Institut für Lebensmittelwissenschaft und Biotechnologie

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Improved prediction of wheat quality and functionality using near-infrared spectroscopy and novel approaches involving flour fractionation and data fusion
(2025) Ziegler, Denise; Buck, Lukas; Scherf, Katharina Anne; Popper, Lutz; Schaum, Alexander; Hitzmann, Bernd; Ziegler, Denise; Department of Process Analytics, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Buck, Lukas; Department of Bioactive and Functional Food Chemistry, Institute of Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Scherf, Katharina Anne; Department of Bioactive and Functional Food Chemistry, Institute of Applied Biosciences, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany; Popper, Lutz; Mühlenchemie GmbH & Co. KG, Ahrensburg, Germany; Schaum, Alexander; Department of Process Analytics, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Hitzmann, Bernd; Department of Process Analytics, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
The accurate and rapid determination of wheat quality is of great importance for the wheat supply chain. Near-infrared (NIR) spectroscopy has become an established method for this purpose. So far, however, predictions for most wheat quality characteristics are not accurate enough to replace reference measurements, with the exception of protein content. This study investigates the potential to improve the prediction of 41 wheat quality parameters (protein- and starch-related parameters, solvent retention capacity, farinograph, extensograph, alveograph) based on a flour fractionation approach (sieve fractionation, dough preparation, gluten washing) and data fusion using the established techniques of NIR spectroscopy and chemometrics. Results show that preprocessing of flour significantly altered the composition of the samples, which reflected in spectral differences of their NIR spectra. This also led to a change in the prediction accuracy for many wheat quality parameters. Compared to the prediction using flour spectra, flour fractionation with or without data fusion improved the RMSECV between 5.6 and 28.6% for 35 out of the 41 quality parameters tested, leading to R2CV between 0.80 and 0.96 for many of them. Gluten, dough, and the 50–75 µm and the 75–100 µm fractions were particularly important for the improved predictions. The best predictions were often based on data fusion of spectra from different sample types, demonstrating the importance of using complementary information from different data sources to improve predictions. The results underline the potential of this novel approach to be established in the industry as an extension of conventional NIR spectroscopy to improve wheat quality prediction.
Influence of meat batter addition in ground beef on structural properties and quality parameters
(2022) Berger, Lisa M.; Gibis, Monika; Witte, Franziska; Terjung, Nino; Weiss, Jochen
The determination of the amount of non-intact cells (ANIC) in ground beef products is usually performed using a time-consuming and subjective histometric approach neglecting structural properties, which is why more objective and faster methods including evaluation of quality parameters are needed. To determine, whether the addition of meat batter increases the histologically determined ANIC ground beef samples containing increasing shares of meat batter (non-intact cells) were investigated histologically and results were compared to other methodological approaches, namely lactate dehydrogenase activity (LDH), soluble protein content, metmyoglobin content, drip loss, firmness, and cooking loss. Histological measurements showed that ANIC increased linearly with the addition of meat batter to ground beef. The quality parameters drip loss ( r = − 0.834, p < 0.01) and firmness ( r = − 0.499, p < 0.01), and the structural parameter metmyoglobin content ( r = 0.924, p < 0.01) revealed significant correlations with the amount of added meat batter, and detected differences between ground beef samples when the difference in the amount of added batter-like-substance was ≥ 25%. Therefore, those methods might be useful to estimate and extrapolate ANIC, and assess product quality of ground beef samples in a faster and simpler way. The cooking loss was not affected by meat batter addition, whereas LDH activity revealed non-repeatable results. Taken together, histometric methods are useful to measure ANIC, nevertheless, it is limited in terms of characterization of morphological and structural changes in the meat. However, other parameters were correlated and could, in addition, be used for assessing the quality of ground meat.
