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.

Separation and characterization of products from acidic methanolysis of plasmalogenic lipids by two-dimensional gas chromatography with online reduction.

The complexity of determining the composition of animal tissue lipids is greatly increased by the presence of plasmalogens in which the alkyl chain is linked to glycerol by an enol ether bond instead of being esterified. Acidic methanolysis of animal tissue lipids provides the simultaneous scission of acyl and alkenyl ether moieties, but the complexity of the products of reaction poses a great challenge in their gas chromatographic analysis. Two-dimensional gas chromatography with online reduction (GC-OR × GC) provided the resolution of all components contained in acid methanolyzed animal lipids, taking advantage of the selective hydrogenation of alkenyl ether methanolysis products prior to the second-dimension separation (2D). In this study, we also studied the chemical transformations occurring during the acidic methanolysis of animal lipids and the subsequent gas chromatographic analysis. In particular, we observed that using methanolysis reagents contaminated with water resulted in the undesired formation of fatty aldehydes, and we made recommendations on how to avoid these side reactions using proper methanolysis conditions. Products of acidic methanolysis were studied by GC-OR × GC, GC-MS, NMR spectroscopy, and GC with flame ionization detection (GC-FID). We defined the GC-FID elution order of animal lipid acidic methanolysis products using 100 m × 0.25 mm 100% bis(cyanopropyl)siloxane columns and two different set of elution conditions: isothermal elution at 180°C, and a temperature program optimized for dairy fats. A simple procedure for isolating dimethyl acetals (DMA) prior to GC analysis is also described.

Trans fat labeling and levels in U.S. foods: assessment of gas chromatographic and infrared spectroscopic techniques for regulatory compliance.

Trans fatty acids are found in a variety of foods like dairy and meat products, but the major dietary sources are products that contain commercially hydrogenated fats. There has been a renewed need for accurate analytical methods for the quantitation of total trans fat since mandatory requirements to declare the amount of trans fat present in food products and dietary supplements were issued in many countries. Official capillary GC and IR methodologies are the two most common validated methods used to identify and quantify trans fatty acids for regulatory compliance. The present article provides a comprehensive discussion of the GC and IR techniques, including the latest attenuated total reflection (ATR)-FTIR methodology called the negative second derivative ATR-FTIR procedure, which is currently being validated in an international collaborative study. The identification and quantitation of trans fatty acid isomers by GC is reviewed and an alternative GC method is proposed using two temperature programs and combining their results; this proposed method deals more effectively with the resolution of large numbers of geometric and positional monoene, diene, and triene fatty acid isomers present in ruminant fats. In addition, the different methylation procedures that affect quantitative conversion to fatty acid methyl esters are reviewed. There is also a lack of commercial chromatographic standards for many trans fatty acid isomers. This review points to potential sources of interferences in the FTIR determination that may lead to inaccurate results, particularly at low trans levels. The presence of high levels of saturated fats may lead to interferences in the FTIR spectra observed for trans triacylglycerols (TAGs). TAGs require no derivatization, but have to be melted prior to IR measurement. While GC is currently the method of choice, ATR-FTIR spectroscopy is a viable, rapid alternative, and a complementary method to GC for a more rapid determination of total trans fats for food labeling purposes.

Combining results of two GC separations partly achieves determination of all cis and trans 16:1, 18:1, 18:2 and 18:3 except CLA isomers of milk fat as demonstrated using Ag-ion SPE fractionation.

