Institut für Lebensmittelwissenschaft und Biotechnologie

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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.
Potential of homopolysaccharide-producing starter cultures in the fermentation of coconut yoghurt alternatives enriched with pea protein isolate
(2026) Libberecht, Sophie; Ristevska, Mia; Gibis, Monika; Loeffler, Myriam; Libberecht, Sophie; Meat Technology & Science of Protein-Rich Foods (MTSP), Department of Microbial and Molecular Systems, Leuven Food Science and Nutrition Research Centre, KU Leuven Campus Ghent, 9000 Ghent, Belgium; Ristevska, Mia; Meat Technology & Science of Protein-Rich Foods (MTSP), Department of Microbial and Molecular Systems, Leuven Food Science and Nutrition Research Centre, KU Leuven Campus Ghent, 9000 Ghent, Belgium; Gibis, Monika; Department of Food Material Science, University of Hohenheim, 70593 Stuttgart, Germany;; Loeffler, Myriam; Meat Technology & Science of Protein-Rich Foods (MTSP), Department of Microbial and Molecular Systems, Leuven Food Science and Nutrition Research Centre, KU Leuven Campus Ghent, 9000 Ghent, Belgium; Martínez-Culebras, Pedro Vicente;; Roig, Patricia;; Martínez-Culebras, Pedro Vicente; Roig, Patricia
This study investigates the use of a homopolysaccharide (HoPS)-producing Latilactobacillus sakei strain for the production of protein-enriched plant-based yoghurt analogues based on coconut milk. Formulations varied in added sucrose (2.5% or 5.0% w / w ), pea protein isolate (PPI; 0–5.0% w / w ), and tapioca starch (0%, 1.5% w / w ), and were fermented with either a HoPS-producing strain ( L. sakei 1.411), or a non-exopolysaccharide (EPS)-producing control strain ( L. sakei 1.2037) with very similar acidification kinetics. Microbial growth and pH were monitored, HoPS content was determined via HPLC, and both firmness and syneresis were assessed during 5 days of storage at 4 °C. EPS yields were significantly higher ( p < 0.05) in samples with 5.0% w / w added sucrose compared to those with 2.5% w / w . Fermentation with L. sakei 1.411 generally resulted in firmer gels ( p < 0.05) and reduced syneresis ( p < 0.05) compared to L. sakei 1.2307 and the enhanced viscosity (sample thickness) was also observed in a sensory analysis. Samples containing starch and 5.0% w / w PPI showed the highest firmness-related values. These findings demonstrate the potential of in situ HoPS production to improve the texture and stability of protein-enriched coconut-based yoghurt analogues. It highlights the importance of matrix formulation, strain selection and process control, which all contribute to the final product quality.
Model-based process design for surfactin production with Bacillus subtilis
(2025) Hiller, Eric; Off, Manuel; Dittmann, Holger; Perino, Elvio Henrique Benatto; Lilge, Lars; Hausmann, Rudolf; Hiller, Eric; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Off, Manuel; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Dittmann, Holger; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Perino, Elvio Henrique Benatto; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Lilge, Lars; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Hausmann, Rudolf; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
Bacillus subtilis is one of the most important production organisms in industrial biotechnology. However, there is still limited knowledge about the kinetics of fed-batch processes in bioreactors, as well as a lack of biological performance indicators, such as production yields, particularly regarding their variation over time. Understanding these kinetics and changes is crucial for optimizing the productivity in fed-batch processes. Fed-batch bioreactor cultures of Bacillus subtilis BMV9 in high cell density processes for surfactin production have been characterized with a kinetic model composed of first-order ordinary differential equations, describing the time course of biomass, substrate, surfactin and acetate. This model contributes to understanding critical restrictions and the knowledge gained was used to design and implement a model-based process. The model integrates biomass growth based on Monod kinetics, substrate consumption, surfactin synthesis and formation of the by-product acetate. After the model was parameterized for B. subtilis BMV9 using 12 different fed-batch bioreactor experiments, the kinetic model was able to accurately describe biomass accumulation, substrate consumption, product formation rates and, to some extent, the overflow metabolism involving acetate. Based on this, the kinetic model was used for a process design, in which the batch was omitted, which led to a product titre of 46.33 g/L and a space–time-yield of 2.11 g/(L*h) was achieved. The kinetic model developed in this study enables the description of the time course of biomass growth, substrate consumption and product formation and thus significantly improves process understanding. The computation of process parameters, which are not analytically accessible at any time, could be realized. A sensitivity analysis identified the maximum specific growth rate, substrate-related maintenance and the maximum acetate formation rate as key parameters influencing model outputs.
Intestinal dysbiosis associated with non-nutritive sweeteners intake: an effect without a cause?
