Volker Heinz

Deutsches Institut für Lebensmitteltechnik, Quakenbrück, Lower Saxony, Germany

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Publications (160)215.26 Total impact

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    ABSTRACT: The watermelon juice was processed by thermal and large-scale alternative pasteurization technologies, pulsed electric fields (PEF) and high pressure processing (HPP). The watermelon juice was compared and evaluated immediately after the treatment as well as a function of shelf-life. As a basis for the comparison, microbial inactivation was chosen. The watermelon juice quality evaluation was performed by a multivariate quality comparison (headspace fingerprinting), studying volatile fractions of the juice. Control and pasteurized juice was evaluated in terms of sensory at the beginning and the end of the shelf-life. Most of the selected markers in control juice were lower in concentration compared to processed classes. Majority of the compounds detected in higher concentration after processing were C6–C9 carbonyls. Their formation is linked to oxidation of fatty acids. Few degradation products of lycopene have been observed in PEF and HPP class. Compounds selected in higher concentration in thermal class were products linked to the Maillard reaction and Strecker degradation products. All compounds detected in lower concentration in thermal class at day-12 compared to PEF and HPP were linked to lycopene degradation. According to the sensory evaluation, a clear differentiation of control from processed samples as well as among processed samples only after the treatment and at the end of the shelf-life was possible.
    No preview · Article · Dec 2015 · European Food Research and Technology
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    ABSTRACT: Ultra-high-pressure homogenization (UHPH) offers new opportunities for continuous high-pressure-assisted thermal sterilization of liquids and production of stable emulsions. As relevant indicator, Bacillus amyloliquefaciens spores were suspended in a coarse oil-in-water (o/w) emulsion (pH 7.6) with 10 % soybean oil and 4 % soy protein isolate at the initial concentration of ~106 CFU/mL. The o/w emulsion was subjected to UHPH treatments at 200, 300 and 350 MPa with the inlet temperature at ~80 °C to inactivate the respective bacterial spores and produce fine emulsion simultaneously. After treatment at 350 MPa with the valve temperature higher than 150 °C, a reduction up to 4 log10 CFU/mL of bacterial spores was obtained, and the emulsion was characterized by smaller particle size and narrow particle size distributions, with the D[3, 4] of 0.210 μm and the span of 0.746. No spore germination was found after any of these UHPH treatments. The microstructure of the emulsion was observed under confocal laser scanning microscopy with fluorescein isothiocyanate and Nile red to stain proteins and fats, respectively. UHPH showed potential to combine sterilization and emulsification into one single process.
    Full-text · Article · Nov 2015 · European Food Research and Technology
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    Sergiy Smetana · Alexander Mathys · Volker Heinz

    Full-text · Dataset · Sep 2015
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    Sergiy Smetana · Alexander Mathys · Volker Heinz
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    ABSTRACT: Insects use for food and feed is called to provide a more sustainable solution (than meat, vegetable, mycelium alternatives) to address protein deficit problems in many regions of the world. The selection of viable comparison units represents one of the challenges for reliable analyses. Environmental assessments and comparisons are not applicable for all the cases of insect production and use due to the early stages of insect production and processing technologies readiness levels (TRLs), diversity of species and nutritional composition. Quite a specific hurdle of insect-based food and feed Life Cycle Assessment (LCA) lays in the absence of proved effective processing technologies. In most cases, TRLs are preliminary and represent a great variation of possible techniques for insects killing and slaughtering, chitin exclusion or transformation, defatting and combination with other ingredients. The selection of processing methods plays a significant role for LCA score changes (up to 20-40%). Insect feeding diet is vital for LCA results as it could change the environmental impact in 28-60%. Higher impacts are especially evident for insects cultivated on high-protein feed grade material (4.8-5 kg CO2eq.; 2.4-3 m2 of arable land; 40-51.2 MJ of non-renewable energy). Low feed quality leads to food security problems, which should be yet studied and understood. Feed challenges are associated with problems of land use changes accountability (responsible for the highest impacts for climate change in food production chains), information lack on generated wastes by production of insects and protein digestibility accounting. Indicated challenges of LCA demonstrate a great potential for production technologies improvement and further research of insect-based food and feed sustainability identification.
