Spray-dried Products Research Articles

Selected Soluble Dietary Fibres as Replacers of Octenyl Succinic Anhydride (OSA) Starch in Spray-Drying Production of Linseed Oil Powders Applied to Apple Juice

The aim of the study was to compare two kinds of soluble dietary fibres in a mixture with OSA-starch as wall components of linseed oil capsules. Comparison was made based on emulsion (droplet size, polydispersity index, and viscosity) and powder properties (outer structure, colour, surface oil content, and encapsulation efficiency). Additionally, linseed oil powders were applied to the food model (apple juice) and the colour, physical stability, and volatile compound profile of fortified juice were determined. Although the obtained linseed oil emulsions with different compositions of polysaccharide components showed some variation in droplet size, polydisperse index and viscosity, their encapsulation efficiency by spray-drying was very high (>98%). The powders produced had a similar structure and low surface oil content, and their 2% addition to apple juice did not change its stability and only slightly decreased its colour lightness and yellowness. However, greater differences in the volatile compounds of obtained juices were observed. Overall, the added powders reduced the volatility of aroma compounds typical of apple juice but introduced propanal and hexanal, especially the powders with the highest OSA-starch share.

Long-Term Physical Stability of Amorphous Solid Dispersions: Comparison of Detection Powers of Common Evaluation Methods for Spray-Dried and Hot-Melt Extruded Formulations

Although physical stability can be a critical issue during the development of amorphous solid dispersions (ASDs), there are no established protocols to predict/detect their physical stability. In this study, we have prepared fenofibrate ASDs using two representative manufacturing methods, hot-melt extrusion and spray-drying, to investigate their physical stability for one year. Intentionally unstable ASDs were designed to compare the detection power of each evaluation method, including X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and dissolution study. Each method did not provide the same judgment results on physical stability in some cases because of their different evaluation principles and sensitivity, which has been well-comprehended only for one-component glass. This study revealed that the detection powers of each evaluation method significantly depended on the manufacturing methods. DSC was an effective method to detect a small amount of crystals for both types of ASDs in a quantitative manner. Although the sensitivity of XRPD was always lower compared to that of DSC, interpretation of the data was the easiest. SEM was very effective for observing the crystallization of the small amount of drug for hot-melt extruded products, as the drug crystal vividly appeared on the large grains. The dissolution performance of spray-dried products could change even without any indication of physical change including crystallization. The advantage/disadvantage and complemental roles of each evaluation method are discussed for deeper understanding on the physical stability data of ASDs.

Influence of Spray Drying Inlet Temperature on the Physical Properties and Antioxidant Activity of Black Garlic Extract Powder

Black garlic is a fermented product from garlic (Allium sativum L.) that is processed by heating fresh garlic at a certain temperature and humidity for several days. Black garlic has higher antioxidant activity and is rich in organosulfur compounds. Therefore, black garlic has an unpleasant taste and odor. Spray drying of black garlic extract is important for wider application, preservation and prolongation of its shelf-life. Black garlic powders were produced using SD-18A mini spray dryer. The purpose of this research was to evaluate the effect of inlet temperatures on the physical properties and antioxidant activity of aqueous black garlic powder. The inlet temperatures ranged from 165 to 225 °C, whereas other conditions were kept constant such as maltodextrin concentration (8 %) and feed flow rate (4.5 mL/min). The black garlic powders were examined for powder yield, moisture content, hygroscopicity, bulk density, wettability, antioxidant activity and total phenolic and flavonoid content. The optimal conditions for the drying process were achieved with an inlet temperature of 225 °C. An increase in the inlet temperature of the spray dryer has increased the powder yield, hygroscopicity, antioxidant activity and total phenolic and flavonoid content of the black garlic powder, but reduced the water content, bulk density and wettability of the spray-dried product. HIGHLIGHTS The best properties of black garlic powder were obtained at an inlet temperature of 225 °C The bioactive compounds of black garlic were stable at high temperatures The higher inlet temperatures increased antioxidant activity in black garlic powders GRAPHICAL ABSTRACT

Residence time distribution and kinetics of insolubility of skim milk powder during spray drying

