Harun Parlar

Technische Universität München, München, Bavaria, Germany

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Publications (189)354.98 Total impact

  • Yen-Chih Chen, Harun Parlar
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    ABSTRACT: Foam fractionation is a promising method for separation and concentration of biochemicals. It is simple, easily scalable, inexpensive, and environment friendly. Foam fractionation thus represents an alternative to the traditional methods used for immunoglobulin enrichment. However, little, if any, literature exists documenting the utilization of foam fractionation in the enrichment of immunoglobulins. Milk were utilized as an immunoglobulin source to serve as examples of a real system in this study. The investigation examined the effects of varying five different process parameters: the initial pH value, the initial concentration of immunoglobulin, the nitrogen flow rate, the column height, and the foaming time. Experimental results demonstrated that immunoglobulin could effectively be enriched from milk by foam fractionation. The maximum enrichment ratio with pretreatment (using pH 4.6 precipitation) was 6.30 along with a more than 92 % recovery for IgG and an enrichment ratio of 5.1 with 85 % recovery for IgM.
    Applied biochemistry and biotechnology 05/2013; · 1.94 Impact Factor
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    ABSTRACT: There is a simple solution for preventing gushing: the danger potential of raw materials (malt) shpuld be known before production. Using the analysis methods (Weihenstephaner Test, Modified Carlsberg Test) developed by MEBAK, the gushing risk is assessed on the basis of the quantity fobbed over after shaking a bottle. As these gushing tests are not suitable for a rapid analysis, R&D Department of the Weihenstephan Research Center for Brewing and Food Quality has developed a novel analytical approach for rapid gushing prediction using combined particle analysis. The latest results of this new rapid analysis for determination the gushing risk are presented.
    Brauwelt International. 08/2012; 30(4):216-219.
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    ABSTRACT: Malsters and brewers can currently check malt raw material for its potential to trigger gushing, using two analytical methods according to MEBAK. The quantity of carbonated wort (malt extract) foamed over after bottle shaking is measured, this is used for determining the gushing potential of the malt. But investigations have shown that the gushing volume may vary, making it difficult to arrive at a precise figure. The Research Center Weihenstephan for Brewing and Food Quality has therefore developed new analytical approaches to quantify gushing (not only on the basis of the quantity foamed over).
    Brauwelt International. 06/2012; 30(3):146-149.
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    ABSTRACT: Die einfachste Lösung, Gushing vorzubeugen, ist, die Rohstoffe (Malz) bereits vor der Produktion auf ihr Gefahrenpotenzial hin zu kennen. Mithilfe der von der MEBAK formulierten Analysenmethoden (Weihenstephaner Test, Modifizierter Carlsberg-Test) wird das Gushing-Risiko durch die übergeschäumte Menge nach dem Flaschen-schütteln bewertet. Weil mit diesen Gushing-Tests eine rasche Analyse nicht möglich ist, wurde in der F&E-Abteilung des Forschungszentrums Weihenstephan für Brau- und Lebensmittelqualität ein neuartiger analytischer Ansatz zur schnellen Vorhersage von Gushing mithilfe der kombinierten Partikelanalytik erarbeitet. Aktuelle Ergebnisse dieser neuen Schnellanalyse zur Bestimmung des Gushing-Risikos werden vorgestellt.
    Brauwelt. 07/2011; 151(27):842-845.
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    ABSTRACT: Zurzeit können Mälzer und Brauer den Rohstoff Malz durch zwei Analysenmethoden der MEBAK auf ihr Gefährdungspotenzial für Gushing prüfen. Hierfür wird die übergeschäumte Menge der karbonisierten Würze (Malzextrakt) nach dem Flaschenschütteln ermittelt, mit der das Gushing-Potenzial des Malzes bestimmt wird. Jedoch zeigen Untersuchungen, dass die Überschäummenge schwanken kann, was eine präzise Bestimmung erschwert. Deshalb wurden am Forschungszentrum Weihenstephan für Brau- und Lebensmittelqualität neue analytische Ansätze entwickelt, Gushing (nicht alleine durch die übergeschäumte Menge) zu quantifizieren.
