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Biochemical parameters and oxidative resistance to thermal treatment of refined and unrefined vegetable edible oilsRajko Vidrih, Sergeja Vidakovič, Helena AbramovičCzech J. Food Sci., 2010, 28(5):376-384 | DOI: 10.17221/202/2008-CJFS In human nutrition fats are physiologically important food constituents but also the components most liable to oxidative degradation. The oils included in the study were refined (sunflower, extra-sunflower, soybean, and rapeseed) as well as unrefined (olive and pumpkin-seed) oils. The aim of our study was to determine the fatty acid composition, tocopherol content, and quality parameters such as the free fatty acid content, peroxide value, and induction time. Extra virgin olive oil had the highest average peroxide value, while unrefined pumpkin seed oil had the lowest one. The acid value of the unrefined oils was higher on average than that of the refined oils. Soybean oil had the highest total tocopherol content and extra virgin olive oil the lowest one. The refined oils with higher contents of saturated and monounsaturated fatty acids and lower polyunsaturated fatty acid contents had a high oxidative stability. A negative correlation has been found in the oils between the induction time and polyunsaturated fatty acid content. Among the oils investigated, unrefined pumpkin seed oil was the most oxidatively stable, the other oils following in the decreasing order: extra virgin olive > high oleic sunflower > rapeseed > soybean > sunflower oil. The oxidative stability of the unrefined oils was better than that of the refined oils. |
Methods for the Determination of Allergenic Substances in FoodsK. Tomková, F. Štumr, P. Dvorská, P. Šafářová, J. Rysová, D. Gabrovská, P. Hanák, J. PlickaCzech J. Food Sci., 2009, 27(10):S369-S371 | DOI: 10.17221/945-CJFS Within the framework of the research project ELISA methods for the quantitative determination of allergenic substances in foodstuff and raw materials were developed. ELISA kits for allergenic proteins of milk (casein, beta-lactoglobulin and BSA) egg white proteins and mustard proteins were validated and collaborative studies were performed to prove the validation of the ELISA methods developed. Various methods of extraction were tested. The parameters as a limit of detection, as a limit of quantification, robustness, repeatability and accuracy were determined. A broad range of zero matrices for allergens were tested as well. The ELISA kits are suitable for the determination of allergens according to EU legislation Directive 2005/26/EC and Directive 2006/142/EC in the laboratories focused on this topic. |
Antibacterial and antifungal effects of alcoholic extracts of 41 medicinal plants growing in TurkeyÖmer ErtürkCzech J. Food Sci., 2010, 28(1):53-60 | DOI: 10.17221/144/2008-CJFS The antibacterial and antifungal activities of crude ethanolic extracts of 41 traditional medicinal plant species belonging to 26 families were tested against four bacteria and two fungi: Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger. Of the 41 plants tested, 39 showed antimicrobial activity against one or more species of microorganisms. While the crude extracts from Nigellea arvensis did not show antimicrobial activity against the test microorganisms, Pistasia lentiscus showed only antifungal activity against A. niger. The most active antimicrobial plants were Cuminum cyminum, Jasminium officinale, Thymus capitatus, Viscum album, Tanecetum sorbifolium, Pimpinella anisum, Galega officinalis, Liguidamber orientalis, Rhus coriaria, Alnus glutinosa, Pimental officinalis, Achillea coarctata, and Cameli sinensis. |
