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Since its invention in 1872 by Samuel Percy, the spray drying of food products has been widely used, whether in products consumed by babies in milk formulations, powdered sweets and cocoa soluble in milk for children, or food supplements rich in proteins, vitamins, and minerals for adults. All of these products were first formulated in solution and then converted into powders to facilitate the transport and preservation of the properties during storage. In recent years, novel technologies such as nano spray drying have emerged for the development of food formulations with high-cost active ingredients. The aim of the present work is to present a review of the literature reported in the last 10 years related to these technologies. The basis of the spray-drying technologies i.e., conventional and nano, are described and compared, emphasizing the instrumental processing conditions for achieving a desired product. Examples of some unwanted reactions presented during the encapsulation of active ingredients are provided.

Increasing research activity on cellulose nanofibril-based materials provides great opportunities for novel, scalable manufacturing approaches. Cellulose nanofibrils (CNFs) are typically processed as aqueous suspensions because of their hydrophilic nature. One of the major manufacturing challenges is to obtain dry CNFs while maintaining their nano-scale dimensions. Four methods were examined to dry cellulose nanocrystal and nanofibrillated cellulose suspensions: (1) oven drying, (2) freeze drying (FD), (3) supercritical drying (SCD), and (4) spray-drying (SD). The particle size and morphology of the CNFs were determined via dynamic light scattering, transmission electron microscopy, scanning electron microscopy, and morphological analysis. SCD preserved the nano-scale dimensions of the cellulose nanofibrils. FD formed ribbon-like structures of the CNFs with nano-scale thicknesses. Width and length were observed in tens to hundreds of microns. SD formed particles with a size distribution ranging from nanometer to several microns. Spray-drying is proposed as a technically suitable manufacturing process to dry CNF suspensions.

Drying is one of the key steps in the coffee production process. It is necessary to dry the coffee extracts to prevent microbial growth and to prolong the storage time of coffee. To this date, mechanical drying methods have been developed and employed in industries to shorten the drying time. However, these drying methods could alter the physicochemical properties of coffee and the compounds present in coffee. Therefore, it is crucial to maintain these factors in the coffee production process as they affect the stability, reconstitution, and aroma of the coffee produced. These properties are crucial as they determine the final quality of coffee. This review will focus on the effect of spray-drying, freeze-drying, and spray-freeze–drying on the physicochemical properties of coffee such as morphology, particle size, moisture content, bulk density, and compound retention. Effects on organoleptic properties are also discussed. Possible advancements to these drying methods such as the encapsulation process, the use of a porous frozen sample, and total solid enhancement of the raw material have been highlighted.

HighlightsN-Ti3C2@CNT microspheres are successfully synthesized by the simple spray drying and one-step pyrolysis.Within the microsphere, MXene nanosheets intimately interact with CNTs constructing porous and highly conductive network, which can provide strong immobilization for polysulfides.N-Ti3C2@CNT microsphere/S cathode shows highly cycling stability in lithium-sulfur battery.

Encapsulated fat-soluble powders containing vitamin A (VA) and E (VE) were prepared as a feasible additive for extruded feed products. The effect of the encapsulating agents (Capsul-CAP®, sodium caseinate-SC) in combination with Tween 80 (TW) as an emulsifier and maltodextrin (MD) as a wall material on the physicochemical properties of emulsions and powders was evaluated. First, nanoemulsions containing MD:CAP:TW:VA/VE and MD:SC:TW:VA/VE were prepared and characterized. Then, powders were obtained by means of spray-drying and analyzed in terms of the product yield, encapsulation efficiency, moisture content, porosity, surface morphology, chemical structure, and thermal properties and thermo-oxidative/thermal stability. Results showed that although nanoemulsions were obtained for all the compositions, homogeneous microcapsules were found after the drying process. High product yield and encapsulation efficiency were obtained, and the presence of the vitamins was corroborated. The characteristics of the powders were mainly influenced by the encapsulating agent used and also by the type of vitamin. In general, the microcapsules remained thermally stable up to 170 °C and, therefore, the proposed encapsulation systems for vitamins A and E were suitable for the preparation of additives for the feed manufacturing through the extrusion process.

The effect of freeze- and spray-drying on physico-chemical characteristics, phenolics compounds and antioxidant activity of papaya pulp was investigated. The frozen pulp was freeze dried at − 62 °C during 48 h. Papaya pulp with 14% DE maltodextrin was also dried in a spray dryer. The organic acids, sugars, color, total soluble solids, pH, carotenoids, phenolic and flavonoid compounds, and antioxidant capacity values were determined. The changes in color, pH and lycopene were negligible. However, lower retention (86.5%) of vitamin C and sugars (glucose—79.7% and fructose—66.1%) was observed in spray dried products. Phenolic and flavonoid compounds were identified and quantified in dried papaya products by UHPLC-QqQ-MS/MS. Spray dried products presented a higher retention of phenolic and flavonoid compounds compared to the freeze dried products. Despite some variations in the parameters studied, the use of freeze- and spray-drying has proven viable options for the drying of papaya pulp.

