Search Results (225)

The aim of the study was to use vacuum impregnation (VI) with onion and beetroot juices as a pre-treatment before drying to develop innovative dried kohlrabi products. Two modern drying techniques were used: freeze-drying (FD) and vacuum drying (VD). The physicochemical properties were determined, including color, water activity, dry matter, density, volumetric gel index, texture, antioxidant capacity, total phenolic content (TPC), and volatile organic compounds (VOCs). It was shown that vacuum impregnation reduced the color lightness and springiness of kohlrabi. In addition, vegetables after VI showed an increase in dry matter, water activity, bulk density, volume gel index, color attributes a* and b*, color difference, hardness, and chewiness. Furthermore, the pre-treatment allowed for the introduction of additional VOCs characteristic of onions (1-Heptene, 2-methyl-(19.81%), Pentyl formate (19.81%), and 4-(Methylthio)butyl isothiocyanate (18.22%) in kohlrabi with onion juice: dimethyl trisulfide, methyl prop(en)yl disulfide, and 3,5-diethyl-1,2,4-trithiolane) and beetroot (dimethyl trisulfide), myrcene. The vacuum impregnation process significantly increased antioxidant capacity and total polyphenol content compared to raw samples. The results of dry weight, water activity, density, TPC, antioxidant capacity and texture in the case of freeze-dried products confirm that FD is a more advantageous method. In addition, freeze-drying allowed for significant preservation of volatile compounds and the color of kohlrabi. The results indicate the potential of VI as a method for modifying the properties of kohlrabi and producing functional and innovative dried products. Full article

Four Botryosphaeria spp. isolated from apple with dieback symptoms, Diplodia mutila, Diplodia seriata, Neofusicoccum arbuti, and Lasiodiplodia theobromae, were subjected to different conditions to induce sporulation, then freeze-dried and stored in glass vials and ampoules at a temperature of 4 ° C using two protective media (skimmed milk powder in water at 20% and a mixture of skimmed milk powder at 20% plus 5% inositol). Viability was assessed after storage periods of 1, 90, 180, and 365 days. Low-nutrient growth conditions on 2% water agar supplemented with pine needles, incubated under UV light (λ = 350 nm) and at 24 ° C, effectively stimulated sporulation of all four Botryosphaeriaceae species. The survival rate of the isolates was similar. Overall viability showed slight but significant differences depending on the type of protective medium and storage container used for the freeze-dried cultures (p < 0.001). Among the tested media, the highest viability was maintained in vacuum-sealed glass ampoules using either a medium containing 20% skimmed milk powder with 5% inositol or 20% skimmed milk powder alone. Full article

To identify the optimal drying methods for turnip slices, vacuum freeze-drying (VFD), air impingement drying (AID), infrared-assisted hot air drying (IR-HAD), and conventional hot air drying (HAD) were evaluated. The physicochemical properties of dried samples were comprehensively assessed under varied drying conditions. The results demonstrated that AID achieved the shortest drying time (240 min). At identical temperatures, AID samples exhibited significantly lower total color difference (ΔE) compared with IR-HAD and HAD, alongside superior retention of total phenols and enhanced antioxidant activity. VFD yielded the highest quality attributes, including optimal rehydration capacity, maximal phenol retention, and the strongest antioxidant activity (DPPH: 16.56 ± 0.26 μmol Trolox/g; FRAP: 13.99 ± 0.04 μmol Trolox/g). SEM analysis revealed that VFD produced a loose, porous microstructure, explaining its enhanced rehydration. Overall, both AID (efficiency) and VFD (quality) show promise for industrial turnip processing. Full article

Oranges are popular worldwide, due not only to their refreshing taste but also to their high content of bioactive compounds. The main phytochemicals in oranges are phenolic compounds, vitamins, and carotenoids, which contribute to their antioxidant and anti-cancer activities. Various drying methods are used to remove the high moisture content in orange products to extend their shelf life. This review summarizes and compares the effects of different drying methods such as hot air drying, freeze drying, vacuum drying, spray drying, microwave drying, solar drying and innovative pretreatment on the physicochemical quality of orange products including slices, peels, and by-products. It lists the key parameters, advantages, and disadvantages of drying methods, as well as a decision tree for “product type-constraints-recommended drying method with pretreatment”. For example, the results indicate that vacuum microwave drying is effective in drying orange slices, and control techniques are employed to assist the drying process. Freeze drying preserves more phytochemicals in orange peels and their by-products, which results in higher antioxidant activity. Pretreatments like pulsed electric field and ozone enhance drying efficiency and phytochemical retention. Different drying methods are adopted to treat different by-products. This work can be used as a guide for selecting the optimal drying technique to balance efficiency, nutritional quality, and industrial scalability for different orange products. Full article