Effect of milk chocolate supplementation with lyophilised Lactobacillus cells on its attributesDorota Żyżelewicz, Ewa Nebesny, Ilona Motyl, Zdzisława LibudziszCzech J. Food Sci., 2010, 28(5):392-406 | DOI: 10.17221/217/2009-CJFS Manufacturing of novel foodstuffs supplemented with live probiotic bacteria has recently been intensively investigated. The supplementation of confectionery with probiotics is troublesome since some unit technological processes are conducted at high temperatures and the products are usually stored at ambient temperature. Our group has developed a method of the production of milk chocolate, sweetened with either sucrose or isomalt and aspartame, containing 32, 36, or 40 g/100 g fat, and supplemented with live cells of probiotic bacterial strains: Lactobacillus casei and paracasei. This new milk chocolate displayed the same sensory properties as the reference, probiotic-free chocolate. The number of live bacterial cells was maintained at the functional level of 106 / 108 cfu/g after keeping for 12 months irrespective of the temperature. The highest number of live probiotic bacteria survived in the chocolate kept at 4°C. Thus the product can be regarded as functional food. |
Differences in the amino acid composition of the breast muscle of wild and farmed pheasantsAdam Brudnicki, Anna Kułakowska, Dominika Pietruszyńska, Małgorzata Łożyca-Kapłon, Jan WachCzech J. Food Sci., 2012, 30(4):309-313 | DOI: 10.17221/17/2011-CJFS Numerous studies show the slaughter yield and also basic chemical composition of pheasant meat. The results reveal a higher biological value of the meat of pheasants which were fed naturally, in comparison to the meat of pheasants fed with commercial mixtures. In many countries, the pheasant is selected with the aim of producing high quality meat with very desirable nutritional values. There are only few publications on amino acid composition of pheasant meat. The knowledge of amino acid composition of pheasant meat can be used to determine its potential nutritional value. The amino acid compositions were compared of the meats of wild and farm pheasants. In the study, the following amino acids were determined: Asp, Thr, Ser, Glu, Pro, Gly, Ala, Val, Ile, Leu, Tyr, Phe, His, Lys, Arg. An improved amino acid profile was found in the breast muscle of pheasants kept at the farm in comparison with that of wild pheasants. |
Reliability of PCR based screening for identification and quantification of GMOsJaroslava Ovesná, Ladislav Kučera, Jan Hodek, Kateřina DemnerováCzech J. Food Sci., 2010, 28(2):133-138 | DOI: 10.17221/67/2009-CJFS Handling with genetically modified organisms (GMOs) is regulated namely in EC. Laboratories often use polymerase chain reaction (PCR) based screening methods to monitor the presence of GM particles in food commodities as a cost effective approach. The reliability was tested of such screening using 35S CaMV promoter as the target sequences. Soya grown from non-GM cultivar as declared by a seed company was investigated after the harvest, transport to the silo, and before processing. The results based on PCR and real-time PCR analysis clearly showed that, the contamination with debris of other species, dust during transport, storage, and other kind of handling led to contamination with detectable amounts of Cauliflower mosaic virus (CaMV). Impurities are allowed by EC regulations but may, as we have shown, interfere with the analytical procedures based on PCR. The identification of 35S CaMV promoter and NOS terminator in food with uncertain history and no approved specific events may indicate unknown GMOs and perhaps emergency situation. |
Changes in quality parameters of vodka filtered through activated charcoalLucie Siříšťová, Šárka Přinosilová, Kateřina Riddellová, Jana Hajšlová, Karel MelzochCzech J. Food Sci., 2012, 30(5):474-482 | DOI: 10.17221/361/2011-CJFS The production technology of high-quality vodka used in Russia involves filtration through activated charcoal. To approach the quality of renowned Russian vodka, one prominent Czech spirit-producing company installed on its production premises a filtration device including a charcoal column, and launched test runs during which different filtration conditions were tested. Samples collected during the test runs were analysed by GC-FID and GC-MS with the aim to compare their composition; sensory analysis was an integral part of the evaluation. The results documented a positive effect of charcoal filtration on the quality of produced vodka, which was not reduced when higher flow rates were applied. |
