Comparison of fatty acid composition of domestic and imported margarines and frying fats in Bulgaria

A total of 82 dietary fats sold on the Bulgarian market in the period 1995—2000 were analyzed. The samples included 68 table margarines (50 of which were imported), 10 frying fats (6 imported) and 4 salad dressings (all imported). A validated analytical method, thin‐layer chromatography‐AgNO₃‐densitometry, was used. It enabled direct determination of all fatty acid groups, differing by degree of unsaturation and double bonds geometry. Low levels of trans fatty acids (TFA) down to 0.1% of the total for mono trans‐trienoic (Tcct) and mono trans‐dienoic (Dct), and down to 0.2% for trans‐monoenoic (Mt) were quantitated, with an error under 3% and a standard deviation of 0.1—1.5. The total content of TFA in table margarines varied from 0 to 26.9% with a mean value of 8.6 ± 7.2% for imported and 1.6 ± 3.4% for Bulgarian samples. Saturated fatty acids (SFA) content varied from 11.5 to 45.7%, with a mean value of 25.4 ± 5.7% for imported and 26.9 ± 5.2% for Bulgarian margarines. A general trend of lower levels of TFA and SFA in imported margarines was observed over the studied period. Additionally, the content of individual saturated fatty acids was determined by gasliquid chromatography in 37 of all studied samples.     

Determination of fatty acids and some undesirable fatty acid isomers in selected Turkish margarines

The fatty acid composition and total trans fatty acid content in 10 margarines produced in Turkey were determined by capillary gas chromatography and Fourier transform‐infrared spectroscopy (FT‐IR) spectroscopy. The fatty acid composition ranged as follows: saturated fatty acids, C16:0 (palmitic) 11.3 to 31.8% and C18:0 (stearic) 5.7 to 8.7%, monounsaturated fatty acids, C18:1 (oleic) 21.8 to 35.7% and C18:1 trans isomers 0.4 to 27.4%, polyunsaturated fatty acid, C18:2 linoleic acid 5.2 to 40.2%. Some positional isomers of C18:1 as cis‐11‐octadecenoic acid varied from 0.7 to 4.6% and cis‐13 trace to 2.4%. The total trans fatty acid contents were between 0.9 and 32.0% when measured with capillary gas chromatography and between 0 and 30.2% with FT‐IR spectroscopy. Some of the margarines analyzed contained trace amount of trans fatty acids which could not be detected by FT‐IR spectroscopy.     

Determination of trans fatty acids and fatty acid profiles in margarines marketed in spain

Two gas chromatography (GC) procedures were compared for routine analysis of trans fatty acids (TFA) of vegetable margarines, one direct with a 100-m high-polarity column and the other using argentation thin-layer chromatography and GC. There was no difference (P>0.05) in the total trans 18∶1 percentage of margarines with a medium level of TFA (∼18%) made using either of the procedures. Both methods offer good repeatability for determination of total trans 18∶1 percentage. The recoveries of total trans isomers of 18∶1 were not influenced (P>0.1) by the method used. Fatty acid composition of 12 Spanish margarines was determined by the direct GC method. The total contents of trans isomers of oleic, linoleic, and linolenic acids ranged from 0.15 to 20.21, from 0.24 to 0.99, and from 0 to 0.47%, respectively, and the mean values were 8.18, 0.49, and 0.21%. The mean values for the ratios [cis-polyunsaturated/(saturated +TFA)] and [(cis-polyunsaturated + cis-monounsaturated)/(saturated +TFA)] were 1.25±0.39 and 1.92±0.43, respectively. Taking into account the annual per capita consumption of vegetable margarine, the mean fat content of the margarines (63.5%), and the mean total TFA content (8.87%), the daily per capita consumption of TFA from vegetable margarines by Spaniards was estimated at about 0.2 g/person/d.     

