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Determination of fluoride in plant material using microwave induced oxygen combustionEmanuel Šucman, Jiří BednářCzech J. Food Sci., 2012, 30(5):438-441 | DOI: 10.17221/480/2011-CJFS Fluorine is essential in human and/or animal nutrition, thus it is important to know its concentration in a diet. One of the important sources of fluorine for humans is tea, containing relatively high amounts of this trace element. A method for fluoride determination in various kinds of tea using microwave supported sample preparation in a high pressure oxygen atmosphere followed by potentiometry with a fluoride ion-selective electrode were described. The parameters of the microwave device for such combustion procedure were checked and optimised in order to find settings ensuring complete sample combustion and/or absorption of the analyte in the absorption solution. For the ion-selective electrode measurement, the technique of standard addition was chosen. The Nernstian slope of the fluoride ion-selective electrode was measured and calculated in the concentration range in which the potential of samples occurred. Concentrations of fluorides in tea in the range from 24.5 mg/kg to 254.5 mg/kg were found. In order to check the accuracy of the method certified reference materials were used. The precision expressed as the relative standard deviation ranged from 3.7% to 15.9%. The method is fast, accurate and reliable for this kind of analysis. |
Buckwheat grains and buckwheat products - nutritional and prophylactic value of their components - a reviewKarolina CHRISTA, Maria SORAL-ŚMIETANACzech J. Food Sci., 2008, 26(3):153-162 | DOI: 10.17221/1602-CJFS Buckwheat is introduced into the diet as an alternative crop of renewed interest due to its nutritive and health-promoting value. Experiments with animal models have demonstrated that buckwheat flour may alleviate diabetes, obesity, hypertension, and hypercholesterolemia. A number of nutraceutical compounds exist in buckwheat grains and other tissues. These are a rich source of starch, proteins, antioxidants, and dietary fibre as well as trace elements. The biological value (BV) of buckwheat proteins is comparable to BV of other protein sources. Besides high-quality proteins, buckwheat grains contain some components with prophylactic value: flavonoids, fagopyrins, or thiamin-binding proteins. For the food industry, buckwheat grains are a valuable raw material to be used for the production of functional foods. Buckwheat flour may be a valuable and important ingredient in diets or food products, taking into consideration its nutritive value and potential promotion of human health.Keywords: |
Biochemical alterations in white yam (Dioscorea rotundata Poir.) under triazole fungicides: impacts on tuber quality .Cheruth Abdul JALEEL, Ragupathi GOPI, Rajaram PANNEERSELVAMCzech J. Food Sci., 2008, 26(4):298-307 | DOI: 10.17221/1117-CJFS An investigation was conducted to find out the effects of two triazole fungicides (triadimefon (TDM) and hexaconazole (HEX) - 15 and 10 mg/l per plant, respectively) on the biochemical constituents and tuber quality of white yam (Dioscorea rotundata Poir.). The exposure of white yam plants to the fungicides showd increased chlorophyll, carotenoids, xanthophylls, and anthocyanin contents and altered the membrane integrity in terms of electrolytic leakage and lipid peroxidation. The triazole treatments enhanced the accumulation of proline and total phenols in tubers. The visible symptoms of fungicides appeared as thickening and darkening of leaves. Both the triazoles increased the antioxidants (ascorbic acid, reduced glutathione, and tocopherol) contents. The data suggests that, apart from their fungicidal properties, the application of triazole fungicides may be a useful tool to increase the tuber quality in yam plants. |
Image vision technology for the characterisation of shape and geometrical properties of two varieties of lentil grown in TurkeyEbru Firatligil-Durmuş, Evžen Šárka, Zdeněk BubníkCzech J. Food Sci., 2008, 26(2):109-116 | DOI: 10.17221/1/2008-CJFS Geometrical features of lentil seeds (Lens culinaris Medik) were analysed using the image analysis LUCIA system Ver. 3.52. The values of the weight of 1000 kernels, kernel density, specific volume, specific surface area, and surface area of 1000 kernels of red and green lentils were determined as 66.61 and 138.56 g, 1504.5 and 1376.4 kg/m3, 0.6647 and 0.7265 cm3/g, 0.594 and 0.579 m2/kg, 395.4 and 801.9 cm2,, respectively. The lentil volume was simulated by an oblate spheroid and two sphere segments and the volumes obtained with both models were compared with that obtained by pycnometric method. Percentage differences of the two sphere segment approximation for red and green lentils were 4.4% and 4.2%, respectively. The height (thickness) of lentils was constant and practically the same with both varieties (2.6 mm) and therefore it was possible to simplify the geometrical models. Thus, 2D image analysis is suitable for a quick evaluation of the specific volume and surface area of grains on the basis of the projected area (equivalent diameter) without the measurement of the height. Image processing provides a simple, rapid, and non-invasive methodology to estimate lentil geometric features and engineering parameters. |
