喷雾干燥条件对浆液催化剂性能的影响

浆液催化剂是LLDPE/HDPE装置使用的主要催化剂,而喷雾干燥是有效控制浆液型催化剂形态及性能的一种技术。本文详细考察了喷雾干燥条件对浆液型催化剂性能的影响,并给出最佳工艺条件。     

Effect of maltodextrin concentration and inlet temperature during spray drying on physicochemical and antioxidant properties of amla (Emblica officinalis) juice powder

The effects of inlet temperatures of 125, 150, 175 and 200 °C and maltodextrin levels at 3, 5, 7 and 9% on the physicochemical properties, total phenolic content (TPC) and 2,2-diphenyl picryl hydrazile (DPPH) scavenging activity of spray dried amla juice powder were studied. Moisture content and hygroscopicity of powder were significantly affected by inlet temperature and maltodextrin level. However, an increase in the level of maltodextrin did not significantly affect the bulk density and water solubility index (WSI). An increase in drying temperature and maltodextrin concentration decreased the free radical scavenging activity of the powder. Morphological study revealed that at higher inlet temperatures the spray dried powder had small sized particles that were densely packed. Spray dried amla juice powder made with 7% maltodextrin and processed at 175 °C inlet temperature had less hygroscopicity, acceptable color and potent free radical scavenging activity.     

Effect of feed concentration and inlet air temperature on the properties of soymilk powder obtained by spray drying

In this study, soymilk powder was produced by spray drying. The inlet air temperature of spray dryer was varied from 200 to 280°C and the feed concentration was varied from 15 to 25% (w/v). Response surface methodology was used to examine the effects of these independent variables on the detailed characteristics in terms of physical, structural, functional properties of powder. Overall, results show that rising the inlet air temperature caused a decrease in tapped and loose bulk density, true density, filling rate, water holding capacity, and water content of powder; and an increase in compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index. An increase in feed concentration led to an increase in true density, compressibility, Hausner ratio, porosity, interstitial air volume, and wettability index; and a decrease in tapped and loose bulk density, filling rate, water holding capacity, and water content; whereas oil holding capacity might be increased or decreased and it depended almost solely on the feed concentration.     

Activity-loss characteristics of spores of Bacillus thuringiensis during spray drying

Survival of spores of Bacillus thuringiensis was determined under various processing conditions for spray drying. The results indicated that the viable spores number of B. thuringiensis decreased with increased inlet air temperature, outlet air temperature and atomising air pressure. When the inlet air temperature ranged from 170 °C to 250 °C, the outlet air temperature (75 °C) and atomising air pressure (0.15 MPa) were fixed, the pseudo-z value (one logarithmic cycle reduction) was 238.1 °C; when the outlet air temperature ranged from 65 °C to 95 °C, the inlet air temperature (200 °C) and atomising air pressure (0.15 MPa) were fixed, the pseudo-z value was 85.5 °C, the activation energy calculated according to the outlet air temperature was 59.96 kJ mol⁻¹; when the atomising air pressure ranged from 0.10 MPa to 0.25 MPa, the inlet air temperature (200 °C) and outlet air temperature (75 °C) were fixed, the pseudo-z value was 3.49 MPa, the variance analysis showed that the atomising air pressure has no significant influence to the spores. The diluting solutions between Tween-80 solution and phosphate buffer have significant influence on the plate count of spores.

The B. thuringiensis powder prepared by spray drying with inlet air temperature 250 °C, outlet air temperature 97 °C, the spores count of powder decreased obviously. But when the inlet air temperature of 155–165 °C, outlet air temperature of 66–70 °C were employed, the spores count of powder approaches to that of freeze drying powder. The spores count of oven drying powder was lower than that of the freeze drying powder, but close to the spray drying powder which inlet air temperature was 200 °C, outlet air temperature was 75 °C.     

Optimization of spray drying process of Sargassum muticum color extract

ABSTRACT

Sargassum muticum is categorized as a brown seaweed species which has been used as a dye fabric colorant in certain regions of Asia. The brown extracts of S. muticum also have antioxidant properties, which could enhance the color and nutrients in food products. However, the color extract is unstable, and also limits the application. This study was performed to encapsulate the color extract with maltodextrin and stabilize the color extract by spray drying technique using combinations of various levels of inlet temperature and feed flow rate. Initially, S. muticum powder was analyzed for moisture content, water activity, solubility, and color properties for optimization purposes. This study showed that the optimum inlet temperature and feed flow rate of the spray drying process to produce good-quality, stable, and acceptable powder properties were at 140°C and 3?rpm, respectively, with 4% of maltodextrin. Then, the powder was analyzed for density, compressibility index, hygroscopicity, particle size, and antioxidant properties. This study represents an interesting food additive to be incorporated in functional food due to the attractive brown colorant and the presence of antioxidants.     

