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Developing strategies for the production of porous particles with controllable structures using a spray-drying method has attracted attention of researchers for decades. Although many papers have reported their successful production of porous particles using this method, information on how to create and control the porous structures as well as what parameters involving and what formation mechanism occurring during the synthesis process are still not clear. To meet these demands, the present review covers strategies in the spray-drying developments for the fabrication of porous particles with controllable structure. This information is important for optimizing the production of porous particles with desirable properties. Regulation of process conditions and precursor formulations are also explained, including composition, type, and physicochemical properties of droplet and raw components used (i.e., host component, template, and solvent). The electrostatic interactions between the individual components and the droplets are also presented, while this information tends to be neglected in the conventional spray-drying process. To clarify how the porous particles are designed, current experimental results completed with illustrations for the proposal particle formation mechanism are presented. The review also completed with the opportunities and potential roles of the changing porous structures in practical uses. This review would provide information on how to produce porous particles that can be used for advanced functional materials, such as catalysts, adsorbents, and sensors.

The nanopowders of zirconia toughened alumina (ZTA) as soft spherical granules were directly synthesized by combining co-precipitation with spray drying (CPSD). The co-precipitation of alumina (Al2O3) and yttria-stabilized zirconia (YSZ) was performed together in one step to obtain the ZTA precipitate. Spray drying, which is the most preferred industrial processing way to produce the nanopowders as spherical granules, was used to atomize, dry and granulate the suspension like milk prepared from the synthesized ZTA precipitate under previously optimized spray drying conditions. However, the important and complex processing parameters of spray drying such as the solid-liquid ratio and the feeding rate of the suspension, the inlet temperature and the flow rate of the hot air have to be optimized depending on the moll mass and volume of the component in the prepared suspension. The ZTA nanopowders containing 4–20 wt% YSZ synthesized by the CPSD method have a crystalline structure of alumina and YSZ, an average nanoparticle size between 26.64 and 46.70 nm with a very high specific surface area (SSA) between 77.43 and 112.41 m2 g−1 in a soft spherical granule form, which were determined by XRD, BET and SEM, respectively. The preparation and drying conditions of the synthesized precipitate, the solid-liquid ratio of the suspension and the molar mass ratio of YSZ in Al2O3 matrix have a significant effect on the crystallinity, morphology, particle size, SSA, and granule form of the synthesized ZTA nanopowders.

In India, groundnut is mainly used for oil extraction or consumed in roasted form prompting a need for diversification to further increase its value and utility. In the present study, spray drying of groundnut milk was carried out using three variables of spray dryer i.e., inlet air temperature (180–220 °C), atomization air pressure (2–3 bar), feed pump speed (24–36 rpm) using Box-Behnken design of Response Surface methodology. The moisture content of powder decreased with an increase in inlet air temperature and atomization air pressure. The bulk density increased with increase in atomization air pressure. Maximum dispersibility (98.48%) was observed at an atomization air pressure of 2.57 bar. The insolubility index of the powder increased and lightness value (L*) decreased with an increase in inlet air temperature. The optimized conditions for spray drying of groundnut milk were inlet air temperature: 186 °C, atomizing air pressure: 2.5 bar and feed pump speed: 27 rpm.

The suitability of the perilla seed oil Pickering emulsion stabilized by the ovalbumin (OVA) - gum Arabic (GA) polyelectrolyte complex for spray drying was investigated and the resultant powder was characterized. The OVA - GA complex conferred enhanced stability to the emulsion than OVA, GA, and their mixture. The viscosity of the Pickering emulsion was highly sensitive to stabilizer concentration and that fabricated by 2% OVA - GA complex showed acceptable viscosity and powder yield. The Pickering emulsion was more effective in preventing oil leakage during spray drying than the OVA-stabilized emulsion and the resultant powder possessed an oil content of up to 77.7%. Besides, the spray-dried Pickering emulsion powder showed greater rehydration and better flowability than that of the OVA-stabilized emulsion powder. Hence, the Pickering emulsion stabilized by the OVA - GA polyelectrolyte complex is promising as a novel feed for the production of oil powders by spray drying.

