Effect of relative humidity on the oxidative and physical stability of encapsulated milk fat

Milk fat was used in this work as a model to study the effects of humidity and physical properties on lipid oxidation. Although milk fat is considered a relatively stable fat because of its low content of unsaturated FA, it can oxidize significantly under certain conditions, as observed, for example, in the case, of dairy-based powders. Humidity and physical properties have a profound influence on the oxidative stability of powders, containing fat, and these factors affect the surface and encapsulated fractions of the fat differently. To examine these effects, encapsulated milk fat powders were stored under conditions of controlled relative humidity. Oxidation of the encapsulated fat as assessed by measurements of PV, losses of FA, and hexanal production increased, with increasing relative humidity (RH). At higher RH, moisture penetrates into the hydrophilic wall, interacting with and plasticizing the components, thereby making them less effective as moisture and oxygen barriers. Total oxidation of the powders was strongly influenced by the extent of oxidation in the encapsulated fraction (>98% of total lipids) although the surface fat fraction was oxidized more rapidly. Better protection against oxidation was obtained when fats were encapsulated and stored at 14 and 44% RH than at 52% RH.     

Spray Drying of Blue Shark Skin Protein Hydrolysate: Physical,Morphological, and Antioxidant Properties

The objective of this work was to evaluate the influence of inlet air temperature and maltodextrin concentration on the physical, morphological, and antioxidant properties of powdered blue shark skin protein hydrolysate. Higher inlet air temperatures led to lower moisture content and bulk density, whereas higher maltodextrin concentrations led to lower moisture content and hygroscopicity, higher bulk density, and larger particles size. Antioxidant capacity was mainly affected by maltodextrin concentration, which was attributed to two possible reasons: the protection provided to the peptides fractions and/or the formation of Maillard reaction products with antioxidant activity. In addition, maltodextrin itself showed a slight antioxidant capacity, which may have contributed to the higher antioxidant capacity of powders compared to the liquid hydrolysate.     

A comparative study on hygroscopic and physiochemical properties of chicken powders obtained by different drying methods

Abstract

Different drying methods (spray drying (SD), vacuum drying (VD), microwave vacuum drying (MVD), and infrared vacuum drying (IFVD)) were applied in order to compare the hygroscopicity behavior of chicken powders. The hygroscopicity curves and glass transition temperature were used to evaluate the influence of ambient humidity and temperature on moisture absorption of powders. The results showed that the chicken powder dried by MVD had the lowest moisture absorption, followed by IFVD, VD, and SD. The hygroscopicity of SD chicken powders was different from other three kinds of chicken powders due to the physical properties of particles and the changes of protein secondary structure as detected by the Fourier transform-infrared spectrometer. For the three vacuum drying methods, the difference of protein secondary structure was the main reason of differences in hygroscopicity. Although MVD chicken powders were slightly inferior to SD chicken powders in taste, MVD chicken powders were the best in terms of smell and color as suggested by instrumental sensory parameter evaluations. It was found that MVD had a positive effect on reducing moisture absorption and maintaining sensory quality of chicken powders.     

影响可再分散聚合物乳胶粉性能的因素分析

采用喷雾干燥法制备可再分散聚合物乳胶粉。探讨了干燥室进口温度、喷雾液黏度、雾化轮转速及喷雾液进料速率对制备可再分散乳胶粉及其性能的影响,并用扫描电镜对乳胶粉进行表征。结果表明:进口温度为120～140℃、喷雾液黏度在15～20 s、雾化盘转速24 000 r/min、进料泵转速为30～35 r/min时,制备的乳胶粉流动性好、无结块,再分散性优良,满足制备乳胶粉的性能要求。     

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.     

Measuring the flow properties of small powder samples using an avalanche tester

The feasibility of using a small-scale avalanche tester to measure the flow properties of pharmaceutical lactose powders was examined. The modes of behavior observed in larger systems were displayed and showed a clear distinction between angular, free-flowing particles and more spherical particles of similar flow characteristics. Angular Lactohale LH100 particles showed slumping behavior at a rotational frequency of 0.33 Hz that disappeared at higher frequencies. Spherical lactose powder with a similar flow function to LH100 only showed rolling behavior under the same conditions, as did more cohesive powders LH200 and LH300. Further investigation of the LH100 data using fast Fourier analysis showed that the slumping frequency was one tenth of the rotational frequency.     

