Boka B.,Eszterházy Károly College |
Adanyi N.,Central Food Research Institute |
Virag D.,Eszterházy Károly College |
Sebela M.,Palacky University |
Kiss A.,Eszterházy Károly College
Electroanalysis | Year: 2012
Three enzyme based amperometric biosensors for biogenic amines were applied for meat spoilage monitoring. With diamine oxidase (EC 220.127.116.11), the total biogenic amine content was measured. Monoamine oxidase A (EC 18.104.22.168) was used for determination of tyramine, tryptamine and phenylethylamine content. Putrescine was selectively detected with putrescine oxidase (EC 22.214.171.124). The enzymes were separately co-immobilized on graphite electrodes with peroxidase and Os mediator (PVI7-dme-Os). A fast extraction method using special centrifugal separator was applied for pork and fish samples stored at different conditions. Although partial extraction was achieved, the results correlate with total biogenic amine content measured by HPLC method. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Futo P.,Eszterházy Károly College |
Markus G.,Markus Tejlabor Kft. |
Kiss A.,Eszterházy Károly College |
Adanyi N.,Central Food Research Institute
Electroanalysis | Year: 2012
The aim of our work was to develop a selective amperometric biosensor for infected milk detection. The catalase enzyme (EC 126.96.36.199) was immobilized onto the surface of a thin-layer enzyme cell. The measurements were carried out in stopped-flow injection analysis system (0.8mLmin -1 flow rate, +590mV polarization potential) in organic phase (6% sodium acetate buffer 200mM pH6.0, ferrocene conductive salt (7.5mgL -1) dissolved in acetonitrile. A certain amount of hydrogen peroxide was degraded by the catalase content of the milk. The degradation of the hydrogen peroxide is proportional to the infection of the milk samples. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Szalontai H.,Eszterházy Károly College |
Adanyi N.,Central Food Research Institute |
Kiss A.,Eszterházy Károly College
Analytical Letters | Year: 2012
A Quartz Crystal Microbalance (QCM) based direct immunosensor was developed for real-time detection of probiotic bacteria. To optimize the immunosensor system, model measurements were carried out with bovine serum albumin (BSA) and anti-BSA IgG (a-BSA) antibody. During the model experiments, two kinds of self-assembled monolayers were created to compare their efficiency on antigen binding. Sulfosuccinimidyl 6-[3-(2-pyridyldithio)propionamido] hexanoate (sulfo-LC-SPDP) and 16-mercapto-hexadecanoic acid (MHDA) cross-linking agents were used for immobilizing anti-BSA antibody onto the gold surface of the AT-cut quartz wafer. Two different measuring procedures, flow-through and stopped-flow methods, were applied, and the frequency responses obtained by both analytical methods were compared.After the model experiments probiotic bacteria, Bifidobacterium bifidum O1356 and Lactobacillus acidophilus O1132 serotypes were detected from buffer solution and from real samples (spiked milk samples, acidophilus, and bifidus milk samples).Using the novel immunosensor, the target bacteria could be detected in the range of 104-107 colony-forming units (CFU)/ml within 60 minutes. The selectivity of a-Bifidobacterium bifidum and a-Lactobacillus acidophilus antibody coated sensors were also tested. © 2012 Copyright Taylor and Francis Group, LLC.
Nagy E.,University of Pannonia |
Kulcsar E.,University of Pannonia |
Nagy A.,Central Food Research Institute
Journal of Membrane Science | Year: 2011
The effect of the concentration boundary layer on the pressure-driven membrane separation like nanofiltration or ultrafiltration is well-known and extensively discussed in the literature. In most of these studies, the effect of the boundary layer and that of the membrane layer on the separation efficiency are discussed separately. This paper presents a general model to describe the convective and diffusive mass transport taking into account the simultaneous effect of both the concentration boundary layer and the membrane layer. It has been demonstrated how the Peclet number of the membrane, the ratio of diffusive mass transfer coefficient of the membrane to that of the polarization layer and the product of the steric partition coefficient and the convection hindrance factor affect the permeate concentration or the rejection coefficient. Comparing the measured and calculated data, it has been proven that the effect of the polarization layer can significantly affect the separation efficiency during practical nanofiltration of uncharged compounds. The model developed gives a general treatment method to evaluate pressure-driven membrane separation processes. © 2010 Elsevier B.V.