    Brauwelt. 06/2011; 151(23):696-699.
  • Jean Titze, Vladimir Ilberg, Harun Parlar
    European Brewery Convention Congress, Glasgow; 05/2011
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    ABSTRACT: Durch das Gushing-Jahr 2008 stieg das Interesse an Vorhersagetests, um das roh­stoffbedingte Gushing-Risiko noch vor der Rohstoffverarbeitung und Bierproduktion einschätzen zu können. Am Forschungs­zentrum Weihenstephan für Brau- und Lebensmittelqualität (FZW) werden zwei Analysenmethoden, Modifizierter Carlsbergtest (MCT) und Weihenstephaner Test (WT, auch Gushing-Schnelltest oder Donhauser-Test genannt), nach Mittel­europäischer Brau- und Analysenkommission e. V. (MEBAK) durchgeführt, um mit ihnen das Gushing-Potenzial von Malzen detektieren zu können. Untersuchungen der F&E-Abteilung des Forschungszentrums ergaben, dass beide Gushing-Tests mit ein und demselben Malz unterschiedliche oder gar gegensätzliche Ergebnisse erzeugen können. Dieser Beitrag diskutiert Gründe für die Unterschiede und stellt neue Erkenntnisse über die Entstehung und Unterdrückung von Gushing im Maisch- und Kochprozess zusammen.
    Brauwelt. 05/2011; 151(18):558-561.
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    ABSTRACT: Cobalt and silver are toxic for cells, but mechanisms of this toxicity are largely unknown. Analysis of Corynebacterium glutamicum proteome from cells grown in control and cobalt or silver enriched media was performed by two dimensional gel electrophoresis (2DE) followed by mass spectrometry. Our results indicate that the cell adapted to cobalt stress by inducing five defense mechanisms: Scavenging of free radicals, promotion of the generation of energy, reparation of DNA, reparation and biogenesis of Fe-S cluster proteins and supporting and reparation of cell wall. In response to the detoxification of Ag+ many proteins were up-regulated, which involved reparation of damaged DNA, minimizing the toxic effect of reactive oxygen species (ROS) and energy generation. Overexpression of proteins involved in cell wall biosynthesis (1,4-alpha-glucan branching enzyme and nucleoside-diphosphate-sugar epimerase) upon cobalt stress and induction of proteins involved in energy metabolism (2-methylcitrate dehydratase and 1, 2-methylcitrate synthase) upon silver demonstrate the potential of these enzymes as biomarkers of sub-lethal Ag+ and Co toxicity.
    Journal of Environmental Science and Health Part B Pesticides Food Contaminants and Agricultural Wastes 10/2010; 45(7):666-75. · 1.10 Impact Factor
  • International Symposium for Young Scientists and Technologists in Malting, Brewing and Distilling, Freising; 05/2010
  • International Symposium for Young Scientists and Technologists in Malting, Brewing and Distilling, Freising; 05/2010
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    ABSTRACT: Die Bildung von Diphenochinonen unter Bedingungen, unter denen die strukturisomeren Dioxine entstehen, fand bisher wenig Beachtung. Mit neuen Aufarbeitungs-und Analysenmethoden können nun chlorierte und nicht chlorierte Diphenochinone in unterschiedlichen Matrices bestimmt werden: Diese neue Klasse von Umweltchemikalien tritt immer in Begleitung von Dioxinen und Dioxin-Analoga auf. Mit den neuen Methoden steht damit ein weiteres Werkzeug zur Bestimmung von chlororganischen Verbindungen zur Verfügung.