Authenticity evaluation of tea-based productsH. Čížková, M. Voldřich, J. Mlejnecká, F. KvasničkaCzech J. Food Sci., 2008, 26(4):259-267 | DOI: 10.17221/10/2008-CJFS This study proposes a method for estimating the content of tea in tea-based products. Broadly, this methodology is based on selecting chemical markers of the quality and authenticity of tea (and, therefore, of tea-based products), optimising the relevant analytical methods, and determining variations (type, origin, quality) among samples of green and black leaf teas. The contents of the selected markers (theobromine, caffeine, theanine, and total polyphenols) in tea-based products (iced teas, instant teas) were determined. Then, the dry tea content in these products, expressed as the equivalent amount of dry tea leaves, was calculated on the basis of two sets of mean data for these analytes: average literature data, and the mean experimental data obtained with our samples of leaf tea. With regards to the latter, we propose to use of the following averages for caffeine, theobromine, theanine, and polyphenols: for 100 g of black tea-based products 1.9 g, 0.13 g, 1.3 g, and 9.1 g, respectively; for 100 g of green tea-based products 1.9 g, 0.16, 1.7 g, and 14.7 g, respectively. Using this method, we found that approximately one third of the analysed samples failed to meet the tea extract levels required by German and Austrian legislations, while about 10% did not comply with the less demanding Czech legislative requirements. |
Fractionation and identification of some phenolics extracted from evening primrose seed mealLucia Zahradníková, Štefan Schmidt, Zuzana Sékelyová, Stanislav SekretárCzech J. Food Sci., 2008, 26(1):58-64 | DOI: 10.17221/1135-CJFS Crude ethanol and ethyl acetate extracts of evening primrose (Oenothera biennis L.) seed meal were separated into fractions using Silicagel L 100/200 column chromatography and methanol as the mobile phase. Six fractions were obtained from the ethanol extract and five fractions from the ethyl acetate extract and their contents of total phenolics were determined. By means of HPLC, the active compounds were identified as catechin, gallic acid, caffeic acid, syringic acid, and ferulic acid. |
Nondestructive identification of tea (Camellia sinensis L.) varieties using FT-NIR spectroscopy and pattern recognitionQuansheng Chen, Jiewen Zhao, Muhua Liu, Jianrong CaiCzech J. Food Sci., 2008, 26(5):360-367 | DOI: 10.17221/1125-CJFS Due to more and more tea varieties in the current tea market, rapid and accurate identification of tea (Camellia sinensis L.) varieties is crucial to the tea quality control. Fourier Transform Near-Infrared (FT-NIR) spectroscopy coupled with the pattern recognition was used to identify individual tea varieties as a rapid and non-invasive analytical tool in this work. Seven varieties of Chinese tea were studied in the experiment. Linear Discriminant Analysis (LDA) and Artificial Neural Network (ANN) were compared to construct the identification models based on Principal Component Analysis (PCA). The number of principal components factors (PCs) was optimised in the constructing model. The experimental results showed that the performance of ANN model was better than LDA models. The optimal ANN model was achieved when four PCs were used, identification rates being all 100% in the training and prediction sets. The overall results demonstrated that FT-NIR spectroscopy technology with ANN pattern recognition method can be successfully applied as a rapid method to identify tea varieties. |
Development of a scientific study for accessing the criteria under Commission Regulation (EC) 2073/2005 on traditional Slovak sheep cheese "bryndza"Lenka Cabanová, Oľga Škuntová, Daniela Matisová, Monika PipováCzech J. Food Sci., 2011, 29(1):31-34 | DOI: 10.17221/151/2010-CJFS A scientific shelf-life study for Listeria monocytogenes in the typical Slovak cheese "bryndza" was performed in accordance with the requirements of the Commission Regulation (EC) 2073/2005. Based on the previous positive findings of L. monocytogenes in the final products, the producer decided to perform laboratory tests, the results of which would allow him a different evaluation of these positive results. Both the physico-chemical (pH, aw) and microbiological examinations of "bryndza" cheese stored at 5.8-6.2°C were performed every two days till the end of the product shelf-life (7 days). Microbiological analyses were performed after artificial contamination of the final product with a mixture of three L. monocytogenes strains. The growth potential of L. monocytogenes was calculated as the difference in the counts of this bacterium between the last day and the first day of the test. The Slovak traditional "bryndza" cheese has been found not to support the growth of L. monocytogenes. Thus, the counts of L. monocytogenes must not exceed 50 CFU/g at the beginning and 20 CFU/g at the end of the product shelf-life in order to ensure its safety for the consumer. |