In spray drying, the particle residence time is the duration of atomized droplet spent inside the drying chamber. Residence time distribution (RTD) is a critical parameter in spray drying that plays a significant role in the properties of the dried powder and the efficiency of the drying process. This study determined the RTD of skim milk powder (SMP) at the drying tower during spray drying using the GEA NIRO mobile minor under various operating conditions. The method was validated using two different feedline systems (short and long) under two distinct operating conditions (hammering and non-hammering). The mean residence time without hammering and hammering conditions were 17 and 23–27 s, respectively. This study also assessed the insolubility formation of SMP at different drying conditions. The insolubility formation of SMP increased with the drying temperature and mean deposition time. The formation of insoluble material followed the first-order kinetics and was well described by the Arrhenius-type relationship. Quantitative wall deposition during drying was 63–75% of the feed dry matter. This study might help optimize the spray drying process, achieving consistent and high-quality spray-dried products.

Low-cost, ecofriendly, and large-scale synthesis of nanostructured Co1−xMnxFe2O4 microgranules with enhanced magnetic performance by chemical spray drying processing

We report, for the first time, the low-cost, eco-friendly, and large-scale synthesis of spray-drying production of Mn-substituted CoFe2O4 (Co1−xMnxFe2O4; x = 0.0–0.2; CMF) microgranules and their structural, morphological, and magnetic properties and performance characteristics in detail. The comprehensive study explored the intimate relationships between cation disorder or inversion degree due to Mn substitution in CoFe2O4 (CF) microgranules and corresponding changes in the structural and magnetic properties. Crystal structure and morphology studies indicate the formation of spherical shape, single cubic mixed inverse spinel structure of all the CMFO- microgranules with a size variation in the range of ⁓6.5–7.5 µm. Small angle X-ray scattering analyses indicate that the nanostructured CMF microgranules exhibit a virtually hard-sphere-like interaction. It is concluded that distortions are related to Co ions at octahedral locations due to Mn substitution in all materials. Raman spectroscopic studies, which corroborate with other structural studies, also reveal that replacing Co with Mn increases the degree of inversion in the cubic inverse spinel structure. Divalent (Co2+, Mn2+) and trivalent (Fe3+, Mn3+) cations are distributed differently across tetrahedral and octahedral sites. In addition to large-scale chemical synthesis, our results demonstrate the enhanced magnetic saturation from 82.27 to 86.18 emu/gm and 77.05–79.87 emu/gm for Co0.9Mn0.1Fe2O4 at 10 K and 300 K, respectively. In order for the proposed architectural design to serve as a crucial building block for a wide range of technological applications and be applicable to a large class of spinel ferrites, we present our attempt to draw the necessary fundamental scientific explanation from the trends in the local structural parameters and magnetic characteristics of CMF nanomaterials.

Optimization of Spray-Drying Conditions of Microencapsulated Habanero Pepper (Capsicum chinense Jacq.) Extracts and Physicochemical Characterization of the Microcapsules

The Habanero pepper (Capsicum chinense Jacq.) is recognized worldwide for its unique organoleptic characteristics, as well as for its capsaicin content; however, other bioactive compounds, such as phenolic compounds with bioactive properties (mainly antioxidant capacity), have been extracted (ultrasound) and identified in this fruit. Moreover, the extracts obtained by ultrasound present a high sensitivity to environmental conditions, making spray drying a viable option to avoid the degradation of bioactive compounds while maintaining their properties after microencapsulation. Response surface methodology (RSM) has been used to optimize spray-drying conditions such as the inlet temperature (IT) and maltodextrin:extract (M:E) ratio. Thus, the objective of this work was to establish the optimal spray-drying conditions (IT and M:E) of a Habanero pepper extract with a final characterization of the spray-dried product. Results showed that the optimal spray-drying conditions included an IT = 148 °C with an M:E = 0.8:1 w/w, where the antioxidant capacity (38.84 ± 0.22% inhibition), total polyphenol content (6.64 ± 0.08 mg Gallic acid equivalent/100 g powder), and several individual polyphenols, such as Protocatechuic acid (26.97 mg/100 g powder), Coumaric acid (2.68 mg/100 g powder), Rutin (18.01 mg/100 g powder), Diosmetin (1.74 mg/100 g powder), and Naringenin (0.98 mg/100 g powder), were evaluated. The microcapsules showed a spherical shape with concavities and moisture less than 5%, and the inclusion of bioactive compounds was confirmed using UPLC and FTIR. The final dried product has the potential to be used as an ingredient for functional food development.

