Effect of Operating Parameters on the Spray Drying of Tomato Paste

The production of tomato powder from tomato paste using the spray drying technique has been investigated in this work. The influence of a number of process variables, namely, feed total solids, feed flow rate, feed temperature, air temperature, air flow rate, and starch addition on the physical properties of spray‐dried tomato powder was investigated. The product properties studied were total solids, average particle diameter, bulk density, and solubility. The increase in the feed total solids increased tomato powder total solids, particle size and bulk density and decreased its solubility, while the increase in the feed flow rate decreased tomato powder total solids and solubility, and increased the average particle size and bulk density.     

Investigation on Side-Spray Fluidized Bed Granulation with Swirling Airflow

Top-spray fluidized bed granulation with axial fluidization airflow from the bottom of the granulator is well-established in the pharmaceutical industry. The application of swirling airflow for fluidized bed granulation was more recently introduced. This study examined the effects of various process parameters on the granules produced by side-spray fluidized bed with swirling airflow using the central composite and Box–Behnken design of experiment. Influence of the amount of binder solution, spray rate, and distance between spray nozzle and powder bed were initially studied to establish operationally viable values for these parameters. This was followed by an in-depth investigation on the effects of inlet airflow rate, atomizing air pressure and distance between spray nozzle and powder bed on granule properties. It was found that the amount of binder solution had a positive correlation with granule size and percentage of lumps but a negative correlation with size distribution and Hausner ratio of the granules. Binder solution spray rate was also found to affect the granules size. High drug content uniformity was observed in all the batches of granules produced. Both inlet airflow rate and atomizing air pressure were found to correlate negatively with granule size and percentage of lumps but correlate positively with the size distribution of the granule produced. Percentage of fines was found to be significantly affected by inlet airflow rate. Distance between spray nozzle and powder bed generally affected the percentage of lumps.     

Analysis of Process Parameters Affecting Spray-Dried Oily Core Nanocapsules Using Factorial Design

The purpose of this work was to optimize the process parameters required for the production of spray-dried oily core nanocapsules (NCs) with targeted size and drug yield using a two-level four-factor fractional factorial experimental design (FFED). The coded process parameters chosen were inlet temperature (X ₁), feed flow rate (X ₂), atomizing air flow (X ₃), and aspiration rate (X ₄). The produced NCs were characterized for size, yield, morphology, and powder flowability by dynamic light scattering, electron microscope, Carr’s index, and Hausner ratio measurement, respectively. The mean size of produced NCs ranged from 129.5 to 444.8 nm, with yield varying from 14.1% to 31.1%. The statistical analysis indicated an adequate model fit in predicting the effect of process parameters affecting yield. Predicted condition for maximum yield was: inlet temperature 140°C, atomizing air flow 600 L/h, feed flow rate 0.18 L/h, and aspiration air flow set at 100%, which led to a yield of 30.8%. The morphological analysis showed the existence of oily core and spherical nanostructure. The results from powder flowability analysis indicated average Carr’s index and Hausner ratio of 42.77% and 1.76, respectively. Spray-dried oily core NCs with size lower than 200 nm were successfully produced, and the FFED proved to be an effective approach in predicting the production of spray-dried NCs of targeted yield.     

香芋粉喷雾干燥工艺研究

我国香芋资源极为丰富,但开发程度远不及山药、甘薯、马铃薯等,所以对香芋加工工艺的研究对其潜在价值的开发具有重要意义。通过单因素试验考察了烫漂温度、烫漂时间、进风温度、进料速度及料液浓度对香芋粉喷雾干燥的影响。试验确定了香芋粉喷雾干燥的最佳工艺为:55℃烫漂10 min、进风温度为180℃、进料速度50 mL/min、料液浓度为0.1 g/mL。     

Ampicillin Nanoparticles Production via Supercritical CO2 Gas Antisolvent Process

The micronization of ampicillin via supercritical gas antisolvent (GAS) process was studied. The particle size distribution was significantly controlled with effective GAS variables such as initial solute concentration, temperature, pressure, and antisolvent addition rate. The effect of each variable in three levels was investigated. The precipitated particles were analyzed with scanning electron microscopy (SEM) and Zetasizer Nano ZS. The results indicated that decreasing the temperature and initial solute concentration while increasing the antisolvent rate and pressure led to a decrease in ampicillin particle size. The mean particle size of ampicillin was obtained in the range of 220–430 nm by varying the GAS effective variables. The purity of GAS-synthesized ampicillin nanoparticles was analyzed in contrast to unprocessed ampicillin by FTIR and HPLC. The results indicated that the structure of the ampicillin nanoparticles remained unchanged during the GAS process.KEY WORDS: ampicillin, nanoparticles, precipitation, supercritical gas antisolvent     