Influence of Alcalase and transglutaminase on immunoreactivity of cow milk whey proteinsBarbara WRÓBLEWSKA, Lucjan JĘDRYCHOWSKI, Gyongyi HAJÓS, Erzsebet SZABÓCzech J. Food Sci., 2008, 26(1):15-23 | DOI: 10.17221/1141-CJFS The aim of the research was to determine the changes in the immunoreactivity of whey protein concentrate (WPC) modified by two enzymes: proteinase, Alcalase 2.4L FG (Novo Nordisk), and cross-linked transglutaminase (EC 2.3.2.13, ActivaTM P, m-TG, Ajinomoto). The new products were characterised by 2D electrophoresis, immunoblotting, and ELISA methods. The WPC hydrolysate obtained with Alcalase contained proteins and peptides characterised mostly by low molecular weight peptides (MW < 14.4 kDa) in the pH range of 3-10. Immunoblotting showed strong immunoreactive properties of the hydrolysate with α-la and β-lg polyclonal rabbit antibodies. The 2D electrophoretic patterns of WPC and its modified product obtained with m-TG did no differ significantly. However, the immunoblot analysis demonstrated that WPC showed a stronger reactivity towards IgE of allergic patients as compared to WPC with m-TG. ELISA methods showed that two-step hydrolysis with Alcalase followed by m-TG significantly reduced the immunoreactive properties of whey proteins. No cross reactions were observed with α-la and only about 0.6% cross-reactivity with β-lg. |
Antioxidant activity, β-glucan and lipid contents of oat varietiesLucia Brindzová, Milan Čertík, Peter RAPTA, Michal Zalibera, Anna Mikulajová, Mária TakácsováCzech J. Food Sci., 2008, 26(3):163-173 | DOI: 10.17221/2564-CJFS The antioxidant activity, total phenolic and β-glucans contents, and the fatty acid profile of total lipids in covered (black and yellow) and naked oats were studied. Oats with black hulls showed a significantly higher antioxidant activity in 2,2'-azino-di-[3-ethylbenzthiazoline sulphonate] (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) based tests in comparison to the grains with yellow hulls and those of the naked varieties. Radical scavenging activity of oats determined by electron paramagnetic resonance (EPR)/spin-trapping test did not depend on the colour of the grain hulls, but the naked grains showed a lower ability in scavenging reactive radicals. A positive correlation between the content of β-glucans in covered oat grains and the amount of reactive radicals scavenged was observed. Total phenolic content in the black oats was significantly higher than in the yellow and naked oat varieties. However, no significant differences in the fatty acid profile between the naked and covered oats were found, and the common fatty acids being linoleic, oleic, and palmitic acids. |
Biofilms and hygiene on dairy farms and in the dairy industry: sanitation chemical products and their effectiveness on biofilms - a reviewHana Vlková, Vladimír Babák, Růžena Seydlová, Ivo Pavlík, Jarmila SchlegelováCzech J. Food Sci., 2008, 26(5):309-323 | DOI: 10.17221/1128-CJFS Microbial biofilms which form on all types of surfaces of technological systems in the dairy industry and on dairy farms adversely affect the quality and safety of final products, i.e. both foodstuffs and raw materials used for their production. The fact that a number of microorganisms are alimentary pathogens, e.g. Staphylococcus aureus or Listeria monocytogenes, makes a serious problem directly affecting human health. Biofilms are usually formed by various species of microorganism, which protect each other against the effects of biocidal (antibacterial) agents and are resistant to these agents. The colonisation of surfaces of the open and closed piping systems, floors, waste, walls and ceilings of the production halls becomes a major problem in the selection of effective sanitation agents for their control. Based on the existing model studies, practical methods for testing the effectiveness of sanitation procedures should be evaluated, including the selection of biocides and comparison of the physical parameters of the sanitation procedures. Testing the effectiveness of the sanitation agents should be performed with the use of standardised tests, which consider microbial, structural, and chemical characteristics of the living microbial communities on specific contact surfaces in the food-processing industry. |
