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The compositions and concentrations of lipid classes, fatty acids and tocopherols were determined in the lipids from Spirulina platensis. Total lipids (TL) recovered using chloroform : methanol (2:1, v/v) were found to be 163.5 g/kg (on dry weight basis). The level of neutral lipids was the highest, followed by glycolipids and phospholipids, respectively. Among TL and lipid classes, palmitic, gamma-linolenic and linoleic acids were the dominating fatty acids. Compared with the neutral lipids, the polar fractions were generally characterised by higher percentages of saturated fatty acids. The recovered lipids were characterised by high percentage of tocopherols, wherein alpha-tocopherol constituted about 73% of total tocopherols present, the rest having been gamma-tocopherol. Spirulina platensis lipids exhibited a strong radical scavenging activity towards stable DPPH free radicals, whereas 27% of DPPH radicals were quenched after 2 h incubation. TL and lipid classes inhibited the growth of different microorganisms except gram-negative bacteria. At high concentrations, the tested lipids appeared more effective against A. niger (28.3+/-1.53 mm).

Fatty-acid esters of dinophysistoxin-1 (DTX1) in scallops Patinopecten yessoensis, mussels Mytilus coruscus, and toxic dinoflagellate Dinophysis species, collected from Japanese seawater, were analyzed by liquid-chromatography mass spectrometry (LC-MS). Precursor ion monitoring, multiple reaction monitoring for 18 fatty-acid esters of DTX1, and full-scan MS/MS spectra obtained with a hybrid triple-quadrupole linear-ion-trap mass spectrometer showed that 14:0, 16:0, and 16:1 esters were the most abundant 7-O-acyl-DTX1 analogues in bivalves. Fatty-acids esters formed by conjugations at hydroxyl positions other than the 7-position of DTX1 was not detected in the bivalves. DTX1 and okadaic acid-16:0 fatty-acid esters have been reported as the most abundant ester in bivalves in several previous studies; however, we found that 7-O-16:1-DTX1 was the most abundant ester in some mussels in which 16:1 was more dominant than 16:0 in the free fatty-acid profile. Comparison between 7-O-acyl-DTX1 and free fatty-acid profiles in the same bivalve samples suggests that polyunsaturated fatty acids are selectively excluded in enzymatic acylation of DTX1. No 7-O-acyl-DTX1 was detected in any single-cell isolates of D. fortii, D. acuminata, D. mitra, D. norvegica, D. tripos, D. infundibulus, and D. rotundata.

The inhibitory effect of four trace elements on production of volatile fatty acids (VFA) and lactate was evaluated in cultures of rumen contents containing lead, mercury, cadmium and arsenic at 50, 100 and 250 microg/ml. The production of VFA in cultures containing Pb2+, Hg2+, Cd2+ and As5+ at 50 microg/ml was decreased by 15.9, 40.0, 29.1 and 35.6%, respectively. The effect of trace elements on molar profile of VFA was variable, which suggests a different toxic effect of elements tested on different groups of rumen microorganisms. Increasing concentrations of Pb2+ in rumen cultures decreased molar proportion of acetate and increased that of butyrate, whereas Hg2+ and Cd2+ increased molar percentages of acetate and decreased butyrate. Lactate concentration in cultures containing Hg2+ increased in a dose-dependent manner from 3.10 to 9.20 microM/ml. Effects of other trace elements on lactate production were not consistent.

The chromatographic results obtained in these studies show that acetonitrile-based mobile phases are superior in comparison with methanol mobile phases for the separation of basic impurities and ZILs. When operated in a gradient mode, these solvents allow shorter analysis time and improve peak shapes. HPLC in combination with tandem MS is capable to characterize all the impurities as well as to establish the fragmentation pattern of ZILs, which is quite similar. The main routes of fragmentation involve charge-induced dissociation at low CEs and homolytic cleavage of the alkyl chain at high CEs, respectively. Some unusual processes may proceed at high CEs, which possibly are based on gas phase carbocation chemistry and include several consecutive ring expansions promoted by the hydrogen transfer. However, the full fragmentation pathways can be proposed only after accurate mass measuring or isotopic labelling experiments.