Characterizing Spray-Dried Powders through NIR Spectroscopy: Effect of Two Preparation Strategies for Calibration Samples and Comparison of Two Types of NIR Spectrometers.

Emerging portable near infrared (NIR) spectroscopic approaches coupled with data analysis and chemometric techniques provide opportunities for the rapid characterization of spray-dried products and process optimization. This study aimed to enhance the understanding of applying NIR spectroscopy in spray-dried samples by comparing two sample preparation strategies and two spectrometers. Two sets of whey protein-maltodextrin matrixes, one with a protein content gradient and one with a consistent protein content, were spray-dried, and the effect of the two preparation strategies on NIR calibration model development was studied. Secondly, a portable NIR spectrometer (PEAK) was compared with a benchtop NIR spectrometer (CARY) for the moisture analysis of prepared samples. When validating models with the samples with focused protein contents, the best PLS protein models established from the two sample sets had similar performances. When comparing two spectrometers, although CARY outperformed PEAK, PEAK still demonstrated reliable performance for moisture analysis, indicating that it is capable as an inline sensor.

Formulation and Evaluation of the Fenofibrate Spray-dried Emulsion Tablets

The present research work deals with the development of a self-micro emulsifying drug delivery system (SMEDDS) of Fenofibrate (FF) followed by spray drying to form solid SMEDDS and tablets with enhanced solubility and dissolution. FF is BCS class II drug with low bioavailability and low aqueous solubility. The solubility of the FF can be improved by formulating SMEDDS. Liquid SMEDDS were developed by adding the drug in oleic acid, Tween 80, and Transcutol HP to get a clear solution. In the spray drying method, dextran was used to form the granules. Further, direct compression method was used to manufacture the tablets. The spray-dried product containing solid SMEDDS of FF showed nearly 30-fold solubility enhancement in distilled water in comparison to pure FF. The optimized formulation containing solid SMEDDS of FF (F9) showed an increased dissolution rate (100% drug release at 60 minutes) in comparison to conventional tablets. The optimized batch showed excellent stability at the accelerated condition for the period of 3 months. The current research work demonstrates spray drying as a potential approach to transfer the liquid SMEDSS to a solid SMEDDS with an enhanced solubility and dissolution rate.

Production of effervescent tablet from jambolan (Syzygium cumini L.) fruit

Jambolan (Syzygium cumini L.) fruit contained numerous phytochemical and bioactive constituents beneficial for human health. However, this underutilized fruit was highly susceptible to quality degradation after harvesting. Due to the seasonality and perishability of the jambolan fruit, it’s very necessary to convert this valuable fruit into instant, stable and convenient form for long-term consumption. This research was conducted at STNanotech laboratory in 2021 to evaluate the exploitation of jambolan fruit for juice extraction, spray drying and effervescent tablet production. Different variables of spray drying conditions such as proportion of wall material (maltodextrin 8-16%), inlet/outlet drying temperature (150/80, 160/85, 170/90, 180/95, 190/100 oC/oC), feed flow rate (7.5-17.5 ml/min) were deeply investigated on physicochemical and antioxidant properties of spray-dried jambolan powder (SDJP). In preparation of effervescent tablet, the spray-dried jambolan powder (SDJP) was mixed with sodium bicarbonate (SB) and magnesium stearate (MS) in five different formulas: F1 (65/10/25), F2 (65/5/30), F3 (70/10/20), F4 (65/15/20), F5 (70/15/15). Results showed that jambolan extract should be spray-dried with maltodextrin 14% as wall material (WM), inlet/outlet drying temperature 170/90 oC/oC, feed flow rate (FFR) 12.5 ml/min to obtain the optimal particle size 7.94±0.05 µm, solubility 96.80±0.02%, yield 56.71±0.01%, microencapsulation efficiency (ME) 93.25±0.05%, total phenolic content (TPC) 298.45±0.79 mg GAE/100 g, anthocyanin content (AC) 76.59±0.06 mg/100 g, and antioxidant activity (AA) 85.63±0.04%. The jambolan effervescent tablet produced by formula F2 (65/5/30) achieved the optimal hardness 47.24±0.05 N, disintegration time (DT) 271.05±2.03 s, TPC 201.03±1.28 mg GAE/100 g, AC 40.89±0.30 mg/100 g, AA 73.12±0.24% and overall acceptance (OA) 8.81±0.05. Jambolan fruit could be utilized to produce spray-dried powder and its effervescent tablet as a versatile functional food with excellent physicochemical, antioxidant and sensorial characteristics under safe and convenient way for all year round.

