14 results on '"L. Demšar"'
Search Results
2. Determination of the fatty acids in fish tissue and feed — comparison of different methods and statistical evaluation
- Author
-
Mirjana Dimitrijević, T. Polak, D. Nikolić, Dejana Trbović, Vesna Đorđević, Nenad Parunović, and L. Demšar
- Subjects
Correlation coefficient ,gas chromatography ,Fish farming ,fatty acids ,01 natural sciences ,Commercial fish feed ,law.invention ,Aquaculture ,law ,Flame ionization detector ,14. Life underwater ,reproducibility ,chemistry.chemical_classification ,Fish tissues ,Chromatography ,quantitation ,biology ,business.industry ,010401 analytical chemistry ,Fatty acid ,04 agricultural and veterinary sciences ,General Chemistry ,biology.organism_classification ,0104 chemical sciences ,Trout ,chemistry ,040102 fisheries ,0401 agriculture, forestry, and fisheries ,Gas chromatography ,business - Abstract
With the aim to reinforce laboratory competence in the field of testing the quality of fish from aquaculture, a study on the precision of fatty acid (FA) analyses in fish meat and fish feed was undertaken. Different methods were performed in laboratories. In situ transesterification method and extraction of lipids from the fish were followed by capillary gas chromatography with flame ionization detection. The reproducibility (R) values of the majority of FM were less than 3% of their absolute values. Differences in calculating ionization detector response factors and/or autoxidation caused by faulty sample-handling could lead to variation in quantification of FAs in fish, especially for FA C22:6n-3. Statistical analysis showed a significant correlation between the two laboratories quantifications of FM in fish and fish feed (Pearsons correlation coefficient; r = 0.987, r = 0.994, and r = 0.997; for fish Z [trout], fish g [rainbow trout], and fish feed, respectively). Overall, adequate accuracy was obtained in this study. The proposed method provides a fast and efficient means of identifying fish and feed for quality control purposes.
- Published
- 2018
- Full Text
- View/download PDF
3. Can long chain n-3 fatty acids from feed be converted into very long chain n-3 fatty acids in fillets from farmed rainbow trout (Oncorhynchus mykiss)?
- Author
-
M Lušnic Polak, L Demšar, U Luzar, and T Polak
- Published
- 2017
- Full Text
- View/download PDF
4. N-Acetylcysteine Ineffective in Alleviating Hangover from Binge Drinking: A Clinical Study.
- Author
-
Podobnik B, Demšar L, Šarc L, Jerin A, Osredkar J, Trontelj J, Roškar R, and Brvar M
- Abstract
Alcohol hangover (veisalgia) is a fairly common phenomenon. The pathogenesis of veisalgia is not understood and treatment has not yet been established. Occasionally, students take N-acetylcysteine (NAC) before binge drinking to alleviate hangover. The aim of this study was to evaluate the effect of NAC on serum levels of electrolytes, enzymes, oxidative stress biomarkers and symptoms of veisalgia in binge drinking. In this randomized, double-blind, placebo-controlled study, healthy students were randomly assigned into two groups: one receiving NAC and the other receiving a placebo. Blood samples were taken before drinking, 30 min after a 1.5 h long drinking session, and the subsequent morning. Serum levels of electrolytes, urea, enzymes, ethanol, 8-Hydroxydeoxyguanosine (8-OHdG) and N-epsilon-hexanoyl-lysine were measured. The participants completed the Acute Hangover Severity Scale (AHSS) assessment based on symptoms, and 40 students (20 male), aged 23 ± 2 years, were included in the study. Their mean blood ethanol concentration was 1.4 g/kg. Serum sodium levels were increased after drinking, and urea decreased the following morning compared to their levels before drinking in both groups. Serum 8-OHdG levels were increased after drinking and remained elevated until the following morning, compared to the levels before drinking, in both groups. NAC had no effect on sodium, urea and 8-OHdG levels or the symptoms of veisalgia. In conclusion, binge drinking causes a transient increase in serum sodium and as a prolonged increase in oxidative marker 8-OHdG levels. NAC had no effect on the sodium and 8-OHdG levels.