Physicochemical Characteristics of Date Powder Produced in a Pilot-Scale Spray Dryer

Date fruit is a good source of bioactive compounds and natural sugar. It has the potential to be utilized as a substitute for added sugar. Although several forms of dates—such as fresh dates, date paste, and date syrup—are available in the market and used for different applications, free-flow date powder would be highly beneficial in improving shelf-life, ease of handling, and blendability with various foods prepared domestically and in industry. The objective of this study was to produce date powder in a pilot-scale spray dryer and determine its physicochemical qualities. Date powder was produced at eight processing conditions (2 carrier agents (maltodextrin (MD) and gum arabic (GA) × 2 inlet air temperature (150°C and 170°C) × 2 feedstock flow rates (25 ml/min and 40 ml/min)). To the carrier agent was added at 0.4 kg per 1.0 kg of date fruits (dry weight basis), and the feedstock to the spray dryer was prepared at 20% concentration. Date powder was obtained in all eight treatments. Color (L*a*b* values), moisture content, bulk density, wettability, solubility index, hygroscopicity, microstructure analysis (using scanning electron microscope (SEM)), and total phenolic compounds were determined for the spray-dried date powder. The physicochemical characteristics of date powder varied significantly with respect to the processing conditions. Although physical properties of date powder were significantly affected by the carrier agent, there was no difference in total phenolic compounds between date powders produced with MD and GA. An SEM study revealed that date powder produced with MD had smooth, regular-shaped spherical particles but with severe agglomeration. Date powder with GA had relatively smaller particles of irregular sphere with dented surfaces.     

Evolution of particle properties during spray drying in relation with stickiness and agglomeration control

Spray drying consists in atomizing a solution into liquid drops in a hot air flow to get dry solid particles after solvent evaporation. The convective drying at the drop surface leads to a very fast evolution of temperature and water content due to initial high differences of temperature and water vapour pressure between the drop surface and the drying air. During drying, the drop surface viscosity is increasing due to potentially amorphous polymers reaching a rubbery state. The drop surface is becoming sticky with consequences on wall deposit. This sticky behaviour which appears in the range of 10 to 30 °C above the glass transition temperature Tg, may be utilized in a positive way for agglomeration of drying particles with dry powders, either recycled fines or new dry powder, to improve instant properties.The evolution of water content of drops along drying, is deduced from measurements of air temperature and relative humidity, at different places in the dryer and used to predict the drying and sticky behaviour of two maltodextrin solutions (DE12 and DE21) with different Tg. The studied parameters in a co-current spray dryer were the inlet air temperature (144, 174, 200 °C) and flow rate (80 and 110 kg h^− 1), the liquid flow rate (1.8, 3.6 and 5.4 kg h^− 1) and the rotation speed of the wheel atomizer. The results on particle water content combined with the evolution of Tg showed that particles are sticky close to the atomiser for the two maltodextrins, and also along the chamber for maltodextrin DE21 due to its lower Tg. The introduction of dry particles at different places in the chamber allowed validating the method to control agglomeration.     

Effect of precursor, ambient pressure, and temperature on the morphology, crystallinity, and decomposition of powders prepared by spray pyrolysis and drying

The effect of reactor pressure and temperature on the morphology, crystallinity, and decomposition behavior of various powders produced by spray pyrolysis or drying is investigated. Zirconia, magnesium sulphate, and sodium chloride powders are produced at the reactor pressures of 760, 400, 250, and 120 Torr, and at the reactor temperatures of 100 °C, 200 °C, and 400 °C. Zirconia and magnesium sulphate powders are spherical, whereas the sodium chloride powders are cubic. Regardless of the pressure, the powders produced at 100 °C and 200 °C appear solid, and powders produced at 400 °C are hollow and disrupted. The experimental data and the calculations indicate that the evaporation rate, which is a function of pressure and temperature, controls the solute distribution within the droplet and as such determines the morphology of the powders. In addition, the shape and morphology of the powders are strong functions of the precursor type. The decomposition and crystallinity of the powders are determined using XEDS and XRD analyses, respectively. The crystallinity and decomposition of the powders are weak functions of pressure and strong functions of temperature.     

