November 2024
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11 Reads
International Communications in Heat and Mass Transfer
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November 2024
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11 Reads
International Communications in Heat and Mass Transfer
November 2024
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18 Reads
Journal of Food Engineering
3D printing of starch-based materials has become of great interest during the last few years. However, the characterization of the printing inks and the prediction of the printing accuracy is still challenging. Therefore, the surface chemistry and particle size distribution of starches from different organic sources (wheat, potato, rice) were characterized, and their influence on printing accuracy was investigated. Starch granules surface is covered with different lipids (e.g. phospholipids) and protein (e.g. puroinduline), which are known to influence the properties of starch and the interaction with other ingredients. These surface-associated lipids (SSAL) and proteins (SSAP) were removed individually from starch granules’ surfaces to investigate the influence of particle-particle interplay on the printing behavior. Therefore, the amount of surface proteins was calculated by XPS analysis based on the nitrogen to carbon (N/C) ratio of each starch granules’ surface. There was a linear correlation (r = −0.84) between the N/C ratio and the printing accuracy, measured by a geometrical deviation, indicating a dominating influence of the surface composition of the individual starch granules. The deviation from the geometrical template was higher for printed samples with smaller N/C ratio and therefore less protein on the starch granules’ surface. No influence of the particle size was found, as the samples from different starches containing the same amount of SSAPs had the same printing accuracy. These results reveal that the particle-particle and particle-polymer interactions mainly influence by the protein content on the starch granule sur face seem to be decisive for the geometrical stability of 3D food printing. It is therefore recommended to use starches with a high amount of SSAPs for 3D printing applications.
October 2024
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16 Reads
Microorganisms
Obligate anaerobic beer spoilage bacteria have been a menace to the brewing industry for several decades. Technological advances in the brewing process aimed at suppressing aerobic spoilers gave rise to problems with obligate anaerobes. In previous studies, the metabolic spectrum of Pectinatus and Megasphaera species has been described, but their metabolism in the beer environment remains largely unknown. We used high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and headspace solid-phase microextraction–gas chromatography–mass spectrometry (HS-SPME-GCMS) to further characterize beer spoiled by 30 different strains from six beer-spoiling species of Pectinatus and Megasphaera (P. cerevisiiphilus, P. frisingensis, P. haikarae, M. cerevisiae, M. paucivorans, and M. sueciensis). We detected differences in carbohydrate utilization and the volatile organic compounds (volatilome) produced during beer spoilage by all six species. We were able to show that glycerol, one of the basic components of beer, is the common carbon source used by all strains. It appears that this carbon source allows for anaerobic beer spoilage by Pectinatus and Megasphaera despite the spoilage-preventing intrinsic barriers of beer (iso-α-acids, ethanol, low pH, scarce nutrients); thus, extrinsic countermeasures are key for prevention.
September 2024
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35 Reads
Sensors
In fermentation processes, changes in yeast cell count and substrate concentration are indicators of yeast performance. Therefore, monitoring the composition of the biological suspension, particularly the dispersed solid phase (i.e., yeast cells) and the continuous liquid phase (i.e., medium), is a prerequisite to ensure favorable process conditions. However, the available monitoring methods are often invasive or restricted by detection limits, sampling requirements, or susceptibility to masking effects from interfering signals. In contrast, ultrasound measurements are non-invasive and provide real-time data. In this study, the suitability to characterize the dispersed and the liquid phase of yeast suspensions with ultrasound was investigated. The ultrasound signals collected from three commercially available Saccharomyces yeast were evaluated and compared. For all three yeasts, the attenuation coefficient and speed of sound increased linearly with increasing yeast concentrations (0.0–1.0 wt%) and cell counts (R2 > 0.95). Further characterization of the dispersed phase revealed that cell diameter and volume density influence the attenuation of the ultrasound signal, whereas changes in the speed of sound were partially attributed to compositional variations in the liquid phase. This demonstrates the ability of ultrasound to monitor industrial fermentations and the feasibility of developing targeted control strategies.