Milk fat is a complex mixture of geometric and positional isomers of monounsaturated and polyunsaturated, including short-, long- and branch-chain fatty acids (FAs). There has been partial success to resolve this mixture of FAs using different GC temperature programs, or a combination of GC isothermal and temperature programs. To overcome the problem associated with overlapping isomers prior silver-ion separation was recommended. However, this procedure is time consuming and not practical for routine analysis. In addition, previous methods focused mainly on the trans and cis isomers of 18:1. The present method takes advantage of differences in the relative elution times between different types of FAs. The method involved analyzing each milk fat using the same highly polar 100-m capillary column and GC instrument, and conducting two separations using temperature programs that plateau at 175 and 150 degrees C. The relative shift among the geometric and positional isomers at these two temperature settings was enough to permit identification of most of the trans and cis 16:1, 18:1 and 20:1, the c/t-18:2 and the c/c/t-18:3 isomers found in milk fat. The identity of these FAs was confirmed by prior separation of the total fatty acid methyl esters (FAMEs) of milk fat using Ag(+)-SPE columns, and comparing the fractions to the total milk fat. The Ag(+)-SPE technique was modified to obtain pure saturated, trans- and cis-monounsaturated and diunsaturated FAMEs. By combining the results from these two separate GC analyses, knowing the elution order, it was possible to determine most of the geometric and positional isomers of 16:1, 18:1, 20:1, 18:2 and 18:3 without a prior silver-ion separation. Only few minor FAs could not be resolved, notable the conjugated linoleic acid isomers that still required the complimentary Ag(+)-HPLC separation. The two GC temperature programs have been successfully used to routinely analyze most FA isomers in total milk and beef fats in about 200 min without the use of prior silver-ion separations.

Improvement of the Fourier Transform Near Infrared Method to Evaluate Extra Virgin Olive Oils by Analyzing 1,2-Diacylglycerols and 1,3-Diacylglycerols and Adding Unesterified Fatty Acids.

Extra virgin olive oils (EVOO) command higher prices because they contain health-promoting nutrients and desirable sensory characteristics. Many targeted methods have limited success in determining olive oil authenticity. Therefore, attention has been paid to rapid spectroscopic methods that provide the composition of multiple components. A Fourier transform near infrared (FT-NIR) method was reported that identified five major fatty acids and volatiles in EVOO, plus four models that identify common adulterants and their content. However, it did not include diacylglycerol (DAG) and unesterified fatty acids (FFA) known to be associated with freshness of the oil. The newly improved FT-NIR method now includes 1,2-DAG and 1,3-DAG models based on the DAG isomer content in freshly prepared EVOO, and a FFA model based on quantitative addition of oleic acid. The new FT-NIR method was used to reassess previously used EVOO products to evaluate their freshness. Based on these results and review of the published data, we propose several revisions to the EVOO regulation: limit FFA to ≤0.5%, include 1,2-DAG and 1,3-DAG in standard, place no limit on 1,2-DAG because it characterizes the oils, set the 1,3-DAG content to ≤1.0%, and lower the content of 18:2n-6 to 1.5%.

Evidence for the Initial Steps of DHA Biohydrogenation by Mixed Ruminal Microorganisms from Sheep Involves Formation of Conjugated Fatty Acids.

Incubation of DHA with sheep rumen fluid resulted in 80% disappearance in 6 h. The products were analyzed as their fatty acid (FA) methyl esters by GC-FID on SP-2560 and SLB-IL111 columns. The GC-online reduction × GC and GC-MS techniques demonstrated that all DHA metabolites retained the C22 structure (no evidence of chain-shortening). Two new transient DHA products were identified: mono-trans methylene interrupted-DHA and monoconjugated DHA (MC-DHA) isomers. Identification of MC-DHA was confirmed by their predicted elution using equivalent chain length differences from C18 FA, their molecular ions, and the 22:5 products formed which were the most abundant at 6 h. The 22:5 structures were established by fragmentation of their 4,4-dimethyloxazoline derivatives, and all 22:5 products contained an isolated double bond, suggesting formation via MC-DHA. The most abundant c4,c7,c10,t14,c19-22:5 appeared to be formed by unknown isomerases. Results suggest that the initial biohydrogenation of DHA was analogous to that of C18 FA.

Fatty acid profiles, tocopherol contents, and antioxidant activities of heartnut (Juglans ailanthifolia Var. cordiformis) and Persian walnut (Juglans regia L.).