Spray drying conditions and encapsulating composition effects on formation and properties of sodium diclofenac microparticles

This paper reports the preparation and characterization of sustained release sodium diclofenac microparticles by spray drying. Aqueous dispersions of ethyl cellulose (Surelease®) and Eudragit RS 30 D® were evaluated as controlled release polymers. The product properties (product moisture, size distribution, particle morphology, flow properties, total drug load, in-vitro dissolution studies, and encapsulating efficiency) were determined as a function of inlet temperature of the spray drying, the feed flow rate and composition of the microencapsulating formulation. In general, lower values of the product moisture content were observed at higher drying temperatures. The spray-dried product was composed mainly by rounded-shape and multi-size particles. The mean particle diameters of the Eudragit based microparticles tended to be slight bigger than the Surelease based microparticles. The spray dried microparticles showed delayed drug dissolution rates, sustaining the drug release for several hours. These findings confirm the feasibility of the spray drying for preparation of microparticles with sustained release properties. The physical and chemical properties of the microparticles can be changed by varying the spray drying parameters as well as the microencapsulating formulation.     

Combined precipitation and spray drying for the synthesis of hydroxyapatite nanopowders as soft spherical granules

The aim of this study is to produce crystalline “hydroxyapatite” (HAp) nanopowders with very high “specific surface area” (SSA) as soft spherical granules in very small size. The HAp nanopowders were synthesized by sol-gel, biomimetic, gel combustion, precipitation and by “Combined Precipitation and Spray Drying” (CPSD). The properties of HAp nanopowders produced by these methods were investigated by XRD, FTIR, BET and SEM, and the results were compared. It was determined that synthesis process and drying conditions have very important influence on the properties of HAp nanopowders. The precipitate used as starting precursor for CPSD process was firstly synthesized by precipitation, and then it was ultrasonically dispersed in an ultrasonic bath assisted by mechanical stirring in order to prepare the “precipitate suspension like milk”, that will be referred to as “suspension” hereafter. Atomization of the suspension and direct drying of the sprays were carried out simultaneously using a spray dryer with a nozzle system at 180?°C. The HAp nanopowders synthesized by CPSD method have a crystalline structure with an average crystallite size of 15.6?nm, and have an average particle size of 15.7?nm with very high SSA (121.34?m²/g) in soft spherical granule form. HAp nanopowders which were synthesized by four other methods and dried at 110?°C have an average particle size larger than ≥?24.6?nm in big, hard and shapeless agglomerate form with a SSA smaller than ≤?77.43?m²/g. They attain a crystalline structure only after heat treatment at 600?°C. The application of CPSD process to produce the crystalline HAp nanopowders as soft spherical granules with very high SSA at very low temperature constitutes the originality of this study.     

Influence of Processing Conditions on the Physicochemical Properties and Shelf-Life of Spray-Dried Palm Sugar (Arenga pinnata) Powder

The influence of spray-drying conditions on some physicochemical properties of palm-sugar powder ( Arenga pinnata ) was studied. Twenty tests were carried out according to a central composite design. Independent variables were: inlet temperature (150–190°C), feed flow rate (9–21 g/min), and maltodextrin concentration (14–25%). Process yield, hygroscopicity, and outlet temperature were analyzed as responses. Results revealed that increasing inlet temperature resulted in higher process yield and outlet temperature and a lower hygroscopicity. Similarly, higher inlet temperature led to lower moisture content, dissolution rate, and total phenolic content of the powder. Conversely, the feed flow rate negatively influenced process yield and hygroscopicity, and positively influenced moisture content. Moreover, maltodextrin exhibited negative influence on process yield and hygroscopicity, respectively. Moreover, storage (30°C, six months) led to noticeable losses in flowability and wettability. Powder morphology was also influenced by the inlet temperature. Lower inlet temperature resulted in particles with shrivelled surfaces while higher temperature produced a greater number of larger particles with smooth surfaces.     