- Published
- 2024
- Full Text
- View/download PDF
5. Meat Starter Culture Reduces Aspergillus parasiticus Production of Aflatoxins on Meat-Based and Salami Model Media.
- Author
-
Zahija Jazbec I, Demšar L, Jeršek B, and Polak T
- Subjects
- Food Microbiology, Food Contamination prevention & control, Food Contamination analysis, Fermentation, Animals, Aflatoxins biosynthesis, Aspergillus metabolism, Aspergillus growth & development, Meat Products microbiology
- Abstract
There is great concern about the risk posed by the consumption of food contaminated with aflatoxins (AF), produced mostly by Aspergillus strains, that can also be found in dry-fermented meat products (DFMPs). The aim of this study was to investigate the inhibitory effect of meat starter culture (SC), frequently used for fermentation in the meat industry, on A. parasiticus growth and the production of aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2), and sterigmatocystin (STE) on different meat-based (CMA) and salami model (SM-G) media. Incubation was carried out under optimal conditions for fungal growth and under typical conditions for ripening of DFMPs for 21 days. Reversed-phase UPLC-MS/MS analysis was performed to determine mycotoxin production. SC reduced A. parasiticus growth more on CMA than on SM-G media. AFB1 formation was inhibited on both types of SC-containing media, although SC generally had a stronger inhibitory effect on AFB1 production on CMA than on SM-G. AFB1 and AFB2 were produced on CMA, while AFB1 dominated in SM-G, AFG1, and AFG2 were not detected in any media. The results show that SC inhibited AFB1 formation of A. parasiticus on SM-G media after 21 days of incubation under typical conditions for the production of DFMPs. These results indicate the necessity to investigate AF on natural matrices in an environment that is as similar as possible to real conditions in the production of DFMPs.
- Published
- 2024
- Full Text
- View/download PDF
6. Production of Aflatoxin B1 by Aspergillus parasiticus Grown on a Novel Meat-Based Media.
- Author
-
Zahija I, Jeršek B, Demšar L, Polak ML, and Polak T
- Subjects
- Tandem Mass Spectrometry, Chromatography, Liquid, Aspergillus, Agar, Aflatoxin B1, Culture Media, Aflatoxins, Meat Products
- Abstract
The aim of the present study was to develop meat-based media with compositions similar to those of dry-fermented meat products and to evaluate their use in studying the growth of Aspergillus parasiticus and the kinetics of aflatoxin B1 (AFB1) production. In our previous experiments, we found that the strain A. parasiticus ŽMJ7 produced a high amount of AFB1. Cooked meat agar (CMA2) was used as a novel complex meat-based medium with four variations: CMA2G (CMA2 supplemented with 1% glucose), CMA2YE (CMA2 supplemented with 0.2% yeast extract), and CMA2GYE (CMA2 supplemented with 1% glucose and 0.2% yeast extract). Media were inoculated with an A. parasiticus spore suspension (10
5 spores/mL) and incubated at 25 °C for up to 15 days. The A. parasiticus lag phase lasted less than 1 day, irrespective of the growth medium, with the exception of control medium CMA1 (cooked meat agar) as an already known meat-based medium. The highest mean colony growth rate was observed on CMA2 and CMA2G. Reversed-phase UPLC-MS/MS analysis was performed to determine the AFB1 concentration in combination with solid phase extraction (SPE). The highest AFB1 concentration in meat-based media was detected in CMA2GYE after 15 days of incubation (13,502 ± 2367 ng/mL media). The results showed that for studying AFB1 production in dry-fermented meat products, novel suitable media such as CMA2-based media are required. This finding could represent a potential concern with regard to the production of dry-fermented meat products.- Published
- 2022
- Full Text
- View/download PDF
7. White Hop Shoot Production in Slovenia: Total Phenolic, Microelement and Pesticide Residue Content in Five Commercial Cultivars.
