Fatty acids including trans content of commercial bakery products manufactured in Spain.

Fifteen samples of the most common industrial bakery products sold in Spain were analyzed for their fatty acid composition. Saturated fatty acids occurred in the largest proportions in all samples (mean = 52.8%), followed by monounsaturated (mean = 23.5%) and polyunsaturated fatty acids (mean = 17.2%). A small percentage of trans fatty acids, which were found in all samples, showed a mean value of 5.7%. According to their fatty acid composition, that is, their saturated, monounsaturated, and polyunsaturated fatty acid contents, the statistical analysis (discriminant analysis) showed three groups of samples, suggesting that the fat incorporated in these samples was obtained from different sources.     

Influence of Cultivar and Environmental Conditions on the Triacylglycerol Profile of Hazelnut (Corylus avellana L.)

The oil of several hazelnut (Corylus avellana L.) samples was extracted and evaluated for their triacylglycerol (TAG) composition. Trials were conducted in two Portuguese localities (Vila Real and Felgueiras) during three consecutive years and involved a total of 19 cultivars. The samples were analyzed by reversed-phase high-performance liquid chromatography with evaporative light-scattering detection. Sample preparation was fast and simple, consisting only of the dissolution of the oil in acetone, homogenization, and filtration, allowing this technique to be suitable for routine analyses. All samples presented a similar qualitative profile composed of eleven compounds: LLL, OLL, PLL, OOL, POL, PPL, OOO, POO, PPO, SOO and PSO (P, palmitoyl; S, stearoyl; O, oleoyl; and L, linoleoyl). The main components were OOO, LOO, and POO, reflecting the high content of oleic acid in hazelnut oils. A total of 79 different samples were studied, and the obtained data were statistically analyzed. Significant differences were verified in canonical variate plots when cultivars were grouped by country of origin. In general, the American cultivars were richer in TAGs with saturated fatty acids moieties, and the group of French, German, and English cultivars was richer in TAGs containing linoleic acid moieties. Differences were also significant when cultivars were grouped by year of production, showing that besides genetic factors, the TAG composition can be influenced by environmental factors.     

Effects of roasting on hazelnut lipids

The effect of roasting on some nutritional characteristics of hazelnut lipidic fraction was investigated. Hazelnuts (Corylus avellana L.) were submitted to several different thermal treatments, comprising different temperatures (125-200 degrees C) and times of exposure (5, 15, and 30 min) and analyzed for their moisture and crude fat. Raw and roasted hazelnuts were also analyzed for their compositions in phytosterols and fatty acids (including trans isomers) by GC-FID, triacylglycerols by HPLC-ELSD, and tocopherols and tocotrienols by HPLC-DAD/fluorescence spectroscopy. Minor changes occurred in the fatty acid and triacylglycerol compositions. As temperatures and roasting periods increased, generally, a modest increase of oleic and saturated fatty acids and a decrease of linoleic acid, expressed as relative percentages, occurred. Similarly, an increase of triacylglycerols containing oleic acid moieties and a decrease of those containing linoleic acid moieties were found in the roasted samples. Roasting caused a modest decrease of the beneficial phytosterols (maximum 14.4%) and vitamin E homologues (maximum 10.0%) and a negligible increase of the trans fatty acids.     

Turkish Tombul hazelnut (Corylus avellana L.). 2. Lipid characteristics and oxidative stability

The quality of crude hazelnut oil extracted from Tombul (Round) hazelnut, grown in the Giresun province of Turkey, was determined by measuring lipid classes, fatty acids, and fat soluble bioactives (tocopherols and phytosterols). Oxygen uptake, peroxide value, thiobarbituric acid reactive substances, and alpha-tocopherol levels of stripped and crude hazelnut oils in bulk and oil-in-water (o/w) emulsion systems were also evaluated as indices of lipid oxidation over a 21 day storage period at 60 degrees C in the dark. The total lipid content of Tombul hazelnut was 61.2%, of which 98.8% were nonpolar and 1.2% polar constituents. Triacylglycerols were the major nonpolar lipid class and contributed nearly 100% to the total amount. Phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol were the most abundant polar lipids, respectively. Sixteen fatty acids were identified, among which oleic acid contributed 82.7% to the total, followed by linoleic, palmitic, and stearic acids. Unsaturated fatty acids accounted for 92.2% of the total fatty acids present. Among oil soluble bioactives, alpha-tocopherol (38.2 mg/100 g) and beta-sitosterol (105.5 mg/100 g) were predominant in hazelnut oil and comprised 88 and 93% of the total tocopherols and phytosterols present, respectively. The results also showed that both stripped and crude hazelnut oils were more stable in terms of lipid oxidation in the bulk oil as compared to those in an o/w emulsion.     

