Spray dried powders

Urea and melamine adhesives represent products of very mature and overaged technologies. Essentially, they are simple reaction products of urea or melamine with formaldehyde they may be Hquids or powders. Liquids are converted to dry powders by "spray drying." Melamine-urea combinations generally are spray-dried powders of co-reacted Hquid melamine and area-formaldehyde resias. 

Spray-dried powders find application in adhesives to build solids, increase viscosity, improve tack, and decrease drying time (145). A primary use is in joint compounds with other applications in mastics and grouts, and patching compounds (146). 

Typically, grape skin extract has a specific gravity of 1.13 g/mL at 20°C, a solids content of 28—32° Brix (=t3°), a pH of 3.0, and a color strength as anthocyanin of about 1.25% (as measured at 520 nm ia pH 3.0 citrate buffet). Grape skin extract is also available as spray-dried powders with color values three to four times those of the liquid. The properties and uses of grape skin extract ate similar to those of grape color extract. 

Later it was found growing in South America where the Indians used the red dye from the seeds as a body paint. An extract of the seeds appears on the market as annatto. This extract is used in coloring butter, margarine, and cheese such as Leicester cheese. In Mexican and South American cuisine, it finds special use as a flavor and coloring matter. The seeds are sold under the name achiote in many Latin grocery stores and markets. Ann at o is available as an aqueous solution, as an oleaginous dispersion, and a spray-dried powder. 

Spray drying 0.05 to 0.5 Low Morphology of spray dried powders can Instant foods, dyes, detergents, ceramics... 

After hardening, UF-resins consist of insoluble, more or less three-dimensional networks and cannot be melted or thermoformed again. At their application stage, UF-resins are still soluble or dispersed in water or are spray dried powders, which in most cases are redissolved and redispersed in water for application. 

Usually spray-dried powders are sold. A purification step is not usually done on the industrial scale. The modification of the extracts are especially aimed at decreasing the sometimes too high viscosity to achieve better handling and application, but also a longer pot life and a better crosslinking [16,17,144]. 

The preparation method also influences the resistivity of f3"-alumina tubes. Bug-den and Duncan [26] showed that the resistivity of tubes made from spray-dried powder is lower (4.3Qcm) than that of tubes of vacuum-dried powder (5.5 Qcm). 

If the tannin blend is made from spray-dried powders, the dilution water must be heated to 160 to 180 °F and the biocide only added when the temperature has cooled below 140 °F. 

The presence of volatile components in alcohol ethoxylates (e.g., free alcohol) places some restriction on the level and type of alcohol ethoxylate that can be spray-dried. Volatile components cause pluming in spray tower emissions. These emissions can be minimized by using a peaked or narrow range ethoxylate or by postdosing the nonionic onto a previously spray-dried powder [36]. The peaked ethoxylate contains inherently less of the volatile components. 

The introduction of concentrated laundry detergent powders in Japan during 1986-1987 produced a substantial increase in the consumption of LAB in the subsequent 3-4 years as the market changed from low-density, spray-dried powders to the concentrated (compact) products. In these products, which may contain up to 40% surfactant, the cost/performance advantages of LAS are of significance. In addition, LAB sulfonic acid is well suited for the production of high-active, high-density (about 1.0 g/cm3) laundry powders by routes other... 

The degradation of proteins in the solid state occur to a lesser extent and typically via different mechanisms than those that occur in solution [109,110]. Lyophilization is currently the more common technique in the manufacture of dried therapeutic proteins however, there is increasing interest in the use of spraydrying, owing to the unique physical nature of the spray-dried powder and its potential usefulness in protein drug delivery. 

S. T. Tzannis and S. J. Prestrelski, Moisture effects on protein-excipient interactions in spray dried powders. Nature of destabilizing effects of sucrose, J. Pharm. Sci, 88(3), 360 (1999). 

In precipitation reactions, powder characteristics depend on the speed of the nucleation of particles and their growth due to the mass flow to the surfaces. In freeze drying and spray drying, powder characteristics primarily depend on the size of droplets, which in turn is determined by the parameters of a nozzle and characteristics of the flow of a carrier gas. Both these methods enable one to obtain powders with very high surface area. 

In friability tests the material s susceptibility to attrition is evaluated. But it is not as simple as it may seem at first to select the suitable test procedure. In this context Pell (1990) gave a simple thought experiment to illustrate the difficulties If we took a batch of rubber stoppers and a batch of diamonds, and rubbed them on abrasive paper, we would conclude that the diamonds were more attrition resistant. If we instead struck the particles with a hammer we would conclude that the rubber were more attrition resistant. So, different test methods can rank materials differently with respect to their attritability. This effect was for example observed by Knight and Bridgwater (1985). They subjected spray-dried powders to a compression test, a shear test and a test in a spiral classifier. They found that each test gave a different ranking of the materials. Obviously, there is no... 

