Institut für Lebensmittelwissenschaft und Biotechnologie

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/6

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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, Germany
Background: 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.
Comparison of binding properties of a laccase-treated pea protein-sugar beet pectin mixture with methylcellulose in a bacon-type meat analogue
(2022) Moll, Pascal; Salminen, Hanna; Stadtmueller, Lucie; Schmitt, Christophe; Weiss, Jochen
A bacon-type meat analogue consists of different structural layers, such as textured protein and a fat mimetic. To obtain a coherent and appealing product, a suitable binder must glue those elements together. A mixture based on pea protein and sugar beet pectin (r = 2:1, 25% w/w solids, pH 6) with and without laccase addition and a methylcellulose hydrogel (6% w/w) serving as benchmark were applied as binder between textured protein and a fat mimetic. A tensile strength test, during which the layers were torn apart, was performed to measure the binding ability. The pea protein–sugar beet pectin mixture without laccase was viscoelastic and had medium and low binding strength at 25 °C (F ≤ 3.5 N) and 70 °C (F ≈ 1.0 N), respectively. The addition of laccase solidified the mixture and increased binding strength at 25 °C (F ≥ 4.0 N) and 70 °C (F ≈ 2.0 N), due to covalent bonds within the binder and between the binder and the textured protein or the fat mimetic layers. Generally, the binding strength was higher when two textured protein layers were glued together. The binding properties of methylcellulose hydrogel was low (F ≤ 2.0 N), except when two fat mimetic layers were bound due to hydrophobic interactions becoming dominant. The investigated mixed pectin–pea protein system is able serve as a clean-label binder in bacon-type meat analogues, and the application in other products seems promising.
Consumption of antioxidant-rich “Cerrado” cashew pseudofruit affects hepatic gene expression in obese C57BL/6J high fat-fed mice
(2022) Egea, Mariana Buranelo; Pierce, Gavin; Park, Si-Hong; Lee, Sang-In; Heger, Fabienne; Shay, Neil
The pseudofruit of A. othonianum Rizzini, “Cerrado” cashew pulp, has been described as rich in flavonoids, phenolic compounds, and vitamin C. The objective of this work was to evaluate the beneficial health effects seen with the addition of “Cerrado” cashew pulp (CP) to an obesogenic high fat diet provided to C57BL/6J male mice. In week 9, the HF-fed group had a significantly higher baseline glucose concentration than the LF- or HF+CP-fed groups. In RNAseq analysis, 4669 of 5520 genes were found to be differentially expressed. Among the genes most upregulated with the ingestion of the CP compared to HF were Ph1da1, SLc6a9, Clec4f, and Ica1 which are related to glucose homeostasis; Mt2 that may be involved steroid biosynthetic process; and Ciart which has a role in the regulation of circadian rhythm. Although “Cerrado” CP intake did not cause changes in the food intake or body weight of fed mice with HF diet, carbohydrate metabolism appeared to be improved based on the observed changes in gene expression.
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, Germany
Background: 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.
CortexVR: Immersive analysis and training of cognitive executive functions of soccer players using virtual reality and machine learning
(2022) Krupitzer, Christian; Naber, Jens; Stauffert, Jan-Philipp; Mayer, Jan; Spielmann, Jan; Ehmann, Paul; Boci, Noel; Bürkle, Maurice; Ho, André; Komorek, Clemens; Heinickel, Felix; Kounev, Samuel; Becker, Christian; Latoschik, Marc Erich
Goal: This paper presents an immersive Virtual Reality (VR) system to analyze and train Executive Functions (EFs) of soccer players. EFs are important cognitive functions for athletes. They are a relevant quality that distinguishes amateurs from professionals. Method: The system is based on immersive technology, hence, the user interacts naturally and experiences a training session in a virtual world. The proposed system has a modular design supporting the extension of various so-called game modes. Game modes combine selected game mechanics with specific simulation content to target particular training aspects. The system architecture decouples selection/parameterization and analysis of training sessions via a coaching app from an Unity3D-based VR simulation core. Monitoring of user performance and progress is recorded by a database that sends the necessary feedback to the coaching app for analysis. Results: The system is tested for VR-critical performance criteria to reveal the usefulness of a new interaction paradigm in the cognitive training and analysis of EFs. Subjective ratings for overall usability show that the design as VR application enhances the user experience compared to a traditional desktop app; whereas the new, unfamiliar interaction paradigm does not negatively impact the effort for using the application. Conclusion: The system can provide immersive training of EF in a fully virtual environment, eliminating potential distraction. It further provides an easy-to-use analyzes tool to compare user but also an automatic, adaptive training mode.
An innovative approach in the baking of bread with CO2 gas hydrates as leavening agents
(2022) Srivastava, Shubhangi; Kollemparembil, Ann Mary; Zettel, Viktoria; Claßen, Timo; Mobarak, Mohammad; Gatternig, Bernhard; Delgado, Antonio; Jekle, Mario; Hitzmann, Bernd
Gas (guest) molecules are trapped in hydrogen-bonded water molecules to form gas hydrates (GH), non-stoichiometric solids that resemble ice. High pressure and low temperature are typical conditions for their development, with van der Waals forces joining the host and guest molecules. This article study investigates the application of CO2 gas hydrates (CO2 GH) as a leavening agent in baking, with particular reference to the production of wheat bread. The main intention of this study is to better understand the complex bread dough formed by CO2 GH and its impact on product quality. This may enable the adaptation of CO2 GH in baking applications, such as those that can specifically influence wheat bread properties, and so the final bread quality. The present research further examines the comparative evaluation of yeast bread with the GH bread’s impact on bread quality parameters. The amount of GH was varied from 10 to 60%/amount of flour for the GH breads. The GH breads were compared with the standard yeast bread for different quality parameters such as volume, texture, and pore analysis. The results show that the bread with 20% and 40% GH obtained the best results in terms of volume and pore size. Moreover, this article also sheds some light on the future applications of the use of CO2 GH as leavening agents in foods. This knowledge could help to create new procedures and criteria for improved GH selection for applications in bread making and other bakery or food products.
Oral processing of anisotropic food structures: A modelling approach to dynamic mastication data
(2024) Oppen, Dominic; Weiss, Jochen
Materials 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.
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, Germany
Objective: 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.

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