Study of the main constituents of some authentic hazelnut oils

This paper describes the composition of authentic hazelnut oils obtained from nuts collected from five countries that are major suppliers of hazelnut oil. Oils were analyzed using standard methods for fatty acids, fatty acids in the triacylglycerol 2-position, tocopherols and tocotrienols, triacylglycerols, sterols, steradienes, and iodine value. The results were generally in good agreement with those of other publications. Tocotrienols, previously unreported in hazelnut oil, were detected in one sample. There were no major differences in the composition of oils from different countries. Roasting the nuts prior to pressing had little effect on oil composition.     

Stereospecific analysis of phospholipid classes in skeletal muscle from rats fed different fat sources

The fatty acid (FA) and dimethylacetal profiles of the sn-1 and sn-2 positions of different phospholipid (PL) classes from skeletal muscle of rats as affected by dietary FA profiles were studied. Rats were fed either a control diet, an olive oil-enriched diet, or a sunflower oil-enriched diet. The FA composition of both positions of the studied PL classes was affected by diet to different extents. The FA composition of the sn-2 position of phosphatidylserine was the most influenced by diet, while phosphatidylinositol was less affected by dietary modification. The FA profile of phosphatidylcholine reflected consumed FA better than any other studied PL. Thus, olive oil rats showed higher oleic acid (C18:1 n-9) contents in both positions of phosphatidylcholine, and sunflower oil rats had higher proportions of arachidonic acid (C20:4 n-6) in the sn-1 position of this PL class. Dimethylacetals were scarcely affected by diet, and only the dimethylacetal composition of phosphatidylethanolamine showed significant modifications.     

Characterization of phospholipid molecular species in the edible parts of bony fish and shellfish

The phospholipid molecular species of freshwater (pangasius, Nile perch, trout), marine fish fillets (horse mackerel, European hake, common sole, European anchovy, European pilchard, Atlantic mackerel) and the edible muscle foot of bivalves (clam, mussel, oyster) commonly available in the Italian market during spring and summer were characterized by means of normal-phase high performance liquid chromatography coupled online with positive electrospray ionization ion-trap tandem mass spectrometry. From principal component analysis (PCA), it was observed that the total fatty acid profile was not suitable to differentiate among the shellfish genera. The fatty acid molecular combinations of phosphatidylcholine, the main phospholipid class, as well as phosphatidylinositol and phosphatidylethanolamine allowed for the differentiation of shellfish from the bony fishes. Phosphatidylserine and phosphatidylethanolamine plasmalogen profile allowed for the discrimination of each bony fish or shellfish genus since PS and pPE classes included a large number of fatty acid combinations that were specific for a fish genus or group.     

