-2010

Studies have shown that higher than usual intakes of trans fatty acids (TFAs) have adverse effects on blood lipids. Because of this, in 2006 the US FDA mandated labeling of TFAs on food packages. The food and restaurant industries, including the potato industry, reformulated their foods to reduce or eliminate partially hydrogenated vegetable oils and TFAs. Before mandatory labeling, grain-based desserts, yeast breads, and French-fried potatoes (FFPs) were the top sources of TFAs in the food supply; by 2007, potato food manufacturers and quick-service restaurants had reduced or eliminated TFAs without increasing saturated fatty acids (SFAs). FFPs are no longer a source of TFAs in the food supply. This study examined energy and fatty acid intake among children aged 6-11 y, adolescents aged 12-18 y, and adults aged ≥19 y across 3 time periods by using data from the NHANES 2005-2006, 2007-2008, and 2009-2010. On average, intakes of total energy, total fat, SFAs, and monounsaturated fatty acids (MUFAs) decreased significantly between 2005-2006 and 2009-2010 among children and adolescents; however, the intake of polyunsaturated fatty acids (PUFAs) did not change. Among adults, intakes of total fat, SFAs, and MUFAs decreased; however, total energy and PUFA intake did not change. On the day of the 2009-2010 survey, ∼13% of children and 10% of adolescents reported consuming fried FFPs, whereas <7% of adults reported consumption of fried FFPs. Intakes of SFAs and TFAs from fried FFPs decreased significantly between 2005-2006 and 2009-2010 among children, adolescents, and adults. This study confirms that intake of TFAs from FFPs is trivial.

Living in a 'fat swamp': exposure to multiple sources of accessible, cheap, energy-dense fast foods in a deprived community

This study assesses the levels of fats, including trans-fatty acids, and salt in common takeaway fast foods in a deprived urban municipality in the West Midlands, England, and implications in the context of the spatial distribution of fast food takeaways. The results of the compositional analysis of over 250 take-out foods were compared with established and derived standards. About 70% of products exceeded the recommendation that a meal should contain less than 30% of a Guideline Daily Amount (GDA). More than half of them exceeded 50% GDA for at least one metric, including 81% of all analyses for SFA. And 17% of samples exceeded the GDA for SFA, including each of two meals that contained about twice the GDA. Over 30% samples exceeded the children's GDA for total fat or SFA. 27% of salt analyses exceeded the GDA. People in Sandwell are exposed to large portion sizes and high levels of fats and salt in takeaway foods, with levels in some foods having increased since 2010. Given this population's limited options to break out of a highly compromising environment of living simultaneously in a 'swamp' of unhealthy, readily accessible and cheap takeaways, and a 'desert' of healthy options, an immediate and innovative package of interventions is required.

Chromatographic Methods in the Separation of Long-Chain Mono- and Polyunsaturated Fatty Acids

This review presents various chromatographic systems, TLC, HPLC, GC, and also SFC, developed for identification and accurate quantification of long-chain mono- and polyunsaturated fatty acids from different samples with emphasis on selected literature which was published during last decade. Almost all the aspects such as preseparation step of fatty acids (cisandtrans), stationary phase, solvent system, and detection mode are discussed.

Innovations in food chemistry and processing to enhance the nutrient profile of the white potato in all forms

Potatoes can be an important part of a balanced diet because they are an excellent source of many nutrients, including nutrients that are commonly underconsumed (dietary fiber and potassium). Despite the existence of many positive nutrients in potatoes, the popular press has recently aligned potatoes, and particularly fried potatoes, with an unhealthy diet. This article examines the nutritional content of potatoes and how these nutrients are affected by cooking and other food-processing operations. In addition, it examines how the nutritional content of potatoes is altered by cooking methods and how fried potatoes can have wide variations in fat content depending on the cooking method. Finally, the potential of new food-processing technologies to improve the nutritional content of cooked potatoes is evaluated.

Mathematical modeling of poly[(R)-3-hydroxyalkanoate] synthesis by Cupriavidus necator DSM 545 on substrates stemming from biodiesel production

Two low structured mathematical models for fed-batch production of polyhydroxybutyrate and poly[hydroxybutyrate-co-hydroxyvalerate] by Cupriavidus necator DSM 545 on renewable substrates (glycerol and fatty acid methyl esters-FAME) combined with glucose and valeric acid, were established. The models were used for development/optimization of feeding strategies of carbon and nitrogen sources concerning PHA content and polymer/copolymer composition. Glycerol/glucose fermentation featured a max. specific growth rate of 0.171 h(-1), a max. specific production rate of 0.038 h(-1) and a PHB content of 64.5%, whereas the FAME/valeric acid fermentation resulted in a max. specific growth rate of 0.046 h(-1), a max. specific production rate of 0.07 h(-1) and 63.6% PHBV content with 4.3% of 3-hydroxyvalerate (3HV) in PHBV. A strong inhibition of glycerol consumption by glucose was confirmed (inhibition constant ki,G=4.28×10(-4) g L(-1)). Applied concentration of FAME (10-12 g L(-1)) positively influenced on PHBV synthesis. HV/PHBV ratio depends on applied VA concentration.