European Journal of Lipid Science and Technology Latest Content

Proficiency test on the determination of mineral oil in sunflower oil

Lubomir Karasek, Thomas Wenzl, Franz Ulberth — 2010-03-12T04:54:00Z

Following the discovery of mineral oil contamination of Ukrainian sunflower oil in April 2008, the Institute for Reference Materials and Measurements (IRMM) of the European Commission's Joint Research Centre (JRC) was requested by the Directorate General Health and Consumers (DG SANCO) to organise a proficiency test on the determination of mineral oil in sunflower oil. The aim of this test was to evaluate the comparability of analysis results gained by laboratories in the EU and the Ukraine. The organisation of the study and the evaluation of the results were done in accordance with "The International Harmonised Protocol for the Proficiency Testing of Analytical Chemistry Laboratories" and ISO Guide 43. Altogether 62 laboratories from 19 EU member states, Switzerland and the Ukraine subscribed for participation in the study. Four test samples at concentration levels between about 100 and 350 mg/kg, comprising contaminated crude sunflower oil, contaminated refined sunflower oil, and spiked sunflower oil, and a solution of mineral oil in n-heptane were dispatched to the participants. The participants were asked to determine the mineral oil content of the test samples by application of their in-house analysis methods. In total, 55 sets of results were reported to the organisers of the study. The performance of laboratories was expressed by z-scores for the oil samples and by relative bias for the mineral oil solution in n-heptane. The percentage of successful laboratories in the determination of the mineral oil content of sunflower oil was for all sunflower oil test materials about 80%.

Identification and characterization of the n-6 fatty acid-producing Mucor rouxii native isolate CFR-G15

Shivaramu S. Mamatha, Prakash M. Halami, Govindarajulu Venkateswaran — 2010-03-12T04:54:00Z

In zygomycetes fungi, many Mucor spp. have been known to produce [gamma]-linolenic acid (GLA) in their biomass. Among 250 soil samples screened, 20 Mucor isolates showed GLA in their mycelial mass under normal cultivation conditions. Sudan Black B was used for screening their qualitative oleaginesity. Among the representative isolates, Mucor sp. CFR-G15, when grown in a fat-producing medium, showed a maximum lipid content of 30 ± 1.32% in its mycelia and 14.42 ± 0.74% GLA. By using gene-specific primers, the 18S rRNA gene and the [Delta]6 DES gene were amplified by PCR technique. The nucleotide sequences of the 18S rRNA and [Delta]6 DES genes exhibited >98% homology with M. rouxii ATCC 24905 (accession nos. AF117923 and AF296076, respectively), suggesting taxonomic identity. The native isolate M. rouxii CFR-G15 reported in this study was found to be promising for the development of an economical process in the industrial production of GLA.

Effect of triacylglycerol species on the crystallizing behavior of a model water/oil emulsion

Leo Tanaka, Tomoyuki Isogai, Susumu Miura, Mototake Murakami — 2010-03-12T04:54:00Z

The crystallizing behavior of a model water/oil (W/O) emulsion with different fat formulas was investigated. The model W/O emulsion was stored in a programmable oven under a temperature fluctuation cycle of 5 °C for 12 h and 20 °C for another 12 h. Crystal growth was observed using a polarization microscope, until the crystals were over 100 [mu]m in diameter, which causes texture degradation. We examined whether the texture degradation is related to the fatty acid formula and the triglyceride formula by carbon number. We also examined the effect of the triglyceride species concentration estimated from the fatty acid formula on the texture degradation. The palmitic acid content was related with texture degradation at high concentration among the fatty acid species. The triglyceride content was not related with texture degradation. Triacylglycerol species with palmitic acid such as tripalmitate (PPP) and 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) were related with texture degradation. The summed up concentration of three triglycerides [PPP, POP and 1,2-dipalmitoyl-3-oleoyl-glycerol (PPO)] was related with texture degradation.

Policosanol characterization and accumulation during ripening of Tunisian Olea europaea L. fruits

Faouzi Sakouhi, Sadok Boukhchina, Christelle Absalon, Eric Fouquet, Habib Kallel — 2010-03-12T04:54:00Z

Policosanol is a mixture of bioactive molecules shown to have beneficial effects in treating hypercholesterolemia. Food products enriched in policosanol are currently available in the US market. In the present study, eight policosanol components were identified by GC-MS during the ripening of Meski olives. The quantitative characterization of these compounds was performed using GC-FID. The results showed that the maximum level of total policosanol components (947.20 mg/100 g oil) was reached at the 26th week after the flowering date of Meski olives. Hexacosanol and tetracosanol were the predominant policosanol components at Meski olive maturity. However pentacosanol, heptacosanol and tricosanol were less present in the olives and they accounted for 14% of the total policosanol at complete maturity of the fruit. The total policosanol content of Meski olives was higher than that of beeswax and whole sugar cane, which belong to the sources of dietary supplements containing policosanol. These findings indicate that olive is a potential source of these health-enhancing compounds for functional foods and nutraceutical applications.