Mushrooms of genus Pleurotus as a source of dietary fibres and glucans for food supplementsAndriy Synytsya, Kateřina Míčková, Ivan Jablonský, Marcela SLUKOVÁ, Jana ČopíkováCzech J. Food Sci., 2008, 26(6):441-446 | DOI: 10.17221/1361-CJFS Fruit bodies (separately pilei and stems) of mushrooms Pleurotus ostreatus (four strains) and Pleurotus eryngii were characterised as a source of polysaccharides. The contents of glucans and dietary fibres were determined with using the respective Megazyme enzymatic kits. Enzymatic analysis of the fruit bodies confirmed significant differences in the contents of these components among the species and strains. The stems contained more insoluble dietary fibres than the pilei in all the cases and more β-glucans in most cases. However, relatively high contents of β-glucan (20-50% of dry matter) could be a result of incomplete enzymatic hydrolysis of insoluble α-1,3-glucans. Nevertheless, low food quality stems of mushrooms Pleurotus sp. could be a valuable source of cell wall glucans for the preparation of food supplements. |
The status of micronutrients (Cu, Fe, Mn, Zn) in tea and tea infusions in selected samples imported to the Czech RepublicRenée Street, Jiřina Száková, Ondřej Drábek, Lenka MládkováCzech J. Food Sci., 2006, 24(2):62-71 | DOI: 10.17221/3301-CJFS A total of 30 tea samples of different origins, thirteen green tea samples, thirteen black tea samples, two semi-fermented tea samples and one white tea, imported to the Czech Republic, were collected and analysed for the total content of copper, iron, manganese, and zinc in tea leaves and tea infusions. The total contents of metals in tea leaves differ according to the type of tea (green or black) and are probably influenced by many other factors, e.g. soil properties. The total contents of Mn were much higher compared to the total contents of Cu, Fe, and Zn, and varied between 511-2220 mg/kg. To compare easily hot water soluble concentrations of Cu, Fe, Mn and Zn, 5 min, 60 min, and 24 h infusions were prepared. The extractability of the elements was in the order Cu > Zn > Mn > Fe. The proportions of the element contents in the infusion related to the respective total contents in leaves were 30 ± 16% Cu, 26 ± 10% Zn, 18 ± 10% Mn, and 1.5 ± 0.8% Fe, respectively. The results confirmed that tea infusion can be an important dietary source of Mn. |
Extraction of carrot (Daucus carota L.) carotenes under different conditionsMartina Fikselová, Stanislav Šilhár, Ján Mareček, Helena FrančákováCzech J. Food Sci., 2008, 26(4):268-274 | DOI: 10.17221/9/2008-CJFS This paper describes carotenes extraction from carrot under different conditions involving different temperatures, treatment of samples, and solvents (ethanol, 2-propanol). Carrot roots (Daucus carota L. cv. Nevis F1) were tested for the extraction yields of carotenes at temperatures 20°C, 40°C, and 60°C, the samples having been examined after harvest, after cold storage (stored at 5°C), and after freezing (-18°C). In connection with the technology of the carotenoid concentrate production from carrots, it was found that the solubility and yield of carotene from carrot depend on the temperature and the time of extraction as well as the treatment of the sample. It was revealed that the best extraction efficiency was achieved with the samples treated by freezing and using the extraction 60°C for 2-4 hours. Higher temperatures caused an increase in the carotenoid concentrations. The carrot variety Nevis F1 and the extraction at 60°C were used for the model production of carotenoid concentrate. |
Screening methods used for the detection of veterinary drug residues in raw cow milk - a reviewPavlína NavrátilováCzech J. Food Sci., 2008, 26(6):393-401 | DOI: 10.17221/2438-CJFS At both national and international levels, increasing attention is paid to the evaluation of the risk of occurrence of veterinary drug residues in foodstuffs and foods of animal origin, and to the introduction of appropriate measures to reduce this risk. The design and strategy of antibiotics and sulphonamide detection in milk involve two different aspects: the ability to sell the milk depending on its quality (technological safety), and the health safety of the milk regulated by the recent legislative regulations (toxicological safety). Veterinary drug residues in milk represent a health risk for the consumer. This review describes the methods used for extensive monitoring of antimicrobial agents - microbial inhibitor methods and rapid specific assays. |
Multi-experimental characterisation of grape skin extractsLenka ŠŤAVÍKOVÁ, Martin POLOVKA, Barbora HOHNOVÁ, 3, Jana ZEMANOVÁCzech J. Food Sci., 2008, 26(10):S43-S48 | DOI: 10.17221/245/2008-CJFS Grape skins contain a plenty of different flavonoids, most of them revealing significant antioxidant properties. In this contribution, a complex study is presented of grape skin ethanol extracts, prepared from grape skins of two vine grape varieties, Svatovavřinecké (St. Laurent) and Alibernet. Extracts were prepared from two different amounts of lyophilised grape skin powders using the pressurised fluid extraction (PFE). The antioxidant activity of the extracts was tested by EPR spectroscopy in Fenton system generating reactive radicals (*OH, O+>) assays. Total phenolic content (TPC) of the individual extracts and their tristimulus colour values (CIE Lab) were evaluated, using an UV-VIS spectrophotometer. All the data obtained were subsequently correlated and discriminated, using the multivariate statistics, involving the canonical discriminant analysis, principal component analysis, and canonical correlation analysis. Results obtained indicated that PFE is a suitable extraction technique, only slightly influencing antioxidant ability as well as composition of the so-prepared extracts. The influence of extraction conditions on the entire monitored characteristics was insignificant. |