Topical Formulation of Nano Spray-Dried Levocetirizine Dihydrochloride against Allergic Edema.

Levocetirizine dihydrochloride active ingredient was microencapsulated using nano spray-drying technology for preparing microparticles containing topical gel against edema. Hydroxyl propyl methyl cellulose (HPMC) was used as a carrier polymer during spray drying. The active ingredient content of the nano spray-dried products was 52.81% (w/w) and 51.33% (w/w) for ex vivo and in vivo experiments, respectively, and the average particle size was 2.6 µm. X-ray diffraction analysis indicated an amorphous state of the active ingredient embedded in the amorphous matrix of the polymer. Dermal oil gels composed of Miglyol 812 gelated by Dermofeel viscolid included 5% (w/w) (for ex vivo) and 10% (w/w) (for in vivo) active ingredient without or with 0.05% (w/w) menthol penetration enhancer. Qualitative ex vivo penetration studies using a confocal Raman microscopic correlation mapping were executed on human abdominal skin. The results showed that the active ingredient was enriched in the epidermis and upper dermis layer of the skin using oleogel loaded with the nano spray-dried drug-HPMC composite. Menthol addition to the oleogel resulted in the concentration of levocetirizine in the dermis. In vivo tests were performed on a mouse model of croton oil-induced ear edema. Negative control and Fenistil-treated groups were compared using the prepared oil gels with and without menthol. Without penetration enhancer, 20 µL of our oil gel loaded with nano spray-dried levocetirizine dihydrochloride composite showed similar effectiveness to the same volume of Fenistil gel, while 5 µL menthol containing sample was sufficient to eliminate the skin irritation similarly to 20 µL Fenistil.

Micromechanical properties of spray-dried core-shell silica aggregates along with drug release tests

In order to enhance the quality of spray-dried products or to adjust material properties for new applications, precise control of the aggregate structure is desirable. For the purpose of preparing hierarchically structured aggregates in the micrometer range, the formulation of the suspension can be specifically designed, utilizing defined nanoparticulate building blocks to achieve a highly uniform structure and porosity. Further adjustments can be made by combining two types of primary particles that differ in size. Thereby, a segregation effect is observed, where nanoparticles with larger particle sizes accumulate rather within the core of an aggregate and those with smaller particle sizes gather mainly near the outer surface, resulting in the formation of a shell. Furthermore, it is possible to produce tailor-made porosities using template particles (e.g. polystyrene) of different sizes as part of the coarse and fine fractions. The removal of these particles by a subsequent tempering process can lead to aggregates with defined porous structures and thus, to different mechanical aggregate properties that can be specifically set by adjusting the process and formulation parameters. As a result, a promising building kit for the hierarchically structure formation via spray drying processes were achieved. For the detailed characterization structural and mechanical material properties were investigated, using e.g. mercury intrusion and SEM. The influence of the formulation parameters of the suspension (primary particle size and template content) on the micromechanical properties of the aggregate structures was systematically investigated by nanoindentation to elucidate structure-property relationships regarding, for example elastic and plastic deformation. As a result, a correlation could be established between the experimentally determined mechanical parameters and the aggregate porosities. Such microstructures with defined properties can be used in a variety of applications, including catalysis or as drug carriers. For instance, these spray-dried aggregates were loaded with ibuprofen as an exemplary active pharmaceutical ingredient and investigated with regard to their drug release behavior.

