Institut für Lebensmittelwissenschaft und Biotechnologie

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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.
Towards sustainable biointelligent food design: structuring potential of plant-based materials exemplified using apricot seed oil oleogels and bigels through 3D food printing
(2025) Reinmuth, Evelyn; Fahmy, Ahmed Raouf; Ribette, Olivia; Jekle, Mario; Reinmuth, Evelyn; Bioeconomy Office Hohenheim, University of Hohenheim, Stuttgart, Germany; Fahmy, Ahmed Raouf; Department of Plant-Based Foods, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Ribette, Olivia; Department of Plant-Based Foods, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany; Jekle, Mario; Department of Plant-Based Foods, Institute of Food Science and Biotechnology, University of Hohenheim, Stuttgart, Germany
Background/Introduction: Biointelligence in the approach of food additive manufacturing represents a significant advancement, enabling the reverse engineering and design of foods. Legislation restricting trans-fats has accelerated research into alternatives, but ingredients like saturated and trans fats play key roles in food quality and functionality. Oleogels are a promising replacement. Food additive manufacturing introduces a biointelligent approach, combining biological and technical components with information technology to optimize food design. This study investigates 3D printing of oleogel and bigel systems using apricot seed oil, aiming to assess their significance, applicability, and printability as sustainable alternatives to trans fats for innovative, resource-efficient food production. Methods: Apricot seed oil, rich in antioxidants and polyunsaturated fatty acids, was processed into plant-based oleogels and bigels. The material systems were incorporated into 3D printed food structures. Material characterization and techno-functional analysis were conducted to evaluate the suitability of apricot seed oil for structuring 3D printed foods and controlling food texture. Results: Adjusting the type and concentration of oil-gelator mixtures enabled tailored texture and lipid distribution to fit consumer preferences. Sustainability impacts were assessed at intermediate processing steps, demonstrating the value of holistic evaluations beyond technical factors. Discussion: Biointelligent 3D printing offers a platform to optimize sensory and sustainability qualities in food design. The integration of apricot seed oil into novel food matrices enables versatile nutritional product development, supporting researchers and industry stakeholders in advancing consumer-centric, sustainable production and consumption practices.
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.
Recombinant production of Paenibacillus wynnii β-galactosidase with Komagataella phaffii
(2024) Bechtel, Anna; Seitl, Ines; Pross, Eva; Hetzel, Frank; Keutgen, Mario; Fischer, Lutz; Bechtel, Anna; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Seitl, Ines; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Pross, Eva; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Hetzel, Frank; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Keutgen, Mario; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany; Fischer, Lutz; Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, University of Hohenheim, Garbenstr. 25, 70599, Stuttgart, Germany
The β-galactosidase from Paenibacillus wynnii (β-gal-Pw) is a promising candidate for lactose hydrolysis in milk and dairy products, as it has a higher affinity for the substrate lactose (low KM value) compared to industrially used β-galactosidases and is not inhibited by the hydrolysis-generated product D-galactose. However, β-gal-Pw must firstly be produced cost-effectively for any potential industrial application. Accordingly, the yeast Komagataella phaffii was chosen to investigate its feasibility to recombinantly produce β-gal-Pw since it is approved for the regulated production of food enzymes. The aim of this study was to find the most suitable way to produce the β-gal-Pw in K. phaffii either extracellularly or intracellularly.ResultsFirstly, 11 different signal peptides were tested for extracellular production of β-gal-Pw by K. phaffii under the control of the constitutive GAP promoter. None of the signal peptides resulted in a secretion of β-gal-Pw, indicating problems within the secretory pathway of this enzyme. Therefore, intracellular β-gal-Pw production was investigated using the GAP or methanol-inducible AOX1 promoter. A four-fold higher volumetric β-galactosidase activity of 7537 ± 66 µkatoNPGal/Lculture was achieved by the K. phaffii clone 27 using the AOX1 promoter in fed-batch bioreactor cultivations, compared to the clone 5 using the GAP promoter. However, a two-fold higher specific productivity of 3.14 ± 0.05 µkatoNPGal/gDCW/h was achieved when using the GAP promoter for β-gal-Pw production compared to the AOX1 promoter. After partial purification, a β-gal-Pw enzyme preparation with a total β-galactosidase activity of 3082 ± 98 µkatoNPGal was obtained from 1 L of recombinant K. phaffii culture (using AOX1 promoter).ConclusionThis study showed that the β-gal-Pw was produced intracellularly by K. phaffii, but the secretion was not achieved with the signal peptides chosen. Nevertheless, a straightforward approach to improve the intracellular β-gal-Pw production with K. phaffii by using either the GAP or AOX1 promoter in bioreactor cultivations was demonstrated, offering insights into alternative production methods for this enzyme.
