Spray-dried products

Spray-dried products are usually recognised for an increase in amorphousness. The technique offers a variety of operative conditions such as inlet and outlet temperatures, drug concentration and solvent, each of which may vary the crystallinity of the final product. Thermal analysis is thus used as one of the techniques to evaluate the final product, for example phenylbutazone and lactose. 

Matsuda et al [146] provided evidence, via DTA, of the polymorphic transformation in spray dried phenylbutazone encouraged by varying the inlet temperature from 30° to 120°C. Importantly and indicative of its use, TGA was utilised to confirm that there was no residual solvent in the sample, in the form of a solvate. Two or three crystal forms were present. At 120°C the 5-form was produced, at 80° and 100°C, a mixture of two forms was formed and a third form was apparent at 70°C [146]. Mixtures containing two forms contained the P- and 8-form, and when three forms were present, they corresponded to the P-, 5- and s-forms. A single DTA endotherm was found in samples prepared at 100° and 120°C with an endothermic peak at 103°C, equivalent to the 5-form. Melting endotherms at 91-92°C were found for samples obtained at 70°C and 80°C. In these samples a recrystallisation exotherm at 93°C, corresponding to the 5-form was found again the 5-form subsequently melted as an endotherm at 103°C [146]. 

The quality of a product may depend on the amorphousness within a sample. Spray-dried lactose is a term that embraces several types of products, depending on how the product was manufactured. If a suspension of a-lactose monohydrate is spray dried, the lactose in solution acts as a binder during the spraying process to bind the crystals of lactose together as aggregates. Thus, the predominant nature of a-lactose is maintained. The amorphousness of the 

Angberg [148] reviewed the manufacture of lactose products. Recrystallisation from a supersaturated lactose solution below 93.5°C yields almost exclusively a-lactose monohydrate. Crystalline lactose powders with a high content of anhydrous forms are manufactured for direct compression. 

However, as described earlier, amorphousness in lactose samples depends on the method of preparation. The amorphous portions are in a high energy state and should easily absorb water vapour. The amorphous portions will crystallise when the glass temperature has been decreased by the increased water content to below the experimental temperature [151]. Angberg [148] considered that in a sorption isotherm, crystallisation will be shown as a rapid drop in the curve, since the freed crystalline parts desorb the superfluous water. The amount of 

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Dmm-dried products ate more affected by heat than spray-dried products. Drying ia a vacuum chamber decreases the temperature and thus the heat effect on the product, although the atmospheric dryers are used more widely. 

Tn comparing the content of drug extract in the final product, teas in granule form are usually very much inferior to instant teas which arc prepared from spray-dried extracts teas in granular form, in addition to 97 -98% filler and carrier substances often contain only 2-3% dry extract, while in spray-dried products almost ten times as much, viz on average 20%, drug extract is present. 

In a typical process a jacketed still fitted with a stirrer and reflux condenser in charged with 240 parts 37% w/w (40% w/v) formalin and the pH adjusted to 8.0-8.5 using sodium carbonate solution with the aid of a pH meter. One hundred and twenty six parts of melamine (to give a melamine formaldehyde ratio of 1 3) are charged into the still and the temperature raised to 85°C. The melamine goes into solution and forms methylol derivatives. For treatment of fabrics, paper and leather this product may be diluted and cooled for immediate use. It may also be spray dried to give a more stable product. Cooling the solution would yield crystalline trimethylolmelamine, which may be air dried but which is less soluble in water than the spray-dried product. 

Spray cleaning, of metal surfaces, 16 213 Spray coating processes, 7 23, 68-76 economic aspects, 7 75-76 Spray column absorbers, 1 27 Spray cone angle, 23 187 Spray correlations, 23 189-192 Spray deposition, of metal-matrix composites, 16 173 Spray-dried products, 11 542-543 Spray-dried resins, production of,... 

The typical flavour load of a spray-dried product amounts to 18-25%. Besides the drying process, the flavour components are also encapsulated in the carrier matrix. After the slurry has been atomised , all volatile components, including water, which are located at the surface of the droplet are immediately evaporated. Thereby the remaining carrier substance forms a membrane around the droplet. This membrane is semipermeable and inhibits further evaporation of flavour molecules. This production step is controlled by diffusion mechanisms. Water as a molecule with a small molecular size can pass through the membrane, while the larger flavour molecules are not able to permeate it. 

An optimal dehumidified spray-dried product consists of small, round particles, whose size is almost similar to their former droplet size. They are hollow and the encapsulated flavour molecules are situated in the outer shell. 

Table VI. Moisture Content of Spray Dried Products...

Total Oil. When compared to the other encapsulation processes, the spray dried products contained the highest amounts of volatile oil. Spray drying typically yields product with volatile oil contents ranging from 15-20% w/w. The extrusion products,... 

The graphs of limonene-1,2-epoxide as a function of storage time at 25, 37 and 50 C are presented in Figures 3, 4 and 5. Limoene-1,2-epoxide appeared to have an induction period where little or no epoxide formation occurs. Beyond the induction period, limonene-1,2-epoxide formation followed first order kinetics for the spray dried products. Gum arabic, M250, and Amiogum consistently showed the fastest rates of epoxide formation at the three storage temperatures. 