The storage of microorganisms in liquid form is the main drawback of commercializing epiphytic coffee yeasts. This work aimed to evaluate the fermentative performance of microencapsulated yeasts by spray drying in a coffee peel and pulp media (CPM). The yeasts, Saccharomyces cerevisiae CCMA 0543, Torulaspora delbrueckii CCMA 0684, and Meyerozyma caribbica CCMA 1738, were microencapsulated using maltodextrin DE10 (MD), high maltose (MA), and whey powder (WP) as wall materials. A Central Composite Rotational Design (CCRD) was used to investigate the effect of operating parameters on the microcapsules' cell viability, drying yield, and water activity. Yeasts reached cell viability and drying yields above 90 and 50 %, respectively. WP maintained the cell viability of the three yeasts over 90 days of storage at room temperature (25 °C) and was selected as a wall material for the three yeasts. M. caribbica showed to be more sensitive to spray drying and less resistant to storage. Some differences were found in the fermentation of the CPM medium, but the microencapsulated yeasts maintained their biotechnological characteristics. Therefore, the microencapsulation of epiphytic coffee yeasts by spray drying was promising to be used in the coffee fermentation process.

Current production of probiotic preparations must meet several criteria to be competitive on the market, like inexpensive growth medium based on sustainable resources, reduction of the number of unit operations, and exploitation of cost-effective preservation method. Implementation of the new solutions should not negatively affect the quality of the product, such as the number of living cells or the product safety. In the present study, we used a highly concentrated, raw corn flour-based (CF) medium for cultivation of probiotic L. plantarum LOCK 0860 strain and as a matrix in the following spray-drying process. Prior to drying, the post-culturing liquid was supplemented with a newly developed, optimized blend of protective agents, shown to increase the cell’s viability over 4-fold. Experimentally obtained data were used for the process model simulation at industrial scale, where the optimized probiotic component was supplemented with inulin as the prebiotic and standardization agent. Techno-economic analysis of this process model indicated a high net present value (NPV) at a selling price of $5.00 per kg of the preparation, which represent highly promising economic benefits. Sensitivity of unit production cost and the number of batches per year was estimated in the simulation, and the critical factors were identified, as well.

A facile synergetic strategy is reported for the synthesis of the LiMnO2@VXC-72R composite microspheres by applying spray-drying technique with nanosized LiMnO2 particles as host material and conductive carbon black (VXC-72R) as dispersing agent. In this hybrid structure, LiMnO2 nanoparticles promote the lithium-ion diffusion due to the nanosized diffusion distance, whereas well-distributed VXC-72R suppress the aggregation of LiMnO2 nanoparticles and enhance the electronic conduction. Moreover, the micro-sized spherical morphology with low specific surface area is conducive to reducing the contact area between electrolyte and composite cathode, which inhibit the manganese dissolution. Benefiting from their synergistic effect, the LiMnO2@VXC-72R composite microspheres achieve the maximum discharge capacity of 187.3 mAh g−1 with good cycling stability at 0.1 C. After 50 cycles, the discharge capacity of composite cathode is still maintained at 173.2 mAh g−1, which is significantly higher compared to the primary LiMnO2 particles. Moreover, the LiMnO2@VXC-72R composite microspheres exhibit outstanding rate performance with high discharge capacity.

Lab-scale experiments were carried out to investigate a new approach of preparing biochar-based catalyst for transesterification reaction. Black liquor (BL) from cotton pulping process was used as a precursor for preparing the catalyst via spray drying followed by fast carbonization in a fluidized bed reactor. Response surface methodology (RSM) was employed to statistically analyze and optimize the entire process of catalytic synthesis of biodiesel from a waste frying oil, consisted of the catalyst preparation and transesterification steps. Several major operation parameters of the biodiesel synthesis process, including alkaline loading in biochar, methanol to oil ratio, catalyst loading, and the carbonization temperature of catalyst, were studied for their effects on biodiesel conversion. The optimal condition for achieving the maximum biodiesel conversion (i.e. 91.5 %) was found to be: 27 wt% alkaline loading in biochar, 600 °C carbonization temperature, 7.7 methanol to oil ratio, and 6.5 wt% catalyst loading. Overall, the spry drying fluidized bed carbonization demonstrated its viability for significantly reducing duration of high temperature carbonization, opening up the prospects of manufacturing the catalyst in a much less energy consumption manor.