- Author
-
Vidmar M, Abram V, Čeh B, Demšar L, and Poklar Ulrih N
- Abstract
Harvesting of white hop shoots might be justified if they can be shown to be beneficial to human health. The aim of the present study is to determine the effects of hop cultivars and year of production on total phenolics, antioxidant potential, microelements and pesticide residues. Biomass per plant was highly variable across the cultivars (3.1-7.1 g dry mass per plant) and depended on hop cultivar and year (2009-2011). Total phenolics as chlorogenic acid equivalents (CAE) on dry mass basis varied from 0.60 to 1.80 mg/g, and showed significant effects across hop cultivar and year. The radical scavenging activities of the samples collected in years 2010-2012 ranged from 11 to 19 µg CAE. Ferric reducing activity was <0.01, with significantly different effects across hop cultivars (p
C ≤0.05) and year (py ≤0.05) observed only in 2012. Traces of microelements and potentially active compounds from the use of pesticides in white hop shoots of Humulus lupulus 'Dana' were analysed. The content of zinc in the hop shoots on dry mass basis was very low (4 mg/kg), and it was below the limit of detection in the soil. The content of copper in the hop shoots was also very low (2.3 mg/kg), while in the soil it was below the critical emission (100 vs 300 mg/kg, respectively). All 182 active ingredients from the residues of the previously used pesticides were below the limits of detection. It can be concluded that these white hop shoots are better antioxidants than hop cones and hop leaves, and that they do not contain any pesticide residues., Competing Interests: CONFLICT OF INTEREST: The authors declare that they have no conflicts of interest.- Published
- 2019
- Full Text
- View/download PDF
8. Degradation of PCBs in dry fermented sausages during drying/ripening.
- Author
-
Lušnic Polak M, Zlatić E, Demšar L, Žlender B, and Polak T
- Subjects
- Animals, Bioreactors, Desiccation, Food Microbiology, Gas Chromatography-Mass Spectrometry, Staphylococcus, Swine, Fermentation, Meat Products analysis, Polychlorinated Biphenyls analysis
- Abstract
The effects of several commercial meat starter cultures on degradation of polychlorinated biphenyls (PCBs) in dry fermented sausages over 28days of drying/ripening were investigated. The sausage batter was prepared according to a classic recipe and spiked with a standard solution of a PCB congener mixture. With addition of different commercial meat starter cultures, five experimental groups were prepared: no further addition; and separate addition of each of four starter cultures: Texel DCM-1, Texel LM-30, Biostar Sprint, and SM-181. Samples were taken at the beginning of fermentation (zero time), and after 4, 7, 14, 21 and 28days. PCB residues were extracted with hexane. The PCB contents were determined using gas chromatography-mass spectrometry. The PCB levels were reduced in all of the experimental groups tested, where addition of starter culture Biostar Sprint (Lactobacillus sakei, Staphylococcus carnosus, Staphylococcus xylosus) showed the highest PCB degradation rates., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