    Full-text · Conference Paper · Sep 2015
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    Tomas Bolumar · Stefan Toepfl · Volker Heinz
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    ABSTRACT: The present paper describes the modification of the lipid fraction of dry-cured fermented sausage through fat reduction (35%) and fat replacement of animal fat with olive oil (up to 10%). High pressure processing (HPP) treated meat was employed as a novel fat replacer to reduce the fat content and as a new strategy to enable a stable incorporation of olive oil in dry-cured fermented sausages. Chemical (proximate composition and fatty acid profile), physical (water retention, structure formation and colour) and sensorial (appearance, texture and flavour) properties were evaluated. It is concluded that 35% of fat reduction is possible without reduction of consumer acceptability. Moreover, the addition of HPP-treated meat as a fat replacer resulted in good mimic of the fat particles together with good physical and sensory properties. Therefore, it resulted in an effective and clean alternative (no added-additives) for fat reduction. However, the incorporation of olive oil either by direct addition (4.3% oil) or within a HPP-created protein network (10% oil) resulted in unacceptable products since the oil was not properly retained inside the sausage matrix. Further studies are needed to find processing strategies that permit a stable incorporation of liquid plant oils to dry-cured fermented sausage for the development of healthier and more sustainable dry-cured fermented meat products.
    Full-text · Article · Sep 2015 · Polish Journal of Food and Nutrition Sciences
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    ABSTRACT: Modern economy depends on global supply chains sourced from regional production. Sustainability of regional production and development is a complex task owing to the lack of universal assessment methodology. Regional economies depending on food production are characterized with dynamic changes caused by weather conditions, consumer acceptance, agri-food commodities prices fluctuations, etc. Effective development and production of innovative food should be assured with complex sustainability assessment applicable to global and regional conditions. Regional Sustainability Assessment Methodology (RSAM) was developed to tackle such issues. It includes natural, social and economic capital transfer accounting through extended Input-Output tables and cyclicity analyses. RSAM reflects static and dynamic qualities of regional system for the assessment of development paths and policies effectiveness. It is based on regional statistic data available from official sources. Separate blocks of RSAM are oriented towards production (e.g. food) assessment in regionalized conditions. RSAM combines LCA techniques to provide detailed performance analysis of a company in the scope of regional production. Such information is aimed for the streamlined hotspot analysis of company performance. Additional intent of such data – provide a consumer with updated information about food origin, environmental and social issues. Global issues are assessed via RSAM combination with sustainability management frameworks on the basis of global and regional weighted supply chain functional unit. RSAM provided a sound analysis of regional development for two counties in Germany and indicated their dependency on resources within regions and on outer sources. Sustainability of development then assessed as regions ability to supply itself with own resources versus dependency on resources from other regions. Resources substitution options are also indicated. Innovative foods intrusion, tested on the example of pig production versus meat substitutes, revealed a minimum level of these products dependency at the current rate of technologies development for the regions. Therefore, RSAM is an effective tool applicable for regional sustainability analysis of development and production cases for supply chain management optimization. Further RSAM development is required for the forecasting qualities improvement via extension with specific environmental and social impact risk assessment.