Gas chromatographic separation of the fatty acid methyl esters prepared from dairy products,partially hydrogenated oils,and refined vegetable oils applying a negative temperature gradient

To date no single gas chromatographic method can simultaneously measure all fatty acids (FA), including trans-FA (TFA), that are contained in dairy products, partially hydrogenated oils (PHO), and refined vegetable oils. Using 100% poly(biscyanopropyl siloxane) capillary columns, ruminant and dairy fats are preferentially analyzed by applying temperature programs that separate short chain FA, but not trans-18:3 from 20:1. Refined vegetable oils and PHO are preferentially analyzed by applying isothermal elutions that provide quantification of all 18 carbon TFA including trans-18:3 FA, but not of all short chain FA. In this short communication, we propose a temperature program method capable of simultaneously measuring short chain FA and all 18 carbon TFA including trans-18:3 by applying a negative temperature gradient after the elution of trans-18:1. A simplified version of the method is also described for equipment not able to perform negative temperature gradients.     

Interference effects from coexisting fatty acids on elaidic acid separation by fractionating crystallization: A model study

A multi‐stage temperature‐programmed fractionating crystallization process was carried out to examine the effects of the presence of stearic acid (SA), oleic acid (OA), and linoleic acid (LA) on the separation of elaidic acid (EA). The results showed that the efficiency of fractionating crystallization of EA depended largely on the crystallization temperature, initial concentration of EA and presence of SA. The content of SA plays very important role for the fractionating performance. It was a characteristic observation that only when SA <2%, substantial crystallization of EA (>50% in stepwise crystal fractions) were obtained regardless of the initial concentration of SA. In general, SA induced crystallization of EA in earlier stage but delayed further crystallization of EA in later stage; the crystallization of EA was independent from co‐existing OA and LA. After reduction of EA content in solution to certain extent (7–10%, at ?20°C), further reduction of EA content requires much lower crystallization temperatures (trans‐fatty acids (TFA) from partially hydrogenated soybean oil (PHSO) is of high commercial interest. One of the strategies is to selectively release TFAs as free fatty acids from PHSO enzymatically. However, all commercially available enzymes are far away from qualified to selectively release TFAs, where there are always substantial non‐trans FAs hydrolyzed simultaneously. Therefore, developing post‐processing technology is requisite in order to recover those non‐trans fatty acids. Thus, this model system was designed based on FA composition characteristic of PHSO, which aimed to acquire some basic data and experience that lack in available literatures, so as to serve designing efficient practical process for removing trans‐fatty acid moieties from PHSO. The results from this work may be of general value to achieve a better understanding of fractionating crystallization behaviors of different FAs, relationship with individual molecular feature and property, and their interference effects, which might contribute to the design of practically feasible protocol to remove TFAs from PHSO and recover non‐trans FAs at the same time.     

Chemical and physical properties of the solid fats in commercial soft margarines

The fats of ten Canadian soft margarines were crystallized from acetone at 15°C to obtain the high-melting glycerides (HMG). The solid fats in the margarines were extracted with isboutanol at 5°C. X-ray diffraction showed that the canola margarines were in the β crystal form, the soybean and sunflower-palm-palm kernel margarines in the β′ form, while those of canola-palm and another sunflower-palm-palm kernel margarines contained a mixture of β′ and β forms. X-ray diffraction of the isolated solids showed additional short spacings compared with those of the original margarines. Differential scanning calorimetry heating curves of the solids were compared with those of the HMG. The melting temperatures of the HMG were 10°C higher than the solids. It is suggested that the polymorphic behavior of soft margarines is related to the chemical composition of the HMG and the solids. Solids in margarines can also be provided by interesterification of palm oil products. Presented at the Annual Meeting, Canadian section of AOCS, October 18–19, 1990, Toronto, Canada.     