Particle Size, Moisture, and Fluidization Variations Described by Indirect In-line Physical Measurements of Fluid Bed Granulation

The aim of this study was to evaluate an instrumentation system for a bench scale fluid bed granulator to determine the parameters expressing the changing conditions during the spraying phase of a fluid bed process. The study focused mainly on four in-line measurements (dependent variables): fluidization parameter (calculated by inlet air flow rate and rotor speed), pressure difference over the upper filters, pressure difference over the granules (lower filter), and temperature of the fluidizing mass. In-line particle size measured by the spatial filtering technique was an essential predictor variable. Other physical process measurements of the automated granulation system, 25 direct and 12 derived parameters, were also utilized for multivariate modeling. The correlation and partial least squares analyses revealed significant relationships between various process parameters highlighting the particle size, moisture, and fluidization effect. Fluidization parameter and pressure difference over upper filters were found to correlate with in-line particle size and therefore could be used as estimates of particle size during granulation. The pressure difference over the granules and the temperature of the fluidizing mass expressed the moisture conditions of wet granulation. The instrumentation system evaluated here is an invaluable aid to gaining more control for fluid bed processing to obtain repeatable granules for further processing.     

A Statistical Approach to Optimize the Spray Drying of Starch Particles: Application to Dry Powder Coating

This article describes the preparation of starch particles, by spray drying, for possible application to a dry powder coating process. Dry powder coating consists of spraying a fine powder and a plasticizer on particles. The efficiency of the coating is linked to the powder morphological and dimensional characteristics. Different experimental parameters of the spray-drying process were analyzed, including type of solvent, starch concentration, rate of polymer feeding, pressure of the atomizing air, drying air flow, and temperature of drying air. An optimization and screening of the experimental parameters by a design of the experiment (DOE) approach have been done. Finally, the produced spray-dried starch particles were conveniently tested in a dry coating process, in comparison to the commercial initial starch. The obtained results, in terms of coating efficiency, demonstrated that the spray-dried particles led to a sharp increase of coating efficiency value.     

Optimization of Process Parameters for a Quasi-Continuous Tablet Coating System Using Design of Experiments

The aim of this study was to identify and optimize the critical process parameters of the newly developed Supercell quasi-continuous coater for optimal tablet coat quality. Design of experiments, aided by multivariate analysis techniques, was used to quantify the effects of various coating process conditions and their interactions on the quality of film-coated tablets. The process parameters varied included batch size, inlet temperature, atomizing pressure, plenum pressure, spray rate and coating level. An initial screening stage was carried out using a 2^6−1(IV) fractional factorial design. Following these preliminary experiments, optimization study was carried out using the Box–Behnken design. Main response variables measured included drug-loading efficiency, coat thickness variation, and the extent of tablet damage. Apparent optimum conditions were determined by using response surface plots. The process parameters exerted various effects on the different response variables. Hence, trade-offs between individual optima were necessary to obtain the best compromised set of conditions. The adequacy of the optimized process conditions in meeting the combined goals for all responses was indicated by the composite desirability value. By using response surface methodology and optimization, coating conditions which produced coated tablets of high drug-loading efficiency, low incidences of tablet damage and low coat thickness variation were defined. Optimal conditions were found to vary over a large spectrum when different responses were considered. Changes in processing parameters across the design space did not result in drastic changes to coat quality, thereby demonstrating robustness in the Supercell coating process.     