    Full-text · Conference Paper · Aug 2015
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    ABSTRACT: http://link.springer.com/article/10.1007/s11367-015-0931-6 Purpose Food production is among the highest human environmental impacting activities. Agriculture itself accounts for 70–85 % of the water footprint and 30 % of world greenhouse gas emissions (2.5 times more than global transport). Food production’s projected increase in 70 % by 2050 highlights the importance of environmental impacts connected with meat production. The production of various meat substitutes (plant-based, mycoprotein-based, dairy-based, and animal-based substitutes) aims to reduce the environmental impact caused by livestock. This article outlined the comparative analysis of meat substitutes’ environmental performance in order to estimate the most promising options. Methods The study considered “cradle-to-plate” meal life cycle with the application of ReCiPe and IMPACT 2002+ methods. Inventory was based on literature and field data. Functional unit (FU) was 1 kg of a ready-to-eat meal at a consumer. The study evaluated alternative FU (the equivalent of 3.75 MJ energy content of fried chicken lean meat and 0.3 kg of digested dry matter protein content) as a part of sensitivity analysis. Results and discussion Results showed the highest impacts for lab-grown meat and mycoprotein-based analogues (high demand for energy for medium cultivation), medium impacts for chicken (local feed), and dairy-based and gluten-based meat substitutes, and the lowest impact for insect-based and soy meal-based substitutes (by-products allocated). Alternative FU confirmed the worst performance of lab-grown and mycoprotein-based analogues. The best performing products were insect-based and soy meal-based substitutes and chicken. The other substitutes had medium level impacts. The results were very sensitive to the changes of FU. Midpoint impact category results were the same order of magnitude as a previously published work, although wide ranges of possible results and system boundaries made the comparison with literature data not reliable. Conclusions and recommendations The results of the comparison were highly dependable on selected FU. Therefore, the proposed comparison with different integrative FU indicated the lowest impact of soy meal-based and insect-based substitutes (with given technology level development). Insect-based meat substitute has a potential to be more sustainable with the use of more advanced cultivation and processing techniques. The same is applicable to lab-grown meat and in a minor degree to gluten, dairy, and mycoprotein-based substitutes.
    No preview · Article · Jul 2015 · The International Journal of Life Cycle Assessment
  • Knut Franke · Ute Bindrich · Volker Heinz
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    ABSTRACT: Mixtures of low and high melting fats (fractions of palm fat, palm kernel fat and milk fat) were characterized after solidification with respect to solid fat content (SFC), firmness, barrier properties against moisture transport and fat crystal network structure (FCNS). The method of Detrended Fluctuation Analysis (DFA) was applied to quantify FCNS which was visualized using confocal laser scanning microscopy (CLSM). A broad range of firmness's of solidified fat mixtures could be observed for comparable SFC confirming the influence of FCNS. Smooth FCNS without dense crystals indicate firmer networks and vice versa. A correlation between the scaling exponent from DFA and firmness was found. Moisture barrier properties of the fat mixtures differed for similar SFC, too. In this case, FCNS with dense crystals and larger areas of interconnected liquid fat resulted in the best barrier effect. Smooth FCNS were found in fat blends possessing only low resistance against moisture transport. For SFC > 35 % at 20 °C, a linear correlation between scaling exponent and moisture barrier effect was detectable.Practical applications: These results can be used to optimize fat mixtures with respect to their performance with respect to barrier layers and define the fat crystal network structures which are required to obtain either high mechanical firmness of the solidified mixture or a efficient prevention of moisture transfer.