Time-delayed cold gelation of low-ester pectin and gluten with CaCO3 to facilitate manufacture of raw-fermented vegan sausage analogs
(2025) Koenig, Maurice; Ahlborn, Kai; Herrmann, Kurt; Loeffler, Myriam; Weiss, Jochen; Kolanowski, Wojciech
To advance the development of protein-rich plant-based foods, a novel binder system for vegan sausage alternatives without the requirement of heat application was investigated. This enables long-term ripening of plant-based analogs similar to traditional fermented meat or dairy products, allowing for refined flavor and texture development. This was achieved by using a poorly water-soluble calcium source (calcium carbonate) to introduce calcium ions into a low-ester pectin—gluten matrix susceptible to crosslinking via divalent ions. The gelling reaction of pectin–gluten dispersions with Ca 2+ ions was time-delayed due to the gradual production of lactic acid during fermentation. Firm, sliceable matrices were formed, in which particulate substances such as texturized proteins and solid vegetable fat could be integrated, hence forming an unheated raw-fermented plant-based salami-type sausage model matrix which remained safe for consumption over 21 days of ripening. Gluten as well as pectin had a significant influence on the functional properties of the matrices, especially water holding capacity (increasing with higher pectin or gluten content), hardness (increasing with higher pectin or gluten content), tensile strength (increasing with higher pectin or gluten content) and cohesiveness (decreasing with higher pectin or gluten content). A combination of three simultaneously occurring effects was observed, modulating the properties of the matrices, namely, (a) an increase in gel strength due to increased pectin concentration forming more brittle gels, (b) an increase in gel strength with increasing gluten content forming more elastic gels and (c) interactions of low-ester pectin with the gluten network, with pectin addition causing increased aggregation of gluten, leading to strengthened networks.
Visual tracking of a moving target in 360-degree virtual reality: analysis of the effects on attention and mood
(2025) Sellner, T.; Ehmann, P.; Spielmann, J.; Gogolla, F.; Rösgen, A.; Mayer, J.; Schoenfeld, M. A.; Flor, H.
The training of attentional capacities is an important part of many rehabilitative efforts, for example, in the treatment of stroke. The Helix-Arena is an innovative virtual reality (VR) training device, which enables multimodal training in a 360-degree virtual environment. A pursuit training was developed for the Helix-Arena. In this study, we evaluate the effectiveness of the pursuit training in the Helix-Arena compared to a control group [CG, training on a personal computer (PC)] in 34 healthy participants. The experimental group (EG, N = 19) participated in four training sessions in the Helix-Arena over a period of 2 weeks. The control group (N = 15) completed similar training sessions in a non-VR environment on a PC. During each training session, changes in attention (Test of Attentional Performance battery, TAP) and general mood (Positive and Negative Affect Schedule, PANAS) were assessed pre- and post-training. A significantly higher pre-to-post improvement was observed in the EG for the TAP subtest attention shift in the subcategory invalid instructor ( p = 0.04) than that in the CG. In addition, we found a higher positive affect after the training in the EG but not in the CG (p < 0.01). These results suggest advantages of the VR environment for attentional and affective processes. The VR training can thus improve not only cognitive abilities but also training motivation. In a next step, the training can be used with patients in a rehabilitation context, but it is also suitable for educational and gaming contexts.