September 2024
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111 Reads
Microbial Cell Factories
Background The market for beverages is highly changing within the last years. Increasing consumer awareness towards healthier drinks led to the revival of traditional and the creation of innovative beverages. Various protein-rich legumes were used for milk analogues, which might be also valuable raw materials for refreshing, protein-rich beverages. However, no such applications have been marketed so far, which might be due to unpleasant organoleptic impressions like the legume-typical “beany” aroma. Lactic acid fermentation has already been proven to be a remedy to overcome this hindrance in consumer acceptance. Results In this study, a statistically based approach was used to elucidate the impact of the fermentation parameters temperature, inoculum cell concentration, and methionine addition on the fermentation of lupine- and faba bean-based substrates. A total of 39 models were found and verified. The majority of these models indicate a strong impact of the temperature on the reduction of aldehydes connected to the “beany” impression (e.g., hexanal) and on the production of pleasantly perceived aroma compounds (e.g., β-damascenone). Positively, the addition of methionine had only minor impacts on the negatively associated sulfuric compounds methional, dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide. Moreover, in further fermentations, the time was added as an additional parameter. It was shown that the strains grew well, strongly acidified the both substrates (pH ≤ 4.0) within 6.5 h, and reached cell counts of > 9 log10 CFU/mL after 24 h. Notably, most of the aldehydes (like hexanal) were reduced within the first 6–7 h, whereas pleasant compounds like β-damascenone reached high concentrations especially in the later fermentation (approx. 24–48 h). Conclusions Out of the fermentation parameters temperature, inoculum cell concentration, and methionine addition, the temperature had the highest influence on the observed aroma and taste active compounds. As the addition of methionine to compensate for the legume-typical deficit did not lead to an adverse effect, fortifying legume-based substrates with methionine should be considered to improve the bioavailability of the legume protein. Aldehydes, which are associated with the “beany” aroma impression, can be removed efficiently in fermentation. However, terminating the process prematurely would lead to an incomplete production of pleasant aroma compounds.
August 2024
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54 Reads
During the primary fermentation of beer, the yeast simultaneously carries out a series of processes such as cell growth, pH shift, and the formation and degradation of essential flavour components. Harvested yeast from a previous fermentation can be used to inoculate the fermentation or fresh cells can be produced through aerobic propagation. This study investigated the influence of different aeration conditions during Saccharomyces pastorianus ssp. carlsbergensis propagation on the cell count development and the production of secondary metabolites during the subsequent primary beer fermentation. Propagations were conducted by applying six different dissolved oxygen concentrations, and the cells were used as inoculum for the subsequent fermentation. Cell count, pH shift, and the development of key aroma compounds were monitored throughout the primary fermentation to evaluate any difference between the conducted fermentations. The outcomes revealed significant distinctions between fermentations using yeast propagated under elevated oxygen levels and those propagated under reduced oxygen levels. Cells propagated using lower oxygen concentrations showed earlier cell growth with 40% lower final cell counts, resulting in 50% reduced biomass yields. Additionally, lower oxygen concentrations during propagation led to lower pH shifts during primary fermentation with 20% more higher alcohols and elevated formation of acetaldehyde, and esters.
August 2024
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47 Reads
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1 Citation
Lupines and faba beans are rising stars among legumes as sources of valuable, vegan plant‐based proteins. To enter new application areas like the production of protein‐rich refreshing beverages, the typical beany aroma impression has to be overcome, and the sensory appearance has to be improved, as it can be accomplished with lactic acid fermentation. An extensive strain screening of 70 lactic acid bacteria from 16 genera was performed to identify suitable strains to transform substrates made from lupines and faba beans into refreshing beverages and to improve their sensory characteristics. By analyzing carbohydrate utilization, production of organic acids and aroma compounds, and sensory appearance, 22 strains for lupine and eight strains for faba bean were preselected. Subsequently, the most suitable strains (five for lupine and three for faba beans) were identified by a trained sensory panel, and finally their growth kinetics were discussed. Generally, the aroma profile varied highly with the utilized strain. However, by selecting suitable strains, the beany impression can be highly reduced and pleasant aroma impressions (e.g., fruity and buttermilk) can be added. Most strikingly, it was proven that using germinated lupines and faba beans instead of raw ones can bypass the usual growth restriction, and the strain selection can be focused exclusively on sensory aspects. This opens the option to use strains usually excluded for the fermentation of legumes due to their lack of utilization of the legume‐typical α‐galactosides.