Determination of soya protein in model meat products using image analysisZdeňka Randulová, Bohuslava Tremlová, Zuzana Řezáčová-Lukášková, Matej Pospiech, Ivan StrakaCzech J. Food Sci., 2011, 29(4):318-321 | DOI: 10.17221/57/2009-CJFS The addition of plant proteins into meat products is nowadays a commonly used practice especially for the technological and economical reasons. Their properties have been known and used in meat products production for a long time. In the past, wheat protein or flour had been used most frequently, however, in these days they are being replaced by soya protein which has much more favourable properties in its use. Considering the possible misuse of raw materials of plant origin for the adulteration of meat products, the existence of highly sensitive and accurate procedures for their detection is needed including the determination of their content. Soya protein can be detected using various methods. In our work, an immunohistochemical method was used with image analysis for the quantification of soya protein. Model meat products with the addition of known amounts of soya protein in various forms were made for this experiment. |
Mercury and methylmercury in muscle tissue of chub from the Elbe River main tributariesKamila KRUŽÍKOVÁ, Zdeňka SVOBODOVÁ, Olga VALENTOVÁ, Tomáš RANDÁK, Josef VELÍŠEKCzech J. Food Sci., 2008, 26(1):65-70 | DOI: 10.17221/1140-CJFS The aim of the present study was to investigate the concentrations of total mercury and methylmercury in muscle of 55 chub (Leuciscus cephalus) from seven main tributaries (Orlice, Chrudimka, Cidlina, Jizera, Vltava, Ohře, Bílina) of the Elbe River and to evaluate the health risks of eating fish from the tributaries monitored. Mercury was determined by means of cold vapour atomic absorption spectrometry using AMA-254, methylmercury in the form of CH3HgCl by gas chromatography. The highest mean concentrations of total mercury and methylmercury were found in the Jizera (0.27 ± 0.19 mg/kg and 0.23 ± 0.15 mg/kg, respectively) and the lowest mean concentrations of total mercury and methylmercury were found in the chub from the Cidlina (0.07 ± 0.05 mg/kg and 0.06 ± 0.04 mg/kg, respectively). The average methylmercury-to-total mercury ratio was 83 ± 15%. The fish intake hazard indexes calculated for the individual tributaries monitored were between 0.01 and 0.03. The results of this study show that the Elbe River is not significantly affected by mercury contamination from its main tributaries |
Assessment of the authenticity of fruit spirits by gas chromatography and stable isotope ratio analysesRenata WINTEROVÁ, Renata MIKULÍKOVÁ, Jiří MAZÁČ, Pavel HAVELECCzech J. Food Sci., 2008, 26(5):368-375 | DOI: 10.17221/1610-CJFS The gas chromatographic (GC) determination of volatile constituents and the determination of 13C/12C isotope ratios by isotope ratio mass spectrometry - IRMS analysis as well as SNIF-NMR analysis of (D/H)I and (D/H)II ratios in ethanol are prospective analytical methods which can be used for checking the authenticity of fruit spirits and for detecting their adulteration. Different concentrations of volatile compounds such as acetaldehyde, ethyl acetate, diethyl acetal, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2- and 3-methyl-1-butanol, volatile fatty acids and isotopic data were demonstrated using discriminant analysis. The results show that the determination of isotope ratios can be used especially for distinguishing between fruit spirits and others spirits, i.e. those made from beet sugar, maize, cane sugar, grain, potato, or synthetic alcohol. Gas chromatography also makes it possible to discriminate between respective spirits derived from one kind of fruit such as sweet cherry brandy, sour cherry brandy, pear brandy, apple brandy, apricot brandy, or plum brandy. |
Evaluation of colour content in grapes originating from south MoraviaJosef BALÍK, Michal KUMŠTACzech J. Food Sci., 2008, 26(10):S18-S24 | DOI: 10.17221/240/2008-CJFS The content of total anthocyanins was determined in grapes of nine grapevine (Vitis vinifera L.) varieties belonging to the traditional blue vine varieties grown in south Moravia (Czech Republic) within the period of 2002-2007. Factors of vintage and health condition of grapes were observed. The material balance of the colour substances in grapes was related to the dry matter of skins of berries and that of fresh grapes used as raw material for vinification. The highest content of pigments was found in the variety Neronet (2.15-4.49 g/kg of fresh grapes), which belongs to the so-called Teinturier varieties. Besides the variety Neronet (containing 30.6-73.4 mg/g of dry skin), high contents of total anthocyanins in dry skins were found in the varieties Dornfelder (24.7-59.0 mg/g of dry skin) and Cabernet Moravia (20.1-59.3 mg/g of dry skin). In the long run, the lowest concentrations of pigments were determined in grapes of the varieties Blauer Portugieser (0.51-1.02 g/kg of fresh grapes) and Pinot noir (0.27-0.60 g/kg of fresh grapes). The highest colour capacity was found in grapes harvested in the 2003 and 2006. Contents of anthocyanins were significantly lower (P = 0.001) in damaged grapes. Grapes containing more than 40% of rotten berries revealed in skins and whole grapes only 41% and 55%, respectively, of the colour capacity of the healthy raw material. |