The fatty acid and tocopherol compositions of three heartnut (Juglans ailanthifolia var. cordiformis) varieties (Imshu, Campbell CW1, and Campbell CW3) were examined and compared with those of two Persian walnut (Juglans regia L.) varieties (Combe and Lake). The major fatty acids found in heartnuts and walnuts were identified by gas chromatography as linoleic (18:2n-6), alpha-linolenic (18:3n-3), oleic (18:1n-9), palmitic (16:0), and stearic acid (18:0). Polyunsaturated fatty acids were the main group of fatty acids found in both heartnut and walnut, ranging from 73.07 to 80.98%, and were significantly higher in heartnut than in Persian walnuts (P < 0.001). In addition, heartnuts had significantly higher levels of 18:2n-6 and lower levels of 18:3n-3 compared to the Persian walnuts. gamma-Tocopherol was the main tocopherol homologue present in both types of nuts, followed by delta- and alpha-tocopherol. The highest concentration of gamma-tocopherol was found in Combe Persian walnut at 267.87 mug/g, followed by Lake Persian walnut and Imshu, Campbell CW1, and CW3 heartnut at 205.45, 187.33, 161.84, and 126.46 mug/g, respectively. Tocopherols, particularly the gamma-tocopherol, were found to contribute the most to the strong total antioxidant activities of both walnut and heartnut oils using either the free radical 2,2-diphenyl-1-picrylhydrazyl assay or the photochemiluminescence method.

Total lipids of Sarda sheep meat that include the fatty acid and alkenyl composition and the CLA and trans-18:1 isomers.

The total lipids of the longissimus dorsi muscle were analyzed from commercial adult Sarda sheep in Sardina taken from local abattoirs, and in the subsequent year from three local farms in the Sassari region that provided some information on the amount and type of supplements fed to the pasture-fed sheep. The complete lipid analysis of sheep meat included the fatty acids from O-acyl and N-acyl lipids, including the trans- and conjugated linoleic acid (CLA) isomers and the alk-1-enyl ethers from the plasmalogenic lipids. This analysis required the use of a combination of acid- and base-catalyzed methylation procedures, the former to quantitate the O-acyl, N-acyl and alkenyl ethers, and the latter to determine the content of CLA isomers and their metabolites. A combination of gas chromatographic and silver-ion separation techniques was necessary to quantitate all of the meat lipid constituents, which included a prior separation of the trans-octadecenoic acids (18:1) and a separation of fatty acid methyl esters and the dimethylacetals (DMAs) from the acyl and alk-1-enyl ethers, respectively. The alk-1-enyl moieties of the DMAs were analyzed as their stable cyclic acetals. In general, about half of the meat lipids were triacylglycerols, even though excess fat was trimmed from the meat. The higher fat content in the meat appears to be related to the older age of these animals. The variation in the trans-18:1 and CLA isomer profiles of the Sarda sheep obtained from the abattoirs was much greater than in the profiles from the sheep from the three selected farms. Higher levels of 10t-18:1, 7t9c-18:2, 9t11c-18:2 and 10t12c-18:2 were observed in the commercial sheep meat, which reflected the poorer quality diets of these sheep compared to those from the three farms, which consistently showed higher levels of 11t-18:1, 9c11t-18:2 and 11t13c-18:2. In the second study, sheep were provided with supplements during the spring and summer grazing season, which contributed to higher levels of 11t-18:1 and 9c11t-18:2. The farm that provided a small amount of supplements during the spring had the better lipid profile at both time periods. The polyunsaturated fatty acid (PUFA) content was higher in the meat from Sarda sheep from the three farms than in the meat from those sheep obtained from commercial slaughter operations. The plasmalogenic lipid content ranged from 2 to 3% of total lipids, the alk-1-enyl ethers consisted mainly of saturated and monounsaturated moieties, and the trans-18:1 profile was similar to that of the FA. The n-6 (6-8%) and n-3 PUFA (2-3%) contents, the n-6/n-3 ratio (3:1), as well as the saturated fatty acid (SFA) content (42-45%) and the SFA to PUFA ratio (4:1 to 5:1) of the Sarda sheep from the three farms were comparable to sheep meat lipids found in similar commercial operations in Europe. Inclusion of small amounts of supplements for the grazing Sarda sheep resulted in improved quality of sheep meat lipids.

Comparing subcutaneous adipose tissue in beef and muskox with emphasis on trans 18:1 and conjugated linoleic acids.

