Heat precipitation

Whey proteins that have been heat precipitated under very high shear have a particle size between 1 and 3 micrometers, and give the impression of fat in some products. These microparticulated whey proteins are being used as fat replacers in frozen desserts and processed cheese substitutes. 

Illustrated for 5-methoxy-tryptamine (1). 1.5 g (1), 30 ml ethanol add 5 g methyl iodide (or equimoiar amount ethyl iodide) and 4.5 g dry sodium carbonate and heat five hours on water bath. Filter hot, heat precipitate with ethanol and filter hot again. Evaporate in vacuum to get 2.5 g l-methyl-5-methoxy-DMT. 

A. (Alternative) To 1 1 g hexamethlenetetramine in 70 ml CHClj, add 18 g trimethoxybenzyl-CI (or other analog) and reflux four hours. Evaporate in vacuum and add 35 ml acetone to cause precipitation. Filter and heat precipitate with 100 ml water for twenty... 

Measure the effects of changes in physical properties (viscosity, specific heat, precipitation, etc.) during the reaction. 

A. Connell (1802) 140 obtained a white precipitate—ferrous iodate—by boiling a soln. of iron in iodic acid, and C. F. Rammelsberg found that the addition of potassium iodate to ferrous sulphate gives a yellowish-white precipitate which is decomposed when heated. It is sparingly soluble in nitric acid, and it dissolves in an excess of ferrous sulphate, and the soln., when heated, precipitates basic ferric iodate. A. Ditte mixed boiling soln. of a ferric salt and an alkali iodate and obtained a brown precipitate—ferric iodate—insoluble in hot nitric acid diluted with its own volume of water. Crystals can be obtained by mixing warm dil. soln. of ferric nitrate, acidified with nitric acid, and sodium iodate. The precipitate... 

Proteins that remain in whey after removing casein from milk are recovered as whey protein concentrates by precipitation with added polyphosphate or other polyvalent anionic compounds, ultrafiltration, ion exchange adsorption, gel filtration, or a combined acid and heat precipitation process. Whey protein concentrates are also manufactured by a combined process involving electrodialysis, concentration, lactose crystallization, and drying (Richert 1975 Morr 1979 Marshall 1982 Anon. 1982 Muller 1982B). 

Cassel JM, Mandelkern L, Roberts DE.The kinetics of the heat precipitation of collagen, J Am Leather Chem Assoc. 1962 51 556-577. 

Alkali treatment has been used to improve the functional properties of the insoluble protein prepared by heat precipitation of an alkaline extract of broken yeast cells (63). Heating yeast protein at pH 11.8 followed by acid precipitation (pH 4.5) yielded a preparation composed of polypeptides with increased aqueous solubility. It also increased foaming capacity of the protein 20-fold. The emulsifying capacity of the modified protein was good whereas the original insoluble protein was incapable of forming an emulsion. Alkali treatment must be carefully controlled to avoid its possible deleterious effects (24,75), e.g. alkaline treatment of yeast protein resulted in a loss (60%) of cysteine (63). 

Biltz (Zeitsch. amorg. Chem., 1908, 59, 273) heated precipitated ferrous sulphide in nitrogen and obtained the value 1197° 2°. 

Although almost all proteins are irreversibly denatured and precipitated on heating, there are exceptions for which heat precipitation constitutes one of the most impor-... 

Whereas heat precipitation is used only very rarely with proteins originating from mesophilic organisms, it is a very common step in the purification protocols of proteins from thermophilic organisms, which have been doned and expressed in E. coli. However, even in these cases, it is important that the incubation time is kept as short as possible to minimise deamidation of glutamine and asparagine residues. 

To perform heat precipitation of acid phosphatase place the beaker from step 10-20 in the hot water bath and stir the solution moderately with a thermometer. AUow the contents of the beaker to warm to 60°C and maintain that temperature for 2.0 to 2.25 minutes. After this incubation quickly plunge the beaker into an ice-water bath and continue stirring the contents until the temperature drops to 6 to 8 C. 10-23. Remove the precipitate by centrifugation using the procedures in steps 10-7 and 10-8. 

The solution is used in mordanting cotton cloth for dyeing and col01 printing the cloth is dipped in the solution, and then heated, precipitating aluminum hydroxide in the fibers and driving off acetic acid ... 

Soluble in water and not coagulated by heat. Precipitated from solution by saturating it with ammonium sulphate, (NH4)2S04 or zinc sulphate, ZnS04. 

The determination of hardness is a useful analytical test that provides a measure of the quality of water for household and industrial uses. The test is important to industry because hard water, on being heated, precipitates calcium carbonate, which clogs boilers and pipes. 

Proteins can be concentrated by isoelectric precipitation, heat precipitation, alcohol precipitation, ultrafiltration, microfiltration, and freeze concentration. Numerous references report differences in function in relation to the method of concentration of the protein. Whey protein produced by acid-heat precipitation (lactalbumin) is essentially insoluble but shows high water binding capacity and for this reason is the whey protein of choice for baking and for formulation of cereal products [89]. The use of ultrafiltration instead of acid precipitation of soy protein provides products with quite different characteristics [108], However, caseinate produced via acid precipitation is nearly as suitable for the production of imitation cheese as is rennet casein produced by the action of chymosin on skim milk [88],... 

Hill, A. R., and Smith, A. K. (1992). Texture and ultrastructure of process cheese spreads made from heat precipitated whey proteins. Milchwissenschaft 47, 71-74. 

Chemistry on soluble polymer matrices has recently emerged as a viable alternative to solid-phase organic synthesis (SPOS) involving insoluble cross-linked polymer supports. Separation of the functionalized matrix is achieved by solvent or heat precipitation, membrane filtration, or size-exclusion chromatography. Suitable soluble polymers for liquid phase synthesis should be crystalline at room temperature, with functional groups on terminal ends or side chains, but must not be not cross-linked they are therefore soluble in several organic solvents. 

The hexahydrate Is hygroscopic and readily loses NH3. It is dried to constant weight by storing for several days in a vacuum desiccator over CaClg. It then contains three (or, according to Holzl, 2.5) moles of H3O. Yield 24 g. (73%). The yellow aqueous solution decomposes on heating, precipitating the hydroxide. 

In introductory chemistry lessons, chemical reactions are usually associated with observable phenomena (e.g., change of colour, evolution and absorption of heat, precipitation of a solid, evolution of a gas) and chemical reactions are presented as proceeding to completion, taking place in one direction (Andersson, 1990). The introduction of chemical equilibrium at a later stage, however, demonstrates the reversibility of chemical reactions and the possibility that chemical reactions do not proceed to completion. Moreover, the dynamic nature of chemical equilibrium requires students to assume that two opposite chemical reactions are taking place, in spite of the fact that this cannot be deduced from observation. As a consequence, the introduction of chemical equilibrium requires students to revise their initial conception of chemical reactions. This is illustrated in Table 1. 

A climate category defined by three weighted climatic indexes, namely, mean annual heat, precipitation, and atmospheric moisture. 

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