Phthalic acid esters (PAEs) in the food chainAlžbeta JarošováCzech J. Food Sci., 2006, 24(5):223-231 | DOI: 10.17221/3318-CJFS Phthalic acid esters (PAEs) rank among the primary risk pollutants and their adverse effects may endanger the environmental balance and affect the ontogenetic development of live organisms and their body functions. Therefore, the aim of this study was to monitor the occurrence of PAEs in packaging materials and plastics (infusion sets), to evaluate the accumulation and distribution of the most common phthalates such as DEHP (di-2-ethylhexyl phthalate) and DBP (di-n-butyl phthalate) in body tissues and organs of pigs and broiler chicks having been administered the phthalates per os, to assess the occurrence of PAEs in pig and cattle farms in the district of Hodonín (1997-1999), and to propose precautionary measures to mitigate the risk of PAE penetration into the food chain and the environments. DEHP and DBP contents in packaging materials ranged from 0.1 to 4259 mg DEHP, and from 0.1 to 1298 mg DBP per 1 kg printed packaging material, respectively. In haemodialysis patients, over 0.5 mg DEHP per 1 kg blood was found after three hours of haemodialysis. In combined feeds for farm animals (pigs, cattle, poultry), DEHP and DBP concentrations ranging from 0.07 to 1.77 and from 0.06 to 2.36 mg/kg feed, respectively, were detected. In all the food samples investigated, measurable levels of DEHP (less than 0.01-0.22 mg/kgsample) and DBP (less than 0.01 to 1.31 mg/kgsample) were found. In the experimental pigs and broilers, phthalates were distributed in all the organs monitored and the highest accumulation was found in adipose tissue as expected. All the samples withdrawn from farms in the Hodonín district had measurable phthalate concentrations; the hygienic limit (4 mg/kg) was exceeded in 2 samples of swine adipose tissue (4.26 and 6.92 mg/kgfresh sample) and in 1 sample of cattle adipose tissue (4.75 mg/kgfresh sample). |
The usefulness of rabbit anti-QQQPP peptide antibodies to wheat flour antigenicity studiesJoanna Leszczyńska, Agata Łącka, Malgorzata Bryszewska, Ewa Brzezińska-BłaszczykCzech J. Food Sci., 2008, 26(1):24-30 | DOI: 10.17221/1124-CJFS The aim of our work was to estimate the usefulness of rabbit polyclonal anti-QQQPP peptide antibodies to determination of gluten proteins and the usage of these antibodies to estimate the changes of allergenicity of wheat flour after enzymatic modification. For enzymatic modification of wheat flour trypsin, subtilisin and transglutaminase were used. By the use of rabbit antibodies against QQQPP peptide we have stated that the products of subtilisin and transglutaminase degradation exert strongly decreased immunoreactivity. |
Antimicrobial properties of some essential oils against some pathogenic microorganismsNazan Celikel, Gökhan KavasCzech J. Food Sci., 2008, 26(3):174-181 | DOI: 10.17221/1603-CJFS Investigations were carried out to assess the efficiency of five plant essential oils: thyme, myrtle, laurel, sage, and orange oils as natural food preservatives. The effect of the plant essential oils against Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Candida albicans at concentrations of 5-20 µl/disk (diameter 6 mm) and 0.5-3% (v/v) was studied in agar diffusion test medium and milk medium. The essential oils of these extracts exhibited markedly antibacterial and bacteriostatic activity, with thyme showing the highest inhibition and orange the lowest. However, with thyme extract, high inhibitory activity was observed for all tested concentrations, L. monocytogenes showed less sensitivity towards essential oil extracts. |
