Institut für Lebensmittelwissenschaft und Biotechnologie
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Publication A research note: effect of pH on meat iridescence in precooked cured pork(2022) Ruedt, Chiara; Gibis, Monika; Weiss, Jochen; Ruedt, Chiara; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Gibis, Monika; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Weiss, Jochen; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, GermanyObjective: The objective of this study was to investigate the effect of pH change of cooked cured pork M. longissimus thoracis et lumborum on iridescence intensity and extent (= percentage of iridescent area) since interaction with light may be related to pH-induced alterations in microstructure. Muscles were injected with brines of different pH values, cooked, sliced perpendicular to muscle fiber direction, and visually evaluated by a panel of 20 experienced panelists. Results: Muscles with lowest pH (5.38) showed the lowest iridescence score of 4.63 (p < 0.05). Iridescence was greatest in muscles with normal (5.78) and high pH (6.03, respectively 6.59), but did not differ significantly (p > 0.05). Iridescence was positively correlated (p < 0.01) with pH and water content, and negatively correlated (p < 0.01) with cooking loss. Hence, hydration state and light scattering from microstructure may be important factors that determine the degree of iridescence in cooked meat products.Publication Assessing the capabilities of 2D fluorescence monitoring in microtiter plates with data-driven modeling for secondary substrate limitation experiments of Hansenula polymorpha(2023) Berg, Christoph; Herbst, Laura; Gremm, Lisa; Ihling, Nina; Paquet-Durand, Olivier; Hitzmann, Bernd; Büchs, Jochen; Berg, Christoph; AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, Germany; Herbst, Laura; AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, Germany; Gremm, Lisa; AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, Germany; Ihling, Nina; AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, Germany; Paquet-Durand, Olivier; Department of Process Analytics & Cereal Science, Institute for Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Hitzmann, Bernd; Department of Process Analytics & Cereal Science, Institute for Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Büchs, Jochen; AVT - Aachener Verfahrenstechnik, Biochemical Engineering, RWTH Aachen University, Aachen, GermanyBackground: Non-invasive online fluorescence monitoring in high-throughput microbioreactors is a well-established method to accelerate early-stage bioprocess development. Recently, single-wavelength fluorescence monitoring in microtiter plates was extended to measurements of highly resolved 2D fluorescence spectra, by introducing charge-coupled device (CCD) detectors. Although introductory experiments demonstrated a high potential of the new monitoring technology, an assessment of the capabilities and limits for practical applications is yet to be provided. Results: In this study, three experimental sets introducing secondary substrate limitations of magnesium, potassium, and phosphate to cultivations of a GFP-expressing H. polymorpha strain were conducted. This increased the complexity of the spectral dynamics, which were determined by 2D fluorescence measurements. The metabolic responses upon growth limiting conditions were assessed by monitoring of the oxygen transfer rate and extensive offline sampling. Using only the spectral data, subsequently, partial least-square (PLS) regression models for the key parameters of glycerol, cell dry weight, and pH value were generated. For model calibration, spectral data of only two cultivation conditions were combined with sparse offline sampling data. Applying the models to spectral data of six cultures not used for calibration, resulted in an average relative root-mean-square error (RMSE) of prediction between 6.8 and 6.0%. Thus, while demanding only sparse offline data, the models allowed the estimation of biomass accumulation and glycerol consumption, even in the presence of more or less pronounced secondary substrate limitation. Conclusion: For the secondary substrate limitation experiments of this study, the generation of data-driven models allowed a considerable reduction in sampling efforts while also providing process information for unsampled