To the Editor: Trans fatty acids, which are created by the partial hydrogenation of liquid vegetable oils in the manufacturing of margarine and vegetable shortening, increase serum levels of low-density lipoprotein cholesterol and decrease those of high-density lipoprotein cholesterol 1 – 3 . The adverse effects of the trans fatty acids on the ratio of total cholesterol to high-density lipoprotein cholesterol is twice that of saturated fatty acids. Higher consumption of trans fatty acids was associated with an increased incidence of coronary heart disease among 85,000 nurses during eight years of follow-up 4 . Information on the trans-fatty-acid content of foods is limited . . .

Mixtures of wheat semolina, 5 % glucose and 0-30 % defatted soybean flour were used for the preparation of extruded samples using a pilot plant single screw extruder, maximum temperature being 140 deg C. Volatile substances were isolated using a SPME procedure and separated using a Fisons GLC 8000 apparatus equipped with a mass spectrometer. Organoleptic analysis was carried out by trained analysts. Only moderate browning reactions were observed. The increase of soybean flour concentration led to the changes in the sensory profile, increased odour intensity and improved sensory acceptability. Among the flavour active volatiles, pyrazines were the most prominent class of compounds, especially methyl and ethyl substituted derivatives. Pyrrole and furan substituted pyrazines were found only in small amounts because of the low extrusion temperature. Other furan and pyrrole derivatives had a lesser effect on flavour because of their relatively low amounts. Aldehydes, fatty acids, ketones, and other aliphatic derivatives contributed only a little to the resulting flavour. Compared to the mixtures of semolina and glucose only, the additions of defatted soybean flour moderately increased the number of substituted pyrazines detected in the extruded mixtures but increased substantially the pyrazine fraction in the total peak area.

The content of selected sterols as declared in the EU Commission Regulation was used to prove the authenticity of olive oils. A modified method using the preparative LC with silica gel packed column and gradient elution with three mixtures of hexane and diethyl ether was used to separate undesirable interfering compounds in the unsaponifiable fraction before the determination of sterols using GC. Model experiments based on the determination of Delta-7-stigmastenol and campesterol (addition of sunflower and soybean oils), or brassicasterol (addition of rapeseed oil) were used to verify that this method is capable of identifying adulteration of olive oils by additions of sunflower, soybean or rapeseed oils. An elevated content of these marker sterols, in comparison with their permitted contents, enables the identification of an addition of 5-10 % of the above mentioned oils to the olive oil. This method was also used to evaluate the authenticity of five samples of olive oils from the SIAL exhibition (Paris) and ten samples of virgin olive oils obtained on the Prague markets. It was revealed that none of the samples showed the signs of adulteration.

The aim of our research was to determine the fatty acids composition in ordinary and omega-enriched eggs. Analyses were made from lipid extracts with gas liquid chromatography in four various prepared samples (raw eggs, soft boiled eggs, hard boiled eggs and fried eggs). The same treatments were repeated after 4 weeks of storage at refrigerator temperature 4 deg C. Experimental data were collected in five groups: methyl esters of saturated fatty acids (SFA), methyl esters of monounsaturated fatty acids (MUFA), methyl esters of polyunsaturated fatty acids (PUFA), methyl esters of omega-3 fatty acids (omega-3 FA) and methyl esters of omega-6 fatty acids (omega-6 FA). With statistical experimental design Split-split-plot different factors were observed: sort of eggs, age of eggs and kind of preparation. Significant differences were noted between SFA and kind of preparation, MUFA and age of eggs, MUFA and kind of preparation, PUFA and sort of eggs, PUFA and age of eggs, PUFA and kind of preparations, omega-3 FA and sort of eggs, omega-3 FA and age of eggs, omega-3 FA and kind of preparation, omega-6 FA and sort of eggs and omega-6 FA and age of eggs.