Discriminatory power assessment of the sensor array of an electronic nose system for the detection of non alcoholic beer agingMahdi GHASEMI-VARNAMKHASTI, Seyed Saeid MOHTASEBI, Maryam SIADAT, Seyed Hadi RAZAVI, Hojat AHMADI, Amadou DICKOCzech J. Food Sci., 2012, 30(3):236-240 | DOI: 10.17221/165/2011-CJFS Many chemical changes in beer aroma occur during storage (aging), and monitoring these changes could give guidelines to the brewers how to manage and control the brewing process to obtain the final product with a high stability in flavour after packaging. In this regard, our laboratory aimed at a research into the application of an electronic nose in order to get the fingerprint of the change of non alcoholic beer aroma during aging. Th discriminatory power of the sensor array of this system was evaluated. Principal Component Analysis (PCA) and Soft Independent Modelling of Class Analogy (SIMCA) techniques were used for this purpose. The results obtained can direct us to performing other parts of our project. Considering the discriminatory power of the sensor array used, we can develop the application of a specific electronic nose system by picking up the most effective sensors or ignoring the redundant sensors. |
Volatile organic compounds as biomarkers of the freshness of poultry meat packaged in a modified atmosphereJana Tománková, Gabriela Bořilová, Iva Steinhauserová, Leo GallasCzech J. Food Sci., 2012, 30(5):395-403 | DOI: 10.17221/408/2011-CJFS The volatile organic compounds (VOCs) in the packing of chicken meat in a modified atmosphere was qualitatively and quantitatively evaluated. The total number of 72 samples of chicken hindquarters were stored under two different modified atmospheres (70% O2, 30% CO2, and 70% argon, 30% CO2) for 20 days. Analyses were performed on Days 0, 4, 8, 12, 16, and 20. VOCs in the headspace samples were detected and quantified by gas chromatography/mass spectrometry (GC/MS) every fourth day of storage. Pentamethylheptane, dimethylsulphide, dimethyl disulphide, dimethyl trisulphide, dimethyl tetrasulphide, hydrogen sulphide and ammonia were detected. Pentamethylheptane and ammonia had similar values for both modified atmospheres (MA). The other compounds were found only in argon MA from the Day 16 of storage with a subsequent increase of values. The measured values for dimethylsulphide were 10.7 and 13.8 mg/l, for dimethyl disulphide they were 1.9 and 10.7 mg/l, dimethyl trisulphide levels were 15.7 and 19.3 mg/l and dimethyl tetrasulphide levels were 93.2 and 418.3 mg/l for Day 16 and 20. The hydrogen sulphide level was detected from 80 to 370 mg/l after the 8th day of storage. We showed that the argon MA is less suitable for packaging raw chicken parts than the oxygen MA in view of the increased amount of microflora and unpleasant odour as assessed by sensory analysis. Oxygen prolonged the shelf life by about four days in comparison with argon. Sensory evaluation was similar for both atmospheres after air exhaustion. The argon MA did not extend the shelf life as compared to the oxygen MA. |
Prevalence, distribution, and antimicrobial susceptibility of Staphylococcus aureus in ready-to-eat salads and in the environment of a salad manufacturing plant in Northern GreeceDaniel Sergelidis, Amin Abrahim, Vasiliki Anagnostou, Alexandros Govaris, Theofilos Papadopoulos, Anna PapaCzech J. Food Sci., 2012, 30(3):285-291 | DOI: 10.17221/37/2011-CJFS The prevalence, distribution, and antibiotic susceptibility of Staphylococcus aureus was investigated in ready-to-eat (RTE) salads, the environment, and the personnel of a salad producing plant in Greece. Staphylococci were isolated from 27% of the samples. Apart from three isolates which were sensitive to all antibiotics, all the others exhibited resistance from two up to five antibiotics. None of the isolates was resistant to oxacillin. Random Amplified Polymorphic DNA (RAPD) analysis showed no genetic relation between the human and salad isolates while one RAPD clone of S. aureus predominated among the salad samples. The results suggest that an effective application of Good Manufacturing Practices (GMP) is needed along the food production chain to prevent the contamination of RTE foods. |