Preformed porous media (PPM) technology has emerged as a transformative approach to enhance heat and mass transfer in vacuum freeze-drying (VFD) of agricultural and food products. This review systematically analyzes recent advances in PPM research, with particular focus on spray freeze-drying (SFD) as the dominant technique for precision pore architecture control. Empirical studies confirm PPM’s efficacy: drying time reductions of 20–50% versus conventional VFD while improving product quality (e.g., 15% higher ginsenoside retention in ginseng, 90% enzyme activity preservation). Key innovations include gradient porous structures and multi-technology coupling strategies that fundamentally alter transfer mechanisms through: resistance mitigation via interconnected macropores (50–500 μm, 40–90% porosity), pseudo-convection effects enabling 30% faster vapor removal, and radiation enhancement boosting absorption by 40–60% and penetration depth 2–3 times. While inherent VFD limitations (e.g., low thermal conductivity) persist, we identify PPM-specific bottlenecks: precision regulation of pore structures (<5% size deviation), scalable fabrication of gradient architectures, synergy mechanisms in multi-field coupling (e.g., microwave-PPM interactions). The most promising advancements include 3D-printed gradient pores for customized transfer paths, intelligent monitoring-feedback systems, and multiscale modeling bridging pore-scale physics to macroscale kinetics. This review provides both a critical assessment of current progress and a forward-looking perspective to guide future research and industrial adoption of PPM-enhanced VFD. Full article

Background: Enhancing bioavailability is the target of most pharmaceutical research; this can be achieved by modifying the physico-chemical characteristics of poorly water-soluble drugs intended for oral administration using different techniques. The preparation of liquitablets by blister molding technique provides an opportunity to increase the bioavailability of the drug using an optimal combination of release-facilitating additives. Lornoxicam is an effective non-steroidal anti-inflammatory drug with low water solubility. This study aimed to formulate a novel lornoxicam-containing liquitablets. The effect of different drying techniques on the physico-chemical properties and in vitro dissolution of lornoxicam was investigated. The physical parameters of the tablets were also studied. Methods: The additives applied in the formulation included Tween^® 80, Polyvinylpyrrolidone (PVP K90), Avicel^® PH-102, and sodium bicarbonate. Vacuum-drying and freeze-drying were employed to produce liquitablets. The influence of various drying methods on crystallinity and intra- and interparticle phenomena was investigated. In Vitro dissolution tests were performed at pH 1.2, and a comparison was made between our products and commercial tablets using the pairwise similarity factor model (f2). Results: The liquitablets demonstrated high hydrophilicity and a lower crystallinity of the drug. Freeze-dried liquitablet showed improved dissolution compared to that of the pure drug or the vacuum-dried product. A similarity was observed between our freeze-dried product and the marketed fast-release tablets. Conclusions: This research demonstrates that preparation of liquitablet in combination with freeze-drying has a significantly positive effect in improving the in vitro dissolution rate of lornoxicam. Full article

Stevia rebaudiana leaves and extracts need to be promptly dried after harvest to prevent microbial activity and preserve their bioactive compounds, including glycosides, flavonoids, and essential oils. Effective drying also reduces moisture and volume, which lowers packaging, storage, and transportation costs. Therefore, innovative drying methods are necessary to maintain stevia’s physicochemical, sensory, and nutritional properties for functional food formulations. This review evaluates various drying technologies for stevia leaves and extracts, including convective hot air, infrared, vacuum, microwave, freeze, and shade drying, and their impacts on product quality and energy efficiency. It also explores the growing applications of dried and extracted stevia in food products. By comparing different drying methods and highlighting the benefits of stevia in these food formulations, this investigation aims to identify future research directions and optimization strategies for utilizing stevia as a natural sweetener and functional ingredient. Convective hot air drying at higher temperatures was found to be the most energy-efficient, though several studies have reported moderate degradation of key bioactive compounds such as stevioside and rebaudioside A, particularly at elevated temperatures and extended drying times. Infrared drying enhanced antimicrobial activity but resulted in lower levels of polyphenols and antioxidants. Vacuum drying effectively preserved anti-inflammatory compounds like flavonoids. Microwave drying presented strong protection of antioxidant activity and superior particle morphology. Freeze drying, while less energy-efficient, was the most effective at retaining antioxidants, polyphenols, and volatile compounds. Shade drying, though time-consuming, maintained high levels of polyphenols, flavonoids, and essential oils. Advanced techniques like spray drying and electrospraying have been reported to enhance the sensory qualities and stability of stevia extracts, making them ideal for food applications such as dairy and baked products, confectionery, syrups, snacks, jams, preserves, and meat products. Overall, stevia not only serves as a natural, zero-calorie sweetener but also contributes to improved health benefits and product quality in these diverse food formulations. 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 efficient use of renewable lignocellulosic biomass has attracted wide interest, as it promises to reduce the environmental impact of fossil fuel consumption. A recently developed batch-scale process, which produces glycol lignin (GL) from softwood biomass, generates a considerable amount of cellulose-rich solid residues (SRs) as a byproduct. In this study, usable cellulose was isolated from SRs in the form of carboxylated cellulose nanocrystals (O-CNCs). The properties of O-CNCs were investigated to establish a possible integrated biomass utilization system based on the GL production technology. Three different forms of purified SRs—never-dried (N-Cel), freeze-dried (F-Cel), and vacuum-dried (V-Cel) cellulose—were subjected to oxalic acid (OA) hydrolysis at 95 °C for 4 h. The average length of O-CNCs ranged from 90 to 120 nm and the height ranged from 3 to 6 nm for separate particles and from 8 to 20 nm for aggregates. The carboxyl group content was 0.11–0.23 mmol/g O-CNCs. The overall results indicated that the yields, dimensions, surface charges, and thermal stability of the O-CNCs were largely influenced by the nature of the starting cellulose. In addition, O-CNCs prepared from recycled OA exhibited similar properties to those prepared from fresh OA. Full article