August 2024
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17 Reads
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1 Citation
Food Research International
June 2024
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18 Reads
Biotechnology and Bioprocess Engineering
Innovative soft sensor concepts can recalibrate automatically when the prediction performance decreases due to variations in raw materials, biological variability, and changes in process strategies. For automatic recalibration, data sets are selected from a data pool based on distance-based similarity criteria and then used for calibration. Nevertheless, the most appropriate data sets often are not reliably selected due to variances in the location of landmarks and process length of the bioprocesses. This can be overcome by synchronization methods that align the historical data sets with the current process and increase the accuracy of automatic selection and recalibration. This study investigated two different synchronization methods (dynamic time warping and curve registration) as preprocessing for the automatic selection of data sets using a distance-based similarity criterion for soft sensor recalibration. The prediction performance of the two soft sensors without synchronization was compared to the variants with synchronization and evaluated by comparing the normalized root mean squared errors. Curve registration improved the prediction performance on average by 24% ( Pichia pastoris ) and 9% ( Bacillus subtilis ). Using dynamic time warping, no substantial improvement in prediction performance could be achieved. A major factor behind this was the loss of information due to singularities caused by the changing process characteristics. The evaluation was performed on two target variables of real bioprocesses: biomass concentration prediction in P. pastoris and product concentration prediction in B. subtilis .
May 2024
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40 Reads
Journal of Food Measurement and Characterization
An ultrasonic-based method was developed to enable in-line measurements of foam structure parameters for highly aerated batters by mode conversion. Biscuit batters were foamed to different degrees (density: 364–922 g/L) by varying the mixing head speed and pressure. Density and foam structure changes were detected by efficient offline analytics (nref measurement = 96). Ultrasonic signal data were recorded using two ultrasonic sensors attached to an industry-standard tube. Mode conversion effects in the ultrasonic signals were obtained to predict the rheological parameters of the batters. The frequency range in which surface waves are expected was particularly suitable for detecting rheological changes in highly aerated batters. An ultrasonic-based, online-capable method for process monitoring was implemented and established regarding feature selection in combination with machine learning and 5-fold cross-validation. The developed ultrasonic sensor system shows high accuracy for online density measurement (R² = 0.98) and offers decent accuracy for measurements of foam structure parameters (Bubble count: R² = 0.95, Relative span: R² = 0.93, Sauter diameter: R² = 0.83). The main benefit of this novel technique is that integrating ultrasonic signal features based on mode conversion leads to a robust foam structure analysis, which has the advantage of being retrofitable into existing processes.
... However, its main use is in the production of malt (Slomp et al., 2020). During malting, the barley grain undergoes hydration, germination and drying, processes that promote biochemical changes that facilitate the release of sugars and essential amino acids, contributing to the sensory quality of the beer (De Carvalho et al., 2018;Almaguer et al., 2024;Polachini et al., 2023). ...
August 2024
Food Research International
... The result of a LAB fermentation depends highly on the selected strain and on the fermentation parameters. High variations in the resulting aroma spectrum were studied in soy [19], lupine, and faba bean [20]. The high impact of the fermentation temperature and the inoculum cell concentration on the resulting aroma profile or sensory attributes were described for the fermentation of beer [21] and kwass [22]. ...