Outdoor environment as a source of Listeria monocytogenes in food chainTereza Gelbíčová, Renáta KarpíškováCzech J. Food Sci., 2012, 30(1):83-88 | DOI: 10.17221/7/2011-CJFS We monitored the presence of Listeria monocytogenes in environmental sources and to evaluate the phenotypic and molecular characteristics of the isolates recovered. L. monocytogenes was isolated in 12 (11.2%) of the 107 samples from the wild, farm environment, and vegetation. Most isolates (83.3%) were of serotype 1/2a and the remainder (2) were of serotype 4b. All 12 isolates were susceptible to the whole range of antimicrobials tested. These12 strains were carriers of the virulence genes prfA, hlyA, actA, plcA, plcB, inlA, inlB, inlC, and inlJ. The detection of the inlA gene in 4 (33.3%) of 12 strains using the PCR-RFLP suggests the potential of some of these strains to penetrate into epithelial cells of the intestinal barrier. Macrorestriction analysis also confirmed clonal identity of some environmental isolates with food and human isolates. These results indicate that the external environment is a source of potentially pathogenic strains of L. monocytogenes. |
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. |
Content of Higher Fatty Acids in Green VegetablesR. Vidrih, S. Filip, J. HribarCzech J. Food Sci., 2009, 27(10):S125-S129 | DOI: 10.17221/621-CJFS Green vegetables are considered an important source of some nutritionally important constituents that have health benefits (e.g. vitamins, minerals, antioxidants, fibre). Epidemiological data suggest that consuming a diet rich in fruit and vegetables can lower the risks for chronic diseases, such as cardiovascular diseases and cancer. Over the past 100-150 years, there have been enormous increases in the consumption of omega-6 fatty acids due to the increased intake of vegetable oils from various seeds. Studies have indicated that a high intake of omega-6 fatty acids shifts the physiological state to one that is prothrombotic and pro-aggregatory, whereas omega-3 fatty acids have anti-inflammatory, antithrombotic, anti-arrhythmic, hypolipidemic and vasodilatory properties. Literature data regarding the contents of higher fatty acids (e.g. omega-6 fatty acids) in vegetables are scarce, although vegetables are known to contain a high proportion of n-3 fatty acids. Here, the fatty acid content and composition was determined for 26 green vegetables that are commonly available in Slovenia, by gas-liquid chromatography and in situ transesterification. The fatty acid analysis revealed C16:0, C16:1, C18:0, C18:1, C18:2n-6 and C18:3n-3. The total fatty acid content in the vegetables ranged from 500 mg/100 g fresh weight (f.w.) in red cabbage, to 4.000 mg/100 g f.w. in tarragon. The proportion of saturated fatty acids (as g/100 g total fatty acids) ranged from 12% to 35%. All of the vegetables contained a high proportion of poly-unsaturated fatty acids (PUFAs), ranging from 45% to 81% of total fatty acids. The omega-3 PUFA proportion ranged from 5% in carrot to 60% in tarragon. The content of mono-unsaturated fatty acids ranged from 1% to 25%. French beans, tarragon and radish sprouts contained the highest concentrations of C16:1, at 5 mg/100 g f.w. Consumption of 100 g of tarragon meets 13.2% of daily requirements for α-linolenic acid; similarly, for radish sprouts 9.4%, for mangold 6.9%, for ruccola 5.4%, for green salad 5.0%, and for kale 4.7%. Green vegetables are an important source of 18:3n-3 PUFAs, especially for vegetarian populations. |
D-Amino Acids and Computer Vision Image Analysis: A New Tool to Monitor Hazelnuts Roasting?M. Arlorio, J. D Coisson, F. Travaglia, M. Rinaldi, M. Locatelli, M. Gatti, A. Caligiani, A. MartelliCzech J. Food Sci., 2009, 27(10):S30 | DOI: 10.17221/914-CJFS The roasting process allows complex chemical reactions in foods leading the formation of the Maillard-related compounds, which are of fundamental importance for colour and aroma development in hazelnuts (Corylus avellana L.). Colour is a charming characteristic of roasted foods; despite of their fundamental role in organoleptic properties, the roasting allows accumulation of some potentially toxic technological contaminants, as showed in other matrices (e.g. acrylamide, furan and D-amino acids). Free and protein-bound D-amino acids (D-aa) in foods can origin by technological processing (their formation is pH, time, and temperature-dependent), and also from bacterial racemases in fermented foods, as recently showed in cocoa ( FRIEDMAN 1999; CALIGIANI et al. 2007) So, these compounds can be used