    Nachrichten aus der Chemie 04/2010; 47(5):541 - 545. · 0.20 Impact Factor
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    ABSTRACT: Long-term stability is one of the most important quality criteria of beer. Three groups of measuring methods are available for its determination: real time tests, predictive tests and indicative tests. One of the most common methods is the predictive forcing test, which is a time-consuming method for accelerating beer ageing, e.g., at 0°C and 60°C. Two ways exist to perform this test: (1) follow-up of haze development and determination of the lag phase or (2) the measurement of haze values after several days. The first option was evaluated by performing a long-term Forcing test over a period of 4 months by analyzing a bottom-fermented beer. It was shown that the haze curve followed a typical course with a lag phase, an increase phase and a station-ary phase. Significant differences between the measurement after the cooling and the warm period were shown. In search of quicker methods and more accurate predictive indicators, the charge titration method was developed as an alternative to deter-mine the particle charge of filtered beers, whereupon the rela-tionship was elucidated between the increase in hazing and de-crease of potential along with the advanced aging of beer. The results showed that with increased particle size due to agglom-eration, the total charge decreased. In this array of trials, two differently stabilized beers were examined. Although both beers showed different haze values in the beginning (0.32 EBC and 1.30 EBC), the less stabilized beer had only 10 warm days and in contrast the beer with the good stabilization had over 20 warm days. With the help of the total charge, predictions were possible regarding the long-term stability of the beer.
    Journal- Institute of Brewing 04/2010; 116(4):405-412. · 0.88 Impact Factor
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    ABSTRACT: Tweezing adsorptive bubble separation (TABS) was used as a method for the enrichment of matrix metalloproteinases (92-kDa type IV, gelatinase B (MMP-9)) and carboxypeptidase A (CPA) from dilute aqueous solutions. The method is based on the chelation of metalloenzymes applying 2-(carbamoylmethyl-(carboxymethyl)amino)acetic acid (ADA) coupled with an octyl part to form a surface active unit. MMP-9 could be enriched with an enrichment ratio of 12.0 and a recovery of 87.3%, and CPA could be enriched 18.8-fold and with 95.3% recovery. Both enzymes were enriched without significant losses of enzymatic activity. To verify that the enzymes were tweezed by ADA-C8 without abstraction of the zinc ions from the active center, TABS trials were additionally conducted with zinc ions in complex with ADA-C8, which revealed only negligible enrichment ratios of the enzymes (2.2 for MMP-9 and 0.2 for CPA). The results obtained impressively demonstrate that zinc-containing proteases can be enriched selectively and efficiently by TABS.
    Applied biochemistry and biotechnology 03/2010; 162(6):1547-57. · 1.94 Impact Factor
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    ABSTRACT: In this work it was first shown how to quantify the gushing potential of malt with a modification of a common gushing test. Today there exist two acknowledged gushing tests for the brewing industry (Modified Carlsberg Test and Weihenstephaner Test). Both analytical methods use the overfoaming amount of a test-specific produced carbonated wort to determine the gushing potential of malt. Unfortunately the overfoaming amount can vary statistically in a way that this parameter can “only” be used for qualitative information if the malt has a potential for gushing or not and if one malt has a higher or lower gushing potential than another one; but a precise quantitative comparison for example between two malts which both have a gushing potential is difficult. This was the focus of this investigation. With two gushing-positive samples (malt A and B) it could be shown that with an increase of the concentration of malt solutes a certain point is reached where gushing appears the first time determined by the overfoaming amount applied the Modified Carlsberg Test. For malt A a frequently higher gushing potential (f ≥ 5) than for malt B was identified. These results were verified by determining the amount of a gushing suppressing hop product that led gushing to zero by having a constant concentration of malt solutes. The results demonstrated enhanced gushing analyses to quantify the gushing potential reproducibly, not by the overfoaming amount but by the “zero point” where gushing begins (concentration of malt solutes) or is neutralized (amount of hop product). The introduced methods enable the chance for the first time to quantify the gushing potential of malt more precisely.
    BrewingScience 11/2009; 62(11/12):164-.171.
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    ABSTRACT: Using a noval physical-chemical method developed at the Research center Weihenstephan for Brewing and Food Quality, it is possible to assess and reliably evaluate the colloidal stability of filtered beers. In this process, the streaming current potential as well as the surface charge density of particles in beer are determined using CAS (= Charge Analyzing System). The fundamentals of the measurement technique have been described in Part 1. In this second part, interpretation of the results abtained is explained and illustrated using three application examples with relevance to the brewing industry.