Impact of agitated drying on the powder properties of an active pharmaceutical ingredient

In this study, the impact of agitated drying on the physical and bulk powder properties of an active pharmaceutical ingredient (API) is presented. The effects of different agitated drying conditions such as agitation rate, drying temperature, drying time pre-agitation, drying time during agitation and number of solvent wash cycles on the bulk density, millability, flow and specific surface area is reported. The crystal morphology is altered from fibrous needles to agglomerates when switching from tray to agitated drying. An increase in bulk density and specific surface area was evident when using agitated drying compared to tray drying as hard coarse granules were produced with an increase in the number of fine particles < 10 μm. The bulk density was found to increase with an increase in agitation speed, drying time and number of solvent wash cycles used during filtration. Controlling both fine and coarse particle size of the granules for this API during agitated drying was difficult to achieve due to the fibrous crystal habit. However, the increase in the bulk density observed has the potential to facilitate improvements in the ease of drug product development. In the case of this system further particle size control was required through the use of dry milling.     

Influence of spray drying temperatures and storage conditions on physical and functional properties of dried egg white

This study investigated the effect of spray drying inlet temperatures (140, 160 and 180°C) and storage conditions (temperature; 25 and 40°C and storage period; 1 and 2 months) on the physical and functional properties of dried egg white. The results showed that the three inlet temperatures did not affect the color of the spray-dried egg white (SDEW) after drying. However, all SDEWs increased in yellow color after storage at 40°C. The solubility (%) of SDEW and gelling properties including gel hardness and water holding capacity of the gel samples were changed when the dried samples were stored, particularly for SDEW drying at 180°C. The changes in gelling properties of the SDEW were related to a decrease in the enthalpy of protein denaturation, an increase in exposed sulfhydryl (SH) contents, a decrease in the total SH contents and the occurrence of protein aggregation as shown by the sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern.     

Reply to the Comment by K. Jorgensen et al. to “Analysis of constant rate period of spray drying of slurry”

Previously developed model for spray drying of slurry droplets with high solid content (Liang, 2001) was revised to describe correctly a boundary condition on the outer surface of droplet on basis of the rate of liquid evaporation.     

Quality evaluation of Panax notoginseng extract dried by different drying methods

Quality control still remains a big issue, affecting herbs, formulations, and even the practice of Traditional Chinese Medicine. A promising solution to the problem is to take advantage of innovative process techniques including alternative drying methods within the pharmaceutical processing. Nowadays, vacuum belt drying (VBD) has gained more and more importance in food and pharmaceutical processing. In this work, Panax notoginseng extract was made into powder by the gentle VBD as well as by classical spray drying (SD), freeze drying (FD), and vacuum drying (VD). Certain chemical and physical properties of the dried powders such as moisture content, drying time, porosity, density, saponins content, pH value and hydroxyl radicals scavenging activity were evaluated. The results showed the qualities of dried products were influenced to different extent by drying methods certainly. Vacuum belt drying was suggested to dry P. notoginseng extract for its high quality assurance of hygroscopic products and suitable for sticky or high viscous products.     

益生菌在喷雾干燥过程中的活性变化与保护策略

肠道菌群对于人体健康具有重要影响。口服足量的活性益生菌,有助于缓解急慢性肠炎、治疗腹泄、改善消化,已在临床治疗中得到一定应用。在食品市场上,益生菌干粉制剂亟需一种生产成本低、制粉简便的生产方法。喷雾干燥的生产能力强、制粉快速,但干燥过程中,雾化液滴经历一个快速升温与脱水过程,对其中的益生菌带来热胁迫、脱水胁迫、氧化胁迫等多种不利因素,造成菌体活性的大量损失。而喷雾干燥塔的结构,使塔内的液滴干燥过程难以追踪,不利于研究益生菌的失活历程以及探索益生菌与载体材料间的相互作用。本文从雾化液滴在干燥塔内的干燥历程着眼,回顾了益生菌活性随液滴干燥动力学变化的趋势,讨论了益生菌在喷雾干燥中经受的亚细胞结构损伤与功能性损伤,并系统总结了目前文献中报道的提升干燥后益生菌活性的主要方法,包括提升菌体耐受性、优化喷雾干燥条件和采用合适的保护性载体,并着重阐述了载体材料与益生菌细胞间的相互作用关系以及干燥历程的重要影响。文章指出为最大程度上保存喷雾干燥粉末中益生菌的活性,应综合微生物、干燥过程与食品化学（材料学）等领域的保护策略,设计一体化统合生产方案。依据微生物-保护载体间的相互作用设计高效保护配方载体,研发统合从微生物细胞培养至粉末储藏的新型生产工艺,是实验室及工业中合理设计工业级喷雾干燥过程、大量生产高活性益生菌制剂的关键。     