as thermal and bacterial markers. Racemisation impairs digestibility/nutritional quality of foods; some D-aa acids are both beneficial and deleterious (DA-WEN SUN 2008). The L*a*b* (international standard for colour measurements adopted by the Commission Internationale d'Eclairage, CIE, 1976) and Red Green Blue (RGB) systems are the most employed methods for colour analysis. Computer Vision Image Analysis (CVIA) coupled with Artificial Intelligence (AI) and related tools (Principal Component Analysis, Artificial Neural Networks, Self Organising Maps) should be considered a powerful approach for evaluating colour development in foods (PATZOLD & BRUCKNER 2006). First aim of our study was to monitor via GC-MS the D-aa formation in hazelnuts during different conditions of roasting. Second aim was to develop a CVIA/AI method to study the colour development in roasted hazelnut, considering the correlation between colour and D-aa too. The racemisation of L-aa (particularly D-aspartic acid plus D-asparagine, D-asx) in hazelnut was time-temperature dependent. Protein-bound D-asx (expressed as D/(L+D); 1.49%) and free D-ala (5.87%) were predominant in Infra-Red roasted samples. Hot-air flow process leads the formation of free-D-aa (D-ala: 6.77%; D-asx: 3.47%; D-glu: 4.50%). Using Back Propagation Neural Network on the Discrete Fourier Transform output (whole surface colour), the identification of hazelnuts samples roasted in different condition was achieved. Red colour decreased according to the correspondent increase of D-amino acids content. Concluding, CVIA/AI is a promising complex tool useful to simplify the comprehension of a complex model system, as colour development in roasted hazelnuts. Keywor |
Changes of free fatty acids during ripening of Niva cheeseE. Vítová, J. Zemanová, Š. Bezděková, L. Babák, B. Loupancová, P. BřezinaCzech J. Food Sci., 2004, 22(10):S310-S313 | DOI: 10.17221/10689-CJFS Changes in the concentrations of free fatty acids in Niva cheese were monitored over the ripening period. Fatty acids were analyzed as methyl esters using gas chromatography with flame ionization detection. Identification has been carried out by comparison of the retention times with those of standard substances. Methanol esterification method using potassium hydroxide catalysis was used for preparing the sample of the fatty acids. The method is simple in respect to instrumentation and chemicals. It can be applied directly to the cheese matrix, which significantly decreases the time for sample preparation. There were total of 30 fatty acids identified in the cheese. Capric, myristic, palmitic, stearic and oleic acids represented the largest proportion of acid content and the most significant changes during ripening. |
Rutin Content in Buckwheat Enriched Bread and Influence of its Consumption on Plasma Total Antioxidant StatusT. Bojňanská, H. Frančáková, P. Chlebo, A. VollmannováCzech J. Food Sci., 2009, 27(10):S236-S240 | DOI: 10.17221/967-CJFS The goal of this study is the evaluation of enriched bread prepared with an addition of buckwheat as a source of biologically active components in nutrition. Experimental pastry was baked using buckwheat wholegrain flour blended with wheat flour in different portions (10%, 20%, 30%, 40% and 50%) in order to observe the influence of buckwheat addition on dough processing and the quality of the final baked products. Taking into account the overall acceptability rating, it was concluded that bread with an addition of up to 30% of buckwheat could be baked with satisfactory evaluation results. The content of rutin in loaves in a consumable form prepared with a buckwheat addition varied between 7.76 mg/kg and 26.90 mg/kg. The clinical study which followed the baking experiment was based on the consumption of enriched bread (30% buckwheat, between 34.7 mg/kg and 38.2 mg/kg rutin content in dry matter) by a group of volunteers during a period of four weeks. The results approved the increase of the total antioxidant status thanks to the buckwheat enriched bread consumption from the value of 1.135 ± 0.066 mmol/dm3 at the beginning of the study to 1.46 ± 0.083 mmol/dm3 at the end of the study, i.e. significant differences. |