Muskox (Ovibos moschatus) are ruminant animals native to the far north and little is known about their fatty acid composition. Subcutaneous adipose tissue (backfat) from 16 wild muskox was analyzed and compared to backfat from 16 barley fed beef cattle. Muskox backfat composition differed substantially from beef and the most striking difference was a high content of 18:0 (26.8 vs. 9.77%). This was accompanied by higher levels of most other saturated fatty acids except beef had more 16:0. Muskox backfat also had a lower level of cis-18:1 and this was related to a lower expression of steroyl-CoA desaturase mRNA. Beef backfat had a higher level of total trans-18:1 (4.25 vs. 2.67%). The most prominent trans-18:1 isomers in beef backfat were 10t-18:1 (2.13%) and 11t-18:1 (0.77%) whereas the most prominent isomers in muskox backfat were 11t-18:1 (1.41%), 13t/14t- (0.27%) and 16t-18:1 (0.23%). The total conjugated linoleic acid (CLA) content was higher in beef backfat than muskox (0.67 vs. 0.50%) with 9c,11t-18:2 as the most abundant CLA isomer. The second most abundant CLA isomer in beef backfat was 7t,9c-18:2 (0.10%) whereas in muskox it was 11t13c-18:2 (0.04%). Muskox backfat had a higher content of 18:3n-3 and its elongation and desaturation products 20:5n-3, 22:5n-3 and 22:6n-3 and a lower n-6/n-3 ratio. Overall, the high forage diet of muskox seemed to produce a healthier fatty acid profile and highlighted the need to develop feeding strategies for intensively raising beef that will not negatively impacting fatty acid composition.

An assessment of the fatty acid composition of horse-meat available at the retail level in northern Spain.

The objective of the present study was to assess the fatty acid composition of horse-meat available at the retail market in northern Spain. Horse steaks (Longissimus thoracis et lumborum muscle; n=82) were purchased from butcher-shops and large grocery stores throughout six northern regions of Spain in two different seasons. Fat content differed significantly among regions (1.12 to 2.77%). Samples with higher intramuscular fat content presented the highest percentages of total monounsaturated fatty acids and the lowest contents of dimethylacetal and polyunsaturated fatty acids (PUFA), while the opposite was found in the leanest samples. A high variability was observed in the muscle and subcutaneous n-3 PUFA content. Overall, total n-3 PUFA content ranged between 1.17% and 18.9% in muscle fat and between 1.52% and 27.9% in backfat. Interestingly, almost 5% of surveyed loins from horse carcasses (4 out of 82) contained over 300mg of linolenic acid per 100g of meat which could have been marketed as a "source" of n-3 FAs according to Commission Regulation (EU) No 116/2010.

First Application of Newly Developed FT-NIR Spectroscopic Methodology to Predict Authenticity of Extra Virgin Olive Oil Retail Products in the USA.

Economically motivated adulteration (EMA) of extra virgin olive oils (EVOO) has been a worldwide problem and a concern for government regulators for a long time. The US Food and Drug Administration (FDA) is mandated to protect the US public against intentional adulteration of foods and has jurisdiction over deceptive label declarations. To detect EMA of olive oil and address food safety vulnerabilities, we used a previously developed rapid screening methodology to authenticate EVOO. For the first time, a recently developed FT-NIR spectroscopic methodology in conjunction with partial least squares analysis was applied to commercial products labeled EVOO purchased in College Park, MD, USA to rapidly predict whether they are authentic, potentially mixed with refined olive oil (RO) or other vegetable oil(s), or are of lower quality. Of the 88 commercial products labeled EVOO that were assessed according to published specified ranges, 33 (37.5%) satisfied the three published FT-NIR requirements identified for authentic EVOO products which included the purity test. This test was based on limits established for the contents of three potential adulterants, oils high in linoleic acid (OH-LNA), oils high in oleic acid (OH-OLA), palm olein (PO), and/or RO. The remaining 55 samples (62.5%) did not meet one or more of the criteria established for authentic EVOO. The breakdown of the 55 products was EVOO potentially mixed with OH-LNA (25.5%), OH-OLA (10.9%), PO (5.4%), RO (25.5%), or a combination of any of these four (32.7%). If assessments had been based strictly on whether the fatty acid composition was within the established ranges set by the International Olive Council (IOC), less than 10% would have been identified as non-EVOO. These findings are significant not only because they were consistent with previously published data based on the results of two sensory panels that were accredited by IOC but more importantly each measurement/analysis was accomplished in less than 5 min.