Preliminary Characterization of a Spray-Dried Hydrocolloid from a High Andean Algae (Nostoc sphaericum).

The search for new natural sources of hydrocolloids with stabilizing, thickening, and good binding capacity, from raw materials that are environmentally friendly and that contribute to the circular economy is a challenge for the food industry. The aim of the study was the preliminary characterization of a spray-dried hydrocolloid from high Andean algae Nostoc sphaericum. Four ecotypes of algae from Peruvian high Andean lagoons located above 4000 m were considered. The samples were collected in the period March–April 2021 and were subjected to a spray drying process in an aqueous medium. The characterization showed that the dehydrated nostoc ecotypes presented high protein and carbohydrate content, making it a potential material for direct use as a functional food for humans. The spray-dried product presented good stability for its use as a hydrocolloid, with zeta potential values (ζ), around 30 mV, evidencing the presence of -CO-, -OH, -COO-, and -CH groups, characteristic of polysaccharides, representing 40% of total organic carbon on average, giving it low water activity values and particle size at the nanometric level. Major minerals such as Ca (>277 mg/100 g), Mg (>19.7 mg/100 g), and Fe (>7.7 mg/100 g) were reported. Spray-dried nostoc is a hydrocolloid material with high potential for the food industry, with good nutritional content and techno-functional behavior.

Thermodynamic Balance vs. Computational Fluid Dynamics Approach for the Outlet Temperature Estimation of a Benchtop Spray Dryer.

The use of design space (DS) is a key milestone in the quality by design (QbD) of pharmaceutical processes. It should be considered from early laboratory development to industrial production, in order to support scientists with making decisions at each step of the product’s development life. Presently, there are no available data or methodologies for developing models for the implementation of design space (DS) on laboratory-scale spray dryers. Therefore, in this work, a comparison between two different modeling approaches, thermodynamics and computational fluid dynamics (CFD), to a laboratory spray dryer model have been evaluated. The models computed the outlet temperature () of the process with a new modeling strategy that includes machine learning to improve the model prediction. The model metrics calculated indicate how the thermodynamic model fits data better than CFD; indeed, the error of the CFD model increases towards higher values of and feed rate (), with a final mean absolute error of 10.43 K, compared to the 1.74 K error of the thermodynamic model. Successively, a DS of the studied spray dryer equipment has been implemented, showing how is strongly affected by variation, which accounts for about 40 times more than the gas flow rate () in the DS. The thermodynamic model, combined with the machine learning approach here proposed, could be used as a valid tool in the QbD development of spray-dried pharmaceutical products, starting from their early laboratory stages, replacing traditional trial-and-error methodologies, preventing process errors, and helping scientists with the following scale-up.

Whole mulberry leaves as a promising functional food: From the alteration of phenolic compounds during spray drying and in vitro digestion

This study investigated the potential of processing whole mulberry leaves as nutraceutical foods rich in phenolic compounds by spray drying with different drying aids. The results indicated that the spray-dried product 6 (24.2% whey protein isolate [WPI], 33.3% mulberry leaves solid, 38.7% maltodextrin, 3.8% soybean lecithin) with high WPI/mulberry leaves solid ratio possessed the best physical properties, the highest total phenolic compounds level and antioxidant capacity among all the products. Specifically, free chlorogenic acid and rutin were increased by two to three times, but free isoquercitrin and astragalin lost more than 50% in product 6 compared with fresh mulberry leaves. For in vitro digestion, rutin, isoquercitrin, and astragalin (the antioxidative phenolic compounds in mulberry leaves) showed higher bioaccessibility than chlorogenic acid (p<0.05) in product 6. Meanwhile, the phenolic compounds bioaccessibility of product 6 was 10-20 times higher than that of fresh whole mulberry leaves. Considering the increased level and bioaccessibility of phenolic compounds, whole mulberry leaves could be developed as potential functional foods by spray drying under the protection of WPI. PRACTICAL APPLICATION: The spray-dried whole mulberry leaves can be consumed as a beverage, meal replacement powder, or used as additive during food processing.

