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Casini M.,Swedish University of Agricultural Sciences | Blenckner T.,University of Stockholm | Mollmann C.,University of Hamburg | Gardmark A.,Swedish University of Agricultural Sciences | And 6 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2012

Understanding the effects of cross-system fluxes is fundamental in ecosystem ecology and biological conservation. Source-sink dynamics and spillover processes may link adjacent ecosystems by movement of organisms across system boundaries. However, effects of temporal variability in these cross-system fluxes on a whole marine ecosystem structure have not yet been presented. Here we show, using 35 y of multitrophic data series from the Baltic Sea, that transitory spillover of the top-predator cod from its main distribution area produces cascading effects in the whole food web of an adjacent and semi-isolated ecosystem. At varying population size, cod expand/contract their distribution range and invade/retreat from the neighboring Gulf of Riga, thereby affecting the local prey population of herring and, indirectly, zooplankton and phytoplankton via top-down control. The Gulf of Riga can be considered for cod a "true sink" habitat, where in the absence of immigration from the source areas of the central Baltic Sea the cod population goes extinct due to the absence of suitable spawning grounds. Our results add a metaecosystem perspective to the ongoing intense scientific debate on the key role of top predators in structuring natural systems. The integration of regional and local processes is central to predict species and ecosystem responses to future climate changes and ongoing anthropogenic disturbances.


Gornas P.,Latvia State Institute of Fruit Growing | Siger A.,University of Life Sciences in Poznań | Polewski K.,University of Life Sciences in Poznań | Pugajeva I.,Institute of Food Safety | Waskiewicz A.,University of Life Sciences in Poznań
European Food Research and Technology | Year: 2014

Qualitative and quantitative determination of tocopherols in filtered and unfiltered coffee brews was investigated. The NP-HPLC/FLD and RP-UPLC-ESI/MSn techniques as well as fluorescence spectroscopy turned out to be very useful tools not only to estimate tocopherol contents, but also to detect contaminants in coffee brew tocopherol extracts. In all analysed coffee brew samples, only α- and β-T were detected. In Arabica coffee brews, the content of the β homologue was three to four times higher than that of the α homologue; however, in Robusta, they were almost identical. Unfiltered coffee brews contained about ten times more tocopherols, 3.02-5.26 and 3.39-16.52, than filtered brews, 0.4-0.71 and 1.26-1.77 μg/100 ml for α-T and β-T, respectively. The reduction in the size of ground coffee beans from 0.7 to 0.3 mm increases the concentration of tocopherols almost three times. Suspended coffee bean dust was the main source of tocopherols in coffee brews. © 2013 Springer-Verlag Berlin Heidelberg.


A new analytical method was established and validated for the analysis of 27 brominated flame retardants (BFRs), including so called "emerging" and "novel" BFRs (EBFRs and NBFRs) in fish samples. High performance liquid chromatography (HPLC) coupled to Orbitrap mass spectrometry (Orbitrap-MS) employing atmospheric pressure photoionization (APPI) interface operated in negative mode was used for the identification/quantitation of contaminants. HPLC-Orbitrap-MS analysis provided a fast separation of selected analytes within 14 min, thus demonstrating a high throughput processing of samples. The developed methodology was tested by intralaboratory validation in terms of recovery, repeatability, linear calibration ranges, instrumental and method limits of quantitation (i-LOQ and m-LOQ), and where possible, trueness was verified by analysis of certified reference materials (CRMs). Recoveries of analytes were between 80 and 119%, while the repeatability in terms of relative standard deviations (RSDs) was in the range from 1.2 to 15.5%. The measured values for both analyzed CRMs agreed with the provided consensus values, revealing the recovery of reference concentrations in 72-119% range. The elaborated method met the sensitivity criterion according to Commission Recommendation 2014/118/EU on monitoring of BFRs in food products for majority of the compounds. The concentrations of polybrominated diphenyl ethers (PBDEs) in real samples determined by HPLC-APPI-Orbitrap-MS method and validated gas chromatography-high-resolution mass spectrometry (GC-HRMS) method were found to be in a good agreement. © 2015 Elsevier B.V.