Grain drying technology is a core process for ensuring food quality, extending storage life, and improving processing adaptability. With the continuous growth of global food demand and the increasing requirements for food quality and energy efficiency, traditional drying technologies face multiple challenges. This paper reviews six major grain drying technologies, comprising hot air drying, microwave drying, infrared drying, freeze drying, vacuum drying, and solar drying. It provides an in-depth discussion of the working principles, advantages, and limitations of each technology, and analyzes their performance in practical applications. In response to challenges such as high energy consumption, uneven drying, and quality loss during the drying process, the paper also explores the research progress of several hybrid drying systems, such as microwave–hot air drying combined systems and solar–infrared drying systems. Although these emerging technologies show significant potential in improving drying efficiency, energy saving, and maintaining food quality, their high costs, scalability, and process stability still limit large-scale applications. Therefore, future research should focus on reducing energy consumption, improving drying precision, and optimizing drying system integration, particularly by introducing intelligent control systems. This would maximize the preservation of food quality while improving the system’s economic efficiency and sustainability, promoting innovation in food production and processing technologies, and further advancing global food security and sustainable agricultural development. Full article

Ammonia borane (AB), with a theoretical hydrogen content of 19.6 wt%, is constrained by its low crystalline density (0.758 g/cm³) and poor thermal stability (decomposing at 100 °C). In this study, AB/ammonium perchlorate (AP) composites were synthesized via freeze-drying at a 1:1 molar ratio. The integration of AP introduced intermolecular interactions that suppressed AB decomposition, increasing the onset temperature by 80 °C. Subsequent vacuum calcination at 100 °C for 2 h formed oxygen/fuel-integrated ammonium perchlorate borane (APB), which achieved decomposition temperatures exceeding 350 °C. The proposed mechanism involved AB decomposing into borazine and BN polymers at 100 °C, which then NH₃BH₂⁺/ClO₄⁻ combined to form APB. At 350 °C, APB underwent the following redox reactions: 4NH₃BH₂ClO₄ → N₂↑ + 4HCl↑ + 2B₂O₃ + N₂O↑ + O₂↑ + 7H₂O↑ + H₂↑, while residual AP decomposed. The composite exhibited improved density (1.66 g/cm³) and generated H₂, N₂, O_2, and HCl, demonstrating potential for hydrogen storage. Additionally, safety was enhanced by the suppression of AB’s exothermic decomposition (100–200 °C). APB, with its high energy density and thermal stability, was identified as a promising high-energy additive for high-burning-rate propellants. Full article

This study aims to identify the chemical structure and immunomodulatory activity of exopolysaccharides (EPSs) from Acetilactobacillus jinshanensis BJ01 and suggest its potential applications in the pharmaceutical field and as functional food additives. The EPS-1 produced by A. jinshanensis BJ01 was purified using column chromatography. The lyophilized powder obtained by vacuum freeze-drying was used for structural characterization and immunomodulatory activity analysis. Gel permeation chromatography (GPC) determined its molecular weight as 156.58 kDa. High-performance anion-exchange chromatography (HPAEC) identified that the EPS-1 is composed of mannose, xylose, and glucose. The structural characterization of EPS-1 by gas chromatography–mass spectrometry (GC-MS) and 1D/2D nuclear magnetic resonance (NMR) spectroscopy demonstrated that EPS-1 is primarily composed of α-D-Manp-(1→, →2,6)-α-D-Manp-(1→, →2)-α-D-Manp-(1→, and →3)-α-D-Manp-(1→. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) illustrated that EPS-1 exhibited a round, flake-like morphology. In vitro experiments with RAW264.7 macrophages demonstrated the high immunomodulatory activity of EPS-1. Significant upregulation of iNOS, IL-6, and TNF-α mRNA levels was confirmed by qRT-PCR (p < 0.05). Western blotting revealed that EPS-1 (6.25 μg/mL) induced phosphorylation of NF-κB (p65, IκBα) and MAPK (ERK) signaling proteins. This study provides the first structural and immunomodulatory characterization of an exopolysaccharide from A. jinshanensis BJ01, highlighting its potential as a novel immune adjuvant. Full article