(2025) Marongiu, Luigi; Brzozowska, Ewa; Hetjens, Svetlana; Hoelzle, Ludwig E.; Venturelli, Sascha; Brzozowska, Ewa; Laboratory of Medical Microbiology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland; Hetjens, Svetlana; Department of Medical Statistics, Biomathematics and Information Processing, University Clinic Mannheim, Mannheim, Germany; Hoelzle, Ludwig E.; Department of Food Microbiology and Hygiene, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Venturelli, Sascha; Department of Nutritional Biochemistry, University of Hohenheim, Stuttgart, Germany
Non-nutritive sweeteners (NNS) are present in various commercial articles, from foodstuffs to oral hygiene products. Despite their alleged safety, mounting evidence indicates that NNS intake is associated with an alteration of intestinal bacterial populations (dysbiosis) in animals and humans. Since NNS are commercialized based on the assumption that they are not metabolized by human cells and negligible effect on bacterial, the insurgence of dysbiosis associated with NNS intake remains unexplained. The current review aims to assess the effect of selected NNS (acesulfame potassium, advantame, aspartame, neotame, saccharin, stevia, and sucralose) on the human intestinal microbiota. Findings from this review suggests that NNS intake is linked not only to alterations in human physiology but also to modifications of bacterial biochemistry, including the hindrance of quorum sensing pathways, in a species-specific manner. Moreover, there were suggestions that NNS could also affect the biology of phages, namely by binding to the active sites of proteins involved in the infection process and altering the induction rate of prophages. The studies gathered in the present review provide a framework for understanding how NNS might be connected to dysbiosis, both directly through alterations in bacterial biochemistry and indirectly through impaired phage activity.
Enabling adaptive food monitoring through sampling rate adaptation for efficient, reliable critical event detection
(2025) Jox, Dana; Schweizer, Pia; Henrichs, Elia; Krupitzer, Christian; Jox, Dana; Department of Food Informatics and Computational Science Hub, University of Hohenheim, 70599 Stuttgart, Germany; Schweizer, Pia; Department of Food Informatics and Computational Science Hub, University of Hohenheim, 70599 Stuttgart, Germany; Niu, Jianwei; Department of Food Informatics and Computational Science Hub, University of Hohenheim, 70599 Stuttgart, Germany; Niu, Jianwei
Monitoring systems are essential in many fields, such as food production, storage, and supply, to collect information about applications or their environments to enable decision-making. However, these systems generate massive amounts of data that require substantial processing. To improve data analysis efficiency and reduce data collectors’ energy demand, adaptive monitoring is a promising approach to reduce the gathered data while ensuring the monitoring of critical events. Adaptive monitoring is a system’s ability to adjust its monitoring activity during runtime in response to internal and external changes. This work investigates the application of adaptive monitoring—especially, the adaptation of the sensor sampling rate—in dynamic and unstable environments. This work evaluates 11 distinct approaches, based on threshold determination, statistical analysis techniques, and optimization methods, encompassing 33 customized implementations, regarding their data reduction extent and identification of critical events. Furthermore, analyses of Shannon’s entropy and the oscillation behavior allow for estimating the efficiency of the adaptation algorithms. The results demonstrate the applicability of adaptive monitoring in food storage environments, such as cold storage rooms and transportation containers, but also reveal differences in the approaches’ performance. Generally, some approaches achieve high observation accuracies while significantly reducing the data collected by adapting efficiently.
Toward food-grade production of the Glutamicibacter halophytocola diamine oxidase using Komagataella phaffii
(2025) Bechtel, Anna; Kettner, Lucas; Hessenberger, Jan; Vlassakakis, Kenny; Fischer, Lutz; Bechtel, Anna; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Kettner, Lucas; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Hessenberger, Jan; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Vlassakakis, Kenny; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Fischer, Lutz; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany
The diamine oxidase from Glutamicibacter halophytocola (DAO-GH) was recombinantly produced in K. phaffii using the constitutive glyceraldehyde-3-phosphate dehydrogenase promoter for methanol-free production. Firstly, K. phaffii clones were generated for intracellular and secretory DAO-GH production that still possessed antibiotic resistance due to the cloning procedure. For intracellular production, a maximum intracellular DAO activity of 15,404 nkat/Lculture was achieved in fed-batch bioreactor cultivations, while for secretory production, the highest extracellular DAO activity of 6,078 nkat/Lculture was achieved using the αMF signal peptide without its EAEA sequence. The intracellularly produced DAO-GH was partially purified in several purification steps with a yield of 80%, a purification factor of about 10 and specific DAO activity of 16.7 nkat/mgprotein. The secretory DAO-GH production resulted in a specific DAO activity of 15.4 nkat/mgprotein already in the cell-free culture supernatant at the end of cultivation without further purification steps. The food industry aims to avoid the use of antimicrobial resistance in enzyme production, therefore, a new cassette plasmid with self-excisable antibiotic resistance markers was constructed for secretory DAO-GH production. The antibiotic-resistance-free K. phaffii clone generated with this plasmid achieved a maximum extracellular DAO activity of 4,770 nkat/Lculture in a fed-batch bioreactor cultivation. The DAO-GH obtained in this cultivation was spray-dried, resulting in a storable powder with 23 nkat/gpowder DAO activity and a water activity value of 0.12. This study demonstrated the secretion of recombinant DAO in a microbial host such as K. phaffii for the first time and provides a strategy for generating antibiotic-resistance-free K. phaffii clones.