Chemical composition and physical properties of soft (tub) margarines sold in Malaysia

Seven samples of domestic and imported Malaysian tub margarines were analyzed for their fatty acid and triglyceride (carbon number) composition, solid fat content, dropping and softening points, crystallization temperature, polymorphic form, color, and textural attributes. Domestic margarines were formulated from palm oil or palm olein and palm kernel oil with a liquid oil but no hydrogenated oils. Two imported products contained hydrogenated palm oil product, which resulted in a high level of β′ crystals, whereas the domestic nonhydrogenated products contained more β than β′ crystals. Crystal habit was related to the fatty acid and triglyceride composition of the high-melting glycerides. Domestic products were firmer in texture, probably because they were formulated to be sold in a tropical climate.     

Fatty acid composition and contents of trans monounsaturated fatty acids in frying fats, and in margarines and shortenings marketed in Denmark

This study examined trans monounsaturated fatty acid contents in all margarines and shortenings marketed in Denmark, and in frying fats used by the fast-food restaurants Burger King and McDonald’s. Trans C_18:1 content was 4.1±3.8% (g per 100 g fatty acids) in hard margarines, significantly higher than the content in soft margarines of 0.4±0.8%. Shortenings had an even higher content of trans C_18:1, 6.7±2.3%, than the hard margarines. Margarines and shortenings with high contents of long-chain fatty acids had about 20% total trans monoenoic of which close to 50% were made up of trans long-chain fatty acids. Both fast-food frying fats contained large amounts of trans C_18:1, 21.9±2.9% in Burger King and 16.6±0.4% in McDonald’s. In Denmark the per capita supply of trans C_18:1 from margarines and shortenings and frying fats has decreased steadily during recent years. The supply of trans C_18:1 from margarines and shortenings in the Danish diet is now 1.1 g per day.     

Fatty acid composition and contents of trans monounsaturated fatty acids in frying fats, and in margarines and shortenings marketed in Denmark

This study examined trans monounsaturated fatty acid contents in all margarines and shortenings marketed in Denmark, and in frying fats used by the fast-food restaurants Burger King and McDonald’s. Trans C_18:1 content was 4.1±3.8% (g per 100 g fatty acids) in hard margarines, significantly higher than the content in soft margarines of 0.4±0.8%. Shortenings had an even higher content of trans C_18:1, 6.7±2.3%, than the hard margarines. Margarines and shortenings with high contents of long-chain fatty acids had about 20% total trans monoenoic of which close to 50% were made up of trans long-chain fatty acids. Both fast-food frying fats contained large amounts of trans C_18:1, 21.9±2.9% in Burger King and 16.6±0.4% in McDonald’s. In Denmark the per capita supply of trans C_18:1 from margarines and shortenings and frying fats has decreased steadily during recent years. The supply of trans C_18:1 from margarines and shortenings in the Danish diet is now 1.1 g per day.     

Effect of grass vs. concentrate feeding on the fatty acid profile of different fat depots in lambs

The aim of this study was to produce high‐quality meat from lambs under different feeding conditions, as measured by the accumulation of n‐3 fatty acids and conjugated linoleic acids (CLA) in muscle and subcutaneous fat. In total, 13 male crossbred lambs (Black Head×Gotland), each at 24 kg live weight, were divided into two feeding groups. Lambs were kept either on pasture (pasture grazing, n = 6) or in the stable (concentrate feeding, n = 7). The linolenic acid (C18:3n‐3) contained in the grass was absorbed and deposited into the different lipid classes of muscle and subcutaneous fat. The proportion of total n‐3 fatty acids in the different lipids of grazing lambs was significantly (p = 0.05) higher compared to that in concentrate‐fed lambs. The n‐6/n‐3 ratio (mean ± SEM) in muscle of grazing lambs was 1.2 ± 0.09 in contrast to 2.3 ± 0.09 (p = 0.05) of the animals kept in the stable. In subcutaneous fat, this ratio was 0.9 ± 0.2 in lambs kept on pasture versus 3.5 ± 0.2 (p = 0.05) after indoor keeping. The relative concentration of C18:1trans‐11 in total muscle lipids, phospholipids, triacylglycerols and subcutaneous fat was significantly increased by grass feeding compared to concentrate feeding. Significant influences of feeding were shown for saturated fatty acids. In concentrate‐fed lambs, a lower content of saturated fatty acids was detected. The proportion of CLAcis‐9,trans‐11 (1.9 ± 0.2% vs. 1.1 ± 0.1% in muscle, 2.5 ± 0.2% vs. 1.4 ± 0.2% in subcutaneous fat, 0.7 ± 0.04% vs. 0.4 ± 0.04% in phospholipids) in lambs was significantly (p = 0.05) higher after grazing than after concentrate feeding, respectively.     

