Newest publications
Hydration-induced reduction strategies of acrylamide in bakery products
(2025) Świacka, Jagoda; Jekle, Mario
Bread is a product made from cereals and/or cereal-based ingredients, which are combined with water or other water-containing liquids. Also, additional ingredients such as oilseeds, legumes, potato products, dairy products, spices, and vegetables may be incorporated into the dough. Products containing these ingredients can be referred to as special bakery products. However, the use of these additional ingredients has been raising food-safety concerns, particularly because of the possibly elevated levels of acrylamide detected in the final products. Acrylamide is a process contaminant, considered undesirable due to its potential carcinogenicity and is currently subject to various European food safety regulations. However, the acrylamide mitigation strategies defined so far for standard bakery products do not appear to be sufficiently effective for special bakery products. This is presumably due to the high levels of precursor molecules and the varying quality of the special ingredients. As a result, there are large variations in the levels of precursors, namely reducing sugars and asparagine in the dough, which consequently lead to unpredictably elevated acrylamide contamination. To address these problems and to gain a deeper understanding of acrylamide formation in special bakery products, further investigation is essential. Therefore, this thesis aimed to identify specific acrylamide precursors, to analyze acrylamide levels, and to assess the effectiveness of hydration-based approaches as mitigation measures for special bakery products. Mitigation was to be achieved either by eliminating the precursors or by adjusting processing conditions.
After a theoretical introduction in Chapter I, a systematic investigation of two special ingredients, with a focus on their specific acrylamide precursors, was presented in Chapter II and Chapter III. Particular attention was drawn to potato flakes, known for their high asparagine content, and carrot strips, awaited to be high in reducing sugars. The effects of these ingredients in combination with varying water additions as hydration approach, were investigated using a model dough recipe. The model dough consisted of wheat flour type 550, water, NaCl, yeast and selected special ingredients. After baking, both bread crust and crumb were analyzed for acrylamide and in parallel, baking qualities of these bakery products were evaluated. Considering acrylamide contamination, increased water addition showed highly raw material-specific effects. In high-asparagine doughs, higher dough water addition tended even to increase acrylamide formation, presumably due to enhanced mobility of precursors. Interestingly, for the carrot-based doughs, the polyphenols emerged as a potential factor significantly reducing acrylamide formation at higher water additions, highlighting their relevance for future mitigation strategies.
Due to the significant differences in the qualities of available carrot strips, shown in Chapter III, Chapter IV described the effects of origin, processing and drying methods on different quality features of dried carrot strips. For that, three carrot varieties were purchased and processed. Processing steps included blanching and drying methods, such as hot-air drying, vacuum drying, or freeze-drying. The impact of each processing method on quality of carrot strips, their acrylamide-forming potential, and the resulting acrylamide levels in model bakery products was analyzed. Blanching in particular, significantly reduced the acrylamide formation potential of the carrot strips. Freeze-drying consistently resulted in the highest concentrations of sugars, free asparagine, and β‑carotene for all carrot varieties, whereas the retainment of these compounds was inconsistent with other drying methods. Asparagine levels during storage were shown to fluctuate, with an initial increase and a following decrease, underlining the importance of timed processing to warrant constant product quality. Overall, the potential of carrot strips for acrylamide formation depended mostly on their variety and storage conditions, which determined primarily their precursor profile.
To investigate a variety-unspecific acrylamide mitigation strategy, soaking was evaluated in Chapter V as an approach for products with dried carrot strips. Additionally, ultrasound-assisted rehydration was investigated as a method to enhance the diffusion of carrot matrix constituents. Regular soaking was compared with ultrasound-assisted rehydration (ultrasonic bath or sonotrode) regarding rehydration rate and leaching of sugars from the carrot strips. The kinetics of rehydration and diffusion were modelled using the ExpAssoc and the Peleg equations. Rehydrated carrot strips were then implemented in model breads and acrylamide concentration in the crust along with baking qualities were analyzed. Overall, longer rehydration led to higher water retention in the carrot strips and increased leaching of sugars and polyphenols. Both ultrasound-assisted rehydration and regular soaking led to reduced acrylamide levels in model breads up to 75%.