Unbound DHA causes a high blank value in [beta]-oxidation assay: a concern for in vitro studies

Zhen-Yu Du, Pedro Araujo, Ingunn Stubhaug, Livar Frøyland — 2010-03-12T04:54:00Z

The information on binding capacity of different fatty acids (FAs) to albumin is incomplete, however, in the majority of in vitro experiments, FAs and albumin were simply mixed and their affinity believed to be complete. In this study, seven [1-14C] FAs were mixed with albumin and assayed for [beta]-oxidation in rat liver homogenates. In the process of identifying the radioactive background of control assay by LCMS/MS, the results indicated different binding capacity of FAs to albumin. The percentage of unbound FAs recovered in clarified acidic solution was lower than 2% with 16:0 and 18:1n-9, nearly 5% with EPA, 7% with 18:2n-6, 18:3n-3 and 20:4n-6, and surprisingly high to 41% with DHA. Various FA/albumin molar ratios as well as different types of albumin only marginally affected these data. Thus, the big mass of unbound free DHA led to a high blank value, which is 60 times higher than the real value in the procedure of [beta]-oxidation measurement in vitro. In the design of future FA research in vitro, the binding capacity of FA to albumin or other proteins must be considered, especially for DHA research.

Extraction of Nitraria tangutorum seed lipid using different extraction methods and analysis of its fatty acids by HPLC fluorescence detection and on-line MS identification

Yourui Suo, Lingyun Wang — 2010-03-12T04:54:00Z

The seed lipid of Nitraria tangutorum was extracted by supercritical carbon dioxide extraction, microwave-assisted reflux extraction, ultrasound-assisted extraction, or solvent reflux extraction. The experimental parameters of supercritical carbon dioxide extraction including pressure, temperature, particle size, and extraction time were investigated. A facile and sensitive method for the simultaneous determination of 30 saturated and 9 unsaturated fatty acids by HPLC with fluorescence detection after pre-column derivatization was developed. Fatty acid derivatives were separated on a reversed-phase Eclipse XDB-C8 column in conjunction with gradient elution. Identification of fatty acid derivatives was carried out by on-line APCI/MS in positive-ion mode. Excellent quantitative linear responses of the 39 fatty acids were observed in the range of 0.014 to 14 [mu]mol/L with correlation coefficients higher than 0.9992. Limits of detection were in the range of 0.32-3.7 nmol/L (S/N = 3). The fatty acids in Nitraria tangutorum seed lipid with or without saponification extracted by the four different methods were determined and compared. The results indicated that the mass percentage of unsaturated fatty acids (mainly oleic acid, linoleic acid and linolenic acid) in Nitraria tangutorum seed lipid was up to 79%, and the best method was supercritical carbon dioxide extraction.

Effect of high-pressure treatment on microbial activity and lipid oxidation in chilled coho salmon

2010-02-19T09:04:00Z

This work studies the effect of a previous hydrostatic high-pressure (HHP) treatment on chilled farmed coho salmon (Oncorhynchus kisutch). Three different HHP conditions were applied (135 MPa-30 s, 170 MPa-30 s, and 200 MPa-30 s for treatments T-1, T-2, and T-3, respectively) and compared to untreated (control) fish throughout a 20-day chilled storage. Microbial activity and lipid oxidation development were analyzed. Assessment of aerobe, psychrotroph, Shewanella spp. and Pseudomonas spp. counts and trimethylamine formation showed a marked inhibitory effect (p <0.05) of HHP treatment on microbial activity, with this effect increasing with the pressure value employed. Related to lipid oxidation development, higher peroxide mean values (day 10-20 period) were found in control samples and fish treated under T-1 condition when compared to their counterparts corresponding to T-2 and T-3 treatments. On the contrary, quantification of thiobarbituric acid-reactive substances and fluorescent interaction compounds showed higher levels (p <0.05) in fish samples corresponding to T-2 and T-3 treatments. In spite of the lipid oxidation development found, polyene index and tocopherol isomer ([alpha] and [gamma]) content did not provide differences (p >0.05) as a result of previous HHP treatment.