Trans fatty acids in margarines marketed in Brazil: Content,labeling regulations and consumer information

A set of 46 different trademarks of margarines produced in Brazil by eight different companies was investigated in terms of the national labeling requirements for trans fatty acids (TFA). Experimental measurements of the content of total saturated fatty acids, cis‐monounsaturated fatty acids, cis‐polyunsaturated fatty acids and total TFA by gas chromatography showed the reliability of the data listed on the nutrition facts panel, which were used as reference for this analysis. The results revealed that 50% of the manufacturers and 13% of all the investigated trademarks of margarines violated the current Brazilian labeling regulations. A group of 200 consumers categorized by age, sex and years of formal education was also questioned about the importance of nutrition labeling information and TFA. Approximately 33% of the consumers interviewed were not informed about the possible detrimental effects of TFA on human health. Individuals with longer years of formal education and those affected by coronary heart diseases attributed to the intake of TFA were most interested in reading the nutrition labeling.     

Hydrolysis of fatty acid esters in subcritical water

Hydrolysis of esters of higher fatty acids by subcritical water, performed in a flow‐through tubular reactor, was investigated at temperatures from 280 up to 340 °C and pressures exceeding 12 MPa, using an ester/water ratio of 1 : 2 or 1 : 4 (vol/vol). The kinetics of the hydrolysis of both the triacylglycerols and the methyl esters obeyed the rate equation valid for first‐order reactions. Conversion of the esters to free fatty acids exceeding 95% was reached at the temperature of 340 °C during 12 min. IR spectroscopy revealed structural changes in the chains of the unsaturated fatty acids and their partial polymerization during the hydrolysis.     

13C nuclear magnetic resonance spectroscopic analysis of the triacylglycerol composition of some margarines

The triacylglycerol fraction of three samples of margarine, namely “Flora” (Holland), “Kaliakra” (Bulgaria), and “Corona” (Holland), were studied by¹³C nuclear magnetic resonance spectroscopy. By examining the various carbon chemical shifts of the saturated and unsaturated carbon nuclei, “Flora” margarine was shown to contain a mixture of hydrogenated and unhydrogenated vegetable oils. This technique allowed all major acyl groups (saturated, oleate, linoleate, and linolenate) and minor acyl components [different positional isomers of long-chain (E)- and (Z)-monoenoic moieties, arising as by-products during catalytic hydrogenation] to be identified. The amount of each fatty acid present in the margarine was also estimated from the relative intensities of the corresponding signals. “Kaliakra” margarine consisted of a blend of unhydrogenated natural fats and oils that contained saturated fatty acids, oleate, and linoleate. There were no signs in the spectrum of “Kaliakra” of any (E)-isomers, nor signals associated with positional unsaturated acyl groups (other than oleate and linoleate). The sample of “Corona” margarine consisted of a mixture of hydrogenated and unhydrogenated vegetable oils and butter (1.3%). The presence of butter in this sample was identified by the characteristic carbon shifts of the C-1 to C-4 carbon atoms of butyrate. The distribution of the fatty acids on the glycerol “backbone” also was estimated by this technique.     

Intake of ruminant versus industrial trans fatty acids and risk of coronary heart disease – what is the evidence?

