Search Results (110)

The objective of this research is to develop environmentally friendly, risk-free and effective adsorbent composite beads that remove Cu(II) ions from aqueous solutions using cost-effective biopolymers (Carboxymethylcellulose (CMC) and sodium alginate (AL)). The synthesized hydrogel beads (AL@CMC) were dried using two drying modes, namely air-drying and freeze-drying, and characterized using scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Brunauer–Emmett–Teller (BET) analysis. The study investigated factors such as pH, adsorbent dosage, reaction time, Cu(II) ions concentration, and temperature to elucidate the adsorption mechanisms involved in removing copper ions. The results indicated that the hydrogel exhibited a maximum adsorption capacity of 99.05 mg·g⁻¹, which is highly competitive compared to previous studies; the AL@CMC beads prepared in this work show a significantly higher adsorption capacity, improved stability due to the interpenetrated biopolymer network, and a clear enhancement from freeze-drying, which greatly increases porosity and active surface area. In addition, the pseudo-second-order nonlinear kinetic model best described the experimental data, implying the chemical nature of the adsorption process. Furthermore, the thermodynamic studies revealed that the adsorption process was endothermic, spontaneous, and homogenous. A Monte Carlo simulation model was utilized to ensure compatibility with the adsorption mechanism, in order to delve deeper into the intricacies of the adsorption process and gain a more comprehensive understanding of its underlying mechanisms and behavior. In conclusion, the prepared hydrogel beads proved to be an effective adsorbent for efficiently removing copper ions, making them a promising solution for addressing Cu(II) ion pollution. Full article

The blast-wave model with Boltzmann–Gibbs statistics is used to examine the transverse momentum spectra of ${K\ast }^0$ mesons generated at the Relativistic High-Energy Collider (RHIC) Beam Energies with mid-rapidity ($\left|y\right|<1$) in symmetric $Au-Au$ collisions. There is a clear correlation between the extracted kinetic freeze-out temperature ($T_0$) and transverse flow velocity (${\beta }_T$) in various collision centralities and center-of-mass energies ($\sqrt{s_{NN}}$). Since a larger initial energy density delays freeze-out and a shorter system lifetime limits cooling, $T_0$ is directly proportional to both $\sqrt{s_{NN}}$ and peripheral collisions. On the other hand, ${\beta }_T$ drops in peripheral symmetric collisions due to weaker collective expansion, while it rises with $\sqrt{s_{NN}}$ because of larger pressure gradients. The concurrence between the thermal and collective energy components in the expanding fireball is reflected in the obvious anti-correlation between $T_0$ and ${\beta }_T$. These findings support hydrodynamic predictions and offer important new information about QGP’s freeze-out behavior. Full article

Strawberries and blueberries are globally recognized for their dense nutritional profile, bioactive compounds, and health-promoting properties. Yet, their perishability and seasonality limit their availability, stability, and functionality in food and nutraceutical formulations. Drying technologies, particularly spray drying and freeze drying, are effective preservation strategies that convert fresh berries into stable, shelf-ready powders. However, the high sugar content, low glass transition temperature (Tg), and hygroscopic nature of berry matrices pose significant challenges in maintaining powder flowability, preventing caking, and ensuring structural integrity during processing, storage, and transportation. This review examines the physicochemical and surface properties of strawberry and blueberry powders as influenced by the drying method, environmental conditions, and carrier selection (e.g., maltodextrin, gum arabic, and whey proteins). Emphasis is placed on glass transition phenomena, moisture sorption behavior, and surface composition as determinants of physical stability and shelf life. The roles of water activity (aw), particle morphology, and interparticle interactions are analyzed in the context of formulation design and powder performance. Analytical techniques in characterizing bulk properties for the amorphous structure and sorption kinetics and probing surface properties of powders are crucial for understanding interactions with water, assessing flow, caking, sintering, and dissolution. By integrating insights from food physical chemistry and materials surface properties, this review provides a framework for the rational design of berry-based powders with improved handling, stability, and bio-functionality. The findings have direct implications for scalable production, global distribution, and the development of functional ingredients aligned with health and wellness priorities worldwide. Full article

The phenomenon of seawater flow-freezing exists during ballast water injection and drainage in polar vessels, but the heat transfer and ice evolution behaviors under low-temperature flow conditions remain unclear. This study developed a computational model for ballast tank freezing using the volume of fluid (VOF) and enthalpy–porosity method, and constructed a scaled experimental platform for the simulation model validation. Based on this model, the flow-heat transfer and ice evolution process in the ballast tank are analyzed in detail, with a focus on the influence of injection velocity, pipe diameter, and position on seawater freezing characteristics. The results show that during low-temperature water injection, phase change occurs preferentially in the tank bottom region, with ice presenting as a slurry morphology; when injection velocity increases from 0.25 m/s to 3.5 m/s, the maximum ice-phase volume fraction increases by 48.9%, indicating faster flow accelerates phase-change freezing; compared to other diameters, DN150 piping exhibits the highest turbulent kinetic energy (0.054 m²/s²) and the maximum shear stress (12.49 Pa), demonstrating optimal freezing resistance; compared to bottom injection, sidewall injection intensifies heat transfer/icing near tank walls and increases ice-clogging risk around ports. This study reveals intrinsic mechanisms of dynamic ice-blockage evolution, providing theoretical basis for anti-clogging design in polar ship systems. Full article