Effect of microwave energy dissipation on drying process of berry puree under microwave foam drying conditions

ABSTRACT

Microwave foam drying (MFD) is a novel drying technology particularly for the drying of agricultural products with high viscosity and thermal-sensitive components. The effect of dissipation of microwave energy on the drying process of berry puree was investigated in MFD conditions. The results show that the dissipation of microwave energy induces the vapor pressure inside the berry puree to improve the formation of bubbles. The changes of pressure inside bubbles of berry puree follow Sine equations. The favorable conditions of bubbles formation inside berry puree are the temperature of 70–80°C with the corresponding viscosity of 70–80?pa?s and moisture content of 80–85% (wb). The dissipation of microwave energy in berry puree tends to decaying trend due to the changes of dielectric properties. Moisture content has the most significant positive effect on both dielectric constant and dielectric loss factor of berry puree, followed by the density, and the drying temperature has the least but significant effect on both indicators. The focusing phenomenon of microwave irradiation depended on the dielectric properties determines the distribution of temperature of berry puree. The findings in current work contribute to a better understanding the MFD behavior of berry puree and will help to optimize the drying conditions of MFD for enhancing energy efficiency and drying quality.     

Effects of drying conditions on physicochemical and antioxidant properties of banana (Musa cavendish) peels

A significant amount of banana peels is generated as waste annually and shows great potential as a lead material for further utilization in the nutraceutical industry. However, potentiality of banana peel utilization largely depends on the favorable drying condition of the material before it can be used for further processing. Therefore, it is necessary to identify the suitable drying conditions for banana peel. This study investigated the effect of six different drying methods on the quality of banana peels. The results showed that different drying conditions significantly affected the physical, chemical, and antioxidant properties of dried peels. Microwave irradiation at the power level of 960?W for 6?min was the most suitable condition, as these dried peels had good physical properties, minimum loss of bioactive compounds, and antioxidant properties. This was followed by freeze-drying, vacuum oven at 60°C, hot air oven at 120°C, dehumidified air at 60°C, and sun drying. The peels dried by microwave possessed a total phenolic content of 25.26?mg of gallic acid equivalents/g of dry matter (DM) and potent antioxidant capacity [(1,1-diphenyl-2-picrylhydrazyl) of 37.70; 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid of 46.35; ferric reducing antioxidant power of 45.94; and cupric ion reducing antioxidant capacity of 64.55?mg of trolox equivalents/g of DM]. Therefore, the study recommends the use of microwave irradiation under the studied condition (power level of 960?W for 6?min) for further processing and utilization.     

Application of Design of Experiments and Multilayer Perceptron Neural Network in Optimization of the Spray-Drying Process

The aim of this study was to investigate the effect of changing spray-drying parameters on the production of a naratriptan/maltodextrin/lactose composite, as well as to evaluate the application of design of experiments and multilayer perceptron (MLP) neural network in studying the spray-drying process. The system was spray dried as an aqueous solution using a Büchi 290-Mini Spray Dryer (Büchi Laboratoriums-Technik AG, Switzerland). A 2^4?1 factorial design study was undertaken to select the spray-drying processing variables that significantly affect the production yield, outlet air temperature, and residual moisture content. The process parameters studied were inlet air temperature, pump speed, aspirator setting (drying air flow rate), and feed concentration. After performing this screening study, three process parameters, pump speed, inlet air temperature, and feed concentration, were selected for further analysis, applying a central composite design and artificial neural network. Overall, the parameter that had the greatest influence on each investigated response was pump speed. It significantly influenced yield, moisture content, and particle size. Interaction between inlet air temperature and feed concentration was the only statistically significant interaction that influenced the moisture content. Particle size was mostly influenced by feed concentration as well as by a pump speed. A multilayer perceptron was the type of artificial neural network applied. The selected MLP structure had three layers: the first layer had three input units, the second layer had three hidden units, and the third layer had four output units. The selected MLP was trained through 10,000 epochs. Design of experiments using response surface methodology allows insight into interactions between variables, and an artificial neural network provides better prediction potential, enabling simultaneously determination of several outputs. Design of experiments and artificial neural network proved to be useful tool for optimization of the spray-drying process, where a design space for achieving the best process yields and optimum particle characteristics was established. There is a possibility that this conclusion can be drawn for other maltodextrin/lactose systems with other drug substances or for other similar spray-dried systems (the feedstock type is a carbohydrate-based aqueous solution). In future work, this will be tested with other materials.