Isolation of anticlostridially active lactobacilli from semi-hard cheeseŠtěpán Tůma, Kateřina Kučerová, Milada PlockováCzech J. Food Sci., 2008, 26(5):324-332 | DOI: 10.17221/115/2008-CJFS The group of 7 strains of facultatively heterofermentative lactobacilli (FHL) of the non starter lactic acid bacteria (NSLAB) isolated from semi-hard cheeses using a well agar diffusion assay possessed a different level of inhibition activity against 16 different strains of Clostridium sp. belonging to the species Cl. butyricum, Cl. tyrobutyricum, Cl. beijerinckii, and Cl. sporogenes. Two selected strains with the production of partially indentified anticlostridially active inhibitory substances, Lb. paracasei ST68 (producing hydrogen peroxide) and Lb. paracasei 171R2 (producing bacteriocin and hydrogen peroxide), were tested for the inhibition activity against gas producing Cl. butyricum 10702 and Cl. tyrobutyricum 184 in cheese slurry. The effects of both strains were different in reducing the numbers of gas producing Cl. butyricum 10702 by > 3 log cycles and Cl. tyrobutyricum 184 by > 1 log cycles in cheese slurry during the tested storage periods of 24 days at 13°C. The Cl. tyrobutyricum strains isolated from spoiled cheese were identified by species-specific PCR for Cl. tyrobutyricum. |
Comparative Lipid Composition Study in Farmed and Wild Blackspot Seabream (Pagellus bogaraveo)V. Álvarez, M. Trigo, S. Lois, D. Fernández, I. Medina, S. P. AubourgCzech J. Food Sci., 2009, 27(10):S274-S276 | DOI: 10.17221/920-CJFS During the latest decades, the fish trade has accorded an increasing attention to aquaculture development as a source of marine food products. In this sense, blackspot seabream (Pagellus bogaraveo) has recently attracted a great commercial interest as a farmed product. This work provides a comparative lipid composition study between wild and farmed individuals. For it, three different edible zones (ventral, dorsal and tail white muscles) were considered. From a nutritional point of view, lipid composition of farmed and wild blackspot seabream showed valuable lipid parameters (total polyunsaturated fatty acids, total ω3/total ω6 fatty acid ratio and α-tocopherol values). Comparison between farmed and wild fishes led to a wide number of differences. Thus, farmed fish muscle showed a higher (P < 0.05) total lipid content than its counterpart wild one. In addition, farmed fish showed higher triglyceride contents but lower (P < 0.05) values in the remaining lipid classes and groups studied (phospholipids, sterols and α-tocopherol). Concerning the fatty acid analysis, farmed fish showed a higher (P < 0.05) monounsaturated fatty acids (ventral and tail zones) content but lower for polyunsaturated fatty acids (ventral and tail zones) and total ω3/ total ω6 ratio. No differences (P > 0.05) were detected between both kinds of fish for the saturated fatty acids proportion. For all parameters studied, both farmed and wild fishes provided very little differences (P < 0.05) among the different muscle zones considered, so that an inhomogeneous distribution in the actual species could not be concluded. |
Effect of a "Fast Food" Diet on the Urinary Excretion of Maillard Reaction ProductsA. Förster, C. Börner, T. HenleCzech J. Food Sci., 2009, 27(10):S160-S162 | DOI: 10.17221/1101-CJFS The impact of a diet consisting mainly of "fast food" on the urinary excretion of glycation compounds compared to a usual diet was studied. 9 volunteers followed a well defined diet, starting with one day of individual diet of choice followed by four days of "fast food" embedded in two day periods of MRP-free diet. 24 h-urine samples were collected and analysed for contents of free Amadori product and pyrraline. Urinary excretion of the glycation compounds decreased by 70% to a basic level as a consequence of the MRP-free diet. The following "fast food diet" lead to an increase in excretion of both lysine derivatives, giving evidence for no significant differences between the urinary MRP contents after the individual diets and the "fast food diet". In summary, our data confirm, that urinary excretion of glycation compounds is affected by the daily diet. Consumption of a "fast food diet" did not lead to an increased urinary excretion of MRPs compared to the diets usually followed by the participants. |
The Natural Products in Protection against the most Important Pathological Changes in Human MetabolismM. Votruba, M. Vecka, L. Prokeš, B. JuráškováCzech J. Food Sci., 2009, 27(10):S31-S34 | DOI: 10.17221/1095-CJFS Inflammation in joint: The liberation of phospholipids from cell membranes represents the first step of inflammation cascade. By action of phospholipase A2 is split of the arachidonic acid. Free arachidonic acid is than metabolised by two enzymes: 5-lipooxygenase and 2-cyclooxygenase to generate the group of prostanoids and leukotrienes which are the first active proinflammation compounds, starting the whole proces of inflammation. We verífied, that 27 flavonoids and flavans, contained in American patent Univestin are really able to interrupt this pathway by inhibition both of those enzymes. All these flavonoids are naturally occurring chemicals, which give color to plants and are found in plants, fruits, grains, nuts and vegetables. Theirs antioxidant capacity eliminates the action of Cyt P450 also and prevents to origine of epoxides. Cancerogenesis: Inositolhexaphosphate (IP6) is found in substantial amounts in whole grains, cereals, legumes, nuts and seeds. As well as inositol, IP6 is contained in most mammalian cells, wherein they are important in regulating vital cellular function such as signal transduction, cell