    No preview · Article · Jul 2015 · European Journal of Lipid Science and Technology
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    ABSTRACT: Ultra high pressure homogenization (UHPH) opens up new areas for dynamic high pressure assisted thermal sterilization of liquids. Bacillus amyloliquefaciens spores are resistant to high isostatic pressure and temperature and were suggested as potential surrogate for high pressure thermal sterilization validation. B. amyloliquefaciens spores suspended in PBS buffer (0.01 M, pH 7.0), low fat milk (1.5%, pH 6.7) and whole milk (3.5%, pH 6.7) at initial concentration of ~106 CFU/mL were subjected to UHPH treatments at 200, 300 and 350 MPa with an inlet temperature at ~80 °C. Thermal inactivation kinetics of B. amyloliquefaciens spores in PBS and milk were assessed with thin wall glass capillaries and modeled using mechanistic linear first order and Weibull models. The residence time during UHPH treatments was estimated to determine the contribution of temperature to spore inactivation by UHPH. No sublethal injury was detected after UHPH treatments using sodium chloride as selective component in the nutrient agar medium. The inactivation profiles of spores in PBS buffer and milk were compared and fat provided no clear protective effect for spores against treatments. Treatment at 200 MPa with valve temperatures lower than 125 °C caused no reduction of spores. A reduction of 3.5 log10 CFU/mL of B. amyloliquefaciens spores was achieved by treatment at 350 MPa with a valve temperature higher than 150 °C. The modeled thermal inactivation and observed inactivation during UHPH treatments suggest that temperature could be the main lethal effect driving inactivation. http://journal.frontiersin.org/article/10.3389/fmicb.2015.00712/abstract
    Full-text · Article · Jun 2015 · Frontiers in Microbiology
  • Dana Middendorf · Knut Franke · Ute Bindrich · Volker Heinz
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    ABSTRACT: The results confirm that differences in flow behavior of sucrose cocoa butter suspensions can be attributed to different surface properties due to the refining process, if particle size distributions are comparable. Especially for roller refining, some remarkable changes compared to ball mill refining were found. Small amounts of immobilized fat, a considerable decrease in yield value and divergent surface topographies as well as adhesion force histograms point to completely different surface properties. With respect to chocolate processing, these surface properties are the reason why roller refining is favored for chocolate making
    No preview · Article · May 2015
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    ABSTRACT: The benefits of high pressure processing (HPP) for microbial inactivation in food production include reduced thermal treatment and minimized effects on sensory and nutritional profiles. These benefits have resulted in increasing commercial production of high pressure pasteurized foods. In this review, the current state of the art in terms of vegetative cell and bacterial spore inactivation by HPP in complex food matrices is assessed with an emphasis on mechanisms of inactivation and treatment of products that have low or non-uniform water activity (aw) profiles. Low aw can be the result of a high concentration in solutes, the presence of oils/fats, or the physical removal of water through dehydration. Microbial inactivation in low aw environments remains a particular challenge for HPP and studies on microbial inactivation observed in the different types of low aw food matrices are reviewed in detail.
    No preview · Article · Feb 2015 · Innovative Food Science & Emerging Technologies
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    ABSTRACT: Nitrate is a natural constituent of the human diet and an approved food additive. It can be partially converted to nitrogen monoxide, which induces vasodilation and thereby decreases blood pressure. This effect is associated with a reduced risk regarding cardiovascular disease, myocardial infarction and stroke. Moreover, dietary nitrate has been associated with beneficial effects in patients with gastric ulcer, renal failure or metabolic syndrome. Recent studies indicate that such beneficial health effects due to dietary nitrate may be achievable at intake levels resulting from the daily consumption of nitrate-rich vegetables. N-nitroso compounds are endogenously formed in humans. However, their relevance for human health has not been adequately explored up to now. Nitrate and nitrite are per se not carcinogenic, but under conditions that result in endogenous nitrosation it cannot be excluded that ingested nitrate and nitrite may lead to an increased cancer risk probably be carcinogenic to humans. In this review the known beneficial and detrimental health effects related to dietary nitrate/nitrite intake are described and the identified gaps in knowledge as well as the research needs required to perform a reliable benefit/risk assessment in terms of long-term human health consequences due to dietary nitrate/nitrite intake are presented.This article is protected by copyright. All rights reserved
    Full-text · Article · Jan 2015 · Molecular Nutrition & Food Research
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    ABSTRACT: Increasing consumer demand for food with a high nutritional value and a “fresh-like” taste has led to the development of new, mild processes to enhance or substitute for conventional techniques, such as heat treatment, for food preservation. Several non-thermal pasteurization methods, including the application of high hydrostatic pressure (HHP) or pulsed electric fields (PEF), have been developed to achieve sufficient microbial reduction while maintaining food quality. Some of the possible applications of PEF as a non-thermal cell membrane permeabilization technique are highlighted in this overview. The low energy consumption (1–2 kJ/kg for stress induction and 1–10 kJ/kg for plant cell permeabilization) and the continuous operability of this short time, waste-free membrane permeabilization technique are key advantages and allow the development of innovative, cost-effective, and sustainable processing concepts in the food and drink, biotechnology, and pharmaceutical industries. The application of PEF to food preservation has shown tremendous potential for preserving high quality products, such as freshly squeezed juices at lower temperatures and short residence times compared to traditional thermal pasteurization while retaining the fresh-like characteristics and nutritional value of the products. In the potato industry, the technique results in cut quality improvement, enhanced raw material usability, and energy savings. Future work should focus on understanding the underlying mechanisms and kinetics of recovery after treatment for bacterial endospores. Future applications of PEF may include algal downstream processing or wastewater treatment, showing the tremendous potential of this emerging technique beyond the few examples presented in this overview.