Model-based control of feed rate and illuminance in a photosynthetic fed-batch reactor for H2S removal

Traditional application of computer to fermentation processes has focused on the measurement and control of parameters such as temperature, pH, vessel pressure, sparge rate, dissolved oxygen, substrate concentration, and product concentration. In a fed-batch reactor with the photosynthetic green sulfur bacterium Chlorobium thiosulfatophilum which converts hydrogen sulfide to elementary sulfur or sulfate, separate measurement of cell mass concentration and sulfur particle concentration turbidimetrically was difficult due to their combined contributions to the total turbidity. Instead of on-line measurement of many process variables, a model-based control of feed rate and illuminance was designed. Optimal operation condition relating feed rate vs. light intensity was obtained to suppress the accumulation of sulfate and sulfide, and to save light energy in a 4-1 photosynthetic fed-batch reactor. This relation was correlated with the inreasing cell mass concentration. A model which describes the cell growth by considering the light attenuation effects due to scattering and absorption, and to crowding effect of the cells, was established beforehand with the results from the experiments. Based on these optimal operating conditions and the cell growth model, automatic controls of feed rate and illuminance were carried out alternatively to the traditional application of computer to fermentation with on-line measurement, realtime response and adjustment of process variables.List of Symbols F ml/min Flow rate of gas mixture - hV lux Average illuminance - Q mmol/(l h) Removal rate of hydrogen sulfide - X mg protein/l Cell mass concentration as protein - X ₀ mg protein/l Initial cell mass concentration - X _m mg protein/l Maximum cell mass concentration - _a h^–1 Apparent specific growth rate     

Performance of a continuous foam separation column as a function of process variables

Enrichment and recovery of bovine serum albumin has been examined in a continuous foam separation column. The effects of the operating factors, superficial air velocity, feed flow rate, feed concentration and pH on the above characteristics was investigated. The protein enrichment decreased with the increase in the value of each of these parameters. Protein recovery increased with increasing air velocity, decreased with increasing feed flow rate and did not change very much with increasing feed concentration. Maximum protein recovery was obtained at the isoelectric point (pH 4.8) of the protein. Maximum protein recovery was found to be a strong function of the air velocity in the range 0.05-0.15 cm/s. Further increase in air velocity did not have much effect on recovery because of very large bubbles formed as a result of coalescence. Bubble size was determined as a function of the above factors in the liquid and foam sections of the column. It was found to be dependent on protein concentration, feed flow rate and solution pH. The effect was more significant in the foam section of the column. The bubbles in the foam section were significantly larger (about 3-10 times) than those in the liquid, with a sharp change at the foam-liquid interface. The bubble size measurements were used to calculate the interfacial area and it was shown that the rate of protein removal increases with increasing interfacial area.     

Formation of Inhalable Rifampicin–Poly(l-lactide) Microparticles by Supercritical Anti-solvent Process

Formation of inhalable microparticles containing rifampicin and poly(l-lactide) (L-PLA) by using supercritical anti-solvent process (SAS) was investigated. The solutions of drug and polymer in methylene chloride were sprayed into supercritical carbon dioxide. The effect of polymer content and operating conditions, temperature, pressure, carbon dioxide molar fraction, and concentration of solution, on product characteristics were studied. The prepared microparticles were characterized with respect to their morphology, particle size and size distribution, drug content, drug loading efficiency, and drug release characteristic. Discrete, spherical microparticles were obtained at high polymer:drug ratios of 7:3, 8:2, and 9:1. The shape of L-PLA microparticles became more irregular and agglomerated with decreasing polymer content. Microparticles with polymer content higher than 60% exhibited volumetric mean diameter less than 5 μm, but percent drug loading efficiency was relatively low. Drug-loaded microparticles containing 70% and 80% L-PLA showed a sustainable drug release property without initial burst release. Operating temperature level influenced on mean size and size distribution of microparticles. The operating pressure and carbon dioxide molar fraction in the range investigated were unlikely to have an effect on microparticle formation. An increasing concentration of feed solution provided larger size microparticles. Rifampicin-loaded L-PLA microparticles could be produced by SAS in a size range suitable for dry powder inhaler formulation.     

The effect of process parameters on the Liquid Flame Spray generated titania nanoparticles