9. Influence of Yellow Light-Emitting Diodes at 590 nm on Storage of Apple, Tomato and Bell Pepper Fruit.
- Author
-
Kokalj D, Hribar J, Cigić B, Zlatić E, Demšar L, Sinkovič L, Šircelj H, Bizjak G, and Vidrih R
- Abstract
The objective of this study is to investigate the effects of irradiation from light-emitting diodes (LEDs) on several fruits during storage. To improve storage and increase the contents of some bioactive compounds, apple, tomato and red bell pepper fruits were exposed to yellow light emitted from the diodes at 590 nm. The contents of ascorbic acid, total phenolics, total flavonoids and several pigments were investigated, along with the antioxidant potential. The colour parameters ( L* , a* and b* ) and firmness of the fruit were also determined. After 7 days of LED light irradiation, there was significantly higher total phenolic content and antioxidant potential in apple peel extracts. The irradiated fruit of tomato had significantly higher levels of total phenolic compounds, and the fruit of red bell pepper had significantly higher antioxidant potential. LED light had no effects on the colour parameters, although there was a tendency to accelerate colour development. Apple fruit irradiated with LED light was significantly less firm. Among twelve analysed pigments, significantly more β-carotene was detected in LED light-irradiated apple and bell pepper fruit, more α-tocopherol and γ-tocopherol in bell pepper fruit, and more lutein in apple peel and bell pepper fruit. The applied LED light slightly accelerated the ripening of the studied fruit, and affected the synthesis of some of the secondary metabolites.
- Published
- 2016
- Full Text
- View/download PDF
10. Effects of industrial and home-made spread processing on bilberry phenolics.
- Author
-
Može Bornšek S, Polak T, Skrt M, Demšar L, Poklar Ulrih N, and Abram V
- Subjects
- Anthocyanins analysis, Antioxidants analysis, Chromatography, Liquid methods, Flavonols analysis, Food Industry, Plant Extracts analysis, Polyphenols analysis, Phenols analysis, Tandem Mass Spectrometry methods, Vaccinium myrtillus chemistry
- Abstract
Bilberries processed into spreads represent an important source of anthocyanins if these remain rich in the final product. The effects of thermal processing were studied with non-ground and ground bilberries processed into spreads according to industrial and home-made procedures. Samples were analysed by LC-DAD-MS/MS and LC-MS. The spreads had 28-60% less total phenolics, 4-62% less anthocyanins, and 1-fold to 2-fold more phenolic acids and total flavonols than the bilberries, but approximately equal flavanols. The home-made spread from ground bilberries had ca. 26% higher antioxidant activity. Delphinidin 3-glucoside and cyanidin 3-glucoside were taken through the two spread procedures, with their degradation to gallic acid (38-57%), protocatechuic acid (1-2%) and 2,4,6-trihydroxybenzaldehyde determined. The amounts of gallic and protocatechuic acids did not reflect well for anthocyanin degradation. The industrial spread procedure with non-ground bilberries is a more suitable procedure to maintain the final content of anthocyanins., (Copyright © 2014. Published by Elsevier Ltd.)
- Published
- 2015
- Full Text
- View/download PDF
11. Oxidative stability of n-3-enriched chicken patties under different package-atmosphere conditions.
- Author
-
Penko A, Polak T, Lušnic Polak M, Požrl T, Kakovič D, Žlender B, and Demšar L
- Subjects
- Animals, Atmosphere, Oxidation-Reduction, Thiobarbituric Acid Reactive Substances analysis, Chickens, Fatty Acids, Omega-3 chemistry, Food Packaging
- Abstract
The oxidation processes were studied in chicken patties, enriched with n-3 fatty acids, after 8days of storage at 4°C, under different aerobic conditions, and following heat treatment. Significant effects were seen on lipid and cholesterol oxidation and the sensory qualities for whole flaxseed addition in the chicken feed (i.e., n-3 fatty acid enrichment), and for the different package-atmosphere conditions. For the raw chicken patties, n-3 enrichment increased the colour L(∗) values while, after the heat treatment, there were higher thiobarbituric acid-reactive substances (TBARs) and cholesterol oxidation products (COPs), and the rancidity was more pronounced. In comparison with the low O2 (<0.5%) package-atmosphere condition, O2 enrichment (80%) increased the instrumentally measured colour values, TBARs, total and individual COPs, and the rancidity became pronounced. The most suitable package-atmosphere condition of these raw n-3-enriched chicken patties is a very low O2 atmosphere, with or without an O2 scavenger., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
12. Phenolic profiles in leaves of chicory cultivars (Cichorium intybus L.) as influenced by organic and mineral fertilizers.