The objectives of the current work were (a) to investigate the suitability of soluplus®, a hydrophilic polymer, as a carrier for the entrapment of curcumin (CUR) SEDDS by the spray-drying process, and (b) to compare soluplus® with neusilin® US2, a hydrophobic high-capacity adsorbent for solid SEDDS. Both carriers produced free flowing powders with high CUR entrapment efficiency. When filled into capsules, approximately 95% of CUR was dissolved from the soluplus® powder within 120 min and only 41% from the neusilin® US2 base powder. When the powders were compressed into tablets, a slow CUR release was observed over 24 h, which varied as a function of compression force and the percentage of disintegrant used. In conclusion, current study demonstrated the feasibility of using soluplus® as a carrier for the preparation of solid SEDDS with more favorable release profiles when compared to the conventional hydrophobic adsorbents.

It is a challenge to develop a facile and scaleable approach to boost the application of high-energy fluorinated iron/manganese phosphate cathode materials for sodium-ions batteries. In this study, for the first time, the porous Na2Fe1-xMnxPO4F/C (x = 0.2, 0.4, 0.6, 0.8) nanocomposites are successfully designed via spray drying, following in-situ pyrolytic carbonization process. To examine this synergetic design, the rate capability, cycling stability, and reaction kinetics of the cathode materials are investigated in detail. It is found that the solid solution Na2Fe0.6Mn0.4PO4F/C cathode delivers the high discharge capacities of 94.8 and 30.0 mAh g−1 at 0.05 C and 1.0 C, respectively, and a reversible capacity of 51.0 mAh g−1 after 100 cycles at 0.2 C with a capacity retention of 89.3%. Particularly, the cycling stability as well as rate capability of Na2Fe0.6Mn0.4PO4F/C are superior to those of the other Na2Fe1-xMnxPO4F/C solid solutions and the two-phase mixture of Na2MnPO4F/C and Na2FePO4F/C. Furthermore, the potential strategies to further improve the electrochemical performance of Na2Fe0.6Mn0.4PO4F/C cathode are proposed based on the kinetics analysis of its electrochemical impedance spectroscopy spectra at various charge/discharge depths. It is expected that our research strategies and findings can be extended to other electrode materials in Li+/Na+ storage and beyond.

In this study, sour cherry seed oil (SCSO) loaded gum Arabic (GA)-Maltodextrin (MD) microcapsules were developed by using spray-drying technique. The optimum processing conditions determined using the response surface methodology (RSM) were as follows: a weight ratio of GA to MD (GA:MD composition) of 1:11, a weight ratio of oil to total solid (core-wall ratio) of 20%, and inlet temperature of 195 °C. SCSO powder (SCSOP) was characterized in terms of morphology and size using scanning electron microscopy (SEM), and a laser particle diameter analyzer. The presence of SCSO in GA/MD matrix was confirmed by using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The thermal stability of the SCSOP was assessed using thermogravimetric (TGA) and differential thermal analysis (DTA). Microencapsulation provided a remarkable oxidative stability to SCSOP compared to free sour cherry oil. The antimicrobial potential of the microcapsules were assessed against pathogenic bacteria, yeast and mold.

Application behavior of spray dried powders such as reconstitution behavior and flowability is indirectly influenced by powder particle morphology. We here investigated the influence of the drying conditions and composition for whey protein (WP), maltodextrin (MD) and their mixtures on particle morphology during pilot-scale spray drying. Even though all powders showed a variety of morphologies, MD powders contained more wrinkled particles and had high bulk density, whereas pure WP powders contained more hollow particles. Mixture powders (75:25 WP:MD) show more hollow particles with increasing inlet temperature, with a lower bulk density. The observed morphologies for different formulations corresponded roughly to previous observations during sessile single droplet drying, but the results indicate that the morphology is also influenced by the faster pilot-scale drying, which was not evident in the slower single droplet drying.