The lyophilized cake must then be milled. The particle size of milled lyophilized powders generally has a broader distribution than spray-dried powder, which is formed one particle at a time in a continuous process. Despite the longer processing time necessary to create a dry powder through lyophilization (and the consequent... 

Bell, J.H., Fisons Patent, Pelletised medieament formulations. Application no. 152047 (1975). Vidgren, M.T., Vidgren, P.A., and Paronen, T.P., Int. J. Pharm., 35 139-144 (1987). Chawla, A., Spray-dried Powders for Use in Dry Powder Aerosol Formulation, PhD Thesis, University of London, 1993. 

Acusol 460 N is an acrylic based copolymer containing a non-ionic monomer bringing a hydrophobic character which decreases the water re-adsorption of the spray dried powder. 

Protein-based drugs have been formulated mainly as stable liquids or in cases where liquid stability is limiting as lyophilized dosage forms to be reconstituted with a suitable diluent prior to injection. This is because their delivery has been limited primarily to the parenteral routes of intravenous (IV), subcutaneous (SC), or intramuscular (IM) administration. There are a few drugs that have been developed for pulmonary delivery, such as rhDNase (Pulmozyme ) and an inhalable formulation of insulin (e.g., Exubra ). However, even such drugs have been formulated as either liquid or lyophilized or spray-dried powders. This chapter will focus only on excipients that are applicable to liquid and lyophilized protein formulations. 

The spray-dried powders were evaluated for surface and encapsulated oil. The data is presented in Table 1 (2). 

Emulsions made with a fine oil droplet particle size, usually less than one micron, are more stable with the oil droplets less likely to coalesce and separate. The encapsulation of a good quality emulsion is generally more efficient with less surface oil on the spray-dried powder. We wanted to build surfactant properties into the starch backbone to improve encapsulation efficiencies. Studies of the mechanism by which surfactants stabilize emulsions were made in order to accomplish this. 

A 10 gram sample was placed in a 200 ml round bottom flask and 100 ml of distilled water added. A Dean-Stark trap and condenser were used and the mixture was brought to a boil. The steam distilled oil was measured after four hours versus control mixtures. In order to measure surface oil on the spray-dried powders, the powder was first washed with a solvent (ethyl ether or hexane) then oil retentions were run by the steam distillation method illustrated above. Differences in oil volume for solvent washed versus non-washed were attributed to surface oil on the spray-dried powders. 

Orange terpenes were emulsified in various carrier s and spray-dried. The spray-dried powders were aged for 3 days at 80 C in a draft oven. Beta-pinene is an oxidation product in orange terpenes which can be measured by GC. The beta-pinene level is proportional to the degree of oxidation of the orange terpenes. High levels of beta-pinene content in the spray-dried powders indicate poor oxidation resistance imparted to the encapsulated terpenes by the carrier. 

The dispersed droplet size, referred to as emulsion or particle size, can be reduced in the spray drier infeed matrix by more vigorous mixing or homogenization. There is also a new technique for creating small emulsions termed microfluidization which will be discussed later. This research was designed to determine whether the size of emulsion in the infeed solution will affect the characteristics of the final spray dried powder. Materials and Methods... 

A 1% solution of spray dried powder in water was prepared and gently stirred with a magnetic stir bar until the powder was completely dispersed. The absence of any clumps when the solution was viewed under a microscope was used as an indicator of complete dispersion. A few mL of solution were placed in the chamber of the Microtrac. In the instrument, the solution flows past a laser beam in an optically clear cell. The angle of diffraction of the laser beam is measured and the size of the emulsion calculated. The calculation is based on the principle that the smaller the emulsion size, the larger the angle of diffraction. The instrument gives results on emulsion size and size distribution as well as calculating the surface area of the emulsion. The entire analysis is computerized. 

Emulsion Stability. The stability of the emulsions was determined by measuring optical density of the solutions following centrifugation. A 0.2% solution of each spray dried powder was prepared in water and the optical density read at 400 nm in a Coleman spectrophotometer. A 0.16% solution of carrier (gum arabic) was used as a blank. This is based on a carrier to flavor ratio of 4 1. The initial optical density of each solution was read and then the solutions were centrifuged in an lEC International Centrifuge at 500 x g for 5, 10, 15, 30, 45 and 60 min. The optical density was read after each time period. 

The extractable surface oil results of the spray dried powders are listed in Table IV. The extractable surface oil decreased as the emulsion size decreased. Based on previous knowledge, one would anticipate that less surface oil would result in a better shelf-life. The results of this study do not support that theory especially when you consider the third set of samples in which the coarse emulsion had the greatest amount of extractable surface oil yet also had the longest shelf-life. 

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