Gasztonyi M.N.,Central Food Research Institute |
Farkas R.T.,Central Food Research Institute |
Berki M.,Central Food Research Institute |
Petroczi I.M.,Cereal Research Non Profit Ltd. |
Daood H.G.,Central Food Research Institute
Journal of Food Composition and Analysis | Year: 2011
This study evaluates the concentration of various forms of ferulic acid in wheat and in wheat varieties grown under comparable organic and conventional conditions over two years. The effect of fungicide application in 2009 was also studied. Soluble conjugated and bound forms of ferulic acid were quantified by HPLC-PAD after extraction, the bound form was present predominantly up to 85-90% of total content. In 2008 the bound form of ferulic acid was measured in the range of 248-550 μg/g, the conjugated form was between 11 and 40 μg/g in all the wheat cultivars as a function of (NPK) treatments. Total ferulic acid content measured in 2009 varied in the range of 275-435; 267-341; 296-378 μg/g, with fungicide and 189-394; 231-366; 182-324 μg/g without fungicide in varieties Békés, Csillag and Petur respectively. In 2008 a significantly higher amount of conjugated ferulic acid was measured in all three investigated cultivars as compared to the content found in 2009 for the same cultivars. As all the samples were treated with fungicide, the main factor was the year (climate conditions). The combination of NPK, fertilizers did not affect significantly the ferulic acid concentration, on the other hand the year (climate conditions) influenced significantly the soluble conjugated ferulic acid content in all fungicide treated varieties. © 2011 Elsevier Inc.
Mortl M.,Central Food Research Institute |
Nemeth G.,Central Food Research Institute |
Juracsek J.,Central Food Research Institute |
Darvas B.,Central Food Research Institute |
And 3 more authors.
Microchemical Journal | Year: 2013
An enzyme-linked immunosorbent assay (ELISA) for the detection of glyphosate was investigated for assay performance characteristics and was applied for determination of glyphosate contamination levels in selected surface and ground water resources in Hungary in 2010 and 2011. Advantages of the method include its simplicity (no laborious extraction) and specificity (cross-reactivity is below 0.1% for related compounds, e.g. aminomethyl-phosphonic acid, glufosinate). On the basis of our experiments, the practical limit of detection (LOD) ranged between 0.05 and 0.12. ng/ml. The standard curve was of sigmoid (logistic) characteristics, and it co-occurred with curves obtained for spiked surface water samples. Matrix effects were observed in tap water, possibly due to chlorination and/or heavy metal ions, e.g. copper and zinc. The method was applied for the analysis of 42 surface and ground water samples collected from Békés county in Hungary at 14 sampling sites in 2010 and 18 surface water samples collected from the Danube River and Lake Velencei in Hungary at 12 sampling sites in 2011. Exceedingly high glyphosate levels (nearly 1. ng/ml) were measured in 5 samples, and significant concentrations were determined in 16 cases (0.54-0.76. ng/ml) in 2010, while practically no contamination was found in 2011. The great contrast between the two sampling regimes is explained by differing agricultural locations, natural precipitation and, to a greater extent, catchment area characteristics, resulting in varying leaching or run-off of glyphosate to surface waters. © 2012 Elsevier B.V.
Hartyani P.,H+ Technology |
Dalmadi I.,Corvinus University of Budapest |
Cserhalmi Z.,H+ Technology |
Kantor D.-B.,Corvinus University of Budapest |
And 2 more authors.
Innovative Food Science and Emerging Technologies | Year: 2011
The consumers have increasing desire towards fresh, long shelf-life and healthy products by consisting favourable sensory properties. As an ambivalent fact appears that the product should meet all these requirements and should be consumable long time. All these demands lead to the importance of the minimal processing methods. The properties of widely common citrus juices (100% orange, - grapefruit, - and tangerine juice) were analyzed by measuring the possible changes in the physical-chemical parameters (pH, Brix°, electric conductivity, colour) respectively the aroma and acid content. The applied technology was pulsed electric field (in furthers: PEF) treatment with the parameters of 28 kV/cm with 50 pulses; respectively high hydrostatic pressure (HHP) technology with the parameter of 600 MPa pressure for 10 min treatment time. The sensory properties of the juices were analyzed with electronic-nose and -tongue to measure the possible changes of the treated juices compared to the untreated (control) samples with the help of these electronic tools, which can serve as a potential detection system for the differentiation of the treatments mentioned above. Industrial relevance: Fruit juices are preserved mainly by heat treatment which can change many prosperous flavour-, acid and sensory properties. The present work shows in case of citrus juices the application of pulsed electric field treatment and high hydrostatic pressure techniques as non-thermal preservation possibilities and the use of electronic tongue and - nose as a new method for sensory testing. © 2011 Elsevier Ltd. All rights reserved.