Complex coacervation and precipitation between soluble pea proteins and apple pectin
(2022) Salminen, Hanna; Sachs, Melody; Schmitt, Christophe; Weiss, Jochen
Complex formation (leading to either coacervation or precipitation) offers a tool to generate plant-based novel food structures and textures. This study investigated the formation of complexes between soluble pea proteins and apple pectin upon varying the protein-to-pectin ratio ( r = 2:1 to 10:1), pH (3–7), and temperature (25 and 85 °C) with a total biopolymer concentration set to 1% (w/w). The results showed that predominantly soluble biopolymer complexes were formed at pH 5, and at low ratio ( r = 2:1), whereas lowering the pH to more acidic condition, and to higher ratios ( r = 4:1–10:1) induced the formation of more insoluble biopolymer complexes. In general, the mean particle sizes of the biopolymer complexes ranged between approximately 20 and 100 μm. Upon heating to 85 °C, the amount of insoluble biopolymer complexes increased at pH 3–5 at all ratios, except at r = 2:1. In addition, the complex sizes became somewhat larger at r = 2:1 to 6:1 upon heat treatment, whereas only trivial size changes were observed at higher ratios ( r = 8:1 to 10:1). Overall, electrostatic and hydrophobic interactions played a major role in the complex formation between the soluble pea proteins and apple pectin. These findings are important for designing solely plant-based food structures.
Spectral similarity score (SSS)-barcoding for the quality control of LACTEM emulsifiers by high-performance thin-layer chromatography
(2026) Schuster, Katharina; Torun, Sedef; Kainz, Inès; Schwarz-Blankart, Max; Hinrichs, Jörg; Steliopoulos, Panagiotis; Oellig, Claudia; Schuster, Katharina; Department of Food Chemistry and Analytical Chemistry (170a), Institute of Food Chemistry, University of Hohenheim, Garbenstrasse 28, Stuttgart, Germany; Torun, Sedef; Department of Food Chemistry and Analytical Chemistry (170a), Institute of Food Chemistry, University of Hohenheim, Garbenstrasse 28, Stuttgart, Germany; Kainz, Inès; Department of Soft Matter Science and Dairy Technology (150e), Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21, Stuttgart, Germany; Schwarz-Blankart, Max; Department of Soft Matter Science and Dairy Technology (150e), Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21, Stuttgart, Germany; Hinrichs, Jörg; Department of Soft Matter Science and Dairy Technology (150e), Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21, Stuttgart, Germany; Steliopoulos, Panagiotis; Chemisches und Veterinäruntersuchungsamt (CVUA), Weißenburgerstrasse 3, Karlsruhe, Germany; Oellig, Claudia; Department of Food Chemistry and Analytical Chemistry (170a), Institute of Food Chemistry, University of Hohenheim, Garbenstrasse 28, Stuttgart, Germany
LACTEM emulsifiers are widely applied in the food industry to adjust and improve techno-functional properties of food products. The study introduces a high-performance thin-layer chromatography−fluorescence detection (HPTLC−FLD) fingerprint method for the similarity assessment of these emulsifiers using a straightforward barcoding approach based on the concept of spectral similarity scores (SSS), referred to as SSS-barcoding. Analysis of 21 LACTEM emulsifiers showed similarities between two emulsifiers as low as 67%, despite the same product labeling. The method also revealed batch-to-batch variability. Limitations were identified when applying the method to fatty matrices. Finally, partial least-squares regression (PLSR) was applied as a proof-of-concept to predict the techno-functional properties of aerosol whipping cream, such as drainage, apparent viscosity, foam firmness, particle size (D90,3), and overrun, from the densitometric data.