Effects of conjugated linoleic acid (CLA) isomers on oxygen diffusion-concentration products in liposomes and phospholipid solutions.

Conjugated linoleic acids (CLAs) are a group of octadecadienoic acids (18:2) that are naturally present in food products and may have beneficial health effects. Liposomes and ethanol solutions were prepared by mixing synthetic phosphatidylcholines (PCs) with c9,t11-CLA, t10,c12-CLA, and linoleic acid (LA) in the sn-2 position into natural PCs from soybean, egg yolk, rat brain, and rat heart at 5 mol %. The oxygen diffusion-concentration products were measured using electron spin resonance spin-label oximetry methods. Individual synthetic PCs, the phospholipid matrix, and the tested lipid systems all exhibited influence on oxygen diffusion-concentration products during lipid peroxidation. Incorporating 5 mol % PC(c9,t11-CLA) into soy and egg yolk PC increased oxygen consumption in liposome suspensions while it was decreased in rat heart and brain PCs. On the other hand, PC(t10,c12-CLA) increased oxygen consumption in mixtures with egg yolk and rat heart PC but decreased it in soybean and rat brain PC. By comparison, PC(LA) decreased oxygen consumption in every case. In ethanol solutions, all of the synthetic PCs suppressed the capacity to generate peroxide radicals in the order of LA > c9,t11-CLA > t10,c12-CLA. In addition, PCs containing individual CLA isomers and LA differed in their capacities to react with and quench DPPH radicals in both ethanol solution and liposome, suggesting differences between CLA isomers and LA in DPPH radical-fatty acid interactions. Incorporation of CLA isomers and LA into dimyristyl-PC reduced the phase transition temperature from 23.6 to 23.1 and 23.3 degrees C, respectively. The results of this study provide evidence that the behavior of CLA isomers differs in the microenvironment of membranes possibly due to structural differences that affect the permeability of membranes to oxygen and lipid peroxidation.

Developing FT-NIR and PLS1 Methodology for Predicting Adulteration in Representative Varieties/Blends of Extra Virgin Olive Oils.

It was previously demonstrated that Fourier transform near infrared (FT-NIR) spectroscopy and partial least squares (PLS1) were successfully used to assess whether an olive oil was extra virgin, and if adulterated, with which type of vegetable oil and by how much using previously developed PLS1 calibration models. This last prediction required an initial set of four PLS1 calibration models that were based on gravimetrically prepared mixtures of a specific variety of extra virgin olive oil (EVOO) spiked with adulterants. The current study was undertaken after obtaining a range of EVOO varieties grown in different countries. It was found that all the different types of EVOO varieties investigated belonged to four distinct groups, and each required the development of additional sets of specific PLS1 calibration models to ensure that they can be used to predict low concentrations of vegetable oils high in linoleic, oleic, or palmitic acid, and/or refined olive oil. These four distinct sets of PLS1 calibration models were required to cover the range of EVOO varieties with a linoleic acid content from 1.3 to 15.5 % of total fatty acids. An FT-NIR library was established with 66 EVOO products obtained from California and Europe. The quality and/or purity of EVOO were assessed by determining the FT-NIR Index, a measure of the volatile content of EVOO. The use of these PLS1 calibration models made it possible to predict the authenticity of EVOO and the identity and quantity of potential adulterant oils in minutes.

Characterization of the fatty acid composition of lamb commercially available in northern Spain: Emphasis on the trans-18:1 and CLA content and profile.

A survey of commercially available lamb meat was performed in northern Spain in order to evaluate their fatty acid (FA) composition with emphasis on trans fatty acid (TFA) and conjugated linoleic acid (CLA) isomers. Samples were collected in spring (n=24) and winter (n=24) of 2013, and were obtained in about equal numbers from grocery stores and butcher-shops. Subcutaneous fat, known to be a sensitive indicator of TFA content in ruminants, was analyzed by GC-FID. In general, very few differences were observed between collection periods and type of stores because of the high variability within the groups that was believed to be associated with differences in genetics and feeding strategies. However, the 10t/11t ratio of all samples showed two clearly identifiable groups irrespective of the source: 1) when 10t/11t was >1, 10t-shifted samples; 2) when 10t/11t was ≤1, non-shifted samples where 11t-18:1 was the predominant isomer. These two groups were clearly identified and associated with distinct FAs using principal component analysis.

