Caking of powders

Role of water in stickiness and caking of powders and crystallization of lactose... 

The best experimental determinations of the structure amplitudes for the various reflections are those of Wyckoff (1930, 1932) and Wyckoff and Corey (1934), who measured the intensities of the reflections from a pressed cake of powder and from a single crystal in the form of a... 

As in true strain, the expression above takes into account cross-sectional area changes in a certain cohesive structure (or cake) of powdered material. If the material is isotropic, another possible expression that includes the Poisson s ratio p (the ratio of transverse strain and axial strain resulting from uniformly distributed axial radial stress during static compression of the material in absolute value). The Poisson s ratio, or bulk modulus, permits prediction of the transverse contraction or expansion that occurs when a stress is applied longitudinally. 

The degree of caking of powdered fertilizers might be classified by reference to the autohesive force (see 1). However, in view of the fact that in time fertilizers cake into a solid mass, the experimental determination of the forces of autohesion between the... 

A number of applications and/or phenomena of technological interest, like freeze-drying, caking of powders, cryopreservation, etc., have been described on the basis of the relevant phase diagrams [45], as well as an application to extrusion processing of flour [52]. A number of papers [53-60] therefore appeared where various experimental approaches to 7g, like DSC, TMA, DTMA, NMR, ESR, fluorescence and phosphorescence decay, etc., were reported and sometimes compared to each other. It however should be emphasized that some... 

Cocoa Powder Manufacture. When chocolate Hquor is exposed to pressures of 34—41 MPa (5000—6000 psig) in a hydrauHc press, and part of the fat (cocoa butter) is removed, cocoa cake (compressed powder) is produced. The original pot presses used in cocoa production had a series of pots mounted vertically one above the other. These have been supplanted by horizontal presses that have four to twenty-four pots mounted in a horizontal frame. The newer presses are capable of complete automation, and by careflil selection of pressure, temperature, and time of pressing, cocoa cake of a specified fat content can be produced. 

A. a-Methoxyphenasine condensation). Two hundred grams (0.42 mole) of powdered lead dioxide (Note 1) is added to a solution of 10 g. (0.07 mole) of pyrogallol monomethyl ether (p. 90) in 3 1. of dry benzene in a 1-gal. narrow-necked acid bottle. The bottle and contents are placed in a shaking machine and shaken for 10-20 minutes (Note 2). The reddish brown solid is filtered through an 11-cm. Buchner funnel, and the filter cake is washed once with 400 ml. of benzene. To this filtrate there is added, immediately and with mechanical stirring, a solution of 6 g. (0.06 mole) of o-phenylenediamine (Note 3) in a mixture of 80 ml. of glacial acetic acid and 200 ml. of benzene. The solu-... 

Potassium /-butoxide is prepared by dissolving potassium metal in t-butanol followed by removal of the excess of -butanol by distillation under reduced pressure. The resultant cake is powdered and used directly in the dibromocarbene additions. 

Preparation of Intermediate Compound 2-Methyl-3-o-Tolyl-6-Sulfamyl-7-Chloro-4(3H)-Quinazoiinone Set up a 5-liter 3-necked flask fitted with a stirrer, condenser and a drying tube. To a stirred mixture of 100 g (0.342 mol) of powdered 4-chloro-5-sulfamyl-N-acetylanthranilic acid, 40.2 g (0.376 mol) of o-toluidine and 2.0 liters of dry toluene was added dropwise, over a period of 15 minutes, 21.7 ml (34.1 g) (0.248 mol) of phosphorus trichloride. The mixture was then refluxed for 10 hours. The solid turned somewhat gummy towards the latter part of the first hour. The mixture then became more free flowing as heating was continued. Let stand overnight. The yellow solid was filtered, washed with toluene and dried. The toluene filtrate was discarded. The dried solid was triturated with 1.5 liters of 10% sodium bicarbonate, filtered and the cake washed with water. The filtrate on acidification yielded 11.5 g of the starting acid. The damp product was dissolved in 4,5 liters of 95% ethanol and the solution treated with charcoal and filtered. On cooling filtrate yielded 69.5 g (55.5%) of the title compound, MP 271.5° to 274°C. 

The filter cake is stirred with 3.1 liters of acetone. The volume of acetone used is about 1.5 times the weight of the cake resulting in about a 65% acetone concentration. The benzoic acid dissolves in the acetone and the urokinase flocculates out. Sodium benzoate, about 1% of the weight of the cake, or 21 grams, is added to speed up the formation of the precipitate. The suspension of crude urokinase in acetone Is filtered on a Buchner funnel using filter paper precoated with a diatomaceous silica product (Celite 505). The precipitate is washed with acetone until the filtrate is water clear. The precipitate is then washed with ether and air dried. The yield of powder so obtained is 2.3 grams. 

Theobromine was determined by GC in various foods (bitter chocolate, milk chocolate, chocolate cake, cocoa powder, chocolate milk), and results are given in graphs and tables.27 Homogenized samples were boiled in alkaline aqueous media, then fat was extracted with n-hexane. The aqueous layer was acidified with diluted HC1 and NaCl was added. Theobromine was extracted from this treated aqueous solution with dichloromethane and the extract was evaporated to dryness. The residue was redissolved in dichloromethane containing an internal standard. GC analysis was performed on a column packed with 1% cyclohexane dimethanol succinate on Gaschrom Q, with FID. Average recoveries were 99 to 101%, coefficient of variation was less than 3% and the limit of detection for theobromine in foods was about 0.005%. 

A typical plot of torque versus amount of liquid (di-butyl-phthalate, DBT) added is given in Fig. 15 for a very porous sodium carbonate powder mixture. The increase in measured torque at around 25% by volume DBT and again at around 65 %, can easily be seen (the final decrease in torque upon the formation of the wet cake is not shown). These two points correspond to the condition under which the continuous network of bridges forms, at about 25% liquid present, and the formation of the dry paste, at around 65%, where enough binder is available to fill most internal voids. The amount of liquid in Fig. 15 is given as a fraction of the total volume of powder, instead... 

The next phase of the freeze-drying process entails the application of a vacuum to the system. When the vacuum is established, the temperature is increased, usually to temperatures slightly in excess of 0 °C. This promotes sublimation of the crystalline water, leaving behind a powdered cake of dried material. Once satisfactory drying has been achieved, the product container is sealed. 

No caking of the powder even under highly humid conditions... 

Mathlouthi, M. and Roge, B. 2003. Water vapour sorption isotherms and the caking of food powders. Food Chem. 82, 61-71. 

Determine the capsule size by using the rule of six. If the amount of powder is less than the required amount to fill the capsules whose size has been determined, add suitable amount of diluent, preferably lactose, to make up the volume. As a confirmation of the size, fill one or two capsules and determine the appropriateness. If the capsule size is correct punch out the remaining capsules after forming a cake on a powder paper or an ointment tile. 

Step 3 Determine the capsule size by using the rule of six. Capsule size 3 can hold 3 grains or 195 mg. Weigh 200 mg of the tablet mixture (which is obtained as 2000 mg of total powder/10 capsules) and try to fill in capsule size 3. If the capsule is not filled or it is too full, go for the next capsule size, i.e., 2 which holds approximately 4 grains or 260 mg of powder. Verify the appropriateness by filling one or two capsules of size 2. If appropriate, select this size. For 10 capsules, the total powder should be 2600 mg. Therefore add 600 mg of lactose in the tablet mixture of 2000 mg by geometric dilution. Transfer the 2600 mg of powder on a clean paper or an ointment tile, compress as a cake, and fill all the capsules by a sliding motion. 

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