    No preview · Chapter · Dec 2014
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    ABSTRACT: This work reports an evaluation and comparison of traditional and novel large scale pasteurisation technologies (pulsed electric fields (PEF) and high pressure processing (HPP)) and consecutive refrigerated storage on the headspace fingerprint of tomato juice. The comparison between technologies was performed based on microbial equivalence. A pilot scale PEF processing system and an industrial scale HPP unit were used in order to imitate industrial application. A fingerprinting approach ('processomics') as a hypothesis-free approach has been used for sample comparison, as volatiles are often involved in process- and storage-induced chemical reactions as intermediate or end products. It has been observed, that all three pasteurisation technologies caused loss of several volatiles compared to non-processed sample. Moreover, all three technologies caused increase of Z-citral and 6-methyl-5-hepten-2-one. The majority of the quality-related chemical reactions observed after processing and during shelf-life were oxidative reaction of fatty acids, carotenoid degradation and degradation of amino acids. Industrial relevance Tomato processing often includes thermal treatments, which can adversely influence sensory and quality attributes of the final product. Novel technologies such as pulsed electric fields (PEF) and high pressure processing (HPP) have been investigated and developed as gentle pasteurisation technologies, with a potential to deliver the product with superior quality compared to their thermal counterparts. The results of this study could be of great importance for implementation of novel technologies and could lead to a new product development and process optimisation. In case of PEF technology, the process efficiency might be an important factor, considering that lower energy levels are needed for pasteurisation and higher capacities can be produced (operating in a continuous process) with extremely short holding times at elevated temperature.
    No preview · Article · Oct 2014 · Innovative Food Science & Emerging Technologies
  • Conference Paper: 1

    No preview · Conference Paper · Oct 2014
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    ABSTRACT: Bacterial endospores through their strong resistance to both chemical and physical hurdles constitute a risk for food industry. Inactivation strategies are based on thermal and/or chemical treatments but rely on incomplete knowledge of the mechanisms of inactivation. Alternative strategies were suggested to achieve food safety while improving product quality. One of them relies on the successive germination and inactivation by pasteurization of bacterial spores. However, to date, a gap of knowledge on bacterial spore germination remains and hinders such an application for food sterilization. Geobacillus stearothermophilus ATCC 7953 spore germination mechanisms were investigated by in situ fluorometry combined with plate counts. G. stearothermophilus spores' inner membrane was stained with Laurdan fluorescent dye. While nutrient pathways showed no strong germination with the combinations tested, successful germination up to 3 log10 could be achieved using 60 mmol l−1 calcium-dipicolinic acid (CaDPA) at 55 °C for 2 h. A model for the CaDPA germination mechanism in two phases could be derived which suggested a potential key role of cortex fragments in the germination path, before completion of the cortex degradation. Additionally, it was confirmed that the germination potential of CaDPA, which does not rely on nutrient receptors, is a widespread germination trigger across spore formers. Understanding germination mechanisms and the limitations of different germination paths is important for the development of multi-hurdle approaches to achieve commercial sterility with reduced thermal load.
    No preview · Article · Sep 2014 · Food Control
  • Waldemar Buxmann · Volker Heinz · Stefan Toepfl
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    ABSTRACT: [EN] Embodiments of the present invention are related to a method for producing a composition containing biologically active follistatin.
