Institut für Lebensmittelwissenschaft und Biotechnologie

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

Browse

Now showing 1 - 20 of 36

Almond-like aroma formation of acid whey by Ischnoderma benzoinum fermentation: potential application in novel beverage development
(2025) Hannemann, Lea; Klauss, Raphaela; Gleissle, Anne; Heinrich, Patrick; Braunbeck, Thomas; Zhang, Yanyan
To address the sourish off-aroma of acid whey and enhance its upcycling, a new basidiomycete Ischnoderma benzoinum -mediated fermentation system was developed using pure acid whey as the sole substrate. A pleasant sweetish and marzipan-like odor was perceived after fermentation within 7 d at 24 °C in darkness, which was shaped from key contributors including 4-methoxybenzaldehyde (odor activity value (OAV) 878), 3-methylbutanal (OAV 511), 3,4-dimethoxybenzaldehyde (OAV 50), and benzaldehyde (OAV 28). The typical sweetish and almond-like odor persisted well after ultrahigh-temperature processing, though its intensity decreased slightly. Concurrently, the fermentation reduced lactose from 52 to 20 g/L but increased the contents of essential amino acids like threonine, leucine, and lysine. No significant cytotoxicity or genotoxicity differences were found between fermented and unfermented whey. Overall, the study highlights the capability of I. benzoinum fermentation to enhance the flavor of acid whey, offering a promising approach for creating nutritional and flavorful acid-whey-based products.
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
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.
Construction and description of a constitutive plipastatin mono-producing Bacillus subtilis
(2020) Vahidinasab, Maliheh; Lilge, Lars; Reinfurt, Aline; Pfannstiel, Jens; Henkel, Marius; Morabbi Heravi, Kambiz; Hausmann, Rudolf
Background: Plipastatin is a potent Bacillus antimicrobial lipopeptide with the prospect to replace conventional antifungal chemicals for controlling plant pathogens. However, the application of this lipopeptide has so far been investigated in a few cases, principally because of the yield in low concentration and unknown regulation of biosynthesis pathways. B. subtilis synthesizes plipastatin by a non-ribosomal peptide synthetase encoded by the ppsABCDE operon. In this study, B. subtilis 3NA (a non-sporulation strain) was engineered to gain more insights about plipastatin mono-production. Results: The 4-phosphopantetheinyl transferase Sfp posttranslationally converts non-ribosomal peptide synthetases from inactive apoforms into their active holoforms. In case of 3NA strain, sfp gene is inactive. Accordingly, the first step was an integration of a repaired sfp version in 3NA to construct strain BMV9. Subsequently, plipastatin production was doubled after integration of a fully expressed degQ version from B. subtilis DSM10T strain (strain BMV10), ensuring stimulation of DegU-P regulatory pathway that positively controls the ppsABSDE operon. Moreover, markerless substitution of the comparably weak native plipastatin promoter (Ppps) against the strong constitutive promoter Pveg led to approximately fivefold enhancement of plipastatin production in BMV11 compared to BMV9. Intriguingly, combination of both repaired degQ expression and promoter exchange (Ppps::Pveg) did not increase the plipastatin yield. Afterwards, deletion of surfactin (srfAA-AD) operon by the retaining the regulatory comS which is located within srfAB and is involved in natural competence development, resulted in the loss of plipastatin production in BMV9 and significantly decreased the plipastatin production of BMV11. We also observed that supplementation of ornithine as a precursor for plipastatin formation caused higher production of plipastatin in mono-producer strains, albeit with a modified pattern of plipastatin composition. Conclusions: This study provides evidence that degQ stimulates the native plipastatin production. Moreover, a full plipastatin production requires surfactin synthetase or some of its components. Furthermore, as another conclusion of this study, results point towards ornithine provision being an indispensable constituent for a plipastatin mono-producer B. subtilis strain. Therefore, targeting the ornithine metabolic flux might be a promising strategy to further investigate and enhance plipastatin production by B. subtilis plipastatin mono-producer strains.
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.