    Brauwelt International. 08/2009; 27(4):212-215.
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    ABSTRACT: The complex phenomenon of gushing occurring in carbonized beverages has been investigated in order to better understand the mechanism and to give input for further research to introduce preventive measures for the industry. The knowledge that microbubbles are stabilized through surface active substances, and in this form can induce gushing, was used to examine a selection of representative surfactants. For the analysis, a particle size distribution method was used which enabled to detect particles at nanometer level, starting from 0.8 nm onwards. The experiments using pure aliphatic surfactants (DTAC, TTAC, CTAC, ODTABr, CPC, SDS, and Tween 20) revealed that only CTAC, solved in CO2 containing table water at 2 g/l (above the critical micellar concentration), induced gushing. CTAC therefore was characterized as gushing typical by its structure (length of hydrophobic part and kind of head group). Gushing caused by CTAC was not only observed through shaking of the bottles, but also without any shaking at all. The latter observed fact was not explainable by the mechanical incorporation of CO2 bubbles stabilized by CTAC monomers, but generally through stabilized microbubbles formed by a mechanism that is yet unknown. The particle size analysis revealed that particles grow, starting from ca. 10 nm to reach several 100 nm, if sufficient amounts of CO2 molecules are present. The growth was accelerated by a mild shaking of the bottles. The results pointed out that CTAC micelles grow by diffusion of CO2 molecules into the hydrophobic core. Thereby, microbubbles are formed and stabilized through CTAC monomers at the interface gas/liquid, and can grow to gushing-relevant sizes of several 100 nm.
    BrewingScience 07/2009; 62(7/8):100-107.
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    ABSTRACT: This work investigated the gushing phenomenon in wort samples by applying commonly used gushing tests (Weihenstephaner and modified Carlsberg test) in order to identify conditions for the development of gushing. The mashing and boiling procedures were modified (Weihenstephaner test), and the amount of wort and time of shaking of the bottle were increased (modified Carlsberg test). For the experiments one malt sample was applied that was identified as gushing-positive (Weihenstephaner test). A changing pattern of the mashing process revealed that gushing was induced after heating up to 97 °C while no gushing was observed until 80 °C. Heating up the mash from 80 °C to 100 °C and boiling it for 5 min afterwards sufficed for gushing to be induced in the wort sample. From the applied malt sample it was possible to produce not only a gushing-positive wort but also a gushing-negative one. By mixing these wort samples, gushing could be reduced, or even entirely suppressed, applying a volume of only 10 % v/v of the gushing-negative sample. The gushing-positive wort could only induce gushing in amounts of above a critical level. Gushing started to develop after a mild shaking for 10 h (modified Carlsberg test) and increased significantly after 20 h of shaking. The results demonstrated that the temperature of the mash is a decisive parameter for the development of gushing.
    BrewingScience 06/2009; 62(5/6):83-89.
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    ABSTRACT: The Research Center Weihenstephan for Brewing and Food Quality has developed a method, based on physical chemistry, for rapid and reliable assessment of colloidal stability by analysing the streaming current potential and surface charge density of particles in filtered beers. In food analysis, the measuring technology is successfully used for fining of fruit juices, for gushing control in sparkling wine production and to determine the influence of clarifying agents on particle charge in beer. Only the surface charge density of particles has been hitherto determined with this method. The new charge titration method developed by Titze & Ilberg additionally makes it possible to reproducibly measure the streaming potential. This first part presents the fundamentals in a simplified manner. In part 2, possibilities of using this method in the brewing industry will be described.
    Brauwelt International. 06/2009; 27(3):130-133.