Transforming liquid smoke to powder form can provide convenience for use and storage. Liquid smoke was prepared by fast pyrolysis technology using a fluidised bed and converted to smoke powder by spray-drying or freeze-drying processes. Both drying processes effectively retained the bioactive compounds in the powder encapsulates with retention efficiencies up to 80%. The bioactive capacities were approximately two times higher than liquid smoke. Spray-drying did not induce thermal damage to the bioactive compounds, and the dominant compounds were retained in the powders. Gas chromatography–mass spectrometry and principal component analysis indicated that the chemical composition was not significantly changed after both drying methods, but small molecular carbonyls, furans and phenols were partially lost. The spray-dried particles had a spherical shape, while freeze-dried particles had irregular shapes because of different powder preparation methods. The particle size of spray-dried powders was in the range of 6.3 to 6.9 µm, while the value for freeze-dried powders was decreased from 580.4 to 134.7 µm by increasing the maltodextrin concentration. The freeze-dried powders performed better in terms of flowability and cohesiveness because of their relatively high density and large particle size. This study revealed that both encapsulation methods could efficiently prepare smoke powder. Spray-drying process would be suitable for large-scale production, while freeze-drying could be used to optimize the encapsulation efficiency of bioactive compounds.

In the paper, an attempt was made to use methods of artificial neural networks (ANN) and Fourier transform infrared spectroscopy (FTIR) to identify raspberry powders that are different from each other in terms of the amount and the type of polysaccharide. Spectra in the absorbance function (FTIR) were prepared as well as training sets, taking into account the structure of microparticles acquired from microscopic images with Scanning Electron Microscopy (SEM). In addition to the above, Multi-Layer Perceptron Networks (MLPNs) with a set of texture descriptors (machine learning) and Convolution Neural Network (CNN) with bitmap (deep learning) were devised, which is an innovative attitude to solving this issue. The aim of the paper was to create MLPN and CNN neural models, which are characterized by a high efficiency of classification. It translates into recognizing microparticles (obtaining their homogeneity) of raspberry powders on the basis of the texture of the image pixel.

Molybdenum carbide (Mo2C) is recognized as an alternative electrocatalyst to noble metal for the hydrogen evolution reaction (HER). Herein, a facile, low cost, and scalable method is provided for the fabrication of Mo2C‐based eletrocatalyst (Mo2C/G‐NCS) by a spray‐drying, and followed by annealing. As‐prepared Mo2C/G‐NCS electrocatalyst displays that ultrafine Mo2C nanopartilces are uniformly embedded into graphene wrapping N‐doped porous carbon microspheres derived from chitosan. Such designed structure offer several favorable features for hydrogen evolution application: 1) the ultrasmall size of Mo2C affords a large exposed active sites; 2) graphene‐wrapping ensures great electrical conductivity; 3) porous structure increases the electrolyte–electrode contact points and lowers the charge transfer resistance; 4) N‐dopant interacts with H+ better than C atoms and favorably modifies the electronic structures of adjacent Mo and C atoms. As a result, the Mo2C/G‐NCS demonstrates superior HER activity with a very low overpotential of 70 or 66 mV to achieve current density of 10 mA cm−2, small Tafel slope of 39 or 37 mV dec−1, respectively, in acidic and alkaline media, and high stability, indicating that it is a great potential candidate as HER electrocatalyst. A simple, low cost, and scalable strategy for the fabrication of Mo2C‐based eletrocatalyst through spray‐drying and followed by annealing is demonstrated. As‐prepared Mo2C/G‐NCS catalyst exhibits excellent hydrogen evolution reaction performance both in acidic and alkaline media, which is attributed to synergistic effect from such an unique structure with graphene wrapping, ultrasmall Mo2C nanocrystallite, nitrogen‐dopant, and the well‐defined porous microspheres.

Electrostatic spray drying (ESD) of a milk protein matrix comprising whey protein isolate (WPI), skim milk powder (SMP), and lactose was compared to conventional spray drying (CSD) and freeze-drying (FD). ESD and CSD were used to produce powders at low (0.12–0.14), medium (0.16–0.17), and high (0.31–0.36) levels of water activity (aw), while FD powders targeted low aw (0.12). Maillard reaction indicators were studied after drying and during storage for up to 28 days at 20, 40, or 60 °C by measuring free -NH2 groups, as an indicator of available lysine, and 5-hydroxymethylfurfural (HMF). After drying, levels of residual free -NH2 groups were ~15% higher in ESD and FD powders than in their CSD counterparts. CSD powders also had ~14% higher HMF concentrations compared to their ESD and FD counterparts. Storage led to reductions in free -NH2 groups and increases in HMF content in all powders, the extent of which increased with increasing storage temperature. Reductions in free -NH2 groups followed first-order reaction kinetics at 20 and 40 °C but second-order reaction kinetics at 60 °C. Lactose crystallization was detected in high-aw CSD powders after 14 d at 40 °C and in both CSD and ESD powders after 7 d at 60 °C. Overall, we found that ESD is a gentle drying technology which enables production of powders with lower Maillard reaction markers.