A diamine oxidase from Glutamicibacter halophytocola for the degradation of histamine and tyramine in foods
(2025) Kettner, Lucas; Freund, Alexander; Bechtel, Anna; Costa-Catala, Judit; Fischer, Lutz; Kettner, Lucas; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599 Stuttgart, Germany; Freund, Alexander; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599 Stuttgart, Germany; Bechtel, Anna; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599 Stuttgart, Germany; Costa-Catala, Judit; Departament de Nutrició, Ciències de l’Alimentació i Gastronomia, Campus de l’Alimentació de Torribera, Universitat de Barcelona, Av. Prat de la Riba 171, 08921 Santa Coloma de Gramenet, Spain; Fischer, Lutz; Department of Biotechnology and Enzyme Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599 Stuttgart, Germany
A novel diamine oxidase (DAO) was discovered in the bacterium Glutamicibacter halophytocola (DAO-GH). The gene of DAO-GH was integrated into the genome of the yeast Komagataella phaffii and recombinantly produced under control of the methanol-inducible AOX1 promoter in a bioreactor cultivation. A high DAO activity of 70.2 ± 5.2 µkat/Lculture (5.25 ± 0.22 µkat/gprotein) was yielded after 90 h of cultivation. The DAO-GH was partially purified by the polyethyleneimine precipitation of nucleic acids, fractionated ammonium sulfate precipitation and hydrophobic interaction chromatography, resulting in a specific DAO activity of 19.7 µkat/gProtein. The DAO-GH was then biochemically investigated regarding its potential for histamine and tyramine degradation in fermented foods and the human small intestine. Interestingly, the DAO-GH showed activity even at a low pH of 5 and low temperature of 6 °C. Both histamine and tyramine were effectively degraded and DAO-GH showed especially very high affinity towards tyramine (Km of 0.009 mM). The DAO-GH was shown to be capable of degrading around 20% of the initially applied histamine in tuna paste (pH 5.6) at 5 °C within 24 h and completely degraded the histamine in a simulated intestinal fluid within 1.5 h in bioconversion experiments. The DAO-GH was spray-dried for the production of a storable enzyme preparation. Only around 17% of activity were lost in this process and the DAO-GH remained stable at room temperature for at least 3 months. The discovery of this DAO with its very advantageous biochemical properties allows the preparation of histamine-reduced or -free fermented foods by a simple enzymatic treatment or the treatment of histamine intolerance symptoms as a dietary supplement or medicine.
Editorial: Microbial biosurfactants: updates on their biosynthesis, production and applications
(2024) Hausmann, Rudolf; Déziel, Eric; Soberón-Chávez, Gloria
Effect of cutting set variations on structural and functional properties of hamburgers
(2024) Berger, Lisa M.; Adam, Felix; Gibis, Monika; Witte, Franziska; Terjung, Nino; Weiss, Jochen
Meat grinders are composed of a combination of individual functional elements (e.g., screw conveyor, perforated plates, knives). This setup, and in particular the chosen cutting set, influences the characteristics of ground meat and hamburgers produced. In this study, we took a closer look at the effect of cutting set variations and process parameters on structural, functional, and physicochemical properties of beef hamburgers produced. It was found that the specific mechanical energy input during grinding increased when cutting levels, i.e., a set of one hole plate and one knife, were increased, causing more cell disintegration ( r = 0.387, p = 0.02). Surprisingly though, an influence on the functional and quality parameters of the hamburgers could not be found for most parameters tested. The findings indicate that variations in the cutting set affect the process parameters and the stress applied to the meat, but residence times in this zone are too small to cause noticeable effects on the analytical and qualitative properties of hamburgers. As such, there are options for energy and cost optimization of industrial grinding processes without sacrificing quality.
Effect of liquefaction temperature and enzymatic treatment on bioethanol production from mixed waste baked products
(2025) Almuhammad, Mervat; Kölling, Ralf; Einfalt, Daniel; Almuhammad, Mervat; Yeast Genetics and Fermentation Technology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 23, 70599, Stuttgart, Germany; Kölling, Ralf; Yeast Genetics and Fermentation Technology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 23, 70599, Stuttgart, Germany; Einfalt, Daniel; Botanical Garden, Ulm University, Hans-Krebs-Weg, 89081, Ulm, Germany
This study investigates the effect of different liquefaction temperatures (50–70 °C) and four commercial enzyme formulations on glucose release and subsequent ethanol yield, using mixed waste baked products as a substrate. Among the enzymes tested, Amylase GA 500 proved to be superior in the hydrolysis of starch at lower temperatures (50 °C and 55°C). At higher liquefaction temperatures (65 °C and 70°C) all four enzyme preparations showed comparable activity. The highest glucose concentration (205.7 g/L) and the highest ethanol yield (92 g/L) were achieved with Amylase GA 500 at 65 °C. Its superior performance is attributed to the synergistic activity of α-amylase and glucoamylase, which facilitates efficient starch hydrolysis. Crucially, we discovered that the liquefaction temperature profoundly affects fermentation speed independently of the initial glucose concentration or the enzyme preparation used for starch hydrolysis. This novel mechanistic insight suggests that higher temperature treatment either makes an additional factor crucial for yeast fermentation available or depletes/destroys an inhibitor present in the complex waste bakery product matrix. These findings highlight the critical role of temperature and enzyme formulation in optimizing bioethanol production from bakery waste, supporting the development of more sustainable and efficient waste-to-biofuel processes.