The stability of orange peel oil depends on the selection of the encapsulation process and the encapsulating agent. The results of this study indicated that the differences in shelf life were greatly accentuated at higher temperatures. The shelf life of the spray dried products ranged from 5-35 days compared to the extrusion and beta-cyclodextrin products which were still acceptable after 180 days at 50 C. 

Nonfat dry milk is produced from skim milk by condensing it with conventional equipment followed by spray or drum drying. The drum-dried product is relatively insoluble and is used principally for animal feeds. Over 95% of nonfat dry milk in the United States is used for human foods (American Dry Milk Institute 1982) and is produced by spray drying. Most instant NDM is made by rewetting the conventionally spray-dried product, allowing the particles to agglomerate, and... 

HAAs HPLC with (i) UV detection at 263 nm (ii) ED at 950 mV (iii) fluori-metric detection at 450 nm (Aex = 360 nm). LiChrosorb RP-Select B column. Mobile phase NH4 (acetate) (pH = 4.5), MeOH, ACN in isocratic and gradient elution. Food flavors, meat extract Cleaning up using the Gross method (94). The spray-dried product was Soxhlet extracted, placed on Kie-selgur, and extracted with ethyl ether. Cleaning up by affinity chromatography on Cu-phthalocya-nine complex. 201... 

Most of our later work was done using this cheapest desulfonated lignin. We did find that a desugared, spray-dried spent liquor worked better than spent-liquor solids dried by merely heating in an oven. The spray-dried product was used for occasional experiments. 

Characteristic sizes of the spray-dried product from SCISR operated continuously... 

Spray dried products, in general, are expected to meet a number of requirements. Properties of interest include size and size distributions, bulk density, moisture content, friability, appearance, reactivity and, with food products, aroma and flavour. Control of these properties requires close attention to all four unit processes described in Section 1.1. 

From the point of view of size enlargement, the property of most interest is, of course, particle size and its distribution. Some of the variables which can be used to increase the size of spray dried products can be summarized ... 

Sodium Sulfate. Although considered a weak builder by some manufacturers, sodium sulfate (Na2S04) contributes little to detergent performance. It is commercially available from natural sources and as a byproduct from rayon processing. In dry mix and agglomerated type products, sodium sulfate is used to improve finished product flow characteristics. In spray-dried products, sodium sulfate acts as an inert filler and aids in density control. 

Typical Particle Size Distribution of Spray Dried Product... 

We spray dried the slurries in a Bowen Engineering Co. No.l Ceramic Type Spray Dryer. The spray dried products were screened to obtain active and selective attrition resistant powders made of 45 to 150 Jm diameter porous microspheres of the catalyst with a thin silica-rich peripheral layer. 

Glucose was the only major sugar and IMP and GMP were the only major nucleotides found. A sensory evaluation of the different processed products Indicated a preference for the drum dried product over the freeze or spray dried product. This preference could not be explained from sugar or nucleotide values and the amino acid data was Inconclusive. Since the authors have amassed such a large data pool for both volatile and nonvolatile compounds 1t Is unfortunate that some form of data analysis such as multlvarlent statistical analysis was not applied so as to determine which compounds were primarily responsible for the perceived flavor preference. 

Walton, D.E., and Mumford, C.J. (1999). Spray-dried products characterization of particle morphology. TransIchemE, 77A, 21-38. 

In addition to lower capital outlay, dry-blending requires considerably less processing energy. Final product density, which is usually near unity, depends on the density of the starting materials and the nature of equipment used to blend these materials. Modern mixing and blending equipment, if properly controlled, can give product density and particle sizes comparable to spray-dried products. 

Corrigan, O.I. Thermal analysis of spray-dried products. Therm. Acta 1995, 248, 245-258. 

Fig. 9 Tricalcium phosphates (hydroxyapatite). Tricaphos, a spray-dried product (A), and Tritab, prepared by roller compaction (B).

Fig. 32 SEM picture showing starting materials and their corresponding spray-dried products. Fumaric acid milled (A) and spray dried (B), L-leucine milled (C) and spray dried (D). Before spray drying both substances show a layered crystal structure but differ significantly after the spray-drying process.

Spray-Dried Products. Spray drying is used to convert solutions, emulsions, or suspensions into powders. The applications in pharmaceutical technology are numerous. Raw materials are spray dried, for instance, to enhance the compressional properties of substances such as lactose and tricalcium phosphate, to distribute a minor component like digoxin more uniformly in a matrix, and to enhance their dissolution rate as described for digoxin in combination with a hydrophilic polymer. ... 

Fig. 34 Spray-dried plant extract solutions used to prepare readily soluble tea preparations. Spray-dried product from an airless high-pressure system leading to a coarse particle size distribution (A) and a magnification thereof (B), detailed view of one particle showing fragments inside (C), and the product from above after a wrong sample preparation (D).

Polysaccharides and water interaction are especially studied for their use in spray-dried products in food and in biotechnology. ... 

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