Banati D.,Central Food Research Institute |
Lakner Z.,Corvinus University of Budapest
Food Control | Year: 2012
The Hungarian catering industry has to face up to numerous challenges nowadays because of rising costs and stagnating purchasing power. Under these conditions the managerial acceptance of the compulsory introduction of the HACCP system is rather mixed. This research is based on a direct question survey, with the aim of analysing the relation amongst the strategies of catering service managers, their attitudes towards food hygiene and the HACCP system, their managerial experiences about working with the HACCP system, as well as the evaluation of hygienic practice of catering service providers by independent specialists. More than 1100 questionnaires were processed. Two main approaches were analysed with regard to the general attitudes of catering managers: the hygiene and the cost-oriented approaches. The acceptance of HACCP systems lacked homogeneity to a significant extent. 28% of the respondents considered that the increasing quality and safety were the really important and necessary tasks. 41% of the respondents had a rather reluctant attitude towards their systems, mainly as a consequence of fear of extra investment and administrative burdens. Last but not least, the third group of managers accepted the importance of hygiene, but did not acknowledge the possibilities offered by HACCP for better work-organisation and clearer determination of responsibility. The structural equation analysis between the managerial strategy and attitudes, as well as the hygienic conditions, have proven numerous significant relations between these factors, but the results highlight the importance of efforts aiming at better integration of the HACCP approach in managerial activities. There is a real danger that this system will be simplified to accomplish administrative tasks. © 2011 Elsevier Ltd.
Nguyen Q.D.,Corvinus University of Budapest |
Rezessy-Szabo J.M.,Corvinus University of Budapest |
Czukor B.,Central Food Research Institute |
Hoschke A.,Corvinus University of Budapest
Process Biochemistry | Year: 2011
A commercially available endo-inulinase from Aspergillus niger was successfully immobilized onto a chitin carrier with 66% yield. The immobilized endo-inulinase showed maximal activity at 65 °C that was 5 °C higher than the optimum temperature of the free enzyme. Also, the optimum pH shifted from 4.5 to 5.0 for free form and 5.5 to 6.0 for the immobilized form. The immobilized endo-inulinase was stable at 4 °C for at least 1 year. The residual activity of 90% and 95% of free and immobilized enzymes were recovered after 5 days of incubation without substrate at 60 °C and pH between 4.5 and 6.5. Kinetic parameters (Km and Vmax) for free and immobilized endo-inulinase were 2.04% (w/v) and 80.88 U/mg protein, and 2.19% (w/v) and 291.58 U/g support, respectively. The half-life time of immobilized endo-inulinase in a packed-bed column reactor was estimated to be 48 days. A continuous production system of inulo-oligosaccharides (IOS) from inulin and Jerusalem artichoke (JA) juice was set up and operated. Using this system, syrups with high IOS content (from 35% to 65%) were successfully prepared. © 2010 Elsevier Ltd. All rights reserved.
Farkas J.,Central Food Research Institute |
Mohacsi-Farkas C.,Corvinus University of Budapest
Trends in Food Science and Technology | Year: 2011
Treatment of food by specific ionizing radiations to improve microbiological safety and storability is one of the most extensively studied technology of the XXth century. However, much of the research has been carried out in laboratories and it is still relatively underutilized commercially. Its application potential is very diverse, from inhibition of sprouting of tubers and bulbs to production of commercially sterile food products. The safety of consumption and wholesomeness of irradiated food have been extensively studied in international cooperations. Numerous international expert groups set up jointly by the FAO, the IAEA and the WHO, or the Scientific Committee on Food of the European Commission concluded that foods irradiated with appropriate technologies are both safe and nutritionally adequate. A Codex General Standard for Irradiated Foods and a Recommended International Code of Practice for Radiation Processing of Food have been developed. Specific applications of food irradiation are approved by national legislations in over 55 countries worldwide. Commercial use of irradiation, however, is still limited. In spite of pioneering past R&D activities in Europe and North-America, the utilization of the process growing faster and increasingly, mainly for sanitary purposes, in fast-developing countries in the (South-East) Asian region and some Latin-American countries. Progress in the European Union is decidedly slower. In the EU, food irradiation is regulated since 1999 by a General Directive, but its implementing directive, the Community list of EU approved irradiated foods contains only a single class of items: " dried aromatic herbs, spices and vegetable seasonings" This slow progress is mainly due to psychological and political factors, misinformation created by various activist groups, and the reluctance to implement the process by the industry is discouraged by such forces. The future of food irradiation will depend on an informed public and better understanding of the role the process can play in the control of food-borne pathogens. © 2010 Elsevier Ltd.