Increasing the Yield of Powder and Bioactive Materials during Extraction and Spray Drying of Dragon Fruit Skin Extracts

One potential utilization of dragon fruit skin is to produce bioactive materials as natural antioxidants and colorants for the food industry by extraction and spray drying. This study investigated the quality (total phenolic compounds/TPC, betacyanin and betaxanthin contents, and antioxidant activity) of the extracts and spray-dried products, and the quantity (powder yield) obtained by the use of different types and amounts of spray drying agents. Two drying agents were introduced during spray drying, i.e. maltodextrin and whey protein isolate (WPI). The result showed that a lower extraction solvent to solid ratio may result in a lower yield of TPC, betacyanin and betaxanthin contents, and also in antioxidant activity of the dragon fruit skin extract. In addition, maltodextrin and WPI were found to be able to significantly increase the yield from spray drying. The highest yield (72.7 ± 8.4%) was obtained with the use of 40% maltodextrin as drying agent, while the control yielded 9.5 ± 1.8%. Furthermore, it was found that the spray-dried product could recover more than 90% of the TPC and betacyanin in the extracts, which indicates that spray drying may be suitable for heat-sensitive materials.

Applicability of Spray Drying Technique to Prepare Nano-Micro Carriers: A Review

Nano-micro carriers loaded with drugs and active biomolecules have gained a lot of attention in the field of health care, agriculture, and the food industry. Various methods have been explored to synthesize nano-micro carriers. However, there is still a constant search to develop a method for the preparation of a large quantity of nano-micro carriers with high loading efficiency. In this regard, spray drying could be a potential technique because of its inherent features like ease to operate, cost-effectiveness, environment-friendly, single step, and scalable. In this review, the focus is on the applicability of spray drying technique to prepare nano-micro carriers which are loaded with drugs, microorganisms, and other active molecules. Subsequently, the application and usefulness of spray-dried products in different research areas like the food industry, remediation of heavy metals and bioprocessing, and drug delivery have been presented. Furthermore, advantages, limitations, and recent developments in the area of spray drying have been discussed. This review presents a glimpse of spray drying techniques to synthesize nano-micro carriers with a wide range of applications.

Formulation and Evaluation of Chitosan/NaCl/Maltodextrin Microparticles as a Saltiness Enhancer: Study on the Optimization of Excipients for the Spray-Drying Process.

Spray-dried chitosan/NaCl/maltodextrin microparticles have the potential to be used to enhance saltiness; however, its notable hygroscopicity results in handling and storage problems, thus limiting its application. In the present study, we attempted to introduce maltodextrin, microcrystalline cellulose (MCC), and waxy starch (WS) as excipients into the spray drying formulation of microparticles to reduce the cohesiveness and caking behavior and improve the yield simultaneously by ameliorating the moisture absorption tendency. The prepared microparticles showed a spherical appearance and had particle sizes ranging from 6.29 to 7.64 μm, while the sizes of the NaCl crystals embedded in the microparticles were 0.36 to 1.24 μm. The crystalline reflections of WS and MCC were retained in the microparticles after the spray-drying process. The handling properties were assessed to be acceptable. The formulation with only maltodextrin as the excipient showed a high moisture absorption rate of 2.83 g/100 g·h and a caking strength of 3.27 kg. The addition of MCC and WS significantly reduced the hygroscopic rate and caking strength. The spray-dried products provided better saltiness perception than native NaCl; as such, they may be promising for seasoning dry food products to achieve sodium intake reduction in the food industry.