Recombinant production of acidophilic L-arabinose isomerase from Lentilactobacillus parakefiri in Bacillus subtilis
(2025) Weber, Nathanael; Götz, Sebastian; Senger, Jana; Lutz-Wahl, Sabine; Fischer, Lutz; Weber, Nathanael; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Götz, Sebastian; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Senger, Jana; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Lutz-Wahl, Sabine; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Fischer, Lutz; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany
Background: The monosaccharide D-tagatose is a promising alternative to sucrose because of its similar sweetness and lower glycemic index. A novel L-arabinose isomerase (L-AI) from Lentilactobacillus parakefiri DSM 10551 (L-AI-Lp) has been biochemically characterized and used to isomerize D-galactose to D-tagatose in skim milk ultrafiltration permeate at pH 4.5 and 6.5. However, like most L-AIs described in the literature, this enzyme has only been produced recombinantly in Escherichia coli. This study aimed to systematically investigate the intracellular recombinant production of L-AI-Lp in Bacillus subtilis, which has qualified for a presumption of safety (QPS) designation from the European Food Safety Authority. Results: The influence of four promoters on L-AI-Lp production in B. subtilis 007 was investigated in shake flask cultivations. Among these, the PAprE promoter yielded the highest volumetric L-AI activity of 69.2 ± 7.4 µkatGal, 65 °C/LCulture. The production yield was further increased to 147.7 ± 1.0 µkatGal, 65 °C/LCulture by using the nonsporulating, surfactin-deficient strain B. subtilis 007 ∆sfp ∆sigF, which was constructed by deleting sigF and sfp in B. subtilis 007. Furthermore, the influence of pH and dissolved oxygen (DO) on bioreactor cultivations of B. subtilis 007 ∆sfp ∆sigF was analyzed. In bioreactor cultivations, the highest L-AI activity of 88.6 ± 2.4 µkatGal, 65 °C/LCulture was measured under unregulated pH and low oxygen conditions (DO ≤ 5%), representing a 3.2-fold increase compared with previous recombinant production in E. coli. The L-AI-Lp was subsequently partially purified by heat treatment and precipitation methods, resulting in a 7.8-fold increase in specific activity to 128.2 nkatGal, 65 °C/mg and a yield of 84%. Conclusions: The L-AI-Lp was recombinantly produced for the first time in a microbial species with QPS status using the nonsporulating and surfactin-deficient strain B. subtilis 007 ∆sfp ∆sigF. The L-AI-Lp was subsequently partially purified via nonchromatographic methods, providing a basis for a low-cost downstream process. These results represent an important step toward potential industrial application of L-AI-Lp and highlight the potential of B. subtilis 007 ∆sfp ∆sigF as an expression host for the recombinant production of L-AIs compared with previously used hosts from the order Lactobacillales.
Tackling foam-based process disruptions in spirit distillation by thermal energy input adaptations
(2022) Heller, Daniel; Roj, Simon; Switulla, Julia; Kölling, Ralf; Einfalt, Daniel
Process impairing foam formation occurs regularly in batch distillation devices of the spirit industry. It negatively influences process and product quality. Up to now, such foam-related problems have not been in the focus of scientific investigations. This study aimed at preventing impairing foam formations by adapting the thermal energy input in fruit and grain mash distillations in larger scale batch distillations. The results showed that a reduction of the thermal energy input to 43 ± 1 W·L −1 during the initial heating of the mash leads to less flooding of the distillation apparatus and to a higher concentration of lower boiling compounds like methanol, acetaldehyde, and ethyl acetate as well as ethanol in the first fractions of the distillates. A standard process time and less energy consumption could be achieved by increasing the energy input again after prior reduction. However, this led to a reduction of the ethanol concentration in the distillate fractions of up to 4.3%vol, also most severe in the first fractions. A significant influence on analyzed volatile compounds in the distillate besides ethanol could not be detected. This is the first study that uses defined thermal energy input adaptations for foam management in larger scale distillation devices. The results lead the way to a more efficient distillation process with less foam formation.
Upscaling of alkaline pea protein extraction from dry milled and pre-treated peas from laboratory to pilot scale: Optimization of process parameters for higher protein yields
(2022) Schmidt, Florian; Blankart, Max; Wanger, Janina; Scharfe, Markus; Scheuerer, Theresa; Hinrichs, Jörg
The upscaling of pea protein extraction from laboratory scale with a centrifuge to pilot scale with a decanter centrifuge was investigated, and the pea protein extraction efficiency from dry milled and pre-treated peas was compared. Upscaling from laboratory to pilot scale is possible since starch was under the limit of detection (< 0.5%). The protein banding pattern of a sodium-dodecyl-sulfate polyacrylamide gel electrophoresis confirmed that albumins and globulins were extracted by alkali extraction. Protein yield increased from 59.5% to 67.1% for dry milled peas due to constant and quick discharge of dry matter in the decanter centrifuge. For pre-treated peas, the protein yield increased from 60.3% to 94.3%, which is explained by an improved cutting and improved separation in pilot scale compared to laboratory scale. The impact of acceleration, mass flow, differential speed and their respective interactions in the decanting process was determined with a design of experiments. For dry milled peas, only the mass flow exceeded the significance level. However, a mass flow of 5 kg h −1 , an acceleration of 1000 g ×and a differential speed of 50 min −1 led to the highest protein yield of 75.6%. The obtained protein yields for the pre-treated peas were in the range of 83 to 96% and therefore did not show significant differences in protein yield.