cultures. Therefore, the practical experiments of this study strongly affirm the previously claimed advantages of 2D fluorescence spectroscopy in microtiter plates.Publication Effect of partial condensation (dephlegmation) in fruit brandy distillation equipment on the composition of apple brandies(2025) Yagishita, Manami; Reber, Oliver; Alter, Daniela; Kölling, Ralf; Einfalt, Daniel; Chinnici, FabioFruit brandy equipment commonly uses partial condensation (dephlegmation) to generate reflux in the distillation column. Here, we examined the effect of dephlegmation on the composition of fruit brandies in both lab-scale and large-scale settings. In lab-scale experiments, the dephlegmator led to a pronounced enrichment of ethanol in the distillate due to preferred condensation of water, while the concentration of flavor compounds was differentially affected. Some compounds were enriched in the distillate, some were depleted, and some were unaffected by dephlegmation compared with the control without a dephlegmator. Large-scale fruit brandy equipment relying exclusively on dephlegmation was compared as standard with an enrichment section containing three trays. In the equipment relying on dephlegmation, tail components such as fusel alcohols were less well separated from the middle run, which led to a reduced yield of clean spirit in the middle run. In triangle tests, the spirits from the two devices could be clearly differentiated, but there was no clear preference for one spirit or the other. This study provides for the first time detailed data on the influence of dephlegmators on the behavior of flavor compounds during fruit brandy distillation.Publication Recombinant production of bovine αS1-casein in genome-reduced Bacillus subtilis strain IIG-Bs-20-5-1(2025) Biermann, Lennart; Tadele, Lea Rahel; Benatto Perino, Elvio Henrique; Nicholson, Reed; Lilge, Lars; Hausmann, Rudolf; Biermann, Lennart; Institute of Food Science and Biotechnology, Department of Bioprocess Engineering, University of Hohenheim, Fruwirthstraße 12, 70599 Stuttgart, Germany; (L.B.); (L.R.T.); (E.H.B.P.); (R.H.); Tadele, Lea Rahel; Institute of Food Science and Biotechnology, Department of Bioprocess Engineering, University of Hohenheim, Fruwirthstraße 12, 70599 Stuttgart, Germany; (L.B.); (L.R.T.); (E.H.B.P.); (R.H.); Benatto Perino, Elvio Henrique; Institute of Food Science and Biotechnology, Department of Bioprocess Engineering, University of Hohenheim, Fruwirthstraße 12, 70599 Stuttgart, Germany; (L.B.); (L.R.T.); (E.H.B.P.); (R.H.); Nicholson, Reed; Motif FoodWorks, Inc., 27 Drydock Ave, Boston, MA 02210, USA;; Lilge, Lars; Institute of Food Science and Biotechnology, Department of Bioprocess Engineering, University of Hohenheim, Fruwirthstraße 12, 70599 Stuttgart, Germany; (L.B.); (L.R.T.); (E.H.B.P.); (R.H.); Hausmann, Rudolf; Institute of Food Science and Biotechnology, Department of Bioprocess Engineering, University of Hohenheim, Fruwirthstraße 12, 70599 Stuttgart, Germany; (L.B.); (L.R.T.); (E.H.B.P.); (R.H.); Fouillaud, MireilleBackground: Cow’s milk represents an important protein source. Here, especially casein proteins are important components, which might be a promising source of alternative protein production by microbial expression systems. Nevertheless, caseins are difficult-to-produce proteins, making heterologous production challenging. However, the potential of genome-reduced Bacillus subtilis was applied for the recombinant production of bovine αS1-casein protein. Methods: A plasmid-based gene expression system was established in B. subtilis allowing the production of his-tagged codon-optimized bovine αS1-casein. Upscaling in a fed-batch bioreactor system for high cell-density fermentation processes allowed for efficient recombinant αS1-casein production. After increasing the molecular abundance of the recombinant αS1-casein protein using immobilized metal affinity chromatography, zeta potential and particle size distribution were determined in comparison to native bovine αS1-casein. Results: Non-sporulating B. subtilis strain BMV9 and genome-reduced B. subtilis strain IIG-Bs-20-5-1 were applied for recombinant αS1-casein production. Casein was detectable only in the insoluble protein fraction of the genome-reduced B. subtilis strain. Subsequent high cell-density fed-batch bioreactor cultivations using strain IIG-Bs-20-5-1 