Summarizing, this thesis systematically examined the addition of potato flakes and carrot strips to bakery products, identifying their critical acrylamide precursors, expected acrylamide levels, and characteristic changes in bread quality. It proved that rehydration is an effective acrylamide mitigation strategy for special bakery products, primarily by promoting precursor leaching and influencing reaction conditions. Overall, this thesis provides guidance on the target raw material qualities and presents (easy-to-apply) mitigation approaches for various manufacturers.
Exploring the potential of immersive virtual reality for social science research
(2025) Hepperle, Daniel; Vogelgesang, Jens
Immersive Virtual Reality (IVR) holds out the promise of laboratory‐grade experimental control while preserving much of the richness of real world experience, yet several issues remain unresolved. The central theme of this dissertation is spanned around the idea of using IVR as a tool to help researchers conducting empirical studies in the domain of social sciences.
To address the question, the thesis incorporates five related studies. Paper 1 introduces the main areas of concern in a typical research process and offers guidance where IVR toolkits might be a valuable addition. Based on those identified areas of concern, the paper suggests solutions such as automation workflows in order to reduce the human‐error (i.e. using predefined scenes that already offer different basic standard methods in order to track all changes in the virtual world). Paper 2 examines seven open‐source IVR toolkits, demonstrating how to standardize modular scene setup, participant sensing, and data export. The analysis clarifies the features currently available in different toolkits and provides a basis for researchers to decide which features and toolkits offer the greatest benefits. We also discuss novel features such as AI‐based analysis which is not present in most toolkits. Based on this we provide guidance for future IVR‐based research software development. Paper 3 offers a PRISMA guided systematic scoping review of 56 publications, mapping the field of studies that compare either IVR with the real world or IVR with 2D screens. In short, the review finds that there are more similarities than differences between IVR and the real world. However, between IVR and 2D screens, more findings show differences between the two environments than similarities. Paper 4 provides an empirical test of transferability: the mere‐exposure effect was successfully replicated in the original study setup (n = 70 m; 49 f) as well as within IVR (n = 39 m; 24 f). Overall, the studies demonstrate the efficacy and practicality of employing IVR to induce effects analogous to those observed in a real‐world context in the case of the mere exposure effect. Finally, Paper 5 introduces asymmetric normalization, a novel manipulation that decouples self‐perception from how others see a participant in social IVR, thereby expanding the experimental design space with the possibility to reduce bias. This may concern various attributes such as size or age, as well as other visual or spatial characteristics. Pilot data from 40 participants shows that this technique reliably alters interpersonal‐distance preferences, opening a new design space for social science research.
This dissertation advances research in the social sciences by showcasing the capabilities of IVR toolkits and illustrating how they can be integrated into established research processes. It further demonstrates that a cognitive‐affective mechanism (mere exposure) also is present in IVR. Moreover, it introduces asymmetric normalization as a novel manipulation technique that expands the experimental design space beyond what is feasible in physical laboratories.
For research practice, the papers within the dissertation lower the barriers to entry for non‐technical scholars, provide a decision matrix for selecting and extending IVR toolkits. Together, they shift IVR from a technological novelty to a mature, shareable, and cost‐effective platform for conducting experiments in the social science domain.