- Author
-
Sinkovič L, Demšar L, Žnidarčič D, Vidrih R, Hribar J, and Treutter D
- Subjects
- Cichorium intybus growth & development, Chromatography, High Pressure Liquid, Coumaric Acids analysis, Discriminant Analysis, Minerals, Plant Leaves chemistry, Principal Component Analysis, Cichorium intybus chemistry, Fertilizers analysis, Phenols analysis
- Abstract
Chicory (Cichorium intybus L.) is a typical Mediterranean vegetable, and it shows great morphological diversity, including different leaf colours. Five cultivars commonly produced in Slovenia ('Treviso', 'Verona', 'Anivip', 'Castelfranco', 'Monivip') were grown in pots under controlled conditions in a glasshouse, with organic and/or mineral fertilizers administered to meet nitrogen requirements. HPLC analysis was carried out to study the phenolic compositions of the leaves. A total of 33 phenolic compounds were extracted from these chicory leaves and were quantitatively evaluated in an HPLC-DAD-based metabolomics study. Among the cultivars, the highest TPC was seen for 'Treviso' (300.1 mg/100 g FW), and the lowest, for 'Castelfranco' (124.9 mg/100g FW). Across the different treatments, the highest TPC was in the control samples (254.3 mg/100 g FW), and the lowest for the organic (128.6 mg/100 g FW) and mineral fertilizer (125.5 mg/100 g FW) treatments. The predominant phenolic compounds in all of the samples were hydroxycinnamic acids, including chlorogenic and cichoric acid. Fertilizer administration provides a discriminant classification of the chicory cultivars according to their phenolic compounds., (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
13. Phenolic content of strawberry spreads during processing and storage.
- Author
-
Kadivec M, Bornšek ŠM, Polak T, Demšar L, Hribar J, and Požrl T
- Subjects
- Cooking methods, Food Storage methods, Fragaria chemistry, Fruit chemistry, Phenols analysis, Plant Extracts analysis
- Abstract
This study provides a comprehensive and systematic evaluation of phenolics in strawberry spreads processed according to different industrial procedures and stored under several storage conditions for up to 19 weeks. Total phenolics were determined spectrophotometrically, and individual phenolics were determined by combined liquid chromatography and mass spectrometry: six anthocyanins, four phenolic acids, two flavonols, one flavanol, and one flavone. During storage, the phenolics were modified. The total anthocyanins, vanillic acid, kaempferol, and luteolin decreased, while salicylic and gallic acids increased. Total phenolics, cyanidin 3-(6″-succinyl-glucoside) (here observed for the first time), protocatechuic acid, quercetin, and catechin remained stable. The best phenolic retention was observed in spreads stored at 4 °C. Therefore, the proposed storage process (use of a cold chain) indicates good retention of phenolics in strawberry spreads, which maintain high nutritional and sensorial quality.
- Published
- 2013
- Full Text
- View/download PDF
14. Fractionation of phenolic compounds extracted from propolis and their activity in the yeast Saccharomyces cerevisiae.
- Author
-
Petelinc T, Polak T, Demšar L, and Jamnik P
- Subjects
- Energy Metabolism, Intracellular Space metabolism, Oxidation-Reduction, Saccharomyces cerevisiae cytology, Phenols isolation & purification, Phenols metabolism, Propolis chemistry, Saccharomyces cerevisiae chemistry, Saccharomyces cerevisiae metabolism
- Abstract
We have here investigated the activities of Slovenian propolis extracts in the yeast Saccharomyces cerevisiae, and identified the phenolic compounds that appear to contribute to these activities. We correlated changes in intracellular oxidation and cellular metabolic energy in these yeasts with the individual fractions of the propolis extracts obtained following solid-phase extraction. The most effective fraction was further investigated according to its phenolic compounds.
- Published
- 2013
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.