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, Fabio
Fruit 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.
Effect of smoldering air volume flow rates and smoking time on quality attributes of Frankfurter-type sausages
(2025) Leible, Malte; Herrmann, Kurt; Gibis, Monika; Weiss, Jochen; Leible, Malte; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599, Stuttgart, Germany; Herrmann, Kurt; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599, Stuttgart, Germany; Gibis, Monika; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599, Stuttgart, Germany; Weiss, Jochen; Department of Food Material Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstrasse 21/25, 70599, Stuttgart, Germany
This study explores the effects of varying smoking conditions on the properties of Frankfurter-type sausages. Using a modified smoldering smoke generator, air volume flow rate and smoking time were varied to assess their impact on color, texture, and sensory characteristics. The results showed significant changes in these characteristics and a wide spectrum in smoke color was produced across the 14 different settings. L* values ranged from 64.32 ± 0.61 to 46.33 ± 0.78, a* values ranged from 11.81 ± 0.29 to 24.18 ± 0.39, b* values ranged from 14.93 ± 0.77 to 41.20 ± 1.25 with an increase in smoking time and air volume flow generally leading to a darker smoking color. Sensory test regarding color showed that the perceived color behaved similarly to the measured color. In these descriptive tests the perceived color ranged from 0.42 ± 0.42 to 9.67 ± 0.43 on a scale from 0 to 10. Smoke odor did not show the strong differences seen in the other results. Here the perceived smoke odor ranged from 4.76 ± 2.00 to 8.64 ± 1.03 on a scale from 0 to 10. Since the study was based on a statistical experimental plan, a predictive model based on a surface plot could be established. These findings provide valuable insights in the qualitative changes in Frankfurter -Type sausages for optimizing smoking parameters in the food industry, potentially enabling precise control over desired sensory and physical properties in smoked meat products.
Effect of varying salt concentration on iridescence in precooked pork meat
(2022) Ruedt, Chiara; Gibis, Monika; Weiss, Jochen
The objective of this study was to investigate the effect of salt concentration on meat iridescence in cured cooked pork products. In addition, the influence of nitrite and pigmentary color on iridescence and its visual macroscopic perception was ascertained. Sample cubes from the pigs M. longissimus thoracis et lumborum were salted with either NaCl (20 g/kg, 40 g/kg) or nitrite curing salt (6 g/kg, 20 g/kg, and 40 g/kg) and subsequently cooked. Control samples were not salted. The effects of NaCl and curing salt on iridescence, instrumental color and microstructure were evaluated. Salt treatment significantly (p < 0.05) increased water-holding capacity, mean myofibers diameters and iridescence and reduced light scattering (L* value). An iridescence limit was reached with the 20 g/kg salt treatments. No differences between sodium chloride and nitrite curing salt were observed for both visual evaluation and colorimetry of the interference colors. Iridescence increases were attributed to a swelling of the myofilament lattice and thus reduction of intermyofibrillar spaces as well as an optical clearing of the myofibrils by dissolution of myofibrillar proteins that both reduce light scattering and allow more reflectance and interference to occur.
Experimental investigation of CO2 uptake in CO2 hydrates formation with amino acids as kinetic promoters and its dissociation at high temperature
(2022) Srivastava, Shubhangi; Kollemparembil, Ann Mary; Zettel, Viktoria; Claßen, Timo; Gatternig, Bernhard; Delgado, Antonio; Hitzmann, Bernd
The dissociation of CO2 gas hydrates (GH) with amino acid kinetic promoters and without promoters was studied at a high temperature of 90 °C for a period of 20 min to understand the percentage of CO2 gas and to select the best promoter that aids CO2 gas entrapment along with stability at a high temperature. The possibility of using four hydrophobic food grade amino acids, namely cysteine, valine, leucine, and methionine, and one surfactant, lecithin, as kinetic promoters for CO2 GH has been studied. The amino acids were added 0.5 g (wt%), and lecithin was added 5 g for the GH production. Furthermore, the amino acids leucine and methionine gave some positive results, therefore, these amino acids were carried further for the experimentation purpose in the production of CO2 GH. Also, a combinational use of these amino acids was studied to investigate the effect on % CO2 retention in comparison to the normal GH. From the results, it was observed that the stability of GH decreases with an increase in temperature, but the addition of promoters, especially leucine + methionine + lecithin increased the CO2 uptake during GH formation.