Effects of lipid-esterified conjugated linoleic acid isomers on platelet function: evidence for stimulation of platelet phospholipase activity.

The effects of four conjugated linoleic acid (CLA) isomers on in vitro collagen-induced human platelet aggregation and thromboxane (TXB(2), the inactive metabolite of the proaggregatory TXA(2)) production were examined. As the free fatty acid (FFA), 9t, 11t-CLA was the most effective inhibitor of these two processes (I(50)s of 2.2 and 4 microM, respectively) and the 9c, 11c-CLA was the least effective (I(50)s of 8.3 and 37 microM) of the isomers tested. When platelets were preesterified with either 25 microM 9t, 11t-CLA or 9c, 11c-CLA, CLA incorporation in total platelet lipids increased from 0.24% to 0.31% and 0.38%, and most of this increase was found to be in the phosphatidyl choline and phosphatidyl ethanolamine subclasses. The decrease in arachidonic acid (AA) content in total fatty acids or phospholipids was an order of magnitude greater. Furthermore, no significant differences between platelets prelabeled with either 9t, 11t- or 9c, 11c-CLA in the inhibition of collagen-induced aggregation and TXB(2) formation were observed. However, platelets prelabeled with 9c, 11c-CLA stimulated basal TXB(2) production (4-fold) which was not observed with platelets pretreated with either 9t, 11t-CLA, linoleic acid or stearic acid. This enhancement was associated with a 2.4-5-fold increase in the release of endogenous AA. Our results suggest that the presence of a conjugated cis, cis double bond appears to change the lipid environment sufficiently to stimulate the basal platelet phospholipase activity, which in turn increases the formation of TXB(2).

A rapid method for the quantification of fatty acids in fats and oils with emphasis on trans fatty acids using Fourier Transform near infrared spectroscopy (FT-NIR).

A rapid method was developed for classifying and quantifying the FA composition of edible oils and fats using Fourier Transform near infrared spectroscopy (FT-NIR). The FT-NIR spectra showed unique fingerprints for saturated FA, cis and trans monounsaturated FA, and all n-6 and n-3 PUFA within TAG to permit qualitative and quantitative comparisons of fats and oils. The quantitative models were based on incorporating accurate GC data of the different fats and oils and FT-NIR spectral information into the calibration model using chemometric analysis. FT-NIR classification models were developed based on chemometric analyses of 55 fats, oils, and fat/oil mixtures that were used in the identification of similar materials. This database was used to prepare three calibration models-one suitable for the analysis of common fats and oils with low levels of trans FA, and the other two for fats and oils with intermediate and high levels of trans FA. The FT-NIR method showed great potential to provide the complete FA composition of unknown fats and oils in minutes. Compared with the official GC method, the FT-NIR method analyzed fats and oils directly in their neat form and required no derivatization of the fats to volatile FAME, followed by time-consuming GC separations and analyses. The FT-NIR method also compared well with the official FTIR method using an attenuated total reflectance (ATR) cell; the latter provided only quantification of specific functional groups, such as the total trans FA content, whereas FT-NIR provided the complete FA profile. The FT-NIR method has the potential to be used for rapid screening and/or monitoring of fat products, trans FA determinations for regulatory labeling purposes, and detection of contaminants. The quantitative FT-NIR results for various edible oils and fats and their mixtures are presented based on the FT-NIR models developed.

Horse-meat for human consumption - Current research and future opportunities.

The consumption of horse-meat is currently not popular in most countries, but because of its availability and recognized nutritional value consumption is slowly increasing in several western European countries based on claims that it could be an alternative red meat. In this review, horse-meat production, trade and supply values have been summarized. In addition, the advantage of horse production is noted because of its lower methane emissions and increased uptake, particularly of n-3 polyunsaturated fatty acids (PUFAs), which is based on its digestive physiology. Of particular interest in this review is the unique fatty acid composition of horse-meat with its high level of the nutritionally desirable PUFAs in both the adipose and muscle fat. Because of its large frame size and digestive physiology, the horse can be considered an alternative to bovine meat, with large advantages regarding the maintenance of less favored mountain grazing areas and its facility to transfer PUFA from feed to meat.