Nanoparticles have become important in many applications. It is essential to be able to control the particle size because the properties of nanoparticles change dramatically with particle size. An efficient way to generate nanoparticles is via aerosol processes. In this study we used Liquid Flame Spray consisting of liquid precursor droplets sprayed into a high-speed hydrogen/oxygen flame where they evaporate, vapours react and nucleate to form titania nanoparticles. Using flame methods, also dopants and sensitizers can easily be introduced in order to, e.g. improve the photocatalytic activity of the nanomaterial. To obtain a practical guideline in order to tailor the final nanoparticle size in the process, we have systematically studied the effects of different process parameters on the particle size of titania. Titania is used, e.g. as a photocatalyst, and then both particle size and crystal structure are important when looking at the efficiency. In this work, the generated nanoparticle size has been measured by aerosol instrumentation and the particle morphology has been verified with transmission electron microscopy. In Liquid Flame Spray method, there are several adjustable parameters such as precursor feed rate into the flame; concentration of the precursor; precursor material itself as well as solvent used in the precursor; mass flow of combustion gases and also the mechanical design of the torch used. We used metal organic based titanium precursors in alcohol solvents, predominantly ethanol and 2-propanol. Large differences in particle production between the precursors were found. Differences could also be seen for various solvents. As for precursor feed in the flame, the more mass is introduced the larger the nanoparticles are, i.e. precursor concentration and precursor feed rate have an impact on particle size. A similar phenomenon can be discovered for the combustion gas flow rates. Torch design also plays an important role in controlling the particle size.     

水溶性三七总皂苷制备与表征

为提高三七总皂苷的水溶性及其制剂在体内的稳定性和生物利用度,运用喷雾干燥法对三七总皂苷进行超细化,利用正交试验分析得到喷雾干燥制备三七总皂苷超细粉的最佳条件并对其各项指标进行检测。经分析所得最佳制备条件为：进口温度为140℃、三七总皂苷的浓度为65 g·L^-1、进料流速为30 L·h^-1和空气脉冲为4。对三七总皂苷原粉和喷雾干燥所得超细粉进行了理化性质检测,SEM扫描结果显示超细粉形貌规则,激光粒度仪测得粒径为70.5 nm;红外光谱检测所得结果证实超细粉化学性质较原粉无明显改变,不影响其药性;通过DSC、X-Ray检测所得结果显示超细粉与原粉相比晶体结晶度有所改变说明其水溶性增加。     

Evaluation of process variables in bench-scale bio-oxidation of the Olympias concentrate

Abstract: A statistically designed set of eight bio-oxidation tests on the Olympias concentrate was conducted in bench-scale equipment to evaluate the effects of important variables on pyrite/arsenopyrite oxidation and gold extraction. The variables studied were total retention time, feed solid concentration and particle size. High degrees of arsenopyrite oxidation were observed in all tests, as the arsenopyrite oxidation was very fast and therefore not dependent on the variables within the studied range. Statistical analysis of the experimental data reveals that the pyrite oxidation and gold extraction are dependent mainly on the retention time and to a lesser extent on the particle size. The feed solid concentration had a small influence only on the gold extraction. Regressed equations of the experimental data can be used to predict proper operating conditions.     

Packed bed dynamics during microbial treatment of wastewater: modelling and simulation

A mathematical model consisting of mass balance equations and accounting for bioreaction and mass transfer is presented to describe both unsteady and steady-state degradation of phenol in a biofilter. The model has been validated for the steady-state situation with literature work. The model has been able to predict the dynamics of the biofiltration process with variations in system and operating conditions as inlet substrate concentration, liquid phase mass transfer coefficients, particle size, Henry's constant, inlet velocity, growth and half saturation constants and bed void fraction. The results show that inlet substrate concentration, inlet velocity, growth and half saturation constants and liquid phase mass transfer coefficients significantly control the operational dynamics. It is also shown that inhibition effects can be neglected for low concentrations (<0.5 kg m(-3)) of phenol. Thus, the model can be used as a design tool for a biofilter.     

The role of food particle size in the growth of juvenile Atlantic salmon (Salmo salar L.)

The effect of particle size of a commercial pelleted feed on the growth of Atlantic salmon from first feeding alevins to first and second year smolts was investigated using 20-day feeding experiments. Ten experiments were performed over a two year period, each comprising six groups of fish separately selected from stock populations. Each group was presented with one of six sizes of food particle ranging from larger than the respective mean mouth breadth (100% feed size), through 50%, 25%, 12·5%, 6·25% to 3·125%. Experiments were performed in six radial flow/circumferential drain tanks under ambient photoperiod and water temperature. Growth rate was found to be closely related to feed size. Maximum growth in each case was shown only on one size of particle; larger and smaller sizes resulted in reduced growth. The particle size for maximum growth increased in direct proportion to fish length. Fish from 4·2 to 20·3 cm in length showed maximum growth on particle diameters 0·022 to 0·026 × fish fork length (PFR). First feeding alevins were found to show comparable growth rate on particle diameters 0·0115 to 0·090 PFR. Some seasonal variation in growth response was indicated. The results are discussed in relation to developmental and seasonal effects. Possible factors affecting the energetics of prey size related differential growth are discussed.     