Exploiting RNA thermometer-driven molecular bioprocess control as a concept for heterologous rhamnolipid production
(2021) Noll, Philipp; Treinen, Chantal; Müller, Sven; Lilge, Lars; Hausmann, Rudolf; Henkel, Marius
A key challenge to advance the efficiency of bioprocesses is the uncoupling of biomass from product formation, as biomass represents a by-product that is in most cases difficult to recycle efficiently. Using the example of rhamnolipid biosurfactants, a temperature-sensitive heterologous production system under translation control of a fourU RNA thermometer from Salmonella was established to allow separating phases of preferred growth from product formation. Rhamnolipids as bulk chemicals represent a model system for future processes of industrial biotechnology and are therefore tied to the efficiency requirements in competition with the chemical industry. Experimental data confirms function of the RNA thermometer and suggests a major effect of temperature on specific rhamnolipid production rates with an increase of the average production rate by a factor of 11 between 25 and 38 °C, while the major part of this increase is attributable to the regulatory effect of the RNA thermometer rather than an unspecific overall increase in bacterial metabolism. The production capacity of the developed temperature sensitive-system was evaluated in a simple batch process driven by a temperature switch. Product formation was evaluated by efficiency parameters and yields, confirming increased product formation rates and product-per-biomass yields compared to a high titer heterologous rhamnolipid production process from literature.
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; Gudiña, Eduardo
In 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.
Food informatics - Review of the current state-of-the-art, revised definition, and classification into the research landscape
(2021) Krupitzer, Christian; Stein, Anthony
Background: The increasing population of humans, changing food consumption behavior, as well as the recent developments in the awareness for food sustainability, lead to new challenges for the production of food. Advances in the Internet of Things (IoT) and Artificial Intelligence (AI) technology, including Machine Learning and data analytics, might help to account for these challenges. Scope and Approach: Several research perspectives, among them Precision Agriculture, Industrial IoT, Internet of Food, or Smart Health, already provide new opportunities through digitalization. In this paper, we review the current state-of-the-art of the mentioned concepts. An additional concept is Food Informatics, which so far is mostly recognized as a mainly data-driven approach to support the production of food. In this review paper, we propose and discuss a new perspective for the concept of Food Informatics as a supportive discipline that subsumes the incorporation of information technology, mainly IoT and AI, in order to support the variety of aspects tangent to the food production process and delineate it from other, existing research streams in the domain. Key Findings and Conclusions: Many different concepts related to the digitalization in food science overlap. Further, Food Informatics is vaguely defined. In this paper, we provide a clear definition of Food Informatics and delineate it from related concepts. We corroborate our new perspective on Food Informatics by presenting several case studies about how it can support the food production as well as the intermediate steps until its consumption, and further describe its integration with related concepts.
Glucoselipid biosurfactant biosynthesis operon of Rouxiella badensis DSM 100043T: screening, identification, and heterologous expression in Escherichia coli
(2025) Harahap, Andre Fahriz Perdana; Treinen, Chantal; Van Zyl, Leonardo Joaquim; Williams, Wesley Trevor; Conrad, Jürgen; Pfannstiel, Jens; Klaiber, Iris; Grether, Jakob; Hiller, Eric; Vahidinasab, Maliheh; Perino, Elvio Henrique Benatto; Lilge, Lars; Burger, Anita; Trindade, Marla; Hausmann, Rudolf; Seo, Myung-Ji
Rouxiella badensis DSM 100043T had been previously proven to produce a novel glucoselipid biosurfactant which has a very low critical micelle concentration (CMC) as well as very good stability against a wide range of pH, temperature, and salinity. In this study, we performed a function-based library screening from a R. badensis DSM 100043T genome library to identify responsible genes for biosynthesis of this glucoselipid. The identified open reading frames (ORFs) were cloned into several constructs in Escherichia coli for gene permutation analysis and the individual products were analyzed using high-performance thin-layer chromatography (HPTLC). Products of interest from positive expression strains were purified and analyzed by liquid chromatography/electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and nuclear magnetic resonance (NMR) for further structure elucidation. Function-based screening of 5400 clones led to the identification of an operon containing three ORFs encoding acetyltransferase GlcA (ORF1), acyltransferase GlcB (ORF2), and phosphatase/HAD GlcC (ORF3). E. coli pCAT2, with all three ORFs, resulted in the production of identical R. badensis DSM 100043T glucosedilipid with Glu-C10:0-C12:1 as the main congener. ORF2-deletion strain E. coli pAFP1 primarily produced glucosemonolipids, with Glu-C10:0,3OH and Glu-C12:0 as the major congeners, predominantly esterified at the C-2 position of the glucose moiety. Furthermore, fed-batch bioreactor cultivation of E. coli pCAT2 using glucose as the carbon source yielded a maximum glucosedilipid titer of 2.34 g/L after 25 h of fermentation, which is 55-fold higher than that produced by batch cultivation of R. badensis DSM 100043T in the previous study.