Properties and Stability of Spray-Dried and Freeze-Dried Microcapsules Co-Encapsulated with Fish Oil,Phytosterol Esters,and Limonene

The objectives of this study were to investigate the properties and stability of microcapsules containing fish oil co-encapsulated with phytosterol ester and limonene, prepared by spray-drying and freeze-drying methods. Whey protein isolate and soluble corn fiber were used as wall materials in the encapsulation process. The properties of microcapsules, including structure, glass transition, volatile/non-volatiles retention, microencapsulation efficiency, oxidation stability, color measurement, and sensory profiles, were evaluated after drying and during a seven-day accelerated storage trial. The finding reveals that drying methods have an effect on the retention of volatile fraction and the physical structure of the wall matrix consisted of WPI and SCF, consequently influencing the storage stability of the powders. Significantly higher retention of volatile fraction (p < 0.05) and lower surface oil were found in the spray-dried samples, resulting in the higher microencapsulation efficiency. However, samples dehydrated by both methods have good redispersion properties, showing no statistical significance (p > 0.05). The oxidation of the encapsulated oils was comparable for both spray- and freeze-dried samples during the seven-day accelerated storage trial but the loss of limonene flavor was significantly higher in the freeze-dried samples (p < 0.05). Sensory evaluation indicated that the addition of limonene could mask the unpleasant fishy odor in the co-encapsulated microcapsules. Overall, freeze drying did not produce powders with superior properties and did not show better protection towards the core materials than spray drying.     

Effect of calcination temperature on the microstructure,composition and properties of nanometer agglomerated 8YSZ powders for plasma spray-physical vapor deposition (PS-PVD) and coatings thereof

Homemade nano-agglomerated powders 8YSZ powders for PS-PVD were prepared by the spray drying, then calcination processes at four different temperatures (500 °C, 700 °C, 900 °C and 1100 °C) were carried out on the spray-dried powders. Checked by laser particle sizer, scanning electron microscope (SEM) and X-ray diffraction (XRD), the physical properties, microstructure and phase constitutions of the calcined powders were investigated. The results show that the size of powders calcined at 500 °C is increased relative to the spray-dried powder, whereas the powders calcined at 700 °C, 900 °C and 1100 °C possess smaller size. The binding force of the primary particles tend to rise with the increase of calcination temperature. When the temperature was up to 900 °C and above, it was found that the sintering neck indicating with strong binding was formed between the primary particles. In parallel, the powders underwent an m-ZrO₂ to t-ZrO₂ transition as the calcination temperature rose. It is also found that the PS-PVD prepared coatings which were obtained by using the above powders undergo a transformation from a feather-like to a dense laminate structure as the calcination temperature rises. It is noteworthy that the coating obtained by the powders calcined at 700 °C have a special three-layer composite structure of near dense surface layer, columnar intermediate layer and dense sub-layer. The composite structural coating has excellent adhesion and thermal shock resistance, with a bonding strength of 81MPa and no major spalling when water quenched 100 cycles at 1100 °C.     

Response surface methodology (RSM) as relevant way to study and optimize texturing by instant controlled pressure drop DIC in innovative manufacturing of egg white and yolk powders

This study aimed to use the Instant Controlled Pressure Drop as a texturing pretreatment prior to air flow drying as a new way for the manufacturing of egg white and yolk powders evaluating the impact of DIC operating parameters; the saturated steam pressure and processing time, on the physical and functional properties of the end products. The obtained results showed that the DIC-textured egg white and yolk powders had high quality attributes compared to those obtained from classical air flow drying. Moreover, it was better than freeze dried powders in terms of water absorption capacity, emulsifying capacity, and foaming capacity and stability.     

Physicochemical Characterization of Whole Egg Powder Microencapsulated by Spray Drying

Physical characterization and oxidative stability of egg powder microencapsulated by spray drying were studied in this work. The wall material (gelatin, lactose, pullulan, and their mixtures) and liquid egg mixtures were prepared by homogenization at 22,000 rpm for 60 s. The spray drying was carried out at pilot-scale spray dryer (Niro Mobile Minor, Søborg, Denmark). The spray-dried egg powders were analyzed for moisture content, water activity, peroxide value, total cholesterol oxidation products (TCOPs), particle properties, and bulk properties. Using gelatin as wall material resulted in a significant increase in the moisture content and water activity of egg powder during storage and it improved flowability. Egg powders containing pullulan as wall material showed a fibrous structure and had the lowest bulk density. Adding lactose as wall material increased the oxidative stability, which was indicated with lowest peroxide value and TCOPs level of egg powder.     