Drying constitutes an essential step in aerogel fabrication, where the drying method directly determines the pore structure and consequently influences the material’s functionality. This study employed various drying techniques to prepare balsa-wood-derived aerogels, systematically investigating their effects on microstructure, density, and performance characteristics. The results demonstrate that different drying methods regulate aerogels through distinct pore structure modifications. Supercritical CO₂ drying optimally preserves the native wood microstructure, yielding aerogels with superior thermal insulation performance. Freeze-drying induces the formation of ice crystals, which reconstructs the microstructure, resulting in aerogels with minimal density, significantly enhanced permeability, and exceptional cyclic water absorption capacity. Vacuum drying, oven drying, and natural drying all lead to significant deformation of the aerogel pore structure. Among them, oven drying increases the pore quantity of aerogels through volumetric contraction, thereby achieving the highest specific surface area. However, aerogels prepared by air drying have the highest density and the poorest thermal insulation performance. This study demonstrates that precise control of liquid surface tension during drying can effectively regulate both the pore architecture and functional performance of wood-derived aerogels. The findings offer fundamental insights into tailoring aerogel properties through optimized drying processes, providing valuable guidance for material design and application development. Full article

Yak meat jerky, a traditional high-protein food commonly consumed in high-altitude regions, is often produced via air-drying, which may adversely affect its nutritional quality and digestibility. This study systematically compared the gastrointestinal digestion profiles of air-dried yak meat (ADM) and vacuum freeze-dried yak meat (VFDM) using a dynamic in vitro human stomach–intestine (DHSI-IV) system. Key digestive parameters, including gastric emptying kinetics, particle size distribution, and protein hydrolysis, were evaluated under physiologically relevant conditions. VFDM exhibited superior hydration capacity, contributing to delayed gastric emptying of the mixed solid–liquid phase (t_1/2 = 85.1 ± 1.0 min) compared to ADM (t_1/2 = 80.4 ± 1.2 min), indicating increased gastric satiety. Conversely, VFDM showed a faster solid-phase gastric emptying (t_1/2 = 107.2 ± 0.8 min) relative to ADM (t_1/2 = 113.1 ± 2.7 min), likely due to improved texture and rehydration. Both jerky types exhibited progressive particle disintegration; by 180 min, large particles (>2.0 mm) decreased to 16.88% ± 2.63% in ADM and 20.04% ± 0.64% in VFDM (p > 0.05). Protein digestibility, measured by SDS-PAGE and the degree of hydrolysis (DH), was significantly higher in VFDM (38.5 ± 3.6%) than in ADM (34.0 ± 0.1%, p < 0.05), with VFDM demonstrating more rapid and extensive protein degradation across gastric and intestinal phases. These improvements may be attributed to the porous microstructure and reduced processing-induced protein cross-linking in VFDM, facilitating enhanced enzyme access. Overall, vacuum freeze-drying substantially improved yak jerky protein digestibility, offering the potential for the development of meat-based functional foods targeted at individuals with compromised gastrointestinal function. Full article

The purpose of this study was to investigate the effect of different drying methods on the structure and properties of semicrystalline polymer aerogels. Aerogels, consisting of either globular or strut-like morphologies, were prepared from poly(ether ether ketone) (PEEK) or poly(phenylene sulfide) (PPS) and dried using vacuum drying, freeze-drying, or supercritical CO₂ extraction. Vacuum drying was found to result in aerogels with a higher shrinkage, smaller mesopores (with pore widths of 2–50 nm), and smaller surface areas compared to the use of supercritical extraction as the drying method. Freeze-dried aerogels tended to have properties between those of vacuum-dried aerogels and aerogels prepared with supercritical extraction. High network connectivity was found to lead to improved gel modulus, which increased the ability of aerogels to resist network deformation due to stresses induced during drying. The PEEK and PPS aerogel networks consisting of highly connected strut-like features were considerably stiffer than those composed of globular features, and thus shrank less under the forces induced by vacuum drying or freeze-drying. The aerogels prepared from PPS were found to have larger mesopores and smaller surface areas than the aerogels prepared from PEEK. The larger mesopores of the PPS aerogels induced lower capillary stresses on the aerogel network, and thus shrank less. This work demonstrates that preparing PEEK and PPS gels with strut-like features can allow aerogel processing with simpler evaporative drying methods rather than the more complex supercritical drying method. Full article