    No preview · Patent · Aug 2014
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    ABSTRACT: A new generation of high pressure homogenizers reaching up to 400 MPa offers opportunities for spore inactivation and high pressure sterilization of foods. A Stansted Fluid Power ultra-high pressure homogenization (UHPH) unit was tested to inactivate bacterial spores in a model buffer system. Bacillus subtilis PS832 and Geobacillus stearothermophilus ATCC7953 spores’ thermal resistances were assessed (D, z-value and Ea). The pressure and valve temperature were monitored during UHPH. Residence times under pressure and high temperature were estimated and enabled comparison with thermal inactivation, indicating the estimated thermal contribution to inactivation. Spore germination was also assessed but no germination was observed. Up to five log10B. subtilis and two log10G. stearothermophilus spores were inactivated by the harshest treatments (> 300 MPa –Tvalve > 145 °C for ~ 0.24 s). The inactivation profiles were similar to the predicted thermal inactivation suggesting that the valve temperature might be a dominant parameter leading to bacterial spore inactivation.
    No preview · Article · Aug 2014 · Innovative Food Science & Emerging Technologies
  • Claudia Siemer · Stefan Toepfl · Volker Heinz
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    ABSTRACT: Pulsed Electric Field (PEF) processing has been investigated in the past for gentle preservation and for the disintegration of biological tissue. The principle is based on polarization of the cell membrane by an external electric field, which results in electroporation. This increases the permeability of the membrane, which positively affects processes in which mass transfer is important. Extraction, such as sugar from sugar beet or juice from fruit, aims to separate ingredients from a matrix. By disintegrating the cells by PEF, a facilitated extraction of sugar or a higher juice yield can be achieved. Beneficial effects were also observed during water removal, as the drying time or the drying temperature can be reduced using PEF as a pre-treatment. Furthermore, a softening of PEF-treated tissue was observed, which can be highly beneficial for the vegetable industry such as in processing French fries or potato chips. The cutting force is reduced and smoother surface with less breakage can be achieved. The chapter gives an overview on the effects achieved in the PEF treatment of solid material.
    No preview · Chapter · Aug 2014
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    ABSTRACT: Bacterial spores have a strong resistance to both chemical and physical hurdles and create a risk for food industry which has been tackled by applying high thermal intensity treatments to sterilize food. These strong thermal treatments lead to reduction of the organoleptic and nutritional properties of food and alternative are actively searched for. Innovative hurdles offer an alternative to inactivate bacterial spores. In particular, recent technological developments have enabled a new generation of high pressure homogenizer working at pressures up to 400 MPa and thus opening new opportunities for high pressure sterilization of foods. In this short review, we summarize the work conducted on (ultra)-high pressure homogenization (U)HPH to inactivate endospores in model and food systems. Specific attention is given to process parameters (pressure, inlet and valve temperatures). This review gathers the current state of the art and underlines the potential of UHPH sterilization of pumpable foods while highlighting the needs for future work. http://journal.frontiersin.org/Journal/104283/abstract
    Full-text · Article · Aug 2014

Publication Stats

3k Citations
215.26 Total Impact Points


  • 2005-2015
    • Deutsches Institut für Lebensmitteltechnik
      Quakenbrück, Lower Saxony, Germany
  • 1996-2013
    • Technische Universität Berlin
      • • Department of Chemistry
      • • Institut für Lebensmitteltechnologie und Lebensmittelchemie
      Berlín, Berlin, Germany
  • 2012
    • Leibniz Institute for Solid State and Materials Research Dresden
      Dresden, Saxony, Germany
  • 2011
    • Klinikum Osnabrück
      Osnabrück, Lower Saxony, Germany
  • 2006
    • New York State
      New York City, New York, United States
  • 2000
    • Georg-August-Universität Göttingen
      • Institute for X-Ray Physics
      Göttingen, Lower Saxony, Germany