Gornas P.,Latvia State Institute of Fruit Growing | Seglina D.,Latvia State Institute of Fruit Growing | Lacis G.,Latvia State Institute of Fruit Growing | Pugajeva I.,Institute of Food Safety
LWT - Food Science and Technology | Year: 2014

Tocochromanols composition in apple seeds, obtained as a by-product during the fruit salad and juice production, of twelve varieties - seven crab apple ('Kerr', 'Kuku', 'Quaker Beauty', 'Riku', 'Ritika', 'Ruti' and K-8/9-24) and five dessert apples ('Antej', 'Beforest', 'Kent', 'Sinap Orlovskij' and 'Zarja Alatau') were studied. Tocopherols and tocotrienols were isolated using the micro-saponification method of high precision and accuracy and they were analysedanalysed by rapid RP-HPLC/FLD and RP-UPLC-ESI/MSn. Four tocopherols, with predominance of homologues α and β, were detected in each tested sample. The seeds from two apple cultivars 'Antej' and 'Beforest' were characterized by unique and similar ratios of all four tocopherol homologues α:β:γ:δ (1.7:1.5:1.3:1.0 and 2.1:2.0:1.3:1.0, respectively). The concentration range of individual tocopherol homologues (α, β, γ and δ) in apple seeds were as follows: 17.22-25.79, 7.53-29.05, 0.61-13.82 and 0.16-10.79mg/100g dry weight basis (dwb), respectively. Moreover, three tocotrienols (α, β and γ) were identified in lesser amounts (0.02-0.74 mg/100g dwb). Use of apple seeds to isolate tocopherol homologues can ensure better environmental sustainability and effective use of natural plant material. © 2014 Elsevier Ltd.


Gornas P.,Latvia State Institute of Fruit Growing | Siger A.,University of Life Sciences in Poznań | Pugajeva I.,Institute of Food Safety | Seglina D.,Latvia State Institute of Fruit Growing
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2014

Thirteen cold-pressed oils (Japanese quince seed, black caraway, flaxseed, rapeseed, hemp, peanut, sunflower, pumpkin, hazelnut, poppy, walnut, almond and sesame oil) manufactured by the same company over a 2-year period (2011-12) were assessed for lipophilic compounds. The presence of sesamin and sesamolin, two characteristic lignans of sesame oil, were detected in all tested plant oils. Both lignans were identified by NP-HPLC/FLD/DAD and confirmed by a RP-UPLC-ESI/MSn method. The lowest amount of sesamin and sesamolin was found for Japanese quince seed oil (0.10 and 0.27 mg/100 g), and the highest, excluding sesame oil, for almond oil (36.21 and 105.42 mg/100 g, respectively). The highly significant correlation between sesamolin and sesamin concentrations was found in all samples tested (r = 0.9999; p < 0.00001). These results indicate contamination of cold-pressed oils from the same source. This investigation highlights the fact that increasing the range of products manufactured by the same company can contribute to a lesser regard for the quality of the final product. Moreover, less attention paid to the quality of final product can be related to the health risks of consumers especially sensitive to allergens. Therefore, proper cleaning of processing equipment is needed to prevent cross-contact of cold-pressed oils. © 2014 Taylor & Francis.


Linsinger T.P.J.,European Commission | Peters R.,Institute of Food Safety | Weigel S.,Institute of Food Safety
Analytical and Bioanalytical Chemistry | Year: 2014

This publication describes the first international intercomparison of particle-size determination by single-particle inductively coupled plasma mass spectrometry (sp-ICPMS). Concentrated monodisperse silver nanoparticle suspensions with particle diameters of 20, 40 and 100 nm and a blank solution were sent to 23 laboratories in Europe, the USA and Canada. Laboratories prepared eight nanoparticle preparations in two food simulants (distilled water; 10 % ethanol) and reported median particle size, Ag particle mass concentration and Ag particle number concentrations. Average repeatability and reproducibility standard deviation (s r and s R) for the median particle diameter were 1 and 14 nm, respectively. Relative precision was worse for Ag particle number concentrations (RSD r∈=∈11 %; RSD R∈=∈78 %). While further improvements of the method, especially with respect to software tools for evaluation, hardware options for shorter dwell times, calibration standards for determining nebuliser efficiency and further experience by laboratories are certainly desirable, the results of this study demonstrate the suitability of sp-ICPMS for the detection and quantification of certain kinds of nanoparticles. © 2013 European Union.


Nguyen H.T.,Institute of Food Safety | van der Fels-Klerx H.J.,Institute of Food Safety | van Boekel M.A.J.S.,Wageningen University
Food Reviews International | Year: 2014

Foods are often heat processed and may contain advanced glycation end products (AGE). One of the most widely studied AGE is Nε{lunate}-(carboxymethyl)lysine (CML); nevertheless, knowledge on dietary CML is fragmentary. This study aimed to review current scientific knowledge on analytical methods to determine CML contents in food, chemical pathways of CML formation in food, occurrence of CML in food, and health implications of dietary exposure to CML. Chemical analyses of CML in food products are carried out by immunochemical assays and instrumental methods, but the former method may interfere with the food matrix. CML is formed in food through various chemical pathways, depending on food ingredients and processing conditions. The compound is present in many cooked foods, with relatively high concentrations in carbohydrate-rich foods and dairy products. Dietary CML is very likely to impair human health, but full cause-effect evidence is not available yet. More studies on metabolic effects and impact of food-derived CML on human health should be performed. Food production should be optimized to minimize CML concentrations, while maintaining acceptable microbiological safety and organoleptic properties of the final food product. To this end, more insights into effects of food composition and processing conditions on CML formation are necessary. © 2014 Copyright Taylor and Francis Group, LLC.