August 2024
... The physically informed deep neural networks (PINN) have emerged as an attractive alternative to conventional numerical methods for solving forward and inverse continuum mechanics problems (Karniadakis et al., 2021;Raissi et al., 2019). They allow the incorporation of known physical laws that are described by partial differential equations (PDE) and associated boundary conditions, on a set of collocation points, directly into the training loss function, such that the trained neural networks obey the underlying physical principles of the problem under consideration (Aygun et al., 2023;Manavi et al., 2024). As a result, PINN require less training data than purely data-driven approaches that do not impose physics constraints, leading to enhanced interpretability and generalizability. ...
January 2024
Engineering Applications of Artificial Intelligence
... Volatolomics examines the volatile organic compounds emitted by organisms (Myridakis et al., 2023). Sensomics investigates the sensory attributes of food and beverages, such as taste, aroma, texture, and appearance (Ritter, Ensslin, Gastl, & Becker, 2024). This study will utilize multi-omics technology to comprehensively evaluate the quality characteristics of various fish soup varieties, focusing on attributes like color, aroma, taste, and nutrition. ...
September 2023
Food Chemistry
... Previously, fermentation of soybean by Rhizopus oligosporus led to a high yield of GABA (Rousta et al., 2023;Jaeger et al., 2024) while the production of asparagine (Asn) was also observed during the same fungal fermentation (Sulagna, 2020). HCA made with side-stream flour containing malt rootlets exhibited higher concentrations of FAAs, consistent with other literature findings (Bretträger et al., 2023). The above-mentioned studies justify also the presence of Asp, Asn, and Orn amino acids in HCA instead of the control sample. ...
September 2023
Journal of the American Society of Brewing Chemists
... Future studies should explore emerging methods for in-situ 682 visualization of evolving particle networks under shear. For example, the connection of a laser 683 scanning microscope (Rheo-CLSM) (Vidal, et al. 2023) or an optical microscope (Rheo-684 optical) (Hao, et al., 2021) with a rheometer could provide valuable insights. Anyway, these 685 findings give us hope that the nano-and mesoscale structure of the network within a fat 686 replacer such as capillary oleogel were to be tailored in a specific way, there is potential for 687 ...
August 2023
Journal of Texture Studies
... The rheological study makes it possible to parameterize the characteristics of the sample with the microstructure of the material, using the determination of the linear viscoelastic regime (LVE) 26,27 . The structural stability of BLs was studied with an angular frequency sweep between 100-0.1 rad s −1 with a constant shear strain of 0.1%. ...
August 2023
Polymers
... Among these, 19 PCs are OHCs (Table S8), known for their flavor-active properties in malt (Coghe et al., 2004;Fors, 1983). These findings align with a recent study showing increased heterocyclic compounds in all (pseudo)cereals after kilning (Almaguer et al., 2023). PCs were grouped based on their respective superclasses, and hierarchical clustering analysis (HCA) was performed on the -log10(FDR) values obtained from the ChemRICH analysis (Table S9). ...
August 2023
... 3-Methyl-1-butanol in QLK, which is the main component of higher alcohols, has a bitter almond flavor and is the main aroma component of Italian Grappa and has also been detected in passion fruit wines (Ye, Zhang, Hao, Lin, & Bao, 2023). Esters usually provide pleasant flavors to food products, and Cynthia Almaguer et al. similarly detected 2,4-hexadienoic acid ethyl ester in barley and rye aroma profiles, which, as a characteristic volatile compound of QLK, contributes to fruit flavors such as apple, banana, and pineapple aromas in QLK (Almaguer, Kollmannsberger, Gastl, & Becker, 2023).The above volatile compounds give QLK its fruity and floral flavor. ...
June 2023
Food Chemistry
... The study focused on ionically crosslinked hydrogels formed through the interaction between alginate and calcium chloride (CaCl₂) solutions. While numerous studies have investigated alginate and CaCl2 hydrogels [29], [30], [31] this work uniquely combines automated hydrogel synthesis with real-time imaging of hydrogel beads, enabling in-situ characterization of the cross-linking process. Alginate is a natural biopolymer derived from brown seaweed, and widely used in biomedical applications [32], [33] due to its ability to form gels in the presence of divalent cations such as calcium. ...
June 2023