Spectroscopic-based prediction of milk foam properties for barista applications
(2022) Brettschneider, Kim Christin; Zettel, Viktoria; Sadeghi Vasafi, Pegah; Hummel, Darius; Hinrichs, Jörg; Hitzmann, Bernd
The important quality parameters of cow’s milk for barista applications are frothability and foam stability. In the past, quality assessment was very time-consuming and could only be carried out after milk treatment had been completed. Since spectroscopy is already established in dairies, it could be advantageous to develop a spectrometer-based measurement method for quality control for barista applications. By integrating online spectroscopy to the processing of UHT (ultra-high temperature processing) milk before filling, it can be checked whether the currently processed product is suitable for barista applications. To test this hypothesis, a feasibility study was conducted. For this purpose, seasonal UHT whole milk samples were measured every 2 months over a period of more than 1 year, resulting in a total of 269 milk samples that were foamed. Samples were frothed using a self-designed laboratory frother. Frothability at the beginning and foam loss after 15 min describe the frothing characteristics of the milk and are predicted from the spectra. Near-infrared, Raman, and fluorescence spectra were recorded from each milk sample. These spectra were preprocessed using 15 different mathematical methods. For each spectrometer, 85% of the resulting spectral dataset was analyzed using partial least squares (PLS) regression and nine different variable selection (VS) algorithms. Using the remaining 15% of the spectral dataset, a prediction error was determined for each model and used to compare the models. Using spectroscopy and PLS modeling, the best results show a prediction error for milk frothability of 3% and foam stability of 2%.
Effect of different oxygen atmospheres on color stability of modified atmosphere packaged beef using non-invasive measurement
(2025) Krell, Johannes; Müller, Theresa; Poveda-Arteaga, Alejandro; Weiss, Jochen; Terjung, Nino; Gibis, Monika; Ziarno, Małgorzata
The influence of a 1% oxygen atmosphere on the color stability of modified atmosphere packaged beef was investigated. Beef silverside slices were packed under 1%, 20%, and 70% oxygen atmospheres and stored at 2 °C for 14 days. Color and reflection data were measured non-invasively. The L*a*b* values were analyzed, the color difference ΔE2000, and the levels of myoglobin (Mb), deoxy-(DMb), oxy-(OMb), and metmyoglobin (MMb) were calculated. The 1% oxygen atmosphere resulted in a rapid MMb formation from 0.63 (day 0) to 1.27 (day 8) (p < 0.05). The other samples showed slight increases from 0.65 to 0.80 MMb (20%) and 0.65 to 0.79 MMb (70%). On day 10, the 20% oxygen sample showed an increased MMb formation (1.33 MMb). The 70% atmosphere resulted in a final value of 0.91 MMb after 14 days. These results show that an oxygen content of 1% accelerates the formation of MMb at an early stage. A higher oxygen content in the packaging delays MMb development through OMb formation, which masks MMb creation, to a certain extent. Measuring the packaged meat pieces over a 14-day storage period provides detailed insights into the development of Mb formation and critical points during storage.