Comparing freeze drying and spray drying of interleukins using model protein CXCL8 and its variants

Spray-dried products, such as synthetic peptides and hormones, have already been approved by the U.S. Food and Drug Agency and the European Medicines Agency, while spray-dried antibodies or interleukins, are not yet available on the market. Concerning the latter group, knowledge on whether and how spray-drying (SD) can be performed without adversely affecting their biological activity is lacking. Accordingly, this study aimed at establishing a SD process (Büchi B-90 spray dryer) using three Interleukin-8 based proteins (7–74 kDa) that were dispersed in phosphate buffered saline to maintain their stability. A Box-Behnken Design of Experiments was conducted to identify the appropriate process parameters taking into account the thermal stability of interleukin-8. In parallel, a FD process was developed. Both powders were stored for up to 12 weeks. Powder characterization included residual moisture evaluation and the mean particle size of the SD powder was investigated with Laser Diffraction Analysis. The hydrodynamic volume was measured via size exclusion chromatography and sodium dodecyl sulfate–polyacrylamide gel electrophoresis. The secondary structure of the model proteins in the solid state was assessed with Fourier-transformation infrared spectroscopy for detecting the protein folding patterns and reconstituted with Circular Dichroism Spectroscopy. Finally, the binding affinity was studied with Surface Plasmon Resonance and Isothermal Fluorescence Titration, the protein stability with Chaotropic Unfolding, and the activity studies were carried out with the chemotaxis assay. The results showed that SD and FD powders with a residual moisture of less than 5 wt% were obtained. The interleukins showed no unfolding upon processing, neither in solid state nor reconstituted. Oligomerization was observed for FD, but not for SD interleukins. However, the unfolding, binding affinity and activity of all interleukins examined did not decrease in neither SD nor FD powders, even after 12 weeks of storage. Thus, it can be concluded that SD of interleukin formulations at outlet temperatures close to ambient temperature is a promising process for transferring them into a stable powder.

Resistant Starch-Based Edible Coating Composites for Spray-Dried Microencapsulation of Lactobacillus acidophilus, Comparative Assessment of Thermal Protection, In Vitro Digestion and Physicochemical Characteristics

Polysaccharides have excellent potential as food-grade coating materials for microencapsulation in pro- and prebiotics-based functional food industry. In this study, potato, maize, and rice resistant starches composite coatings with D-mannose, maltodextrin, and whey protein concentrate were prepared for the spray-dried microencapsulation of Lactobacillus acidophilus KLDS 1.1003. Assessment of different polysaccharide coatings to enhance the longevity of probiotics at high temperatures of spray-drying process, storage, and targeted delivery in the gastrointestinal tract were the key objectives of the present study. The highest microencapsulation efficiencies were shown by maize (95.80%) and potato (94.30%) resistant starches. Similarly, maize resistant starch (MRS)-based composites provided the highest thermal resistance, with Tg 38.77 ± 1.10–93.13 ± 0.81 °C and showed the least 2.1 log cycles viability loss in simulated GI tract. Viability losses during storage were in the following order: control &gt; RRS &gt; PRS &gt; MRS, and the inactivation rate of the microencapsulated cells followed the first-order kinetics (R2 = 0.9264–0.9918). The resistant starch-based spray-dried microcapsules possessed 27.00 ± 0.03 to 52.28 ± 1.02 µm size range and SEM micrographs showed a unified smooth surface without cracks and ruptures. These findings will expand the potential use of natural food-grade coatings in functional foods and allied industries involving spray-dried products.

A review of Maillard reactions in spray dryers

Maillard reactions in liquid systems have been studied extensively, while those occurring during the spray-drying process have been less well studied. Current studies on Maillard reactions in spray dryers have been focussed heavily on empirical studies of the effects of the operating parameters. However, only modest attention has been paid to the fundamental reactions or to the interactions with the fundamental spray-drying process. Studies on the spray-drying process have shown that component segregation occurs during the process. Component segregation causes different ratios between various reacting components in different parts of particles, and this segregation process may change the kinetics of Maillard reactions. Particle residence times and the re-entrainment of wall deposits may also affect the extent of Maillard reaction since they determine the reaction time in spray dryers. Improving the design of spray dryers may also help to reduce the extent of the Maillard reactions in spray-dried products. • Kinetic studies for Maillard reactions for spray drying have been reviewed. • Features of Maillard reactions related to spray drying have been reviewed. • The importance of component segregation has been highlighted. • The importance of the particle-wall interaction has been discussed. • Techniques for measuring particle RTD in spray dryers have been reviewed.