Genome-wide association reveals host-specific genomic traits in Escherichia coli
(2023) Tiwari, Sumeet K.; van der Putten, Boas C. L.; Fuchs, Thilo M.; Vinh, Trung N.; Bootsma, Martin; Oldenkamp, Rik; La Ragione, Roberto; Matamoros, Sebastien; Hoa, Ngo T.; Berens, Christian; Leng, Joy; Álvarez, Julio; Ferrandis-Vila, Marta; Ritchie, Jenny M.; Fruth, Angelika; Schwarz, Stefan; Domínguez, Lucas; Ugarte-Ruiz, María; Bethe, Astrid; Huber, Charlotte; Johanns, Vanessa; Stamm, Ivonne; Wieler, Lothar H.; Ewers, Christa; Fivian-Hughes, Amanda; Schmidt, Herbert; Menge, Christian; Semmler, Torsten; Schultsz, Constance
Background: Escherichia coli is an opportunistic pathogen which colonizes various host species. However, to what extent genetic lineages of E. coli are adapted or restricted to specific hosts and the genomic determinants of such adaptation or restriction is poorly understood. Results: We randomly sampled E. coli isolates from four countries (Germany, UK, Spain, and Vietnam), obtained from five host species (human, pig, cattle, chicken, and wild boar) over 16 years, from both healthy and diseased hosts, to construct a collection of 1198 whole-genome sequenced E. coli isolates. We identified associations between specific E. coli lineages and the host from which they were isolated. A genome-wide association study (GWAS) identified several E. coli genes that were associated with human, cattle, or chicken hosts, whereas no genes associated with the pig host could be found. In silico characterization of nine contiguous genes (collectively designated as nan-9 ) associated with the human host indicated that these genes are involved in the metabolism of sialic acids (Sia). In contrast, the previously described sialic acid regulon known as sialoregulon (i.e. nanRATEK-yhcH , nanXY , and nanCMS ) was not associated with any host species. In vitro growth experiments with a Δ nan-9 E. coli mutant strain, using the sialic acids 5- N -acetylneuraminic acid (Neu5Ac) and N -glycolylneuraminic acid (Neu5Gc) as sole carbon source, showed impaired growth behaviour compared to the wild-type. Conclusions: This study provides an extensive analysis of genetic determinants which may contribute to host specificity in E. coli . Our findings should inform risk analysis and epidemiological monitoring of (antimicrobial resistant) E. coli .
Investigation of biochars in terms of vitamin E adsorption capacity
(2025) Witte, Franziska; Dinh, Ngoc Huyen Anh; Juadjur, Andreas; Heinz, Volker; Visscher, Christian; Weiss, Jochen; Terjung, Nino; Gao, Bin; García Rodríguez, Juan
Featured Application: This study provides insights into optimising biochar as a carrier for vitamin E delivery in ruminant nutrition. By demonstrating the correlation between pore size distribution and adsorption capacity, the findings suggest that theoretical models can reduce the number of experimental trials needed to identify effective adsorbents. This approach could improve the efficiency of vitamin E supplementation in animal feed, potentially enhancing nutrient absorption and animal health. Abstract: Vitamin E is important for ruminants’ health. To increase the rate of vitamin E resorption, the use of a carrier is recommended. One authorised porous feed additive is biochar. Biochar’s adsorption capacity is affected by its pore volume, which is determined, among other factors, by the biomass and the production process applied. For this purpose, the vitamin E adsorption capacity of ten commercial biochars with a varying surface area in the range of 2.6 to 20 nm was investigated. The results of these single-point batch experiments were compared to the theoretical results using a monolayer adsorption model. Our hypothesis was proven, as the theoretical model could predict the experimental adsorption capacity. This generally suggests that the number of trials required to identify optimal adsorbents can be reduced. A high percentage of vitamin E adsorption (>90%) was obtained with a short adsorption time of 10 min using an adsorbent dosage of 15.78 g/L and a vitamin E concentration of 1.70 g/L. The highest correlation of vitamin E adsorption existed for the mesopore class, ranging from 3.22 to 4.03 nm in Barrett–Joyner–Halenda surface area. This indicates the necessity of knowing the size of the adsorptive and the adsorbent in order to optimise sorption kinetics.