This paper reports the synthesis of LiNi0.8Co0.15Al0.05O2 (NCA) cathode powders using a simple flame assisted spray pyrolysis (FSP) and a spray drying (SD) processes, in which metal salt precursors dissolved in glycerol were used for spraying. X-ray diffraction confirms that the NCA powders have a layered structure, with a low order of cationic mixing. Electron microscopy shows that the particles produced by FSP have a relatively smaller size and a smoother surface than that produced by SD. The NCA powder from the FSP process has an initial discharge capacity of 200.2 mAh/g in voltage range of 3.0–4.3 V at 0.1C. It shows very good capacity retention of 91.5% at 1C and 89.4% at 5C after 200 cycles. These results demonstrate that glycerol can replace water and be used as a solvent in spray processes to make cathode powders, promising a new environmentally-friendly synthesis route for battery powder materials production.

This study investigated the microencapsulation of fermented noni juice (FNJ) via a novel pilot scale micro-fluidic-jet-spray-dryer (MFJSD). Different concentrations of maltodextrin (M1, 10–13 DE; M3, 17–20 DE) and gum acacia (GA) were used as wall materials. The physicochemical properties, microstructure, droplet-to-particle formation process and bioactives stability of the powders produced by the MFJSD were examined. Results showed that the M1 powders with 28% solid content (M1, 28%) exhibited better bulk density, particle size, glass transition temperature and hygroscopicity than the other three powders produced (namely the M1 (21%), M3 (28%) and GA (21%) powders). The FNJ powders underwent five different stages during the drying process, from isotropical drying, crust formation, solidification and buckling to final particle formation. The external surface morphology of the powders was obviously influenced by the wall materials selected. However, the drying and wall material type have limited effect on the stability of bioactives in the FNJ powders after microencapsulation and during storage. This study provided insight into the micro-fluidic-jet spray drying of FNJ, and evaluated the properties and stabilities of the powders produced.

Anchovy oil was successfully encapsulated into multi-core microcapsule powder using a two-step microencapsulation method. The inner and outer shells of the microcapsules were created separately using gelatin-SHMP complex coacervates as shell materials. Fucoidan extract was used to crosslink these complex coacervates shells of microcapsules before spray drying. The spray dried microcapsules produced using the two-step method exhibited high encapsulation efficiency (99.83%), low surface oil content (0.10%), high oil payload (55.68%) and significantly improved oxidative stability. The formation of the outer shell during the second cooling step of two-step microencapsulation method significantly improved the oxidative stability of the anchovy oil by smoothing the surface of the microcapsules.

The main goal of this work was to assess if the Supercritical CO2-Assisted Spray Drying (SASD) is a competitive technology for the production of inhalable trehalose and leucine composite particles with advantageous properties and aerodynamic performance while ensuring a high process throughput and yield. For that purpose, a systematic Quality-by-Design approach using the design of experiments tool, followed by a statistical analysis were implemented. A full-factorial design was used to assess the impact of the static mixer pressure, inlet drying gas temperature and feed flowrate on the powder physical properties and in vitro aerodynamic performance. The powders were produced through SASD with yields up to 70%, while enabling the optimization of the overall throughput. Improved in-vitro aerodynamic performance was driven by the successful manipulation of the process parameters, namely by decreasing the feed flowrate and increasing the inlet drying temperature, yielding powders with fine particle fraction values up to 86%.

The formulation of bioactive powders is crucial to their property, functionality and bioaccessibility. This study investigated the incorporation of Ca2+ as a protectant aid for producing active dry probiotics via spray drying, and explored the mechanism underlying the positive effect of Ca2+ on cell viability. At inlet temperature of 98 °C and outlet temperature of 65 °C, supplementing 1 mM CaCl2 to either 10 wt% lactose or 10 wt% trehalose solution increased the survival ratio of Lactobacillus rhamnosus GG (LGG) from 5% to 30%. The growth capability of dried LGG was also enhanced in the presence of calcium. Powder properties including particle morphology, amorphous state and infrared spectrum were minimally influenced at such a low Ca2+ loading. By contrast, adding 1 or 100 mM Ca2+ in reconstitution solution or MRS agar plates notably improved the survival of LGG cells during single droplet drying with pure lactose protectant. The findings suggested that the protective mechanism of Ca2+ is based on enhancing the intrinsic tolerance of LGG cells, rather than modifying the powder properties. Given the protective effect of Ca2+ on probiotic cells under stressful conditions, calcium-containing dry probiotic products that confer duel benefits to consumers may be developed as new types of functional foods.