Influence of wet extrudates from pumpkin seed proteins on drying, texture, and appearance of dry-cured hybrid sausages
(2022) Ebert, Sandra; Jungblut, Florence; Herrmann, Kurt; Maier, Barbara; Terjung, Nino; Gibis, Monika; Weiss, Jochen
Hybrid meat products represent a promising, more sustainable alternative to all-meat formulations. However, differences among plant- and animal-based proteins may alter traditional handling and final product properties. In this study, pork meat was partially replaced with texturized pumpkin seed proteins at 12.5, 25, 37.5, and 50% to obtain dry-cured hybrid meat sausages and their ripening (acidification, drying) during 21 days and final product properties (texture, sensory) were characterized and compared to a control (all-meat formulation). The drying behavior and distribution of moisture and free water of hybrids with extrudate contents of 12.5 and 25% were comparable to the sample made with meat and no significant ( p > 0.05) differences in proximate composition were found. In contrast, higher meat replacement levels resulted in distinct changes of compositional and textural attributes i.e. chewiness was decreasing by up to 70%. Results suggested 25% of extrudates as an important threshold in manufacture of hybrid dry-cured sausages due to alterations in their ability to bind or release water. Results may be used to understand the influence of alternative texturized proteins in hybrid formulations and help product developers to understand related process and product relevant changes.
Benchmarking of secure group communication schemes with focus on IoT
(2024) Prantl, Thomas; Bauer, André; Engel, Simon; Horn, Lukas; Krupitzer, Christian; Iffländer, Lukas; Kounev, Samuel
As Internet of Things (IoT) devices become ubiquitous, they face increasing cybersecurity threats. Unlike standard 1-to-1 communication, the unique challenge posed by n-to-n communication in IoT is that messages must not be encrypted for a single recipient but for a group of recipients. For this reason, using Secure Group Communication (SGC) schemes is necessary to encrypt n-to-n communication efficiently for large group sizes. To this end, the literature presents various SGC schemes with varying features, performance profiles, and architectures, making the selection process challenging. A selection from this multitude of SGC schemes should best be made based on a benchmark that provides an overview of the performance of the schemes. Such a benchmark would make it much easier for developers to select an SGC scheme, but such a benchmark still needs to be created. This paper aims to close this gap by presenting a benchmark for SGC schemes that focus on IoT. Since the design of a benchmark first requires the definition of the underlying business problems, we defined suitable problems for using SGC schemes in the IoT sector as the first step. We identified a common problem for the centralized and decentralized/hybrid SGC schemes, whereas the distributed/contributory SGC schemes required defining an independent business problem. Based on these business problems, we first designed a specification-based benchmark, which we then extended to a hybrid benchmark through corresponding implementations. Finally, we deployed our hybrid benchmark in a typical IoT environment and measured and compared the performance of different SGC schemes. Our findings reveal notable impacts on calculation times and storage requirements without a trusted Central Instance (CI) in distributed/contributory SGC schemes.
Dairy byproducts as sustainable alternatives to FCS in 2D and 3D skeletal muscle cell cultures
(2025) Baldeweg, Tobias Horst; Hubel, Philipp; Günther, Johannes; Ostertag, Fabian; Nellinger, Svenja; Heine, Simon; Kluger, Petra Juliane
Skeletal muscle tissue engineering is a rapidly developing field with applications in disease modelling, tissue replacement, biorobotics, and cultivated meat. The need for more sustainable and ethical biotechnologies has grown due to concerns about resource scarcity, climate change, and animal welfare. One major challenge is replacing fetal calf serum (FCS), a widely used but ethically and environmentally highly problematic media supplement. A promising alternative is the utilization of natural byproducts such as whey and colostrum from the dairy industry, which provide essential nutrients and growth factors. In this study, wheys produced by microfiltration of raw milk and colostrum were investigated as FCS replacements for culturing C2C12 skeletal muscle cells. Composition analysis confirmed a variety of pro-proliferative compounds in both substances. Cell culture experiments led to the development of an optimized medium formulation based on colostrum whey. Colostrum whey medium (CM) supported cell proliferation and maintained the myogenic differentiation potential for over 30 days. Additionally, a CM-based freezing solution enabled effective cryopreservation throughout culture. In 3D static suspension culture, CM sustained viable spheroids for over 14 days. Spheroids showed significantly higher proliferation compared to those in serum-containing medium, making CM suitable for 3D modelling and scale-up of biomass production. These findings highlight CM as a sustainable, cost-effective, and ethical alternative for skeletal muscle tissue engineering, particularly in cultivated meat production.