Application of AprX from Pseudomonas paralactis for the improvement of the emulsifying properties of milk, plant and insect protein and estimation of their hydrolysate’s bitter potential
(2025) Volk, Veronika; Ewert, Jacob; Longhi, Miriam; Stressler, Timo; Fischer, Lutz
Protein properties can be modified by selective enzymatic hydrolysis. In this study, the alkaline metalloendopeptidase AprX (Serralysin; EC 3.4.24.40) from Pseudomonas paralactis was used for the tailored hydrolysis of different food proteins resulting in the production of protein hydrolysates with improved emulsifying properties. Sodium caseinate, wheat gluten and buffalo worm protein were used for AprX hydrolysis at 40 °C and pH 8 to cover a spectrum of different protein sources. A maximum degree of hydrolysis (DH) of 13.1 ± 0.2%, 14.2 ± 0.1% and 20.7 ± 0.1% was reached for sodium caseinate, wheat gluten and the worm protein, respectively. The corresponding hydrolysate properties were analyzed regarding their particle size, peptide composition, solubility, viscosity, surface hydrophobicity and interfacial tension. The emulsifying properties were investigated by the oil-droplet size, ζ-potential and stability of emulsions prepared from the hydrolysates. Using partially hydrolyzed sodium caseinate (DH = 10.6%) as an emulsifier lead to an eightfold increase of the emulsion stability (t1/2 = 180 ± 0 min) compared to unhydrolyzed sodium caseinate. The emulsion stability using wheat gluten hydrolysates (DH = 11.9%) was increased 30-fold (t1/2 = 45 ± 5 min). Simultaneously, the solubility of gluten was increased by 60%. Buffalo worm hydrolysates (DH = 14.6%) had a twofold (t1/2 = 85 ± 5 min) increased emulsion stability. In conclusion, AprX can be used to improve the solubility and emulsifying properties of food proteins at a relatively high DH.
Seasonal variation in the diurnal activity pattern of Eurasian blackbirds (Turdus merula) in the forest
(2024) Schlindwein, Xenia; Randler, Christoph; Kalb, Nadine; Dvorak, Jan; Gottschalk, Thomas K.
Camera traps are increasingly used to estimate the density of animals as well as their activity patterns. As camera traps allow monitoring of animals over long periods of time without disturbance, they are especially useful to observe changes in diurnal activity patterns over time. In ornithology, camera trapping is still in its infancy. To our knowledge, no study has yet investigated the activity pattern of a songbird over the full annual cycle. We used camera traps in the Rammert, a small mountainous forest area near Rottenburg in Southwest Germany to monitor the diurnal activity pattern of forest-dwelling Eurasian blackbirds ( Turdus merula ). As the activity level of animals is known to be affected by day light, we used double-anchoring transformation of day times to account for the variation in sunrise and sunset across the different seasons. By generating activity models, we investigated the pattern of blackbird activity during the four seasons of the year and compared the patterns of male and female birds, respectively. A significant difference between a unimodal activity pattern in spring and a bimodal pattern for the rest of the year was found which might be related to breeding and territorial behaviour in spring. Moreover, we observed that the activity pattern of males and females overlapped greatly but still showed some variation in the number and timing of density peaks.
Using ground oyster mushroom and chia seeds for the fortification of wheat bread-Nelder–Mead simplex optimisation
(2025) Schneider, Yannik; Zettel, Viktoria
Wheat bread was enriched with ground chia and ground oyster mushroom to improve its nutritional properties regarding protein and fibre content within the context of food fortification while maintaining a high specific volume and a soft crumb. A bread made from 100% wheat flour was used as reference. The Nelder–Mead simplex algorithm was used to determine the optimal proportions of chia and oyster mushroom substitution in the recipe. Bread quality was analysed and rated. Chia has a positive effect on the baking result due to its water-binding capacity, while mushrooms have a rather negative effect caused by the enzymes they contain. It was possible to replace 1.6% of wheat flour with ground oyster mushroom and 1.2% chia without any deviations from the control within 7 steps Furthermore, the partially substituted breads showed 3.8% lower contents of carbohydrates with a reduction of 4.1% of total sugar and higher contents of dietary fibre and protein, 22.7% and 2.3% respectively in comparison with the control sample. The wheat flour in bread can be replaced by chia flour and ground oyster mushrooms in small quantities without compromising the quality of the bread while improving some nutritional values.