不同生长阶段墨瑞鳕脂肪酸组成及主成分分析

为比较不同生长阶段墨瑞鳕肌肉中脂肪酸组成的变化,本研究通过气相色谱技术测定墨瑞鳕幼鱼、成鱼、亲鱼肌肉中脂肪酸含量,并对脂肪酸组成进行主成分分析。结果表明,3个不同生长阶段墨瑞鳕的不饱和脂肪酸(UFA)总量分别为52.2%、58.2%、60.1%;在高度不饱和脂肪酸(HUFA)中DHA含量均最高。随着鱼体生长,墨瑞鳕棕榈油酸、油酸、亚油酸、亚麻酸含量均呈上升趋势,从高到低依次为亲鱼>成鱼>幼鱼;肉豆蔻酸、花生一烯酸、花生四烯酸、EPA、DHA 含量呈下降趋势,从高到低依次为幼鱼>成鱼>亲鱼;UFA总量和单不饱和脂肪酸(MUFA)含量呈上升趋势,从高到低依次为亲鱼>成鱼>幼鱼;多不饱和脂肪酸(PUFA)总量和必需脂肪酸(EFA)总量含量呈先升后降趋势,从高到低依次为成鱼>亲鱼>幼鱼。墨瑞鳕不同生长阶段脂肪酸含量大部分存在显著差异,特别是幼鱼与成鱼的脂肪酸含量(除二十碳三烯酸外)均存在显著差异;肉豆蔻酸、花生一烯酸、花生四烯酸、EPA和DHA等5种脂肪酸是墨瑞鳕的主要特征脂肪酸,这5种主要特征脂肪酸之间均互呈强正相关。随着墨瑞鳕的生长发育应及时提高相应阶段功能性脂肪酸的比例,降低相应阶段呈强负相关的主要特征脂肪酸的比例。本研究结果为墨瑞鳕的开发利用以及饲料营养需求等提供了理论参考。     

Formation and evolution of monoepoxy fatty acids in thermoxidized olive and sunflower oils and quantitation in used frying oils from restaurants and fried-food outlets

The formation and evolution of monoepoxy fatty acids, arising from oleic and linoleic acids, were investigated in olive oil and conventional sunflower oil, representatives of monounsaturated and polyunsaturated oils, respectively, during thermoxidation at 180 degrees C for 5, 10, and 15 h. Six monoepoxy fatty acids, cis-9,10- and trans-9,10-epoxystearate, arising from oleic acid, and cis-9,10-, trans-9,10-, cis-12,13-, and trans-12,13-epoxyoleate, arising from linoleic acid, were analyzed by gas chromatography after oil derivatization to fatty acid methyl esters. Considerable amounts, ranging from 4.29 to 14.24 mg/g of oil in olive oil and from 5.10 to 9.44 mg/g of oil in sunflower oil, were found after the heating periods assayed. Results showed that the monoepoxides quantitated constituted a major group among the oxidized fatty acid monomers formed at high temperature. For similar levels of degradation, higher contents of the monoepoxides were found in olive oil than in sunflower oil. Ten used frying oils from restaurants and fried-food outlets in Spain were analyzed to determine the contents of the monoepoxides in real frying oil samples. Levels ranged from 3.37 to 14.42 mg/g of oil. Results show that, for similar degradation levels, the monoepoxides were more abundant in the monounsaturated oils than in the polyunsaturated oils.     

Capillary electrophoresis of free fatty acids by indirect ultraviolet detection: application to the classification of vegetable oils according to their botanical origin

A method for the determination of fatty acids in vegetable oils by capillary electrophoresis with indirect UV-vis detection has been developed. The separation of fatty acids was optimized in terms of Brij surfactant nature and concentration and organic modifier (2-propanol) percentage. The optimal background electrolyte consisted of 10 mM p-hydroxybenzoate, 5 mM Tris at pH 8.8, 80 mM Brij 98, 40% acetonitrile, and 10% 2-propanol. Under these conditions, vegetable oils from five botanical origins (avocado, corn, extra virgin olive, hazelnut, and soybean) were analyzed and the fatty acid contents established. Linear discriminant analysis (LDA) models were constructed using fatty acid peak areas as predictors. An excellent resolution among all category pairs was obtained, and all samples were correctly classified with assignment probabilities of >95%.     

Diet alters the fatty acid composition of individual phospholipid classes in beef muscle