Physicochemical Properties of Phytopharmaceutical Preparations as Affected by Drying Methods and Carriers

This article reports a study of the effects of the drying methods and drying carriers on system performance and physicochemical properties of spray- and spouted bed–dried phytopharmaceutical preparations from Bidens pilosa L. Colloidal silicon dioxide, β-cyclodextrin, maltodextrin dextrose equivalent (DE) 10, and microcrystalline cellulose were used as drying carriers. The dried product was characterized by the particle size and morphology, total flavonoid content, solubility, flowability, and water activity. High-performance liquid chromatography (HPLC) was used to detect four marker compounds previously reported for this plant. Spray and spouted bed drying systems were compared through energetic efficiency, product recovery, elutriation, and product accumulation. The crystalline state of the powders was assessed by X-ray diffraction. Results showed high degradation rates for total flavonoid content and marker compounds during spouted bed drying. Depending on the drying carrier added to extractive solutions, different degrees of protection from degradation were conferred, and the physical characteristics of the product were changed accordingly. The lowest flavonoid degradation (8.6%) and the higher concentration of marker compounds were obtained using β-cyclodextrin as the drying carrier. Particle size was higher when a blend of Aerosil (Evonik Degussa, Hanau, Germany) and cellulose was employed as the drying carrier. A maximum product recovery of 86.9% was achieved by spray drying and 72.9% by spouted bed drying with the Aerosil : cellulose composition.     

Manufacturing Better Quality Food Powders from Spray Drying and Subsequent Treatments

In this article three major aspects of spray-dried food powders are discussed. We first address several practical problems involved during spray drying that may greatly influence product quality. The second issue identifies how an accurate drying kinetics model can form a useful tool to predict changes in the physical and biological quality aspects and the microstructure of the particle during processing. Dryer-wide simulations using the accurate drying kinetics model can significantly reduce the number of experimental trials for optimizing the process. To date, such success has been restricted to production runs for pilot-scale or small-scale industrial operations. The final issue addresses some of the challenges encountered when evaluating the functionality of the spray-dried powders during their reconstitution. The superior functionality of the spray-dried food product needs to be established more scientifically, which can help commercial operations to achieve high-quality reconstitution.     

A Comparison of Compacting and Caking Behavior of Carbonate-Based Washing Powders

Two types of sodium carbonate powder produced by spray drying (SD) and dry neutralization (DN) were studied for their compaction properties using a uniaxial compression tester. A comparison was also made with Persil washing powder. Dry neutralized sodium carbonate showed greater resistance to compression and also produced a weaker compact when compressed to 100 kPa. Spray-dried sodium carbonate had an absence of fine particles but compacted easily. Differential scanning calorimetry (DSC) showed that both types of powder were predominantly amorphous in nature. Moisture sorption measurements showed that both powders behaved in a similar way below 50% relative humidity (RH). However, dry neutralized sodium carbonate had a high moisture affinity above this RH. Particle structures were also examined using scanning electron microscopy, showing the heterogeneous interior of the spray-dried particles.     

Spray-dried ceramic powders: A quantitative correlation between slurry characteristics and shapes of the granules

The characteristics and consequently the properties of ceramic coatings performed using plasma spraying means depend not only on the operating conditions but also on the powder feedstock. Oxide powders are commonly prepared in one stage or in a combination of stages of fusing, crushing, agglomerating and sintering. The spray drying process (which corresponds to the agglomerating route) is a technique in which small constituent particles dispersed in water (which is called slurry) are sprayed in hot air and granulated thanks to a binder (latex or PVA). Spray drying is carried out for a variety of reasons, two major motivations being the production of composite and shape controlled powders for thermal spray applications. The aim of the present work was to establish a correlation between the slurry formulation and the characteristics of the spray dried granules for two oxide ceramics: Al₂O₃ and Y₂O₃-ZrO₂. Detailed studies on the dispersion and stability of the slurries were performed using sedimentation tests, electrophoretic mobility measurements as well as adsorption isotherms experiments. Then, a drying experimental test based on the drying of a suspended droplet was developed to assess the drying mechanisms, identify the correlation between the slurry characteristics and the morphology of the dried granules and finally to predict the shapes of the spray-dried powders. It was shown that there is a qualitative relation between the sedimentation behaviour (as measured by the sediment ratio) and the granule shape (solid or hollow) and a quantitative relation between the thickness of the shell (for hollow granule) and the state of dispersion and the nature of the binder used. Finally, several powder batches were prepared in the spray-dryer which confirm the reliability of the drying simulation test.     

偶联剂改性对磁敏NR/SBR并用胶性能的影响

将NR和SBR与改性羰基铁粉机械共混制备磁敏NR/SBR并用胶,研究偶联剂KH-550,KH-560,KH-570和NDZ-401改性羰基铁粉对磁敏NR/SBR并用胶的物理性能和磁流变效应的影响。结果表明:不同偶联剂改性的羰基铁粉对NR/SBR并用胶性能有一定的影响;采用偶联剂KH-570改性的羰基铁粉填充的NR/SBR并用胶表现出较好的物理性能和磁流变效应。     

Drying of Seabuckthorn (Hippophae rhamnoides L.) Berry: Impact of Dehydration Methods on Kinetics and Quality

Convective hot air drying and freeze drying were investigated as potential dehydration processes to obtain powders of seabuckthorn fruit pulp. Halved seabuckthorn fruits were placed in a hot air dryer and dried at 1 m/s and at 50 or 60°C or freeze dried at less than 30 mTorr and at 20 or 50°C shelf plate temperature. An initial characterization of the seabuckthorn pulp (moisture, pH, soluble solid content, vitamins C and E, total phenolics, and carotenoids) was performed. Water loss, total phenolic compounds, total carotenoids, and vitamin C were determined at different processing times. Vitamin E was determined before and at the end of drying.