Process development for spray drying of aroma rich herbs and spices : challenges, strategies and experimental results
(2025) Heimbach, Julia; Kohlus, Reinhard
Conventional air drying of herbs and spices is associated with a loss of quality due to degradation reactions that occur during the process. Spray drying was introduced to the processing of herbs and spices to evaluate the suitability of this method in an attempt to create a dried product of improved quality. Basil and ginger were used as model systems. Different options for the conversion of the frozen raw material into an atomisable feed liquid were reviewed. For basil, milling with a mincer with subsequent particle removal by a screw press gave the best results. Rapid and oxygen-free processing was crucial to prevent the development of bitterness. Ginger was juiced and subjected to a split-stream process, where the ginger fibres were dried and milled separately before being reintroduced to the juice as drying aid to prevent stickiness. The resulting feed material was dried in a pilot plant spray dryer and the effect of process parameters on volatile retention was investigated. Increasing air inlet temperature and decreasing air outlet temperature enhanced essential oil retention for both systems. In addition, large particle sizes and short residence times improved retention when drying basil. The dry matter content of the feed material was identified as key factor for volatile retention in all systems studied. Additional approaches to improve volatile retention were explored using a maltodextrin-linalool model system. The aim was to reduce the volatile partial pressure gradient between the atmosphere and the droplet in order to reduce volatile transition. While the use of zeolite for selective dehumidification and volatile enrichment did not show the desired effect, elevating the condenser temperature and increasing linalool loading of the feed proved to be effective. A relationship was found between volatile organic compound content in the atmosphere and volatile retention in the powder. The experimental results obtained were used to assess the accuracy of a retention prediction model based on the selective diffusion theory. Good estimates were obtained for linalool- and methanol-maltodextrin systems. The linalool model was transferred to basil material to test the prediction quality in a highly heterogeneous food material, which was successfully represented. Analysis of the influence of process parameters on the retention model emphasized the significance of particle size in maximising retention. This work highlights the challenges of processing and spray drying aromatic herbs and spices. While the process without carrier it is not an alternative to conventional drying, the addition of encapsulation material significantly improves the result.
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.
Decoding the aroma of Jägermeister liqueur through sensory-directed flavor analysis combined with solvent-assisted flavor evaporation and headspace-stir bar sorptive extraction
(2025) Zhu, Lin; Lin, Zexin; Zheng, Yan; Liang, Jiaqi; Li, Yupan; Kramp, Sarah; Zhang, Youfeng; Xiang, Can; Chen, Leyin; Rigling, Marina; Hannemann, Lea; Oellig, Claudia; Zhang, Yanyan
Jägermeister liqueur is one of the most famous herbal liqueurs worldwide, distinguished by its unique anise-like, bitter, and caramel-like flavor. This study comprehensively analyzed its aroma components using sensory-directed flavor analysis combined with gas chromatography-mass spectrometry and gas chromatography-sulfur chemiluminescence detector. Results identified eugenol (clove-like, OAV = 1260), anethole (anise-like, OAV = 723), p-anisaldehyde (almond-like, OAV = 97), linalool (flowery, OAV = 25), and terpinen-4-ol (apple-like, OAV = 119) as key aroma-active compounds in Jägermeister. Two sulfur-containing compounds with meaty and caramel-like aromas were detected; however, their OAVs were below 1. Ethers (53.2 mg/L), phenolics (27.8 mg/L), and terpenoids (10.5 mg/L) were the most abundant compounds in Jägermeister, while esters were present at relatively low concentrations (254 μg/L). A comparative analysis revealed that Jägermeister exhibits a unique aroma profile among ten European herbal liqueurs, particularly enriched in caramel-like and licorice-like notes, which showed positive correlations with key aroma compounds such as vanillin. This work not only provides the first systematic aroma deconstruction of Jägermeister, but also offers new insights into the compositional patterns and classification of European herbal liqueurs, contributing to quality control, product authentication, and flavor optimization.
Food fermentation: an essential unit operation towards secure, sustainable, safe, and sustaining food systems
(2025) Gänzle, Michael G.; Seifert, Jana; Weiss, Jochen; Zijlstra, Ruurd T.
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.
Integrating sensor data, laboratory analysis, and computer vision in machine learning-driven E-Nose systems for predicting tomato shelf life
(2025) Senge, Julia Marie; Kaltenecker, Florian; Krupitzer, Christian
Assessing the quality of fresh produce is essential to ensure a safe and satisfactory product. Methods to monitor the quality of fresh produce exist; however, they are often expensive, time-consuming, and sometimes require the destruction of the sample. Electronic Nose (E-Nose) technology has been established to track the ripeness, spoilage, and quality of fresh produce. Our study developed a freshness monitoring system for tomatoes, combining E-Nose technology with storage condition monitoring, color analysis, and weight-loss tracking. Different post-purchase scenarios were investigated, focusing on the influence of temperature and mechanical damage on shelf life. Support Vector Classifier (SVC) and k-Nearest Neighbor (kNN) were applied to classify storage scenarios and storage days, while Support Vector Regression (SVR) and kNN regression were used for predicting storage days. By using a data fusion approach with Linear Discriminant Analysis (LDA), the SVC achieved an accuracy of 72.91% in predicting storage days and an accuracy of 86.73% in distinguishing between storage scenarios. The kNN yielded the best regression results, with a Mean Absolute Error (MAE) of 0.841 days and a coefficient of determination of 0.867. The results highlight the method’s potential to predict storage scenarios and storage days, providing insight into the product’s remaining shelf life.