Novel, Rapid Identification, and Quantification of Adulterants in Extra Virgin Olive Oil Using Near-Infrared Spectroscopy and Chemometrics.

A new, rapid Fourier transform near infrared (FT-NIR) spectroscopic procedure is described to screen for the authenticity of extra virgin olive oils (EVOO) and to determine the kind and amount of an adulterant in EVOO. To screen EVOO, a partial least squares (PLS1) calibration model was developed to estimate a newly created FT-NIR index based mainly on the relative intensities of two unique carbonyl overtone absorptions in the FT-NIR spectra of EVOO and other mixtures attributed to volatile (5280 cm(-1)) and non-volatile (5180 cm(-1)) components. Spectra were also used to predict the fatty acid (FA) composition of EVOO or samples spiked with an adulterant using previously developed PLS1 calibration models. Some adulterated mixtures could be identified provided the FA profile was sufficiently different from those of EVOO. To identify the type and determine the quantity of an adulterant, gravimetric mixtures were prepared by spiking EVOO with different concentrations of each adulterant. Based on FT-NIR spectra, four PLS1 calibration models were developed for four specific groups of adulterants, each with a characteristic FA composition. Using these different PLS1 calibration models for prediction, plots of predicted vs. gravimetric concentrations of an adulterant in EVOO yielded linear regression functions with four unique sets of slopes, one for each group of adulterants. Four corresponding slope rules were defined that allowed for the determination of the nature and concentration of an adulterant in EVOO products by applying these four calibration models. The standard addition technique was used for confirmation.

Conjugated linoleic acid pork research.

The driving force behind most conjugated linoleic acid (CLA) research in swine has been related to potential improvements in animal production. Early work that used rodent models indicated that feeding CLA could potentially reduce body fat, increase lean content, increase growth rate, and improve feed conversion efficiency. Producer-backed funding organizations were, therefore, receptive to proposals to extend this research to pigs, and many studies have been completed worldwide. In general, improvements in body composition were found, but evidence indicating that CLA improves growth rate or feed conversion was limited. Inclusion of CLA into pig diets was, however, shown to increase muscle marbling fat and fat hardness, and both of these characteristics have the potential to increase carcass value. Currently, Badische Anilin- & Soda-Fabrik AG (BASF) has the international marketing license to include synthetic CLA in animal feeds, but to date this practice is not approved in Canada or the United States. If and when approval is granted, the next step in realizing CLA's economic potential would be to seek approval for claiming CLA enrichment in pork and pork products. Given the ability of swine to accumulate relatively high amounts of CLA in their tissues, pork and pork products could become an important vehicle for delivery of physiologically significant amounts of CLA to consumers.

Analysis of conjugated linoleic acid and trans 18:1 isomers in synthetic and animal products.

The chemistry of conjugated fatty acids, specifically octadecadienoic acids (18:2; commonly referred to as conjugated linoleic acid, or CLA), has provided many challenges to lipid analysts because of their unique physical properties and the many possible positional and geometric isomers. After the acid-labile properties of CLAs during analytic procedures were overcome, it became evident that natural products, specifically dairy fats, contain one dominant (c9,t11-CLA), 3 intermediate (t7,c9-, t9,c11-, and t11,c13-CLA), and up to 20 more minor CLA isomers. The best analytic techniques to date include a combination of gas chromatography that uses 100-m highly polar capillary columns, silver ion-HPLC, and a combination of silver ion-thin-layer chromatography and gas chromatography to analyze the CLA and trans 18:1 isomers, because some of them serve as precursors of CLA in biological systems. These analytic techniques have assisted commercial suppliers to prepare pure CLA isomers and have permitted the evaluation of individual CLA isomers for their nutritional and biological activity in animal and human systems. It is increasingly evident that different CLA isomers have distinctly different physiologic and biochemical properties. These techniques are essential to evaluate dairy fats for their CLA content, to design experimental diets to increase the amount of CLA in dairy fats, and to determine the CLA profile in these CLA-enriched dairy fats. These improved techniques are used to evaluate the CLA profile in pork products from pigs fed different commercial CLA mixtures.