Apple pomace, a by-product of juice production, is a rich source of dietary fiber and bioactive compounds, making it a promising functional ingredient for bakery applications. This study evaluated the physicochemical and sensory properties of shortbread cookies enriched with apple pomace dried under different conditions, while also analyzing the drying process, focusing on drying kinetics and powder characteristics. Pomace dried by either contact drying or freeze-drying was ground and used to replace 20% of wheat flour in the cookie formulation. Drying kinetics were best described by the modified Page model, and freeze-dried pomace showed higher grindability than contact-dried samples. Cookies enriched with pomace exhibited similar overall composition, with differences mainly observed in fiber content (9.82–11.75%). Those containing freeze-dried pomace were lighter, with reduced red and increased yellow tones, and were firmer, requiring approximately 30% higher cutting force. Despite differences in physical properties, enriched cookies were consistently rated higher in overall acceptability than the controls. The results indicate that the drying method and temperature influence the physicochemical properties of apple by-product and the resulting cookies, while having mainly minor effects on sensory acceptance, confirming the potential of apple pomace as a functional ingredient in bakery products. Full article

Over the past few years, consumers’ preference for wines with a distinct regional identity has shifted producers to adopt traditional grape varieties and has increased interest in the indigenous grapevine microbiome, due to its potential influence on the wine quality characteristics. In the present study, indigenous Saccharomyces cerevisiae strains were isolated from 3 local grape varieties (“Keratsouda”, “Karnachalas”, and “Bogialamas”) of the Soufli region in northern Greece. After molecular identification, all strains were evaluated for key oenological traits (ethanol resistance, SO₂ resistance, H₂S production, and aminoacid decarboxylation). Three representative strains (one per grape variety) were further evaluated for their long-term survival after freeze-drying and their fermentation potential at 12 °C and 22 °C. Ethanol content ranged in similar values (11.9–12.5%) for all wines, but kinetic parameters were significantly affected by the strain used and the fermentation temperature. Principal component analysis revealed that the volatile composition as well as practical wine attributes were affected by both the strain used and the fermentation temperature and resulted in distinct sensory profiles in the new products. Full article

In this study, we investigated environmentally responsive photoluminescence color changes in water using an amphiphilic flavin derivative (1a) functionalized with an alkylsulfonate group. At low concentrations and room temperature, 1a exhibited a green emission. Upon increasing the concentration, thermodynamically stable micelle-like aggregates were formed, leading to a yellow emission. In contrast, under rapid freezing conditions, fibrous aggregates were formed under kinetic control, which also exhibited a yellow emission. These distinct aggregation modes are attributed to the cooperative effects of molecular design: the π-stacking ability of the tricyclic isoalloxazine core, flexible long alkyl chains, and the hydrophilic sulfonate moiety. This work demonstrates photoluminescent color switching based on aggregation-state control of a biogenic and potentially sustainable flavin luminophore, offering a new perspective for designing responsive and sustainable photofunctional materials. Full article

Ice nucleation temperatures and associated ice growth rates are critical parameters in defining the initial ice morphology template, which governs dry layer resistance during sublimation and therefore impacts primary drying kinetics and overall process time. In this study, we developed a through-vial impedance spectroscopy (TVIS) method to determine both ice nucleation temperature and average ice growth rate, from which future estimation of average ice crystal size may be possible. Whereas previous TVIS applications were limited to solutions containing simple, uncharged solutes such as sugars, our adapted approach enables the analysis of conductive solutions (5% sucrose with 0%, 0.26%, and 0.55% NaCl), covering osmolarities below and above isotonicity. We established that the real part capacitance at low and high frequencies—either side of the dielectric relaxation of ice—provides the following: (i) a temperature-sensitive parameter for detecting the onset of ice formation, and (ii) a temperature-insensitive parameter for determining the end of the ice growth phase (unaffected by temperature changes in the frozen solution). This expanded capability demonstrates the potential of TVIS as a process analytical technology (PAT) for non-invasive, in situ monitoring of freezing dynamics in pharmaceutical freeze-drying. Full article