Application of a PAT/QbD concept onto a Pharmaceutical Bioprocess
(2025) Graf, Alexander; Schaum, Alexander
In 2022 close to a hundred billion units of pharmaceuticals were sold in Germany alone (Radtke, 2023). Patient safety and high efficacy are the most critical factors in producing these drugs. This results in a need for manufacturers to constantly output high-quality products. Consequently, there has been an ongoing adoption of Quality by Design (QbD) and Process Analytical Technologies (PAT) in the industry over the last decades. This thesis focused on advancing different spectroscopic methods as PAT tools in the context of QbD. First, a novel 2D-fluorescence (2DF) sensor was investigated for its usability in-process monitoring of mammalian cell cultures – qualitative and quantitative. Second, Raman spectroscopy was examined for its use in bioprocess development and as a control device in production bioreactors. In the first part of this work, the 2DF technology demonstrated its versatility as, on the one hand, an effective method for golden batch monitoring, i.e., for promptly detecting deviations within the process. On the other hand, the fluorescence signals can be correlated to cell count and viability, making it a suitable in-line alternative to traditional off-line cell counting. In the context of QbD, fluorescence spectroscopy can furthermore give the user more insight into the cellular metabolism, as, for example, co-enzymes like NADH can be detected. The second part focuses on Raman spectroscopy as a valuable tool during process development and for in-line process control of critical process parameters. First, a Raman spectrometer was integrated into two automated mini-bioreactor systems – one with 15 mL and the other with 250 mL single-use vessels. These systems are commonly used in cell line development and upstream process development campaigns, especially for economic execution of Design of Experiment studies. Integrating a Raman spectrometer in these highly automated systems made it possible to efficiently generate a large Raman dataset for robust modeling of several essential process parameters, such as glucose, lactate, glutamine, glutamate, and target protein titer. In the case of the glucose model, scale-up to a 50 L bioreactor was successfully made for in-line monitoring of said parameter. Finally, Raman spectroscopy was integrated into a perfusion process. In combination with a biocapacitance probe for in-line cell count control, the Raman system was successfully utilized for on-line control of the glucose concentration. This paper proves that PAT sensors can be utilized as enablers for process intensification and, consequently, as a step toward continuous processing.
Brewing a sustainable future: a firm-level analysis of sustainability initiatives in the coffee sector
(2025) Boller, Meta Leonie; Bosch, Christine; Heinzel, Kathleen; Birkenberg, Athena; Krupitzer, Christian
The coffee industry has long relied on third-party certification as their approach to sustainability, driven by customer demand and changing consumer behavior. Today, multiple forms of sustainability engagement have developed in the industry. This study uses a machine learning approach to analyze the engagement in sustainability initiatives of 100 firms active in the German market. Results reveal that company size and value chain position influence choice and engagement intensity in sustainability initiatives. A complementary literature analysis on policy recommendations to promote sustainability engagement in the coffee industry revealed a fragmented and insufficiently granular picture to address the diverse needs of stakeholders. While company characteristics significantly influence their choice of sustainability initiatives, policymakers often adopt generic approaches that do not reflect these nuances. Future research could extend this approach to deepen understanding or validate findings of policies for sustainable transformation in the coffee sector to other critical crops.