The objective of this study was to investigate the effect of diet on the distribution of phospholipid classes and fatty acid profiles of individual phospholipid classes in longissimus muscle of beef. An experiment was established to examine the effect of pasture-based versus concentrate diet offered to two different breeds (German Holstein and German Simmental bulls) to enhance the content of beneficial fatty acids in beef and improve the meat quality for the consumer. High-performance thin-layer chromatography was utilized to separate the phospholipid classes. The fatty acid composition of the individual phospholipid classes was determined by gas chromatography. The main phospholipid classes in the muscle were phosphatidylethanolamine and phosphatidylcholine, representing approximately 60% of the total phospholipids, followed by phosphatidylinositol ranging between 11.8 and 14.8%. The results have shown that the fatty acid profiles in the detected seven phospholipid classes can be affected by different feeding systems. Pasture-based feeding resulted in an enrichment of total and individual n-3 fatty acids in all phospholipid classes of muscle lipids of bulls compared with those fed on concentrate. In contrast, pasture-based diet significantly decreased the proportion of total and individual n-6 fatty acids in phospholipid classes, except in the sphingomyelin fraction. The total saturated fatty acid proportions in the phospholipid classes were different and ranged between 4.5% in the cardiolipin fraction and 50.5% in the sphingomyelin fraction of muscle lipids of bulls. Furthermore, the diet effects on the saturated fatty acid proportion in the different phospholipid classes differ widely. The results have shown that the C18:1 trans and CLA profiles in the detected seven phospholipid classes can be affected by different feeding systems.     

Seasonal variations of fatty acid compositions in various Korean shellfish

Seasonal variations of fatty acids in various Korean shellfish were investigated in relation to the changes in total fatty acids contents, the ratio of polyunsaturated fatty acids to saturated fatty acids (P/S), and that of n-3 fatty acids to n-6 fatty acids (n-3/n-6). A distinct seasonal pattern was found in total fatty acids contents with maximal values in early summer and minimal values in late summer. The percentage of monounsaturated fatty acids was lowest in most species throughout the year. In summer months, the proportion of polyunsaturated fatty acids decreased while that of saturated fatty acids increased. The major contributing factor to the seasonal variation of polyunsaturated fatty acids was n-3 fatty acids. These results led to the lowest levels of P/S and n-3/n-6 in summer. Nevertheless, the data suggest that bivalve shellfish would be excellent sources of n-3 fatty acids, especially eicosapentaenoic acid and docosahexaenoic acid.     

Functional lipid characteristics of Turkish Tombul hazelnut (Corylus avellana L.)

The quality of crude oil extracted from Tombul (Round) hazelnut, grown in the Giresun province of Turkey, was evaluated for its fatty acid, triacylglycerol (TAG), tocol, and phytosterol compositions. Oleic acid contributed 82.78% to the total fatty acids, followed by linoleic, palmitic, and stearic acids. Among 12 TAGs separated, 11 were identified (including one unknown): LLL, OLL, PLL, OOL, POL, PPL, OOO, POO, PPO, SOO, and PSO (where P, palmitoyl; S, stearoyl; O, oleoyl; and L, linoleoyl). The main components were OOO (71.31%), OOL (12.26%), and POO (9.45%), reflecting the high content of oleic acid present in hazelnut oil. Seven tocol isoforms (four tocopherols and three tocotrienols) and eight phytosterols as well as cholesterol were positively identified and quantified; among these, alpha-tocopherol (40.40 mg/100 g) and beta-sitosterol (134.05 mg/100 g) were predominant in hazelnut oil and contributed 78.74 and 81.28% to the total tocols and phytosterols present, respectively. Tocotrienols were detected in small amounts (1.02% to the total tocols). The crude hazelnut oil extracted from Turkish Tombul hazelnut, thus, serves as a good source of nutrients, bioactives, and health-promoting components.     

Effects of conservation treatment and cooking on the chemical composition and antioxidant activity of Portuguese wild edible mushrooms

The effects of processing and cooking practices on the chemical composition and antioxidant activity of Portuguese wild edible mushroom species (Lactarius deliciosus, Macrolepiota mastoidea, Macrolepiota procera, and Sarcodon imbricatus) were investigated. Dried, frozen, and cooked samples were analyzed for proximate constituents (moisture, fat, crude protein, ash, and carbohydrates) and nutritional value. Fatty acid and sugar profiles were also obtained by gas-liquid chromatography/flame ionization detection and high-performance liquid chromatography/refraction index, respectively. The antioxidant properties were evaluated by several biochemical assays: 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity, reducing power, inhibition of beta-carotene bleaching, and inhibition of lipid peroxidation in brain tissue using thiobarbituric acid reactive substances. Results of this study show that mushroom species and processing and cooking practices are all effective determinants for either chemical composition or antioxidant properties. Cooked samples proved to have lower nutrient concentrations and lower antioxidant activities than either dried or frozen samples. In what concerns fatty acids and sugar individual profiles, only cooking proved to be relevant: The cooked samples presented higher monounsaturated fatty acid and lower polyunsaturated fatty acid and sugars contents.     