Size Control in the Nanoprecipitation Process of Stable Iodine (127I) Using Microchannel Reactor—Optimization by Artificial Neural Networks

In this study, nanosuspension of stable iodine (¹²⁷I) was prepared by nanoprecipitation process in microfluidic devices. Then, size of particles was optimized using artificial neural networks (ANNs) modeling. The size of prepared particles was evaluated by dynamic light scattering. The response surfaces obtained from ANNs model illustrated the determining effect of input variables (solvent and antisolvent flow rate, surfactant concentration, and solvent temperature) on the output variable (nanoparticle size). Comparing the 3D graphs revealed that solvent and antisolvent flow rate had reverse relation with size of nanoparticles. Also, those graphs indicated that the solvent temperature at low values had an indirect relation with size of stable iodine (¹²⁷I) nanoparticles, while at the high values, a direct relation was observed. In addition, it was found that the effect of surfactant concentration on particle size in the nanosuspension of stable iodine (¹²⁷I) was depended on the solvent temperature.

Graphical Abstract

Open in a separate windowNanoprecipitation process of stable iodine (127I) and optimization of particle size using ANNs modeling.KEY WORDS: ANNs, microfluidic, nanoprecipitation, particle size, stable iodine     

超临界流体强化溶液分散法制备Eudragit S100纳米颗粒

目的:制备Eudragit S100纳米颗粒。方法:采用超临界流体强化溶液分散(SEDS)法制备,考察了Eudragit S100浓度、超临界CO2流速、溶液流速、压力、温度对Eudragit S100纳米粒形貌和粒径的影响,并用场发射扫描式电子显微镜、激光粒度分析仪、差示扫描量热仪、傅里叶变换红外光谱仪对样品进行表征。结果:SEDS法可以制备球形的、粒径分布窄的Eudragit S100纳米粒,所得纳米粒的平均粒径在90~220 nm之间。降低Eudragit S100浓度和温度、升高压力有利于制备形貌好、粒径小的纳米粒;提高超临界CO2流速和降低溶液流速也有利于制备粒径小的纳米粒,但当超临界CO2流速升高至4 kg/h或溶液流速降低至0.5 ml/min时,纳米粒的产率较低。SEDS处理后Eudratit S100仍以无定形态存在,且SEDS过程没有对Eudratit S100的化学键造成破坏。结论:采用SEDS法可用于Eudragit S100纳米粒的制备,工艺简单可行。     

Metal affinity protein precipitation: effects of mixing, protein concentration, and modifiers on protein fractionation

Previous work by us and others has shown that mixing impacts apparent protein solubility in single protein precipitations. In this work, we probe the effects of contacting conditions on fractional precipitation behavior at the bench scale. We have chosen metal affinity precipitation as our model system; the kinetics of this mode of precipitation are very rapid and largely irreversible and, consequently, mixing conditions govern the extent of fractionation and purity of the product in such a process. Our experimental strategy involved a three-pronged approach to control the effects contacting conditions on precipitate yield, purity, and particle size distribution. First, we studied the impact of process variables that control precipitant concentrations in the reactor including impeller speed and precipitant addition rate. Second, we controlled the rate of precipitation by changing the initial protein concentration to alter the protein-protein collision rate. Third, we examined the role of the molecular-level kinetics of affinity precipitation by using modifiers that compete with surface moieties to bind the metal ion, thereby reducing its availability. Our model process and protein system consisted of zinc precipitations of mixtures of bovine serum albumin and bovine gamma-globulins, carried out at a nominal 1-L scale; glycine was examined as a modifier. Faster impeller speeds and lower precipitant addition rates increased the desired protein yields, decreased purities, and reduced average precipitate particle size. Higher initial protein concentrations were found to produce precipitates with higher yields, lower purities and diminished particle size. Experiments with glycine indicated that modifiers in the precipitant solution serve to increase product purity, decrease yield, and increase the average particle size in bench-scale precipitations. (c) 1995 John Wiley & Sons, Inc.