Tackling the rich vehicle routing problem with nature-inspired algorithms
(2022) Lesch, Veronika; König, Maximilian; Kounev, Samuel; Stein, Anthony; Krupitzer, Christian
In the last decades, the classical Vehicle Routing Problem (VRP), i.e., assigning a set of orders to vehicles and planning their routes has been intensively researched. As only the assignment of order to vehicles and their routes is already an NP-complete problem, the application of these algorithms in practice often fails to take into account the constraints and restrictions that apply in real-world applications, the so called rich VRP (rVRP) and are limited to single aspects. In this work, we incorporate the main relevant real-world constraints and requirements. We propose a two-stage strategy and a Timeline algorithm for time windows and pause times, and apply a Genetic Algorithm (GA) and Ant Colony Optimization (ACO) individually to the problem to find optimal solutions. Our evaluation of eight different problem instances against four state-of-the-art algorithms shows that our approach handles all given constraints in a reasonable time.
Stability of anthocyanin extracts from chokeberry, grape, hibiscus, and purple sweet potato in ω-3-fatty acid rich oil-in-water emulsions
(2024) Klinger, Evelyn; Salminen, Hanna; Bause, Karola; Weiss, Jochen
The food industry is actively investigating the stability of natural red pigments to replace artificial food colorants from all food applications in the near future. In this study, the stability of coloring extracts from chokeberry, grape, hibiscus, and purple sweet potato was investigated in ω-3 fatty acid-rich flaxseed oil-in-water emulsion during storage. The red color of the oil-in-water emulsions faded within 4 days, indicating that the anthocyanin extracts were susceptible to lipid oxidation reactions of the ω-3 fatty acids. The color stability varied between all used extract sources: The chokeberry (degradation constant k = 19.6 h−1) and grape (k = 15.2 h−1) extracts showed similar degradation kinetics, whereas purple sweet potato extract (k = 10.7 h−1) degraded significantly slower, and hibiscus extract (k = 110.2 h−1) significantly faster. The differences can be explained by the different anthocyanins contained in the plant extract, especially by the proportion of acylated anthocyanins.
Improved prediction of wheat baking quality by three novel approaches involving spectroscopic, rheological and analytical measurements and an optimized baking test
(2025) Ziegler, Denise; Buck, Lukas; Scherf, Katharina Anne; Popper, Lutz; Schaum, Alexander; Hitzmann, Bernd
Baking quality, defined as loaf volume, is one of the most important quality attributes of wheat. An accurate and rapid determination is of great interest for the wheat supply chain. However, this remains difficult to date, because reported predictions based on other wheat characteristics (e.g. protein content) or flour spectroscopy are poor. This study investigates three novel approaches to improve the prediction of specific loaf volume determined by an optimized mini-baking test. The predictions are based on a large variety of rheological and analytical data as well as fluorescence, near-infrared (NIR) and Raman spectroscopy of flour and flour fractions. Furthermore, the influence of data fusion on the predictions is investigated. All three approaches presented promising results and showed great potential for practical application with R2CV > 0.90 for various regression models. For example, the combination of farinograph data with solvent retention capacity data or NIR flour spectra yielded R2CV of 0.91 in both cases. Combining Raman spectra of the < 32 μm and 75–100 μm fractions as well as NIR spectra of gluten, flour and starch both also yielded R2CV of 0.91. The results underline that loaf volume is a complex quality characteristic that can be better predicted when different data types are combined. Different rheological and analytical tests and different spectroscopic methods capture specific wheat quality characteristics that have different relations to baking volume and can therefore provide complementary information for improved predictions. Furthermore, the importance of rheological tests (especially farinograph, extensograph, alveograph) and the baking procedure for the prediction of baking quality are emphasized.

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