High-performance thin-layer chromatography for the detection of compositional changes in LACTEM emulsifiers during storage
(2025) Schuster, Katharina; Blankart, Max; Hinrichs, Jörg; Oellig, Claudia
Quality control of food emulsifiers, such as lactic acid esters of mono- and diacylglycerols (LACTEM), is crucial in the reproducible production of food products. The current study investigated compositional changes of LACTEM emulsifiers using high-performance thin-layer chromatography (HPTLC) during storage at 60 °C for 8 weeks. Ultraviolet (UV) and fluorescence images of the HPTLC silica gel F254s plates after primuline derivatization and densitometric data were analyzed to assess changes in the composition. Significant changes were observed for minor LACTEM components (< 10% relative intensity), specifically a decrease in higher-lactylated monoacylglycerols and an increase in triacylglycerols. Techno-functional properties, such as particle size distribution, apparent viscosity, overrun, foam firmness, drainage, and residual cream of aerosol whipping cream (0.8 g 100 g−1 LACTEM) were investigated. While emulsion stability was not affected, the foam firmness increased significantly, corresponding to a visibly more brittle foam. On the basis of these results, monitoring compositional changes in the food-manufacturing process is necessary to maintain constant food quality.
Impact of microfluidization on colloidal properties of insoluble pea protein fractions
(2021) Moll, Pascal; Salminen, Hanna; Schmitt, Christophe; Weiss, Jochen
Microfluidization is a technique commonly used to disrupt and homogenize dispersions such as oil-in-water emulsions or cellular suspensions. In this study, we investigated its ability to alter the physicochemical properties of plant-derived insoluble protein aggregates such as those found in pea protein extracts. Insoluble pea protein dispersions (5% w/w, pH 7) were homogenized at 25–150 MPa for 1–5 cycles. Increasing the homogenization pressure and cycles decreased the particle size (d43) of the unhomogenized insoluble pea proteins from 180 ± 40 μm to 0.2 ± 0.0 μm (at ≥ 125 MPa), leading to more transparent dispersions. Furthermore, the solubility of the insoluble pea proteins increased from 23 ± 1% to 86 ± 4%. Treatments with chaotropic agents, dithiothreitol and urea, revealed that insoluble pea protein aggregates were stabilized not only by disulphide bonds but also by hydrogen bonds and hydrophobic interactions. These molecular interactions were disrupted by microfluidization. The study provides insights into the disruption mechanism of insoluble pea proteins by applying microfluidization and offers a mean to improve their technofunctional properties to facilitate further use in food manufacture.
Influence of fruit logistics on fresh-cut pineapple (Ananas comosus [L.] Merr.) volatiles assessed by HS-SPME–GC–MS analysis
(2021) Steingass, Christof B.; Dickreuter, Jennifer; Kuebler, Sabine; Schweiggert, Ralf M.; Carle, Reinhold
Green-ripe pineapples are shipped overseas by sea freight, while those picked at full maturity need to be transported by airfreight over the same large distance. In this study, fresh-cut pineapple cubes were assessed two, five, and eight days after processing from green-ripe pineapples after mimicked sea freigh (SF) and fully ripe air-freighted (AF) pineapples. The sea-freighted samples displayed elevated titratable acidity (TA), thus resulting in smaller ratios of total soluble solids and TA compared to the AF pineapples. Differences in the carotenoid levels of the two fresh-cut categories were found to be insignificant. By contrast, hierarchical cluster analysis (HCA) and principal component analysis (PCA) calculated on the basis of the volatiles analysed by headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME–GC–MS) permitted to distinguish all six individual sample types and to segregate them into two major clusters (SF and AF). The effect of storage on the volatiles was further evaluated by partial least squares (PLS) regression. Substantial chemical markers to differentiate the individual samples and to describe the effect of storage were deduced from the PCA and PLS regression, respectively. In general, fresh-cut products obtained from fully ripe AF fruit displayed higher concentrations of volatiles, in particular, increased concentrations of diverse methyl esters. With progressing storage duration, the concentrations of ethanol and diverse ethyl esters increased. Moreover, products from AF pineapples displayed lower microbial counts compared to those from SF fruit.

Browse

Browsing Institut für Lebensmittelwissenschaft und Biotechnologie by Sustainable Development Goals "9"