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    ABSTRACT: In this work, Fourier transform infrared (FTIR) spectroscopy was used and evaluated as a tool to determine the most important quality parameters of Congress wort. All density-related parameters (calculated based on density values using acknowledged conversion tables), after calibration using 256 Congress wort samples, could be determined with high accuracy, as indicated by coefficient of determination (R(^2)) values of nearly 1.0 (0.985 for wort extract). The total nitrogen of barley parameter (not related to density) could also be determined with good accuracy (R(^2) = 0.892). Other parameters such as viscosity and boiling color of wort could not be determined using FTIR spectroscopy. For the quantitative determination of malt and wort parameters related to protein content, FTIR spectroscopy was of limited applicability (e.g., dependencies related to harvest year were found during calibration of the soluble nitrogen parameter [different influences of samples harvested in 2006 and 2007]). In addition, identical beer samples were analyzed as controls prior to each series of wort measurements in order to evaluate the stability of the FTIR spectroscopy system. Stable results over a period of 131 days were delivered, which was the basis for comparative measurements of Congress wort samples. Furthermore, 10 different beer parameters of pilot samples were accurately measured over a period of 130 days, with repeatability deviations falling between those proposed by MEBAK (e.g., 0.062% [wt/wt] for original wort compared with 0.150% [wt/wt] for MEBAK). The results impressively demonstrated that, with the help of an accurately calibrated database, FTIR spectroscopy can serve very well as a combined beer and wort analyzer, proving its feasibility for use in routine analysis in the brewing industry. In addition, it has the advantage of saving time and money.
    Journal of The American Society of Brewing Chemists - ASBC. 04/2009; 67(4):193-199.
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    ABSTRACT: Polychlorinated biphenyls (PCB) were widely used in numerous industrial and commercial applications in high quantities in the past. Based on their persistence in the environment, their tendency to accumulate in the organism and their specific health effects, PCBs have to be assessed as critical substances. Because the dietary intake was assumed to be the main intake route, the Integrated Exposure Assessment Survey (INES) aimed to measure the recent exposure to PCBs in Germany. The study consisted of 10 female and 10 male participants living in Munich and surroundings. The participants collected dietary duplicates of all food consumed and prepared as for consumption over 7 consecutive days. Altogether the 6 non-dioxin-like PCB congeners 28, 52, 101, 138, 153 and 180 ndl-PCB or, respectively, indicator PCB and furthermore the congener 118 were detected using a gas chromatographic method. Dietary intake was calculated using the amount of food eaten daily and the results from the duplicates. Using the sum of PCB 138, 153 and 180 multiplied by 4, the daily intake ranged from 4.0 to 24.1 ng/kg b.w. (median: 9.5 ng/kg b.w.). On the contrary, the daily intake was 2.9 to 20.6 ng/kg b.w. (median: 11.2 ng/kg b.w.) if the sum of the 6 indicator PCBs multiplied by factor 2 was used for quantification. No sex-related difference of the dietary intake was observable. Overall, it can be concluded that the dietary PCB intake has further decreased in the last years in Germany. At present, the toxicological database is not suitable to assess the risks coming solely from the non-dioxin-like PCBs because it is not possible to differentiate between non dioxin-like and dioxin-like effects in toxicological studies. Nevertheless, a further reduction of PCB exposure via food by searching for possible sources is needed.
    Das Gesundheitswesen 04/2009; 71(5):275-80. · 0.94 Impact Factor

Publication Stats

785 Citations
354.98 Total Impact Points

Institutions

  • 1982–2013
    • Technische Universität München
      • • Chair of Chemical-Technical Analysis and Chemical Food Technology
      • • Research Department of Nutrition and Food Sciences
      München, Bavaria, Germany
  • 2009
    • Ege University
      • Department of Bioengineering
      İzmir, Izmir, Turkey
  • 2004
    • Stockholm University
      Tukholma, Stockholm, Sweden
  • 2001
    • Cukurova University
      • Department of Environmental Engineering
      Adana, Adana, Turkey
  • 1998
    • Fisheries and Oceans Canada
      • Institute of Ocean Sciences
      Ottawa, Ontario, Canada
  • 1987–1996
    • Universität Kassel
      • Department of Biochemistry
      Cassel, Hesse, Germany
  • 1973–1976
    • Deutsches Herzzentrum München
      München, Bavaria, Germany
    • University of Bonn
      • Institute for Inorganic Chemistry
      Bonn, North Rhine-Westphalia, Germany