resulted in a volumetric casein titer of 56.9 mg/L and a yield of 1.6 mgcasein/gCDW after reducing the B. subtilis protein content. Comparative analyses of zeta potential and particle size between pre-cleaned recombinant and native αS1-casein showed pH-mediated differences in aggregation behavior. Conclusions: The study demonstrates the potential of B. subtilis for the recombinant production of bovine αS1-casein and underlines the potential of genome reduction for the bioproduction of difficult-to-produce proteins.Publication Structure elucidation and characterization of novel glycolipid biosurfactant produced by Rouxiella badensis DSM 100043T(2025) Harahap, Andre Fahriz Perdana; Conrad, Jürgen; Wolf, Mario; Pfannstiel, Jens; Klaiber, Iris; Grether, Jakob; Hiller, Eric; Vahidinasab, Maliheh; Salminen, Hanna; Treinen, Chantal; Perino, Elvio Henrique Benatto; Hausmann, Rudolf; Harahap, Andre Fahriz Perdana; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany; (A.F.P.H.); (J.G.); (E.H.); (M.V.); (E.H.B.P.); Conrad, Jürgen; Department of Organic Chemistry (130b), Institute of Chemistry, University of Hohenheim, Garbenstr. 30, 70599 Stuttgart, Germany; (J.C.); (M.W.); Wolf, Mario; Department of Organic Chemistry (130b), Institute of Chemistry, University of Hohenheim, Garbenstr. 30, 70599 Stuttgart, Germany; (J.C.); (M.W.); Pfannstiel, Jens; Mass Spectrometry Unit, Core Facility Hohenheim, University of Hohenheim, Ottilie-Zeller-Weg 2, 70599 Stuttgart, Germany; (J.P.); (I.K.); Klaiber, Iris; Mass Spectrometry Unit, Core Facility Hohenheim, University of Hohenheim, Ottilie-Zeller-Weg 2, 70599 Stuttgart, Germany; (J.P.); (I.K.); Grether, Jakob; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany; (A.F.P.H.); (J.G.); (E.H.); (M.V.); (E.H.B.P.); Hiller, Eric; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany; (A.F.P.H.); (J.G.); (E.H.); (M.V.); (E.H.B.P.); Vahidinasab, Maliheh; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany; (A.F.P.H.); (J.G.); (E.H.); (M.V.); (E.H.B.P.); Salminen, Hanna; Department of Food Material Science (150g), Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 21/25, 70599 Stuttgart, Germany;; Treinen, Chantal; Cellular Agriculture, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany;; Perino, Elvio Henrique Benatto; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany; (A.F.P.H.); (J.G.); (E.H.); (M.V.); (E.H.B.P.); Hausmann, Rudolf; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany; (A.F.P.H.); (J.G.); (E.H.); (M.V.); (E.H.B.P.); Serianni, Anthony S.Microbial biosurfactants have become increasingly attractive as promising ingredients for environmentally friendly products. The reasons for this are their generally good performance and biodegradability, low toxicity, production from renewable raw materials, and benefits for the environment perceived by consumers. In this study, we investigated the chemical structure and properties of a novel glycolipid from a new biosurfactant-producing strain, Rouxiella badensis DSM 100043 T . Bioreactor cultivation was performed at 30 °C and pH 7.0 for 28 h using 15 g/L glycerol as a carbon source. The glycolipid was successfully purified from the ethyl acetate extract of the supernatant using medium pressure liquid chromatography (MPLC). The structure of the glycolipid was determined by one- and two-dimensional ( 1 H and 13 C) nuclear magnetic resonance (NMR) and confirmed by liquid chromatography electrospray ionization mass spectrometry (LC-ESI/MS). NMR analysis revealed the hydrophilic moiety as a glucose molecule and the hydrophobic moieties as 3-hydroxy-5-dodecenoic acid and 3-hydroxydecanoic acid, which are linked with the glucose by ester bonds at the C2 and C3 positions. Surface tension measurement with tensiometry indicated that the glucose–lipid could reduce the surface tension of water from 72.05 mN/m to 24.59 mN/m at 25 °C with a very low critical micelle concentration (CMC) of 5.69 mg/L. Moreover, the glucose–lipid demonstrated very good stability in maintaining emulsification activity at pH 2–8, a temperature of up to 100 °C, and a NaCl concentration of up to 15%. These results show that R. badensis DSM 100043 T produced a novel glycolipid biosurfactant with excellent surface-active properties, making it promising for further research or industrial applications.Publication Consumption of yeast-fermented