Several studies have reported a positive association between intake of trans fatty acids and risk of heart disease. It has been suggested that trans fatty acids from ruminant sources are less detrimental than trans fatty acids from industrial sources. Legislation or advice on limiting trans fatty acids has, in some instances, been restricted to trans fatty acids from industrial sources. However, comparisons of ruminant and industrial trans fatty acids have been based on few studies using relative intake data (e.g. quintiles of intakes). Therefore, we have reviewed data describing the associations between absolute intake (g eaten per day) of ruminant and industrial trans fatty acids and risk of coronary heart disease, and examined the associations graphically. Where direct comparison is possible, there are no differences in risk of coronary heart disease between total, ruminant and industrial trans fatty acids for intakes up to 2.5 g/d. At higher intakes (more than 3 g/d) total and industrial trans fatty acids are associated with an increased risk of coronary heart disease but there is insufficient data available on ruminant trans fatty acids at this level of intake. The scarce data do not support discrimination between ruminant and industrial trans fatty acids in dietary recommendations or legislation.     

Geometrical isomerisation of double bonds in acid‐catalysed preparation of fatty acid methyl esters

Acid‐catalysed methylation is frequently applied for the preparation of fatty acid methyl esters used for gas chromatographic analysis of fatty acids. A series of artefacts were observed in hydrochloric acid‐catalysed direct methylation of herring (Clupea harengus L.) muscle. The artefacts were identified as trans isomers of eicosapentaenoic and docosahexaenoic acid, and their levels increased with reaction time. The isomers were not found after methylation of a lipid extract of the herring muscle, even after extreme reaction times. In general, the trans isomers are only observed after methylation of certain marine tissues, indicating catalytic activity in these samples. Based on these results, it is recommended that direct methylation procedures are thoroughly validated with each matrix type analysed, and that reaction times should not be longer than necessary to complete the methylation.     

Liquid chromatographic-mass spectrometric analysis of conjugated diene fatty acids in a partially hydrogenated fat

A commercially available partially hydrogenated fat was analyzed for fatty acids containing conjugated dienes. The fatty acids were isolated by high-performance liquid chromatography (HPLC), and analyzed with a photodiode array detector and an atmospheric-pressure ionization mass spectrometer. Conventional and second-derivative ultraviolet (UV) spectra of the peaks eluting from the HPLC were recorded with the photodiode array detector, and peaks displaying second-derivative UV spectra characteristic of the conjugated diene chromophore were analyzed by mass spectrometry. The UV and mass spectra of the fatty acids with conjugated dienes, present in the partially hydrogenated fat, were identical to those of reference preparations of linoleic acid isomers with conjugated dienes. The results obtained emphasize that care must be exercised in the interpretation of clinical and experimental data concerning the detection of conjugated dienes in tissues or body fluids of humans and experimental animals. The conjugated dienes may not reflect an ongoing process of lipid peroxidation, but may be of dietary origin.     

Dietary C18:1 trans fatty acids increase conjugated linoleic acid in adipose tissue of pigs

The effect of dietary C18:1 trans fatty acids on back fat composition in pigs was investigated with special emphasis on conjugated linoleic acids (CLA). A total of 12 × 4 siblings of Large White and Swiss Landrace breed were housed in groups and fattened from 22 to 103 kg live weight. Pigs were fed a control diet (barley, wheat, soybean meal) or experimental diets which consisted of the control diet with a 5% replacement of olein or stearin fractions of pork fat, or partially hydrogenated fat. The hydrogenated fat was rich in C18:1 trans fatty acids but contained only negligible amounts of CLA. In contrast olein and stearin fractions contained far less C18:1 trans fatty acids but some CLA. In the control diet no C18:1 trans fatty acids and only traces of CLA were detected. The partially hydrogenated fat led to the highest CLA content in back fat (0.44%). Intermediate amounts of CLA were measured in pigs fed the fractionated pork fat (0.22/0.23%). In pigs fed the control diet, also small amounts of CLA were detected. The results indicate that CLA may be produced by endogenous Δ9‐desaturation out of dietary trans vaccenic acid in pigs.     