The current study explores the changes in beef quality following partial freezing and during superchilled storage, alongside chilled storage comparisons. Kinetic models were developed to predict changes in colour difference (∆E), thiobarbituric acid−reactive substances (TBARS), total volatile basic nitrogen (TVB−N), drip loss and firmness. Beef samples were partially frozen in an air blast freezer at −30 °C for 9 min prior to storage at −5 °C, −4 °C, −2.8 °C, −1.8 °C. Chilled beef samples were directly stored at 2 °C and 6 °C without partial freezing. All samples were stored for 21 days. The lightness (L*), redness (a*), yellowness (b*) and colour difference (∆E) were significantly lower in superchilled storage samples compared to chilled storage samples. The pH of beef samples increased gradually over time (p < 0.05). TBARS, TVB−N and drip loss increased while firmness decreased with the increase in storage time in both storage conditions (p < 0.05). Overall, beef quality was affected by both storage duration and temperature. Firmness followed the first order kinetic model; drip loss, TVB−N, TBARS and colour difference (∆E) fitted the zero−order kinetic model. Temperature dependence was adequately modelled using Arrhenius−type equation with the activation energy values of 110.111, 52.870, 68.553, 119.480, 47.301 kJ/mol for drip loss, firmness, TBARS, TVB−N and colour difference (∆E), respectively. The models demonstrated strong predictive performance, with RMSE and MAPE values within ±10%. The developed kinetic models successfully predicted quality changes within the −5 °C to 6 °C temperature range. Full article

This study employs advanced numerical simulation to investigate the influence of shelf temperature on the freeze-drying kinetics and product quality of Cordyceps militaris. Emphasis is placed on the glass transition and structural collapse mechanisms during the primary drying stage. A detailed computational model was developed to predict temperature profiles, glass transition temperature, collapse temperature, and moisture distribution under varying process conditions. Simulation results indicate that maintaining the shelf temperature below 10 °C minimizes the risk of structural collapse and volume shrinkage while improving drying efficiency and product stability. Based on the model, an optimal freeze-drying protocol is proposed: shelf heating at 0 °C, condenser plate at −32 °C, and chamber pressure at 35 Pa. Experimental validation confirmed the feasibility of this regime, yielding a shrinkage of 9.52%, a color difference (ΔE) of 4.86, water activity of 0.364 ± 0.018, and a rehydration ratio of 55.14 ± 0.789%. Key bioactive compounds, including adenosine and cordycepin, were well preserved. These findings underscore the critical role of simulation in process design and optimization, contributing to the development of efficient and high-quality freeze-dried functional food products. Full article

This study describes both experimental and numerical investigations into the heat and mass transfer processes governing the vacuum freeze drying of camel milk, with a specific focus on improving the energy efficiency. A three-dimensional model was developed and solved using the finite element method to simulate temperature evolution and sublimation interface progression during drying. The numerical model was validated against experimental data, achieving strong agreement, with an $R^2$ value of 0.94. A detailed parametric analysis examined the effects of the shelf temperature, sample thickness, and chamber pressure on the drying kinetics and energy input. The results indicate that optimising these parameters can significantly reduce the energy consumption and processing time while maintaining product quality. Notably, reducing the sample thickness to 4 mm shortened the drying time by up to 40% and reduced the specific energy consumption (SEC) from 358 to 149 kWh/kg. These findings offer valuable insights for the design of more energy-efficient freeze drying systems, with implications for sustainable milk powder production and industrial-scale process optimisation. Full article

The objective of this study was to obtain and evaluate a coffee aroma extract/oil with sensorial attributes close to the original brew of Greek coffee for use in an instant Greek coffee powder. The oil was obtained directly from commercial Greek coffee by solid-liquid extraction using hexane as a solvent and treated with a series of hexane-ethanol mixtures (0:10, 1:4, 1:9) to remove the intense roasted flavor of the crude coffee oil obtained by hexane; the de-oiled coffee was used for the recovery of water-soluble compounds, and the produced water extract was freeze-dried. The aromatic volatiles of the coffee oil samples were analyzed by using a purge-and-trap device coupled to GC-MS, as well as sensory analysis. The instant Greek coffee powder was produced by mixing the freeze-dried base (74.4%) with the extract derived after treatment of the crude oil with hexane-ethanol mixture 1:4 (18.2%) and foaming agent (7.4%). Two different materials were studied as bases: instant coffee (F3_Gr-D) and ground Greek coffee (reference sample, C_Gr). The shelf-life stability of the produced powders was examined at three storage temperatures (25, 45, 60 °C). Instrumental analysis (purge-and-trap GC-MS) of aroma and sensory analysis (aroma, taste, staling, total sensory quality on a 1–9 hedonic scale) was conducted. Aroma loss (furfuryl alcohol, furfural, dimethyl pyrazines, ethyl methyl pyrazines) and scores for sensory attributes during storage were modeled using 1st and 0-order reaction kinetics, respectively. The storage temperature effect was expressed by the Arrhenius model (activation energy E_a). According to the results, the developed instant coffee powder presented satisfactorily the aroma characteristics of regular Greek coffee. The shelf life for the instant Greek coffee powder was estimated as 80 days (air packed) (based on 20% retention of furfuryl alcohol that was the most abundant aromatic volatile of Greek coffee aroma, ground as well as extract oil). Full article