wheat and rye breads increases colitis and mortality in a mouse model of colitis(2022) Zimmermann, Julia; De Fazio, Luigia; Kaden-Volynets, Valentina; Hitzmann, Bernd; Bischoff, Stephan C.; Zimmermann, Julia; Department of Nutritional Medicine/Prevention, University of Hohenheim, Stuttgart, Germany; De Fazio, Luigia; Department of Medical and Surgical Science (DIMEC), University of Bologna, Bologna, Italy; Kaden-Volynets, Valentina; Department of Nutritional Medicine/Prevention, University of Hohenheim, Stuttgart, Germany; Hitzmann, Bernd; Department of Process Analytics and Cereal Science, University of Hohenheim, Stuttgart, Germany; Bischoff, Stephan C.; Department of Nutritional Medicine/Prevention, University of Hohenheim, Stuttgart, GermanyBackground: Cereals are known to trigger for wheat allergy, celiac disease and non-celiac wheat sensitivity (NCWS). Inflammatory processes and intestinal barrier impairment are suspected to be involved in NCWS, although the molecular triggers are unclear. Aims: We were interested if different bread types influence inflammatory processes and intestinal barrier function in a mouse model of inflammatory bowel disease. Methods: Epithelial caspase-8 gene knockout (Casp8 ΔIEC ) and control (Casp8 fl ) mice were randomized to eight groups, respectively. The groups received different diets for 28 days (gluten-free diet, gluten-rich diet 5 g%, or different types of bread at 50 g%). Breads varied regarding grain, milling and fermentation. All diets were isocaloric. Results: Regardless of the diet, Casp8 ΔIEC mice showed pronounced inflammation in colon compared to ileum, whereas Casp8 fl mice were hardly inflamed. Casp8 fl mice could tolerate all bread types. Especially yeast fermented rye and wheat bread from superfine flour but not pure gluten challenge increased colitis and mortality in Casp8 ΔIEC mice. Hepatic expression of lipopolysaccharide-binding protein and colonic expression of tumor necrosis factor-α genes were inversely related to survival. The bread diets, but not the gluten-rich diet, also decreased colonic tight junction expression to variable degrees, without clear association to survival and inflammation. Conclusions: Bread components, especially those from yeast-fermented breads from wheat and rye, increase colitis and mortality in Casp8 ΔIEC mice highly susceptible to intestinal inflammation, whereas control mice can tolerate all types of bread without inflammation. Yet unidentified bread components other than gluten seem to play the major role.Publication Fed-batch bioreactor cultivation of Bacillus subtilis using vegetable juice as an alternative carbon source for lipopeptides production: a shift towards a circular bioeconomy(2024) Gugel, Irene; Vahidinasab, Maliheh; Benatto Perino, Elvio Henrique; Hiller, Eric; Marchetti, Filippo; Costa, Stefania; Pfannstiel, Jens; Konnerth, Philipp; Vertuani, Silvia; Manfredini, Stefano; Hausmann, Rudolf; Gugel, Irene; Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy, (S.V.);; Vahidinasab, Maliheh; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstrasse 12, 70599 Stuttgart, Germany; (E.H.B.P.);; Benatto Perino, Elvio Henrique; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstrasse 12, 70599 Stuttgart, Germany; (E.H.B.P.);; Hiller, Eric; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstrasse 12, 70599 Stuttgart, Germany; (E.H.B.P.);; Marchetti, Filippo; Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy, (S.V.);; Costa, Stefania; Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy, (S.V.);; Pfannstiel, Jens; Core Facility Hohenheim, Mass Spectrometry Unit, University of Hohenheim, Ottlie-Zeller-Weg 2, 70599 Stuttgart, Germany; Konnerth, Philipp; Department of Conversion Technology of Biobased Resources, University of Hohenheim, Garbenstrasse 9, 70599 Stuttgart, Germany;; Vertuani, Silvia; Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy, (S.V.);; Manfredini, Stefano; Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy, (S.V.);; Hausmann, Rudolf; Department of Bioprocess Engineering (150k), Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstrasse 12, 70599 Stuttgart, Germany; (E.H.B.P.);; Gudiña, EduardoIn a scenario of increasing alarm about food waste due to rapid urbanization, population growth and lifestyle changes, this study aims to explore the valorization of waste from the retail sector