The influence of dietary rumen‐protected linoleic acid on milk fat composition,spreadability of butter and energy balance in dairy cows

The aim of this study was to determine the effects of a diet supplemented with rumenprotected linoleic acids (C18:2) on the composition of milk fat and the energy balance of dairy cattle during the first 15 wk of lactation. The 32 Holstein‐Friesian cows were allotted in two treatment groups; in the experimental group one‐third of the starch (relative to the control group) was substituted with protected fat on an energy basis. Milk samples from all cows were collected weekly from week 2 to 15 postpartum (p.p.). To analyze the milk fat composition milk samples from 16 cows in each group were collected from week 6 and 7 as well as from week 13 and 14 p.p. and were mixed together, respectively. Triglyceride analysis demonstrated an extensive use of depot fat in both cow groups at the beginning of the lactation period. However, calculated energy balance, triglyceride composition and back fat thickness showed that the usual deficit of energy intake in early lactation was significantly shortened in the experimental group by three weeks. In comparison with the control group the content of the saturated fatty acids (FAs) C12, C14 and C16 in the experimental group decreased by 17.3% at 6 to 7 wk and by 19.2% at 13 to 14 wk. The stearic acid content of milk fat was increased by 25.9% at 6 to 7 wk and by 27.7% at 13 to 14 wk in the experimental group. The content of cis Δ9 oleic acid was increased by 21.6% at 6 to 7 and by 30.3% at 13 to 14 wk, while the C18:2 FA content was doubled as compared with the control group. Thus besides the increase of the trans‐C18:1 FA (TFA) content the nutritional value of fats could be improved using the experimental fat supplement. The TFA content still remained within the range of variation of natural milk fats. Additionally the experimental fat intake led to a number of desired effects; an increase in the content of conjugated linoleic acids (cis Δ9, transΔ11) by 55.9% (6 to 7 wk) and by 97.1% (13 to 14 wk p.p.), respectively, and a decrease in the cholesterol level. Further, the butyric acid content increased relatively by more than 20%. The addition of this fat resulted simultaneously in a changed triglyceride composition with increased C50, C52 and C54 contents. Thus a markedly improved spreadability of the resulting butter might be expected.     

反式脂肪酸测定方法的研究

简要介绍了反式脂肪酸(TFA)的生成途径及主要的食物来源,反式脂肪酸对人体健康的主要危害和影响,综述了反式脂肪酸的分析检测方法如气相色谱法、红外光谱法、Ag离子色谱技术、毛细管电泳法等,并比较了各种方法的优缺点。     

Plastic fats with zero trans fatty acids by interesterification of mango,mahua and palm oils

Speciality plastic fats with no trans fatty acids suitable for use in bakery and as vanaspati are prepared by interesterification of blends of palm hard fraction (PSt) with mahua and mango fats at various proportions. It was found that the interesterified samples did not show significant differences in solid fat content (SFC) after 0.5 or 1 h reaction time. The blends containing PSt/mahua (1:1) showed three distinct endotherms, indicating a heterogeneity of triacylglycerols (TG), the proportions of which altered after interesterification. The SFC also showed improved plasticity after interesterification. Similar results were observed with other blends of PSt/mahua (1:2). These changes in melting behavior are due to alterations in TG composition, as the trisaturated‐type TG were reduced and the low‐melting TG increased after interesterification. The blends containing PSt/mango (1:1) showed improvement in plasticity after interesterification, whereas those containing PSt/mango (2:1) were hard and showed high solid contents at higher temperature and hence may not be suitable for bakery or as vanaspati. The blends with palm and mahua oils were softer and may be suitable for margarine‐type products. The results showed that the blends of PSt/mahua (1:1, 1:2) and PSt/mango (1:1) after interesterification for 1 h at 80 °C showed an SFC similar to those of commercial hydrogenated bakery shortenings and vanaspati. Hence, they could be used in these applications in place of hydrogenated fats as they are free from trans acids, which are reported to be risk factors involved in coronary heart disease. For softer consistency like margarine applications, the blends containing palm oil and mahua oil are suitable.