This study systematically investigated the drying kinetics and quality characteristics of Houttuynia cordata Thunb. (HCT) under different processing conditions, evaluating how freeze-drying and hot-air drying (40 °C, 50 °C, 60 °C) affect bioactive compound preservation, antioxidant efficacy, and metabolic profiles to identify the optimal drying method for maximizing its functional benefits. A thin-layer drying model was established to evaluate drying parameters such as effective diffusion coefficient and activation energy. Changes in chemical composition, sensory properties, and antioxidant activity were analyzed using UHPLC-LTQ-Orbitrap-MS, electronic nose/tongue, and HepG2 cell assays. Results showed that the Aghabashlo model was optimal for demonstrating the drying process with the best fit. The 50 °C heating temperature was shown to yield the highest diffusion coefficient. Hot-air drying at 50 °C balanced efficiency and sensory quality, whereas 60 °C significantly altered flavor and metabolite composition. Results of the metabolomic analysis indicated that freeze-drying enhanced the retention of phenolic acids and flavonoids, while hot-air drying led to increased fatty acid metabolites. Freeze-drying preserved the antioxidant activity and natural flavor of HCT. Nevertheless, the metabolic fate of rutin, quercetin, and chlorogenic acid was not significantly affected by the drying method (freeze-drying vs. 50 °C drying). These findings provide a theoretical foundation for improving HCT’s therapeutic and sensory qualities through optimized drying techniques. Full article

The performance degradation of sodium-ion batteries (SIBs) in extremely low-temperature conditions has faced significant challenges for energy storage applications in extreme environments. This review systematically establishes failure mechanisms that govern the performance of low-temperature SIBs, including significantly increased electrolyte viscosity, lattice distortion and adverse phase transitions in electrodes, and sluggish desolvation kinetics at the solid electrolyte interface. Herein, we specifically summarize a series of multi-scale optimization strategies to address these low-temperature challenges: (1) optimizing low-freezing-point solvent components and regulating solvation structures to increase ionic diffusion conductivity; (2) enhancing the hierarchical structure of electrodes and optimizing electron distribution density to improve structural stability and capacity retention at low temperatures; and (3) constructing an inorganic-rich solid electrolyte interphase to induce uniform ion deposition, reduce the desolvation barrier, and inhibit side reactions. This review provides a comprehensive overview of low-temperature SIB applications coupled with advanced characterization and first-principles simulations. Furthermore, we highlight solvation-shell dynamics, charge transfer kinetics, and metastable-phase evolution at the atomic scale, along with the critical pathways for overcoming low-temperature limitations. This review aims to establish fundamental principles and technological guidelines for deploying advanced SIBs in extreme low-temperature environments. Full article

This study aimed to investigate the impact of ultrasonic pretreatment vacuum drying (UAVD) and temperature on drying kinetics and qualitative attributes of blood oranges in comparison to several drying methods: hot air drying (HAD), vacuum drying (VD), and freeze drying (FD). The drying kinetics and modeling, total phenolic content (TPC), antioxidant capability (assessed using DPPH and ABTS tests), individual phenolic profiles, vitamin C concentration, and color factors were meticulously examined. Drying times were recorded as 22.5 h, 12.5 h, and 9 h for HAD; 11.5 h, 9.5 h, and 8.5 h for VD; and 10 h, 8.5 h, and 7.5 h for UAVD at 50, 60, and 70 °C, respectively. The HAD, VD, and UAVD procedures were conducted at 50, 60, and 70 °C, resulting in reduced drying periods with increasing temperature. The integration of ultrasound markedly lowered drying durations. Eleven thin-layer drying models were utilized to recreate the drying process precisely. The D_eff values of the HAD, VD, and UAVD dried samples varied from 9.08 × 10⁻⁶ to 2.82 × 10⁻⁵ m²/s, from 2.60 × 10⁻⁵ to 2.96 × 10⁻⁵ m²/s, and from 2.20 × 10⁻⁵ to 2.99 × 10⁻⁵, respectively. Among the desiccated blood orange slices, the greatest total phenolic content (TPC) was observed in freeze-dried samples (131.27 mg GAE/100 g), followed by those dried using ultrasonic-assisted vacuum drying (UAVD) at 50 °C (128.77 mg GAE/g DM). Dried blood orange slices had a vitamin C content of 29.79 to 49.01 mg/100. The drying process substantially impacted the color parameters L*, a*, and b*. These findings highlight the efficacy of ultrasound-assisted drying in decreasing drying duration while improving the retention of bioactive components in blood orange slices. Full article