Migration of Printing Ink Constituents from Packaging into Food SimulanZ. Dupáková, K. Klaudisová, L. Votavová, J. Dobiáš, M. VoldřichCzech J. Food Sci., 2009, 27(10):S429 | DOI: 10.17221/1098-CJFS Printing inks contain many substances, the use of which is not allowed in food contact materials. Recently the migration of printing ink constituents from the printed packaging materials into food either through the packaging material or via the set-off phenomenon has been reported. The aim of presented study was to quantify the transfer of selected printing ink plasticisers, i.e. acetyl tributyl citrate (TBAC), bis(2-ethylhexyl) adipate (DEHA), bis(2-ethylhexyl) phthalate (DEHP), 2-ethylhexyl diphenyl phosphate (EHDPP) and tributoxyethyl phosphate (TBEP), from printing of packaging materials into food simulants. Two polymer packaging films, i.e. polyethylene film (LDPE, thickness 50 μm) and laminated polyethylene terephthalate and polyethylene film (PET/LDPE 12 μm/35 μm) were printed with flexography technique to obtained the packaging materials with defined content (0.05 mg/dm2 and 0.5 mg/dm2) of free above mentioned substances in printing layer. The migration of the tested additives through the packaging films into distilled water and 95% ethanol was studied at 6°C and 23°C. The set-off transfer of all plasticisers into LDPE film in contact with printing was tested at 23°C and 40°C. The results confirmed quite easy migration of all tested additives into 95% ethanol through the LDPE film when more than 90% of the total amount of TBAC and DEHP in printing was extracted into the stimulant during 30 day storage at 23°C at both content levels. Lower migration was found for DEHA (i.e. about 86% and 55% for higher and lower content in printing, respectively), TPEC (about 62% and 50%) and EHDPP (69% for lower content in printing). The migration through the laminated PET/PE film was generally about two thirds of that for LDPE film with an exception of DEHA. For DEHA migration through the both tested films were comparable. As expected the plasticiser transfer into distilled water was about 5-10 times slower compared with the migration into 95% ethanol. Surprisingly high levels of the set off transfer from printing into LDPE film at 40°C after 30 days were determined for all tested plasticisers. The found levels of plasticiser transport were as follows: 32%-40% for TBAC, 28% for DEHP, 25% for DEHA, 12% for TBEP and about 2% for EHDPP. The study confirmed the fact that composition of printing inks can significantly influence the safety of food packaging materials and the necessity of acceptation of suitable legislation for the quality control of printing inks for food packages. |
Lipid Oxidation Inhibition in Frozen Farmed Salmon (Oncorhynchus kisutc h ): Effect of PackagingA. Rodríguez, M. Trigo, R. Pérez, J. M. Cruz, P. Paseiro, S. P. AubourgCzech J. Food Sci., 2009, 27(10):S182-S184 | DOI: 10.17221/1084-CJFS : Coho salmon (Oncorhynchus kisutch) has recently attracted a great interest as a farmed product. This research focuses on its commercialisation as a frozen product. For it, an advanced storage technology combining vacuum and a polyphenolic rich-film was applied for a 9-months storage period (-18°C). The study was addressed to lipid hydrolysis and oxidation changes and to endogenous antioxidant content in salmon muscle. No effect of packaging conditions could be observed on free fatty acid formation. However, vacuum packaging conditions provided a partial inhibition of primary (peroxide) and secondary (anisidine value) lipid oxidation development; this inhibitory effect was accompanied by a lower tocopherol isomers loss. The employment of a film including polyphenolic compounds led to a partial inhibition of α-tocopherol breakdown and to a lower secondary (anisidine value) and tertiary (fluorescent compound formation) lipid oxidation development. A partial inhibitory effect on lipid oxidation development is concluded for the employment of a polyphenolic compound rich-film packaging when applied to farmed coho salmon. |