Zacs D.,Institute of Food Safety | Zacs D.,University of Latvia | Bartkevics V.,Institute of Food Safety | Viksna A.,University of Latvia
Chemosphere | Year: 2013

Seventeen polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDFs) of the highest priority as well as twelve dioxin-like polychlorinated biphenyls (dl-PCBs) were analyzed in the muscle tissues of the following freshwater fish species sampled from eleven Latvian freshwater lakes: perch (Perca flavescens), carp (Cyprinus carpio), eel (Anguilla rostrata), bream (Abramis brama), chub (Leuciscus cephalus), pike (Esox lucius), sheatfish (Silurus glanis) and roach (Rutilus). To analyze the selected persistent organic pollutants in fish matrices, an optimization of EPA-1613 and EPA-1668A clean-up procedures was carried out, followed by validation of the analytical procedure according to Commission Regulation (EC) No 1883/2006. The adopted analytical procedure was in compliance with requirements of the more recent Commission Regulation (EU) No 252/2012. Modifications of carbon column chromatography clean-up and separation steps were used for treatment of the fish samples. Other clean-up procedure stages were performed according to the methods EPA-1613 and EPA-1668A and involved gel permeation chromatography (GPC), as well as manual acidic silica and Florisil column chromatography for purification and fractionation of the samples. An isotope dilution method was used for the qualitative and quantitative determination of individual congeners. Analytes of interest were separated and detected using gas chromatography - high resolution mass spectrometry. The concentration of PCDD/PCDFs and dl-PCBs in freshwater fish and eel samples ranged from 0.05 to 8.0pg WHO(1998)-PCDD/PCDF-PCB-TEQ g-1 fresh weight. These levels are below the EU maximum permissible limits although calculation of the content of these compounds relative to the weight of fat shows contamination levels similar to those found in Baltic herring and sprats, that are known to be highly contaminated. A difference in congener pattern between the Baltic Sea fish and freshwater fish was detected with lower contribution of 2,3,4,7,8-PeCDF to the contamination of inland water fish. © 2012 Elsevier Ltd.


Gornas P.,Latvia State Institute of Fruit Growing | Pugajeva I.,Institute of Food Safety | Seglina D.,Latvia State Institute of Fruit Growing
European Food Research and Technology | Year: 2014

Tocochromanol composition was analysed in the seeds of nine various fruits: apple (Malus domestica Borkh.), red currant (Ribes rubrum L.), gooseberry (Ribes uva-crispa L.), grape (Vitis vinifera L.), pomegranate (Punica granatum L.), Japanese quince (Chaenomeles japonica (Thunb.) Lindl. ex Spach), sea buckthorn (Hippophae rhamnoides L.), watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) and canary melon (Cucumis melo L.), recovered from by-products of fruit industry. The concentration range of subsequent tocopherols (Ts) and tocotrienols (T3s) was as follows: 1.29-29.30, 0.00-11.68, 0.42-95.11, 0.00-7.66, 0.03-5.03, 0.00-0.18 and 0.00-6.68 mg/100 g of seed dry weight for α-T, β-T, γ-T, δ-T, α-T3, β-T3 and γ-T3, respectively. The δ-T3 was not detected in any of the tested seeds. All tocochromanols were successfully separated by rapid RP-HPLC/FLD method and confirmed by the RP-UPLC-ESI/MS3 technique. © 2014 Springer-Verlag Berlin Heidelberg.


Birzaks J.,Institute of Food Safety
Zoology and Ecology | Year: 2012

This study analyses the structure of fish communities in 201 Latvian rivers: the number of species, their diversity, abundance and biomass of fish in accordance with the nationally accepted river typology and its parameters, i.e. the river basin area and the average slope. The number of species and their diversity as well as the abundance and biomass of fish vary significantly in rivers with different basin areas and temperature regimes. Latvian rivers can be classified into the following types based on the fish communities therein: (I) small coldwater rivers with trout and stone loach as dominant species, (II) small warmwater rivers dominated by stone loach, minnow, pike and perch, (III) medium coldwater rivers with such dominant species as brook lamprey, trout, minnow, stone loach and sculpin, (IV) medium warmwater rivers with pike, roach, gudgeon, minnow, stone loach and perch as dominant species, and (V) large potamal warmwater rivers dominated by pike, roach, chub, gudgeon, minnow, riffle minnow, bleak, stone loach, loach and perch. This study has not analysed anthropogenic impact, therefore the fish-based river typology needs further development. Copyright © 2012 Nature Research Centre.

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