proliferation and differentation. Inositol and IP6 are contend in product Inocell and there is additional evidence that inositol alone may further enhance the anti-cancer effect of IP6. Beside decreasing cellular proliferation IP6 also causes differentation of malignant cells ofen resulting in a conversion to normal phenotype, what leads to starting of apoptose in those cells. Inocell greatly enhances NK cell activity, regulates cell growth and has very strong antioxidant capacity. The suggestion we can demonstrate on succesfful efects of Inocell in concrete causes of patients with various types of cancerogenesis. Peptic ulcer disease and gastric cancer: The ability of Vaccinium macrocarpon, the North American cranberry, to prevent bacterial adhesion has been used to advantage in the prevention of urinary tract infections and has recently been described for the prevention of adhesion of bacteria responsible for oral infections and stomach ulcers as well in Helicobacter pylori. |
Chemical Changes in Chilled Farmed Sea Bass (Dicentrarchus labrax): Effect of Advanced Icing ConditionsJ. Pena, M. Trigo, G. Bouzada, D. Fernández, J. Barros-Velázquez, S. P. AubourgCzech J. Food Sci., 2009, 27(10):S277-S279 | DOI: 10.17221/1080-CJFS The present research was focused on the commercialisation of fresh farmed sea bass (Dicentrarchus labrax). A slurry ice prototype (60% water/40% ice) coupled to an ozone generator (700 mV, 0.17 mg/l) was tested for the slaughtering and chilling storage (up to 7 days) of this species; comparison with slurry ice treatment alone was undergone. The study was addressed to chemical constituent changes (autolysis, lipid hydrolysis and oxidation, volatile amine formation) in fish muscle related to quality loss; comparison to sensory assessment (skin, eyes, external odour, gills, consistency) was carried out. Increasing values (P < 0.05) with icing time could be observed for autolysis (K value assessment), lipid hydrolysis (free fatty acid formation) and microbiological activity (trimethylamine formation); however, no effect (P > 0.05) of icing time on lipid oxidation (primary and secondary compounds) could be depicted. Concerning differences between both icing conditions, a lower (P < 0.05) free fatty acid formation was concluded for individuals kept under slurry ice-ozone condition. For both icing conditions, acceptable sensory quality was accorded at day 7, being scores better (eyes and gills) in the case of fish where ozone was incorporated to slurry ice. |
Chemical Changes in Chilled Farmed Salmon (Oncorhynchus kisutch): Effect of Previous High Pressure TreatmentA. Rodríguez, I. Ortea, M. Trigo, Y. Sierra, J. M. Gallardo, G. Tabilo-Munizaga, M. Pérez-Won, S. P. AubourgCzech J. Food Sci., 2009, 27(10):S20-S22 | DOI: 10.17221/630-CJFS Coho salmon (Oncorhynchus kisutch) has recently attracted a great interest as a farmed product. This research focuses on its commercialisation as a chilled product. Thus, the effect of a previous hydrostatic high pressure (HHP) treatment on chemical changes related to quality loss was studied. A marked effect of HHP treatment was observed on lipid hydrolysis (free fatty acid formation), lipid oxidation (primary, secondary and tertiary compounds) and protein breakdown (sarcoplasmic fraction) throughout the chilling storage; however, no influence could be observed on nucleotide degradation and polyene index. Sensory analysis (putrid and amine odour development) showed a profitable effect of HHP on chilled salmon quality; however, no effect could be concluded on rancid odour development. |
Aroma Formation during Thermal Food Processing: Why do Thermally Treated Foods Smell Differently?P. SchieberleCzech J. Food Sci., 2009, 27(10):S40 | DOI: 10.17221/953-CJFS During thermal processing of foods non-volatile precursors undergo various types of reactions leading to the unique aromas of well-accepted product such as cocoa, coffee, cereals or nuts. It is without doubt that the reaction between free amino acids and carbohydrates or their degradation products, known as the Maillard reaction, is among the most important "flavor delivery" systems in such foods. However, studies using approaches of "molecular sensory science" have shown that the majority of the Maillard-type reaction products, identified so far, do not show a contribution to the aroma of processed foods. In addition, many of the key Maillard aroma compounds, such as 4-hydroxy-2,5-dimethyl-3(2H)-furanone, the Strecker aldehydes or various pyrazines were found to be identical in many processed foods. Using several foods as examples, the lecture is intended to show that the quantitative balance of potent Maillard-type flavor compounds is a key to explain the differences in the different aroma perception of thermally processed foods. In addition, the presence of lipid degradation products and/or single "character impact odorants" transferred from the raw materials into the final products have to be considered as "modifiers" of the overall "aroma orchestra". |