Freeze-drying kinetics were faster than air drying, probably due to lower moisture diffusion in the compact, sugary, and oily structure of the air-dried tissue. The temperature had an important impact on hot air–drying and freeze-drying kinetics. Drying method and processing times affected the remaining phenolic, carotenoid, and vitamin contents of seabuckthorn berries. Freeze drying was revealed as a superior method to obtain seabuckthorn powders because of the lower residual moisture content, the ease of grinding, as well as the better nutritional retention.     

Ceramic particles and layers for functional application

Besides ‘bulk’ structural and functional ceramic, a third interesting group of inorganic or ceramic materials exists: particles used for medical applications like contrast agent as building blocks for photonic crystals, as thin or thick layers with controlled porosity or grain sizes showing interesting thermal or electrical behaviour or finally nanostructured ceramic with novel optical and mechanical properties. As high-tech ceramic this type of ceramic needs very well synthesised powders of high purity, defined sizes for the use of quantum effects and small size distributions. Very often, complex powders like core–shell particles with nanometer thin layers are needed to fulfil physical as well as biological demands. Additionally, powder processing is one of the key factors to reach outstanding structural and functional properties. Especially the stability of colloidal suspensions and the drying step during the film manufacturing are objects of the research because nanosized particles cause particular problems normally not observed with micron- or submicron-sized powders. Application of nanosized superparamagnetic iron oxide particles for molecular imaging and cancer treatment and results regarding the manufacturing of thin nanostructured layers for interesting physical (thermal conductivity) and medical (drug delivery) will be presented.     

Vacuum Drying for Ultrafine Alumina Powders

It is well known that the drying of liquid-borne powders will create agglomerates and the problem of agglomeration is particularly acute in the nanoscale range. To eliminate/mitigate the agglomeration problem, in this study, a vacuum drying technique was used for drying the colloid solution with θ-Al₂O₃ ultrafine particles. For comparison purposes, other drying methods including oven drying, microwave drying, and freeze drying were also applied for drying of the same kind of colloid solution. The results indicate that the redispersibility, which is closely related to the degree of agglomeration, of the dried powders obtained from vacuum drying is better than that obtained from freeze drying. More surprisingly, results showed that the dried powders obtained from the vacuum drying assisted by microwave heating has the redispersibility close to 100%.     

细颗粒振动流态化行为的二维床观察

本文利用一种新型复合振动充化装置，使在一般操作条件下无法实现正常流化的细颗粒床层处于良好的流化状态。通过观察发现，振动的引入可以破坏沟流的存在而使细颗粒流化；其振动流化有三种存在形式，提出了振动流化的物理模型和流化相同，可以解释细颗流化状态与振动条件及其物性的关系。     

Development of a tribolelectric procedure for the measurement of mixing and drying in a vibrated fluidized bed

Fluidization of fine, pharmaceutical powders makes them easier to dry, coat and mix. Fine powders, however, are difficult to fluidize well with gas flow only. Vibration can often help achieve smooth fluidization at a lower gas flow. The objective of the present study was, thus, to develop reliable and quick experimental methods to characterize mixing and drying in vibrated fluidized beds of fine powders.Effective mixing is critical in many industrial applications and, in gas-solid fluidized beds, requires gas velocities greater than the minimum bubbling velocity (U_mb). There are a number of techniques available for determining U_mb. However, they often are impossible or impractical to use in an industrial application. A new measurement technique involving the use of triboelectric probes was developed. Signal characteristics obtained from sophisticated signal analysis were used to identify the minimum bubbling velocities. These predictions corresponded well with the values obtained from more traditional laboratory methods such as the bed pressure gradient.In a fluidized bed, particles hitting a metal probe will generate a small triboelectric current. Triboelectric probes are able to detect rapid changes in particle surface properties. Surface properties of the particles were modified by wetting the particles in a low shear mixer. This change was detected by triboelectric probes at various locations inserted throughout the bed. The water adsorbed on the particles will begin to evaporate when exposed to the gas stream and the surface properties of the particles will gradually return to their original dry state. The triboelectric probes were able to monitor this drying process. The effects of vibration amplitude on the mixing and drying rate of the bed were also determined.