as potential substrates for the biotechnological production of biosurfactants. With a perspective of increasingly contributing to the realization of the circular bioeconomy, a vegetable juice, derived from unsold fruits and vegetables, as a carbon source was used to produce lipopeptides such as surfactin and fengycin. The results from the shake flask cultivations revealed that different concentrations of vegetable juice could effectively serve as carbon sources and that the fed-batch bioreactor cultivation strategy allowed the yields of lipopeptides to be significantly increased. In particular, the product/substrate yield of 0.09 g/g for surfactin and 0.85 mg/g for fengycin was obtained with maximum concentrations of 2.77 g/L and 27.53 mg/L after 16 h, respectively. To conclude, this study provides the successful fed-batch cultivation of B. subtilis using waste product as the carbon source to produce secondary metabolites. Therefore, the consumption of agricultural product wastes might be a promising source for producing valuable metabolites which have promising application potential to be used in several fields of biological controls of fungal diseases.Publication Editorial: Microbial biosurfactants: updates on their biosynthesis, production and applications(2024) Hausmann, Rudolf; Déziel, Eric; Soberón-Chávez, GloriaPublication Bioprocess exploitation of microaerobic auto-induction using the example of rhamnolipid biosynthesis in Pseudomonas putida KT2440(2025) Grether, Jakob; Dittmann, Holger; Willems, Leon; Schmiegelt, Tabea; Benatto Perino, Elvio Henrique; Hubel, Philipp; Lilge, Lars; Hausmann, Rudolf; Grether, Jakob; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany; Dittmann, Holger; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany; Willems, Leon; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany; Schmiegelt, Tabea; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany; Benatto Perino, Elvio Henrique; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany; Hubel, Philipp; Core Facility Hohenheim, Mass Spectrometry Core Facility, University of Hohenheim, Ottilie-Zeller-Weg 2, 70599, Stuttgart, Germany; Lilge, Lars; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, Germany; Hausmann, Rudolf; Department of Bioprocess Engineering, Institute of Food Science and Biotechnology, University of Hohenheim, Fruwirthstr. 12, 70599, Stuttgart, GermanyBackground: In biomanufacturing of surface-active agents, such as rhamnolipids, excessive foaming is a significant obstacle for the development of high-performing bioprocesses. The exploitation of the inherent tolerance of Pseudomonas putida KT2440, an obligate aerobic bacterium, to microaerobic conditions has received little attention so far. Here low-oxygen inducible promoters were characterized in biosensor strains and exploited for process control under reduction of foam formation by low aeration and stirring rates during biosynthesis of rhamnolipids. Results: In this study, homologous promoters of P. putida inducible under oxygen limitation were identified by non-targeted proteomic analyses and characterized by fluorometric methods. Proteomics indicated a remodeling of the respiratory chain and the regulation of stress-related proteins under oxygen limitation. Of the three promoters tested in fluorescent biosensor assays, the promoter of the oxygen-sensitive cbb3-type cytochrome c oxidase gene showed high oxygen-dependent controllability. It was used to control the gene expression of a heterologous di-rhamnolipid synthesis operon in an auto-inducing microaerobic two-phase bioprocess. By limiting the oxygen supply via low aeration and stirring rates, the bioprocess was clearly divided into a growth and a production phase, and sources of foam formation were reduced. Accordingly, rhamnolipid synthesis did not have to be controlled externally, as the oxygen-sensitive promoter was autonomously activated as soon as the oxygen level reached microaerobic conditions. A critical threshold of about 20% oxygen saturation was determined. Conclusions: Utilizing the inherent tolerance of P. putida to microaerobic conditions in combination with the application of homologous, low-oxygen inducible promoters is a novel and efficient strategy to control bioprocesses. Fermentation under microaerobic conditions enabled the induction of rhamnolipid production