Mapping knowledge domains of regenerative agriculture with a focus on on-farm nitrogen fertilization experimentation and response surface regression
(2025) Abdipourchenarestansofla, Morteza; Piepho, Hans-Peter
In the face of growing environmental concerns and the global demand for sustainable agriculture, achieving balanced nitrogen (N) management is critical for both maximizing crop productivity and maintaining environmental health. This dissertation proposes an innovative framework to address this challenge within the scope of regenerative agriculture, which emphasizes sustainable farming practices. Regenerative agriculture aims to reduce chemical inputs while maintaining yield levels yet implementing these practices at scale is complex due to the intricate interactions between biological, environmental, and technological factors on farms. This research tackles these challenges by introducing a Knowledge Domain Mapping (KDM)-based framework, integrating advanced technologies—including remote sensing, Internet of Things (IoT) telemetry, geospatial sciences, statistical modeling, machine learning, and cloud computing—to create a holistic and scalable system for optimizing nitrogen applications. Central to this research is the accurate estimation and spatial allocation of the Economic Optimum Nitrogen Rate (EONR), a crucial element for reducing nitrogen use and enhancing yield. A key contribution of this study is the development of a robust Response Surface Model (RSM) that leverages multispectral indices (MSIs) from Sentinel-2 imagery, historical IoT telemetry data, and on-machine nitrogen sensors. This RSM approach allows for precise EONR predictions tailored to field-specific conditions, reducing the need for traditional plot-based trials and achieving an average prediction error of just 14.5%. Applied to a 7-hectare winter wheat field, the model successfully predicted EONR values ranging from 43 kg/ha to 75 kg/ha across zones, showcasing the adaptability and accuracy of RSM for field-specific nitrogen recommendations. This precisionfocused approach exemplifies the study’s goal of minimizing environmental impacts while ensuring sustainable yield improvements. Beyond the initial field-level implementation, this research examines the generalizability of the RSM framework using two modeling strategies: a single RSM across fields and a weighted average model that aggregates individual field-specific RSMs. The weighted model demonstrated superior adaptability and high prediction accuracy, with a root mean square error (RMSE) of 11 kg N/ha for the EONR, highlighting the framework’s potential for broader application across different agricultural settings. Such generalizability supports the framework’s adoption in diverse farming environments, enabling precise and informed nitrogen management at scale. To facilitate widespread adoption and practical application, the dissertation also introduces a cloud-based infrastructure that integrates the KDM framework with real-time IoT data and satellite imagery. Leveraging cloud services like Amazon Web Services (AWS) Batch for job orchestration, Amazon S3 for scalable data storage, and RDS Postgres for structured data management, this8 infrastructure allows for seamless handling of both real-time and historical data. Spatial interpolation techniques, such as Kriging, enhance the model’s capability to generate real-time nitrogen prescription maps, enabling precise nutrient management for large-scale agricultural operations. Automated data quality control and data harmonization embedded within this cloud architecture provide a strong foundation for managing increasing data volumes and diverse field conditions, making the system cost-effective, adaptable, and efficient for modern agriculture. In summary, this dissertation maps regenerative agriculture via a comprehensive roadmap for translating regenerative agriculture principles into practical, operational nitrogen management practices. Through KDM an interdisciplinary approach is mapped by the integration of advanced modeling, data processing, and cloud technologies. This framework enables sustainable crop management and aligns with global goals for environmentally responsible food production. The innovations introduced here support a scalable, data-driven approach to agricultural sustainability, bridging scientific research with real-world applications to meet the evolving demands of modern agriculture.
The role of the circadian clock, the microbiome and time-restricted feeding on the development and treatment of colitis
(2025) Haasis, Eva Annett Kristin; Lorentz, Axel
Mammals possess an internal circadian clock in almost all tissues that regulates biochemical and physiological processes over the course of 24 hours. In detail, transcription-translation feedback loops regulate the oscillation of genes over 24 hours. Inflammatory bowel diseases (IBD) such as ulcerative colitis (UC) and Crohn's disease (CD) are chronic immune activations and inflammations in the gastrointestinal tract. The etiology of IBD is not completely understood, but is associated with a disrupted circadian clock, e.g. shift work is an increased risk factor for the development of IBD.
The aim of this thesis was to investigate the relationship between circadian clock and IBD. Altered light/dark cycles, consisting of four hours of light and four hours of darkness, were used to disrupt the circadian rhythm in a dextran sulfate sodium (DSS)-induced colitis mouse model and an IL-10 knockout (IL-10-/-) mouse model. Food intake is an important Zeitgeber for the circadian clock. Therefore, the potential of time-restricted feeding (TRF) to restore disturbed circadian rhythms and as a therapy for IBD should be investigated. Since fecal microbiota transplantation (FMT) could also be a possible therapy against colitis by improving the composition of the gut microbiota, the transferability of inflammatory and healthy phenotypes by fecal transplantation should be investigated. As bacterial supplementation, both a bacterium that prevents colitis and a bacterium that potentially promotes colitis were used.