Cysteine Mediated Formation of N-ε -Carboxymethyllysine (CML) on ProteinsU. Schwarzenbolz, T. HenleCzech J. Food Sci., 2009, 27(10):S156-S159 | DOI: 10.17221/1106-CJFS The reaction of glyoxal with nucleophilic amino acids was monitored for β-casein as well as β-lactoglobulin. As predicted from previous experiments with hippuryl amino acids, a measurable decrease of arginine can be found in the thiol-free β-casein, while the lysine content remained almost unchanged. For β-lactoglobulin, the incubation with glyoxal led to a slight decrease in the lysine content, while the arginine residues remained unmodified. Here, in accordance with nucleophilicity, it is suggested, that mainly cystein residues react with glyoxal. In solutions containing β-casein with or without glutathione, the effects were less pronounced and regarding the lysine and arginine content, the influence of thiols could hardly be recorded on a significant level. However, comparing the CML levels in the different incubations, it becomes obvious, that glutathione is favouring CML formation in a concentration depended manner. Therefore, the use of CML as an indicator, e.g. for the Maillard reaction, must be related to the composition of the reaction system. |
Analysis of the lipid fractions of coffee creamers, cream aerosols, and bouillon cubes for their health risk associated constituentsLenka Karšulínová, Blanka Folprechtová, Marek Doležal, Jana Dostálová, Jan VelíšekCzech J. Food Sci., 2007, 25(5):257-264 | DOI: 10.17221/679-CJFS Fifteen coffee creamers, 10 cream aerosols, and 5 bouillon cubes from the retail market were analysed, principally for their contents of trans-fatty acids that are known to increase the risk of coronary heart disease, and for their contents of 3-chloropropane-1,2-diol (3-MCPD) fatty acid esters that possibly have a bioaccumulation potential. The contents of trans-fatty acids in coffee creamers, cream aerosols and bouillon cubes were in the range of 0.2-32.8%, < LOD - 6.0%, and 0.5-2.1% of total fatty acids, respectively. All samples contained high levels of 3-MCPD fatty acid esters that were determined after releasing the free 3-MCPD by methanolysis. The 3-MCPD levels in coffee creamers, cream aerosols, and bouillon cubes were in the range of 130-730 µg/kg (540-4480 µg/kg fat), 50-730 µg/kg (220-2880 µg/kg fat), and 380-670 µg/kg (2650-4840 µg/kg fat), respectively. The results showed that the refined and hydrogenated oils may represent a certain risk. The highest levels of 3-MCPD esters were found in a sample of refined palm oil (4170 µg/kg). Currently, there is no information available on how these 3-MCPD esters are metabolised, to which extent they are hydrolysed or biosynthesised in the body, to which extent they are deposited in tissues, and how they influence the properties and functions of tissues (if they really do it). |
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. |
Risk analysis in Turkey milk productionHalil Kizilaslan, Nuray KizilaslanCzech J. Food Sci., 2007, 25(3):144-150 | DOI: 10.17221/743-CJFS The present study has been done in order to determine the risks inherent in the milk production in Turkey. For that objective, factors such as the milk yield, the gross revenues realised, and the price levels as reflected to the producer's benefits, have been taken into account. Upon the calculation of the measures for variables, fluctuations were found in the milk yield, prices, and gross revenues. Based on the hypothesis that the information possessed by the producer on the economic and technological developments is scarce and restrained, the variable coefficient has been calculated as 10.81% for yield, 23.26% for prices, and 30.01% for gross revenues, respectively. With the hypothesis that the producers are aware of and informed on the economic and technological developments, these ratios, that is to say, the fortuitous variable coefficients would be, respectively, 2.07%, 15.96%, and 16.07%. According to the conclusions reached, an environment in which the producers can take rational decisions concerning the milk production can be said not to exist. For this reason, the government intervention through efficient measures for the dairy production will be necessary. Furthermore, the producers should be given informational support through the published studies in the agricultural extension. |
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. |