by low oxygen levels, while foam formation was limited by low aeration and stirring rates.Publication Oral processing of anisotropic food structures: A modelling approach to dynamic mastication data(2024) Oppen, Dominic; Weiss, JochenMaterials that have been generated through a directionally oriented growth process often exhibit anisotropic properties. Plant materials such as tubers and roots or animal matter used to produce products such as steaks or pasta filata are characterized by an alignment of molecules, aggregates or cells in certain dimensions leading to differing properties depending on direction. Such an anisotropic property behavior is important for a wide range of quality attributes such as texture, appearance, stability and even aroma and taste. Especially the former is of critical importance to consumer liking and acceptance of foods. Structure-texture relationships have already been established for certain foods. For anisotropic foods though, a determination of such relationships is difficult, since the comminution of foods during chewing causes complex changes to the underlying anisotropic structure elements that are not easily measurable using conventional mechanical texture analysis tests such as cutting, shearing or compression. On the other hand, sensory tests using panels are very time consuming and often do not reveal structural causes for texture like or dislike by consumers. The lack of availability of suitable analytical techniques that allow for a description of texture properties relevant to mastication hampers especially the development of meat substitutes that are currently trending. The aim of this work was therefore to characterize changes to anisotropic structures induced by chewing (henceforth referred to as "oral processing") using a novel measurement approach that records kinematic and electromyographic properties of the chewing process. The kinematics of jaw movement were recorded using a 3D motion tracking system. Muscle activity was recorded using an electromyograph. From the measured data, characteristics for individual chews were calculated, which were represented in a linear mixed model as a function of the food structure. Section I provides the scientific basis for this work through a preface and a literature review. Grown and manufactured anisotropic foods are identified and described. A general overview of the production, phase phenomena and characterization methods for anisotropic food materials is given. Section II contains the oral processing experiments. In Chapter III, the focus was put on the impact of fiber length of grown structures on mastication behavior. Meat model systems with different microstructures but the same composition were produced. The model systems with anisotropic and isotropic microstructures were comminuted to different sizes, and the fiber length was inferred from the length of the particles, taking into account the particle size effect of chewing. The results indicate that longer fibers cause greater jaw movement and muscle activity. For instance, estimate peak muscle activity of anisotropic samples is 58.2857 µV higher (p=0.0156) compared to isotropic samples. Chapter IV describes minced meat products in which certain phase volumes were replaced by a finely comminuted meat mass. The aim of the study was to find detection limits beyond which an increase or decrease in muscle fiber cells does not lead to a further adjustment of the mastication properties. In the study, a transition point was identified at around 50 % of batter-like substances. Food models with more than 50 % of batter-like substance showed a smaller change in mastication parameters. The effect was more pronounced with higher proportions of fibrous material. Chapter V dealt with the topic of meat substitutes. A simple model of meat substitutes was used to test whether the effects found in anisotropic animal-based products can also be found in plant-based products. Hydrocolloid gels with different phase volumes of wet textured plant protein were produced. Similar effects for the animal-based products were observed, although the correlation was not as strong. It was hypothesized that a large part of the effect was due to the weak binding ability of hydrocolloid gels. Thus, the anisotropic particles could not be held together with a low proportion of the outer hydrocolloid gel