Optimizing aroma compound fractionation in pear brandy distillation by controlling their relative volatility
(2025) Yagishita, Manami; Reber, Oliver; Alter, Daniela; Kölling, Ralf; Einfalt, Daniel
This study aims at improving the fractionation of key odor compounds in pear brandies by controlling their relative volatility through novel fractionation strategies. Two approaches were tested: one using a high cooling water flow rate at the dephlegmator with a slow distillate flow and another employing a distillation column with 12 trays. Both effectively elevated ethanol concentration on the top tray, altering the relative volatility of compounds in the liquid phase and influencing the final product composition. The behavior of compounds closely aligned with their relative volatility data. Elevated ethanol concentrations reduced the relative volatility of higher alcohols, delaying their release from the column and producing sharper peaks compared to the broader profiles in the control distillation. This enabled the effective separation of beta-damascenone and ethyl (E,Z)-2,4-decadienoate (pear ester) from higher alcohols, creating an aroma-rich tails fraction enriched with these desirable compounds. Mixing this tails fraction with the hearts fraction produced a blend that was significantly preferred in sensory evaluations over the standard hearts fraction. These findings highlight the importance of tailoring ethanol profiles in the distillation apparatus to optimize compound separation and enhance the quality of pear brandies.
Recommendation of secure group communication schemes using multi-objective optimization
(2023) Prantl, Thomas; Bauer, André; Iffländer, Lukas; Krupitzer, Christian; Kounev, Samuel
The proliferation of IoT devices has made them an attractive target for hackers to launch attacks on systems, as was the case with Netflix or Spotify in 2016. As the number of installed IoT devices is expected to increase worldwide, so does the potential threat and the importance of securing these devices and their communications. One approach to mitigate potential threats is the usage of the so-called Secure Group Communications (SGC) schemes to secure the communication of the devices. However, it is difficult to determine the most appropriate SGC scheme for a given use case because many different approaches are proposed in the literature. To facilitate the selection of an SGC scheme, this work examines 34 schemes in terms of their computational and communication costs and their security characteristics, leading to 24 performance and security features. Based on this information, we modeled the selection process for centralized, distributed, and decentralized schemes as a multi-objective problem and used decision trees to prioritize objectives.
Die Erweiterung des genetischen Codes als molekulare Prozesskontrolle
(2025) Hiller, Eric; Hermann, Alexander; Lilge, Lars
Bioproduction of bioactive compounds on a large-scale poses challenges that require molecular strain engineering. By integrating the principle of genetic code expansion (GCE), the biosynthesis of the surfactin biosurfactant has been controlled in the production host Bacillus subtilis depending on the supply of a defined non-canonical amino acid. The regulation of this molecular process control has been transferred to high-cell-density fed-batch bioreactor procedures, allowing an initial upscaling.
Chemical compositions and oxidative stabilities of cold‐pressed walnut oils (Juglans regia L.): effects of chemical refining, water degumming, and molecular distillation
(2024) Liu, Longfei; Cai, Hongling; Zhang, Youfeng; Jin, Qingzhe; Wang, Xingguo; Jin, Jun
Walnut oils are of important academic and economic value, and are becoming one of the most important woody oils. Accurate and moderate refining techniques are required to produce high‐quality walnut oils. In this work, walnut oils obtained from cold processing were refined in three typical techniques, mainly chemical refining, water degumming, and molecular distillation. Physicochemical properties (acid value and peroxide value [POV]), minor components (tocopherol, polyphenols, and phytosterol), oxidative stability indices, and volatile compounds were analyzed to find out the appropriate refining method for the cold‐pressed walnut oils. Quality indices of all the refined oils from the three different refining methods met the requirements of the national standard, of which the POV of chemically refined oil (0.241 g/100 g) was higher than crude oil (0.058 g/100 g). Water degumming was most suitable for retaining of bioactive compounds, for example, the tocopherol was 259.40 mg/kg, the polyphenols was 44.54 mg GAE/kg, and the phytosterol was 987.32 mg/kg, but oxidation stability of the obtained oil (3.09 h) was lower than that of molecular distilled oil (4.18 h). Initial physicochemical properties especially the POV had a significant impact on oxidation stability. There is a trade‐off between the retention of nutrients and extending shelf life, indicating appropriate refining techniques should be developed; that is, water degumming is suggested to be involved in producing high‐quality cold‐pressed walnut oils.