DSS treatment over eight days only led to early signs of inflammation and was slightly influenced by external light disruption with alternating 4 hours of light and 4 hours of darkness. The protocol for DSS treatment may not have been well suited. The same light disruption led to different results in IL-10-/- mice in two experiments. While in the first experiment an external light disruption led to an increased incidence of colitis and higher inflammation levels, these results were no longer present in the second experiment. The external light disruption led neither to an increased incidence of colitis nor to increased inflammation values. A further experiment, in which samples were taken every six hours, showed that the external light disruption had an effect in wild type (WT) animals and led to a disruption of circadian gene expression. In IL-10-/- mice, the expression of circadian genes was already disrupted at a normal light/dark rhythm of 12 hours/12 hours and further disruption by external light conditions was not possible, which could be an explanation for the different results regarding the occurrence of colitis in IL-10-/- mice with a disrupted light/dark rhythm.
Eight-hour restricted feeding of IL-10-/- mice resulted in reduced incidence of colitis, low levels of inflammation and improved circadian clock expression independent of external circadian clock disruption, suggesting that TRF is an effective and useful therapeutic approach for colitis. This observation should be further tested in human studies. Administration of the fecal microbiota of mice with an inflammatory phenotype only led to increased inflammation levels, while an influence of the litter affiliation of the mice was also found in histologic scores and intestinal clock gene expression. Akkermansia muciniphila (A. muciniphila) was given as a colitis-promoting bacterium and led to increased gene expression of inflammatory markers and tight junction proteins, while Lactobacillus taiwanensis (L. taiwanensis), as a potentially colitis-preventing bacterium, improved the expression of the intestinal circadian clock. Neither FMT nor bacterial supplementation had any influence on the occurrence of colitis. The transfer of different phenotypes by FMT was only possible to a limited extent and does not appear to be an effective treatment option for colitis. A. muciniphila can be regarded as an inflammation-promoting bacterium, while a probiotic effect of L. taiwanensis could not be confirmed.
In summary, this thesis has shown that a disrupted circadian clock is associated with intestinal inflammation and that TRF reduces inflammation and delays the onset of colitis, suggesting that TRF may be an effective therapy for intestinal inflammation.
Metabolic profiling of ‘Elstar’ and ‘Nicoter’ apples: impact of storage time, dynamic controlled atmosphere and 1-MCP treatment
(2024) Thewes, Fabio Rodrigo; Büchele, Felix; Uhlmann, Lilian Osmari; Lugaresi, Adriana; de Oliveria Neuwald, Daiane Quadros; Brackmann, Auri; Both, Vanderlei; Wagner, Roger; Neuwald, Daniel Alexandre; Yao, Jia-Long
The aim of this work was to evaluate the effect of CA and DCA on sugars, tricarboxylic acid cycle (TCA), anaerobic metabolism and some volatile compounds of ‘Elstar’ and ‘Nicoter’ apples. This study also aimed to evaluate the effect of ethylene action blocking by 1-MCP (0.650 ppm). The storage conditions tested for both cultivars were (1) CA; (2) DCA-CF; (3) DCA-RQ 1.3; (4) DCA-RQ 1.5; (5) DCA-CD 1.1; and (6) DCA-CD 1.3. The lowest oxygen limit (LOL) was higher for the ‘Nicoter’ apples, and the three DCA methods were able to detect this difference between the cultivars. Sorbitol had a trend of accumulation when the fruit was stored under DCA-RQ and DCA-CD, especially in higher RQ and CD, showing a negative Pearson correlation with the oxygen partial pressure over the storage period. The 1-MCP treatment induced sorbitol accumulation even when the fruit was stored under CA. The TCA intermediaries, such as citrate, 2-oxoglutarate, succinate, fumarate and oxaloacetate, were the most affected by the atmosphere conditions and the 1-MCP treatment for both cultivars. Malic acid was more affected by the storage time than the atmosphere conditions. Succinate and fumarate had an accumulation trend when the fruit was stored under DCA-RQ.