Betaine supplementation affects the cholesterol but not the lipid profile of pigs

José M. Martins, José A. Neves, Amadeu Freitas, José L. Tirapicos — 2010-02-19T09:04:00Z

This study was undertaken to investigate the effects of long term betaine intake on the cholesterol and lipid profile of Alentejano (AL) pigs. At ~36 kg body weight (BW), castrated male and female pigs fed a commercial (C) diet, were divided into two groups: i) Group C, consuming the C diet; and ii) Group CB, consuming the C diet supplemented with 1 g/kg betaine. Pigs were slaughtered at ~100 kg BW. Fasting plasma concentrations of protein, urea, glucose, TAG, phospholipids, homocysteine, total and LDL- and HDL-cholesterol were determined. Liver TAG, phospholipids, and total and free cholesterol were analyzed, as well as total lipids, cholesterol contents, and fatty acid (FA) composition of M. semimembranosus and dorsal subcutaneous fat. Betaine supplemented pigs presented significantly higher plasma concentrations of TAG, phospholipids, cholesterol, and lipoprotein cholesterol. Dorsal subcutaneous fat cholesterol concentration was also significantly higher in CB than in C pigs. No differences were detected in the most abundant FA profile (including the unsaturated to saturated FA ratio) of muscle and subcutaneous fat tissues among treatments. These data suggest that betaine induces dyslipidemia, and increases cholesterol concentration in dorsal subcutaneous fat, without affecting the FA profile of M. semimembranosus and dorsal subcutaneous fat.

Kinetic study of [beta]-carotene and lutein degradation in oils during heat treatment

2010-01-29T08:40:00Z

The kinetics of trans-[beta]-carotene and trans-lutein degradation were individually investigated in palm olein and Vegetaline®, at four temperatures ranging from 120 to 180 °C. HPLC-DAD analysis was carried out to monitor trans and cis carotenoid variations over the heating time at each temperature. In both oils, initial trans-[beta]-carotene and trans-lutein degradation rates increased with temperature. Trans-lutein was found to degrade at a slower rate than trans-[beta]-carotene, suggesting a higher thermal resistance. The isomers identified were 13-cis- and 9-cis-[beta]-carotene, and 13-cis-, 9-cis-, 13'-cis-, and 9'-cis-lutein. In spite of the higher number of lutein cis isomers, their total amount was lower than that of [beta]-carotene cis isomers. Trans and cis carotenoids were involved in degradation reactions at rates that increased with temperature. All degradation rates were generally found to be lower in Vegetaline® than in palm olein. These results were explained by the initial composition of the two oils and especially their peroxide and vitamin E contents.

Frying performance of the hull oil unsaponifiable matter of Pistacia atlantica subsp. mutica

Reza Farhoosh, Mohammad Hossein Tavassoli Kafrani — 2010-01-26T15:01:00Z

The anti-rancidity effect of the hull oil unsaponifiable matter (USM, 100 ppm) of Pistacia atlantica subsp. mutica (Bene) on sunflower oil (SFO) during frying at 180 °C was investigated and compared to that of tert-butylhydroquinone (TBHQ, 100 ppm). The unsaponifiable constituents of the Bene hull oil (BHO) were separated into hydrocarbons (3.7%), carotenes (3.6%), tocopherols and tocotrienols (24.7%), linear and triterpenic alcohols (0.9%), methylsterols (5.7%), sterols (3.2%), triterpenic dialcohols (4.7%), and triterpenic dialcohol methylesters (4.5%), by means of silica gel TLC. The results obtained from the measurements of total polar compounds, conjugated diene value, carbonyl value, and acid value during 32 h of frying showed that the frying stability of SFO improves more in the presence of the USM of BHO than in the presence of TBHQ. Moreover, compared to TBHQ, the USM had a better protective effect on the indigenous tocopherols of SFO during frying.

Response surface modeling and optimization of biodiesel production from Cynara cardunculus oil

2010-01-26T15:01:00Z

Cardoon (Cynara cardunculus L.) is a perennial spontaneous thistle grown in Mediterranean countries and well adapted to marginal lands, recently considered as a non-food energy crop. Their seeds contain 24% of oil (dry basis). In this study, modeling and optimization of the production of fatty acid methyl esters (FAME) from cardoon oil for biodiesel uses was performed at laboratory scale, via response surface methodology, following a central composite rotatable design. FAME were obtained by transesterification of crude cardoon oil with methanol in the presence of a catalyst (sodium methoxide) for 120 min. The temperature ranged from 26 to 94 °C, the amount of sodium methoxide varied between 0.12 and 2.5 wt-% and the molar ratio methanol/oil from 0.95 : 1 to 11 : 1. The estimated yield of FAME (97%) was obtained after 30 min, at 52 °C, for a molar ratio of 6.4 : 1 and 1.4 wt-% of catalyst. In laboratory-scale model validation experiments, 94% of FAME yield was obtained after 30 min of reaction. Transesterification was performed in a 30-L reactor, under previously optimized conditions: A yield of 88% FAME was obtained after 90 min of reaction time, due to mass transfer limitations. After purification, the biodiesel showed high quality according to DIN EN 14214 standard specifications.