Influence of low oxygen concentrations on color stability of modified atmosphere packaged beef
(2026) Krell, Johannes; Aeckerle, Luis; Poveda-Arteaga, Alejandro; Weiss, Jochen; Terjung, Nino; Gibis, Monika
The influence of low oxygen concentrations on the development of color and the myoglobin redox states over storage time was analyzed, to determine whether there are conditions that increase discoloration. Beef slices were packaged in atmospheres containing nitrogen gas and 0 %, 0.5 %, 1 %, 1.5 %, 3 %, and 5 % of oxygen. The samples were stored at 2 °C for 14 days. During storage, color, reflectance and oxygen concentration were measured optically through the packaging. The color difference ΔE2000 and the relative oxymyoglobin (OMb), deoxymyoglobin (DMb), and metmyoglobin (MMb) levels were calculated. After 14 days, the oxygen concentrations changed to 0.09 % (0 %), 0.36 % (0.5 %), 0.92 % (1 %), 1.28 % (1.5 %) 2.55 % (3 %), and 4.29 % (5 %). Regarding MMb formation, the 0 % samples (ΔMMb0–14d 11.1 %) were significantly (p < 0.05) more stable compared to the other samples, which showed an increase of MMb formation with rising oxygen concentration after 14 days. The other samples reached a ΔMMb0–14d increase of 21.1 % (0.5 %), 26.7 % (1 %), 30.0 % (1.5 %), 31.1 % (3 %), and 34.4 % (5 %). The color stability showed significantly (p < 0.05) increasing ΔE values of 2.49 (0 %), 3.39 (0.5 %), 4.66 (1 %), 5.14 (1.5 %), 6.03 (3 %), and 7.34 (5 %) with rising oxygen contents. These findings suggest that to ensure the color stability of beef with minimal MMb formation, it is important to completely exclude oxygen from the packages, since the destabilizing effect of oxygen already started at 0.5 %. The non-invasive measurement of the oxygen concentration and the reflectance data over 14 days gave new insights into the discoloration process of beef stored in low-oxygen atmospheres.
Toward food-grade production of the Bacteroides helcogenes protein-glutamine glutaminase with an optimized Bacillus subtilis strain
(2026) Senger, Jana; Keutgen, Mario; Roth, Nicole; Seitl, Ines; Fischer, Lutz; Senger, Jana; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr 25, 70599, Stuttgart, Germany; Keutgen, Mario; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr 25, 70599, Stuttgart, Germany; Roth, Nicole; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr 25, 70599, Stuttgart, Germany; Seitl, Ines; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr 25, 70599, Stuttgart, Germany; Fischer, Lutz; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr 25, 70599, Stuttgart, Germany
Protein-glutamine glutaminases (PGs; EC 3.5.1.44) have gained attention in the food industry due to their application in plant protein products. The recently discovered PG from Bacteroides helcogenes (PGB) has especially been shown to provide promising characteristics for improving the techno-functional properties of plant proteins. A prerequisite for food enzymes, such as the PG, is their production with an expression host that meets food safety and yield requirements. The antibiotic-free and secretory production of the PGB was targeted in this study using the undomesticated Bacillus subtilis 007. The CRISPR/Cas9-mediated approach enabled specific genomic PGB integrations, while simultaneously deleting unwanted B. subtilis traits. Firstly, the PGB expression cassette was integrated into the sigF gene, leading to an asporogenic strain and extracellular activity of 4.1 µkat/Lculture in bioreactor cultivations. However, excessive foaming hampered the production process tremendously. Consequently, a second PGB copy was integrated into the sfp locus, which is involved in the production of lipopeptides, such as surfactin. As a result, the PGB activity was increased to 5.4 µkat/Lculture, and foaming during cultivation was reduced significantly. The introduction of a third PGB copy for preventing cell motility did not increase production; however, the integration into the well-established amyE locus improved the PGB yield during reactor cultivations. A final extracellular activity of 9.5 µkat/Lculture was reached. The multiple genomic integrations of the PGB gene enabled the efficient PGB secretion in an optimized B. subtilis host without the need for antibiotics.Key points• Site-specific PGB integration enabled by genome sequencing of B. subtilis 007.• Antibiotic-free and secretory PGB production with an optimized B. subtilis host.• Increased PGB production reaching 9.5 µkat/Lculture.

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