Microbiological quality of ice cream after HACCP implementation: a factory case studyEmmanuel N. Kokkinakis, Georgios A. Fragkiadakis, Souzana H. Ioakeimidi, Ilias B. Giankoulof, Aikaterini N. KokkinakiCzech J. Food Sci., 2008, 26(5):383-391 | DOI: 10.17221/1126-CJFS The microbiological quality of the final product and the safety of the production procedures were screened in an ice cream factory, after implementation of a Hazard Analysis Critical Control Points (HACCP) system. We analysed 30 vanilla (IC1), 30 strawberry (IC2), and 30 chocolate flavoured (IC3) samples of ice cream; 30 of water; 90 of personnel's hands flora; 150 of plastic ice cream containers flora; 50 of sanitised equipment-surfaces flora. After HACCP introduction, Staphylococcus aureus was not further detectable in ice cream and Escherichia coli was mostly less than 10 CFU/g, while the spoilage markers (total coliforms - TC, aerobic plate counts - APC) in ice cream and the environment were reduced by 20-35%. Mean log CFU/g, for IC1: TC from 2.20 reduced to 1.57, APC from 4.58 reduced to 3.62. For IC2: TC from 2.29 reduced to 1.65, APC from 4.61 reduced to 3.49. For IC3: TC from 2.67 reduced to 1.76, APC from 5.08 reduced to 3.81. |
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". |
Determination of free and bound 3-chloropropane-1,2-diol by gas chromatography with mass spectrometric detection using deuterated 3-chloropropane-1,2-diol as internal standardV. Divinová, B. Svejkovská, M. Doležal, J. VelíšekCzech J. Food Sci., 2004, 22(5):182-189 | DOI: 10.17221/3422-CJFS An improved routine, simple and sensitive method is presented for the determination of free and bound 3-chloropropane-1,2-diol (3-MCPD) in different foods using capillary gas chromatography with mass spectrometric detection and deuterated 3-MCPD as internal standard. The optimised method was linear within the working calibration standard concentrations in the range of 0.009-1.3 mg 3-MCPD per 1 kg of sample. The LOD and LOQ were 0.003 µg/kg and 0.009 µg/kg, respectively. Validation of the method was carried out by analysing standards of 3-MCPD, acid-HVP, roasted coffee samples, and the same samples spiked with 3-MCPD. Repeatability (expressed as RSD) of the method was in the range 1.0-4.2%, the average spike recoveries were 99.1-99.5% (RSD = 0.8-1.4%), respectively. 3-MCPD bound in esters with higher fatty acids was isolated as fat, the isolated fat was subjected to methanolysis and 3-MCPD generated was quantified using the same method. The LOD and LOQ were determined to be 1.1 mg/kg of lipids and 3.3 mg/kg of lipids, respectively. Using the optimised method, 20 samples of retail food products were analysed for their free and bound 3-MCPD. All samples contained free 3-MCPD at 9.6-83 µg/kg (RSD = 0.4-7.0%). The level of the bound 3-MCPD varied between the LOD and 2.4 mg/kg with RSD = 0.3-2.4%. |
Optimised procedure to analyse Maillard reaction-associated fluorescence in cereal-based productsCristina Delgado-Andrade, José A. Rufián-Henares, Francisco J. MoralesCzech J. Food Sci., 2008, 26(5):339-346 | DOI: 10.17221/39/2008-CJFS Fluorescent Maillard compounds measurement provides more specific information on the extent of the Maillard reaction than other unspecific tools to monitor the reaction, and is suitable, as the first approach, to assess the nutritional quality of foods as related to protein damage. This work presents an optimised laboratory procedure for the measurement of total fluorescent intermediate compounds (FIC) associated with Maillard reaction, described and evaluated in a cereal-based product. Total FIC are evaluated using increased pronase E concentrations and different incubation times for the enzymatic hydrolysis, as well as three different sample clean-up steps after the enzymatic digestion. The effects of basic/acid media are considered for the stability of the fluorescent compounds. The standardised procedure is finally applied to breakfast cereals as a model of cereal-based products, analysing the correlation between total FIC production and fibre and protein contents. It is demonstrated that fluorescent compounds are mainly linked to the protein backbone in ready-to-eat breakfast cereals. Fluorescence measurement is presented as an inexpensive, rapid and accurate procedure to study the extent of Maillard reaction in breakfast cereals. |