Secretion of the cytoplasmic and high molecular weight β-galactosidase of Paenibacillus wynnii with Bacillus subtilis
(2024) Senger, Jana; Seitl, Ines; Pross, Eva; Fischer, Lutz
Background: The gram-positive bacterium Bacillus subtilis is widely used for industrial enzyme production. Its ability to secrete a wide range of enzymes into the extracellular medium especially facilitates downstream processing since cell disruption is avoided. Although various heterologous enzymes have been successfully secreted with B. subtilis, the secretion of cytoplasmic enzymes with high molecular weight is challenging. Only a few studies report on the secretion of cytoplasmic enzymes with a molecular weight > 100 kDa. Results: In this study, the cytoplasmic and 120 kDa β-galactosidase of Paenibacillus wynnii (β-gal-Pw) was expressed and secreted with B. subtilis SCK6. Different strategies were focused on to identify the best secretion conditions. Tailormade codon-optimization of the β-gal-Pw gene led to an increase in extracellular β-gal-Pw production. Consequently, the optimized gene was used to test four signal peptides and two promoters in different combinations. Differences in extracellular β-gal-Pw activity between the recombinant B. subtilis strains were observed with the successful secretion being highly dependent on the specific combination of promoter and signal peptide used. Interestingly, signal peptides of both the general secretory- and the twin-arginine translocation pathway mediated secretion. The highest extracellular activity of 55.2 ± 6 µkat/Lculture was reached when secretion was mediated by the PhoD signal peptide and expression was controlled by the PAprE promoter. Production of extracellular β-gal-Pw was further enhanced 1.4-fold in a bioreactor cultivation to 77.5 ± 10 µkat/Lculture with secretion efficiencies of more than 80%. Conclusion: For the first time, the β-gal-Pw was efficiently secreted with B. subtilis SCK6, demonstrating the potential of this strain for secretory production of cytoplasmic, high molecular weight enzymes.
Interactions between lipid oxidation and anthocyanins from black carrots in ω-3 fatty acid-rich flaxseed oil-in-water emulsions
(2024) Klinger, Evelyn; Salminen, Hanna; Bause, Karola; Weiss, Jochen
The application of anthocyanins as red colorants in lipid-containing foods such as oil-in-water emulsions is challenging due to their ability to act as antioxidants and their instability under various environmental conditions. In this study, we investigated the kinetics of black carrot anthocyanin degradation and the subsequent color loss influenced by lipid oxidation reactions in 1% ( w/w ) flaxseed oil-in-water emulsions stabilized by 0.1% ( w/w ) sodium dodecyl sulfate (SDS) at pH 2 upon storage at 35 °C for ten days under light and in the dark. Oxidatively stable Miglyol oil-in-water emulsions and SDS solutions were used as reference. The results showed simultaneous formation of lipid hydroperoxides and degradation of anthocyanins. The addition of anthocyanins decreased lipid hydroperoxide formation, confirming the antioxidant activity of anthocyanins through radical scavenging mechanism. The kinetic modelling of lipid oxidation and anthocyanin degradation are particularly important for estimating color stability in colored emulsion-based food systems such as dairy or non-dairy milk or yoghurt drinks.
Transforming agricultural waste from mediterranean fruits into renewable materials and products with a circular and digital approach
(2025) Castagna, Antonella; Aboudia, Aouatif; Guendouz, Amine; Scieuzo, Carmen; Falabella, Patrizia; Matthes, Julia; Schmid, Markus; Drissner, David; Allais, Florent; Chadni, Morad; Cravotto, Christian; Senge, Julia; Krupitzer, Christian; Canesi, Ilaria; Spinelli, Daniele; Drira, Fadoua; Ben Hlima, Hajer; Abdelkafi, Slim; Konstantinou, Ioannis; Albanis, Triantafyllos; Yfanti, Paraskevi; Lekka, Marilena E.; Lazzeri, Andrea; Aliotta, Laura; Gigante, Vito; Coltelli, Maria-Beatrice; Hilliou, Loic
The Mediterranean area is one of the major global producers of agricultural food. However, along the entire supply chain—from farming to food distribution and consumption—food waste represents a significant fraction. Additionally, plant waste residues generated during the cultivation of specific fruits and vegetables must also be considered. This heterogeneous biomass is a valuable source of bioactive compounds and materials that can be transformed into high-performance functional products. By analyzing technical and scientific literature, this review identifies extraction, composite production, and bioconversion as the main strategies for valorizing agricultural by-products and waste. The advantages of these approaches as well as efficiency gains through digitalization are discussed, along with their potential applications in the Mediterranean region to support new research activities and bioeconomic initiatives. Moreover, the review highlights the challenges and disadvantages associated with waste valorization, providing a critical comparison of different studies to offer a comprehensive perspective on the topic. The objective of this review is to evaluate the potential of agricultural waste valorization, identifying effective strategies while also considering their limitations, to contribute to the development of sustainable and innovative solutions in Mediterranean bioeconomy.

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