and required less muscle activity despite a higher content of structured phase. Section III assessed alternative data evaluation strategies to the linear mixed model. The aim of the study in Chapter VI was to anticipate the model products from Chapter III using a classification approach. Algorithms of three categories were trained with the data set of the chewing processes. Two approaches were used to evaluate whether the algorithms could either resolve each individual food model with variations in microstructure (anisotropy) and macrostructure (particle size) or in microstructure only. For both approaches, the algorithms performed significantly better compared to a random guessing. The best classification results were achieved by the boosted ensemble learner "XGBoost", which assigned 96.617 % of all bites to the corresponding food microstructure. Furthermore, it was demonstrated that standardized and normalized oral processing data are almost not subject-dependent. In addition, feature importance analysis confirmed that lateral jaw movement is a good indicator of the presence of anisotropic food material and, with a weight of 0.39205, is the most important feature for classifying samples according to their structure. In summary, this work was able to show that the dynamic characteristics of mastication change depending on anisotropic properties. In general, modeling of mastication characteristics has never been conducted before and represents a promising advance over mean-based evaluation. The machine learning approach is also new in the field of oral processing and proved to be promising. For future research, it is proposed to correlate the dynamic features with sensory texture data to obtain direct correlations between chewing characteristics and texture attributes.Publication Ingenious wheat starch/Lepidium perfoliatum seed mucilage hybrid composite films: Synthesis, incorporating nanostructured Dy₂Ce₂O₇ synthesized via an ultrasound-assisted approach and characterization(2025) Zinatloo-Ajabshir,Sahar; Yousefi, Alireza; Jekle, Mario; Sharifianjazi, FariborzIn this study, Dy₂Ce₂O₇ nanostructures were fabricated using an environmentally friendly, ultrasound-assisted method. These nanostructures were then incorporated into a blend of wheat starch (WS) and Lepidium perfoliatum seed mucilage (LPSM), along with sodium montmorillonite (Na-MMT) nanoparticles. The composite films were produced through a casting method, combining these components to enhance the films' structural and functional properties. FTIR results confirmed the chemical interactions between the NPs and the biopolymeric matrix of the nanocomposites. SEM surface morphology and XRD crystallography results indicated that up to a 1 % weight ratio, the dispersion of Dy₂Ce₂O₇ in the nanocomposite matrix was uniform, while at higher percentages, due to nanoparticle aggregation, crystallinity increased. Interestingly, the elongation of nanocomposites containing Dy₂Ce₂O₇ increased, while their tensile strength and elastic modulus decreased. More than 92 % of UV radiation in the 240–360 nm range was absorbed with the inclusion of 1 % wt. Dy₂Ce₂O₇, and the water vapor permeability (WVP) significantly decreased. Among the Dy₂Ce₂O₇-based nanocomposites, TGA results showed that the WS/LPSM/MMT/Dy1 % sample had the highest thermal stability. Overall, based on the results of this study, the WS/LPSM/MMT/Dy1 % sample was introduced as a composite film with suitable physicochemical and mechanical properties for food and pharmaceutical packaging.Publication Bioprocess strategies for efficient microbial conversion of acetate as alternative biotechnological carbon source derived from lignocellulose streams(2024) Kiefer, Dirk; Hausmann, RudolfIn near future, humanity will be faced with the global challenges from climate change, fossil fuel depletion to food shortage. Our current economic system will thus need to make a transition into a sustainable bioeconomy which uses key technologies like biotechnology for conversion of renewable feedstocks. The majority of all biotechnological carbon sources is generated from food plants. In context to the global population growth coming along with food insecurity, competing use of these food plants for human and animal nutrition creates a substrate dilemma for future biotechnology. Future biorefineries will thus need to realize