Effect of storage on cholesterol oxide formation and fatty acid alterations in egg powder

The effect of the storage of egg powder on cholesterol oxide formation and alterations in the fatty acid composition was studied. Two commercial brands, A and B, were studied at 0 time and then monthly for up to 6 and 12 months, respectively. Five cholesterol oxides were identified and quantified (7-ketocholesterol, 7beta-hydroxycholesterol, 7alpha-hydroxycholesterol, 5,6alpha-epoxycholesterol, and 5,6beta-epoxycholesterol), the amounts of which increased during storage, although the cholesterol contents remained constant. The polyunsaturated fatty acid contents reduced during storage, whereas the levels of saturated and monounsaturated fatty acids and total lipids remained constant. High cholesterol oxide and trans fatty acid contents were found, a fact of concern because these compounds are hazardous to health, and egg powder is used in various food products widely consumed by the population, principally by infants.     

Oxidative stability of tree nut oils

The oxidative stability of selected tree nut oils was examined. The oils of almond, Brazil nut, hazelnut, pecan, pine nut, pistachio, and walnut were extracted using two solvent extraction systems, namely, hexane and chloroform/methanol. The chloroform/methanol system afforded a higher oil yield for each tree nut type examined (pine nut had the highest oil content, whereas almond had the lowest). The fatty acid compositions of tree nut oils were analyzed using gas chromatography, showing that oleic acid was the predominant fatty acid in all samples except pine nut and walnut oils, which contained high amounts of linoleic acid. The tocopherol compositions were analyzed using high-performance liquid chromatography, showing that alpha- and gamma-tocopherols were the predominant tocopherol homologues present; however delta- and beta-tocopherols were also detected in some samples. The oxidative stability of nonstripped and stripped tree nut oils was examined under two conditions, namely, accelerated autoxidation and photooxidation. Progression of oxidation was monitored using tests for conjugated dienes, peroxide value, p-anisidine value, and headspace volatiles. Primary products of oxidation persisted in the earlier stages of oxidation, whereas secondary oxidation product levels increased dramatically during the later stages of oxidation. Hexanal was the major headspace aldehyde formed in all oxidized samples except walnut oil, which contained primarily propanal. Results showed that chloroform/methanol-extracted oils were more stable than hexane-extracted oils in both the accelerated autoxidation and photooxidation studies. Oils of pecan and pistachio were the most stable, whereas oils of pine nut and walnut were the least stable.     

Positional distribution of conjugated linoleic acid in triacylglycerol of Saccharomyces cerevisiae

Saccharomyces cerevisiae was cultivated in the presence of cis-9,trans-11 or trans-10,cis-12 isomers of free conjugated linoleic acid (CLA), and the effects of the isomers on the regioisomerisms of triacylglycerol (TAG) of the yeast were elucidated. Both isomers constituted about 34% of all fatty acids and increased drastically the number of different TAG species. Nearly all of the species contained CLA in at least one sn-position. In the most abundant species analyzed (20% of total species), the cis-9,trans-11 isomer appeared in combination with monounsaturated fatty acids (C16:1, C:18:1) whereas trans-10,cis-12 isomer was most frequently present with a medium chain fatty acid (C10:0 or C12:0) in the sn-2 position and C16:0 in one of the end positions (14% of total species). With either isomer, the amount of TAG species in which CLA encompassed all sn-positions was ca. 4%. Thus, S. cerevisiae can be used to produce edible single cell oil characterized by very heterogeneous distribution of CLA among the different TAG species.     