a paradigm shift to carbon sources generated from non-competing or waste resources. As such, especially lignocellulosic biomass is regarded as the central feedstock for a bio-based industry. Among the different substrate streams obtained by lignocellulose refining strategies, the C2 carboxylic acid acetic acid (from now on referred to as acetate) is one of the most common occurring components. In contrast to its high economic role as building block in the chemical industry, acetate shows low relevance as biotechnological carbon source yet. This is mainly related to its inhibitory characteristic, the reason for why acetate has been used in food preservation for thousands of years. However, most industrial platform organisms are also capable to grow on acetate as sole carbon source. It also shows several attractive characteristics for bioprocessing which is why research studies on microbial acetate conversion have significantly increased in the past years. Together with the potential routes to generate non-fossil bio-acetate in large quantities from non-food competing resources like lignocellulose and biomass-derived/waste C1 gas streams, acetate might become a next-generation platform substrate for a future bio-industry. In order to make acetate-based bioprocesses competitive to those using conventional sugar-based carbon sources, adapted process strategies for efficient acetate conversion need to be established. The present thesis is aimed to address efficient bioprocess strategies for biotechnological conversion of lignocellulosic acetate into microbial biomass and growth-coupled products under fed-batch culture conditions. The experimental studies presented in this work were divided into two parts: In Part I, the potential of acetate as carbon source for high cell density cultivation of industrial platform bacterium Corynebacterium glutamicum was evaluated. Preliminary growth studies with different initial acetate concentrations revealed a high natural acetate tolerance for wild-type ATCC 13032 with growth at high acetate levels up to 60 g/L. In addition, it was shown that maximum growth rates (μmax) of 0.47 h-1 for acetate concentrations below 10 g/L are competitive to that on D-glucose as common carbon source. By implementation of an online feeding control which enables automated supply of pure acetic acid (HAc) via pH control, high cell density cultivation on lignocellulosic acetate was demonstrated for the first time in a 42 L stirred-tank bioreactor. Optimization of the molar carbon-to-nitrogen feeding ratio resulted in a highly efficient bioprocess yielding cell densities up to 80.2 g/L CDW after 28.9 h with biomass yields (YXIS) of 0.35 g/g and space-time yields (STY) of 66.6 g/L·d. Part II focused on the potential of acetate as carbon source for integrated protein production in C. glutamicum. Batch cultures of genome-reduced strains MB001/MB001(DE3) demonstrated that acetate clearly shows no inhibitory effect on protein production of eYFP as model protein using C. glutamicum as production host. Interestingly, comparative expression studies with C. glutamicum T7 expression system indicated an up to 83 % higher biomass-specific production on acetate compared to D-glucose as carbon source. By transferring the implemented pH-coupled online feeding control for high cell density cultivation of strain MB001(DE3) pMKEX2-eyfp in a 42 L stirred-tank bioreactor, this study showed efficient protein accumulation on lignocellulosic acetate yielding final protein titers of 2.7 g/L after 27 h with product yields (YPIX) of 40 mg/g and volumetric productivities (PV) of 0.10 g/L·h. In conclusion, the presented results demonstrate the high biotechnological potential of acetate as alternative carbon source. In contrast to most other studies before, it is shown that a suitable process strategy based on pH-coupled online feeding control allows efficient microbial acetate conversion under industry-relevant fed-batch culture conditions. This work provides exemplary proof-of-concept bioprocesses for high cell density cultivation on lignocellulosic acetate and its growth-coupled conversion into protein using industrial platform organism C. glutamicum. Therefore, the presented thesis contributes to the development of efficient concepts for microbial conversion of next-generation platform substrates like lignocellulosic acetate.