Lipase-catalyzed acidolysis of tripalmitin with hazelnut oil fatty acids and stearic acid to produce human milk fat substitutes

Structured lipids (SLs) containing palmitic, oleic, stearic, and linoleic acids, resembling human milk fat (HMF), were synthesized by enzymatic acidolysis reactions between tripalmitin, hazelnut oil fatty acids, and stearic acid. Commercially immobilized sn-1,3-specific lipase, Lipozyme RM IM, obtained from Rhizomucor miehei was used as the biocatalyst for the enzymatic acidolysis reactions. The effects of substrate molar ratio, reaction temperature, and reaction time on the incorporation of stearic and oleic acids were investigated. The acidolysis reactions were performed by incubating 1:1.5:0.5, 1:3:0.75, 1:6:1, 1:9:1.25, and 1:12:1.5 substrate molar ratios of tripalmitin/hazelnut oil fatty acids/stearic acid in 3 mL of n-hexane at 55, 60, and 65 degrees C using 10% (total weight of substrates) of Lipozyme RM IM for 3, 6, 12, and 24 h. The fatty acid composition of reaction products was analyzed by gas-liquid chromatography (GLC). The fatty acids at the sn-2 position were identified after pancreatic lipase hydrolysis and GLC analysis. The results showed that the highest C18:1 incorporation (47.1%) and highest C18:1/C16:0 ratio were obtained at 65 degrees C and 24 h of incubation with the highest substrate molar ratio of 1:12:1.5. The highest incorporation of stearic acid was achieved at a 1:3:0.75 substrate molar ratio at 60 degrees C and 24 h. For both oleic and stearic acids, the incorporation level increased with reaction time. The SLs produced in this study have potential use in infant formulas.     

Chemical composition of selected edible nut seeds

Commercially important edible nut seeds were analyzed for chemical composition and moisture sorption. Moisture (1.47-9.51%), protein (7.50-21.56%), lipid (42.88-66.71%), ash (1.16-3.28%), total soluble sugars (0.55-3.96%), tannins (0.01-0.88%), and phytate (0.15-0.35%) contents varied considerably. Regardless of the seed type, lipids were mainly composed of mono- and polyunsaturated fatty acids (>75% of the total lipids). Fatty acid composition analysis indicated that oleic acid (C18:1) was the main constituent of monounsaturated lipids in all seed samples. With the exception of macadamia, linoleic acid (C18:2) was the major polyunsaturated fatty acid. In the case of walnuts, in addition to linoleic acid (59.79%) linolenic acid (C18:3) also significantly contributed toward the total polyunsaturated lipids. Amino acid composition analyses indicated lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) to be the first limiting amino acid as compared to human (2-5 year old) amino acid requirements. The amino acid composition of the seeds was characterized by the dominance of hydrophobic (range = 37.16-44.54%) and acidic (27.95-33.17%) amino acids followed by basic (16.16-21.17%) and hydrophilic (8.48-11.74%) amino acids. Trypsin inhibitory activity, hemagglutinating activity, and proteolytic activity were not detected in the nut seed samples analyzed. Sorption isotherms (Aw range = 0.08-0.97) indicated a narrow range for monolayer water content (11-29 mg/g of dry matter). No visible mold growth was evident on any of the samples stored at Aw < 0.53 and 25 degrees C for 6 months.     

Phospholipid fatty acid profiles as indicators for the microbial community structure in soils along a climatic transect in the Judean Desert

 Analyses of phospholipid fatty acids (PLFAs) were used to assess variations in soil microbial biodiversity, community structure and biomass, and consequently, the soil microbial successions in time along the climate gradient of the Judean Desert. Principal component analysis of the PLFA data revealed that the degree of time- and space-related variations in PLFA composition and microbial community structure was high among the desert habitats. Significant shifts of specific groups of fatty acids caused by climatic variations were observed. The biomass represented by the total amounts of PLFAs indicated that the greater the average amount of precipitation, the higher the biomass. The results indicate that at least three different microorganism strategies were probably followed: (1) in soils with a high biomass during the rainy period, a significant biomass decrease occurred during the dry period, mainly due to an extraordinary decrease of Gram-negative bacteria as indicated by the decrease of typical monounsaturated fatty acids and hydroxy-substituted phospholipid fatty acids in semi-arid climates; (2) in soils with low biomass content during the rainy period, a significant increase of biomass during the dry period occurred, due mainly to the increase of eukaryotes, Gram-positive, and Gram-negative bacteria characterized by polyunsaturated, branched chain and some of the monounsaturated fatty acids, respectively; and (3) relatively low and constant biomass during the entire observation period in the more arid zones of the Judean Desert. Received: 12 January 1998