Decanter Centrifuge
Shenzhou Machinery - Professional Industrial Centrifuge Machine Manufacturer and Centrifugal Separators Supplier in China
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Shenzhou Machinery - Professional Industrial Centrifuge Machine Manufacturer and Centrifugal Separators Supplier in China
CASEIN PRODUCTION - USE OF SEPARATOR AND DECANTER IN DAIRIES
At a proportion of approximately 80 percent, casein is the most important protein fraction in cow‘s milk. Isolated casein is a valuable raw material for a wide variety of industrial sectors. The food industry uses casein in powdered form as high-quality protein. It also has great importance As a binder for paints, for gluing plywood, as a photoresist in etching and for the manufacture of adhesives, putty, textile finishes and block stains for leather.
Casein is present in milk in colloidal solution. Depending on temperature, casein particles have different sizes. Smaller particle sizes are described as casein submicelles, above that as casein micelles. Casein consists of long chains of molecules of different amino acids. These molecule chains are combined into submicelles which are held together by phosphate salts.
In order to isolate the casein, the casein micelles must be precipitated out of the milk. This becomes possible when the surface charge and consequently the repulsion forces of the casein molecules are reduced so that coagulation can take place. The alternative processes are called acid or rennet precipitation.
In acid precipitation using a mineral acid, the positively-charged hydrogen ions penetrate the casein micelles, as a result of which the negative net charge of the casein micelles drops. Simultaneously
the hydrate shell and the number of the doubly charged calcium ions are also reduced. The same-polarity charge and therefore the repulsion forces are reduced, so that the forces of attraction predominate. The heat energy of the particles causes them to collide and unite into larger aggregates which then precipitate out of the milk.
Unlike acid precipitation, which is reversible, in rennet precipitation, micelle components are irreversibly cleaved off. The rennet enzyme cleaves the calcium-insensitive hydrophilic part. Around 50 percent of the net negative charge of the casein surface is thus lost, weakening the protective hydrate shell and exposing the calcium-sensitive part of the casein on the surface of the micelle. Aggregation now takes place in the second coagulation phase following the enzymatic reaction. The actual gelation takes place by bridging the aggregates with calcium ions.
Bacteria removal from the skimmed milk
Whether using rennet or acid precipitation, a well degreased skimmed milk is the starting point for producing casein. In order to be able to manufacture a perfect end product, the skimmed milk not only has to be pasteurized but also as free of germs as possible. In the bacteria removing separator, the bacteria and germs are centrifugally separated and discharged from the bowl by partial ejection. The bacterially clarified skimmed milk is subsequently heated to coagulation temperature in a plate heat exchanger.
Casein recovery from whey
Depending on the casein type (acid or rennet), the casein is precipitated either by inline addition of technical acid or by the use of enzymes with the addition of rennet. The latter method of precipitation requires a certain amount of time and is therefore carried out in batch. To support and promote the coagulation process, further indirect temperature treatments with subsequent reaction stages follow. Actual separation of the coagulated casein from the whey is performed by decanters. The whey which forms is cooled, clarified and then passed on for further processing. In order to increase the degree of purity of the raw casein, it needs to be largely freed from the minerals and lactose adhering to it. To achieve this, it is washed several times on the countercurrent principle and is then dried to a residual water content of maximum 10 percent.
Casein production
Casein is the structural protein in milk and therefore the main ingredient in curd-cheese and cheese. Casein is produced from skimmed milk to which hydrochloric acid is added. This causes the milk proteins to precipitate; they may then be extracted with decanters and filtering systems. The casein produced in this way is washed and conveyed to a second decanting stage and subsequently dried
CASEIN PRODUCTION - USE OF SEPARATOR AND DECANTER IN DAIRIES
At a proportion of approximately 80 percent, casein is the most important protein fraction in cow‘s milk. Isolated casein is a valuable raw material for a wide variety of industrial sectors. The food industry uses casein in powdered form as high-quality protein. It also has great importance As a binder for paints, for gluing plywood, as a photoresist in etching and for the manufacture of adhesives, putty, textile finishes and block stains for leather.
Casein is present in milk in colloidal solution. Depending on temperature, casein particles have different sizes. Smaller particle sizes are described as casein submicelles, above that as casein micelles. Casein consists of long chains of molecules of different amino acids. These molecule chains are combined into submicelles which are held together by phosphate salts.
In order to isolate the casein, the casein micelles must be precipitated out of the milk. This becomes possible when the surface charge and consequently the repulsion forces of the casein molecules are reduced so that coagulation can take place. The alternative processes are called acid or rennet precipitation.
In acid precipitation using a mineral acid, the positively-charged hydrogen ions penetrate the casein micelles, as a result of which the negative net charge of the casein micelles drops. Simultaneously
the hydrate shell and the number of the doubly charged calcium ions are also reduced. The same-polarity charge and therefore the repulsion forces are reduced, so that the forces of attraction predominate. The heat energy of the particles causes them to collide and unite into larger aggregates which then precipitate out of the milk.
Unlike acid precipitation, which is reversible, in rennet precipitation, micelle components are irreversibly cleaved off. The rennet enzyme cleaves the calcium-insensitive hydrophilic part. Around 50 percent of the net negative charge of the casein surface is thus lost, weakening the protective hydrate shell and exposing the calcium-sensitive part of the casein on the surface of the micelle. Aggregation now takes place in the second coagulation phase following the enzymatic reaction. The actual gelation takes place by bridging the aggregates with calcium ions.
Bacteria removal from the skimmed milk
Whether using rennet or acid precipitation, a well degreased skimmed milk is the starting point for producing casein. In order to be able to manufacture a perfect end product, the skimmed milk not only has to be pasteurized but also as free of germs as possible. In the bacteria removing separator, the bacteria and germs are centrifugally separated and discharged from the bowl by partial ejection. The bacterially clarified skimmed milk is subsequently heated to coagulation temperature in a plate heat exchanger.
Casein recovery from whey
Depending on the casein type (acid or rennet), the casein is precipitated either by inline addition of technical acid or by the use of enzymes with the addition of rennet. The latter method of precipitation requires a certain amount of time and is therefore carried out in batch. To support and promote the coagulation process, further indirect temperature treatments with subsequent reaction stages follow. Actual separation of the coagulated casein from the whey is performed by decanters. The whey which forms is cooled, clarified and then passed on for further processing. In order to increase the degree of purity of the raw casein, it needs to be largely freed from the minerals and lactose adhering to it. To achieve this, it is washed several times on the countercurrent principle and is then dried to a residual water content of maximum 10 percent.
LACTOSE PRODUCTION - USE OF SEPARATOR AND DECANTER IN DAIRIES
Another important by-product from cow‘s milk is lactose. Lactose is produced in the cow‘s udder. Chemically speaking, lactose belongs to the disaccharide family and is composed of galactose and glucose molecules. Lactose is much in demand by industry. For example, it is used as a filler in foods or as a fat binder in baking. In the pharmaceutical sector, lactose functions as a filler, binder and adsorber as well as a coating for pills and tablets. Separators guarantee efficient recovery of lactose in concentration, crystallization and washing allow lactose to be obtained particularly economically and reliably in the process lines.
In the first step the whey from the cheese factory has to be cleaned.
The traditional starting product for lactose production is sweet or sour whey, usually in the form of a permeate. The permeate has the advantage that the whey proteins have already been removed, which simplifies process management for improved yields. The purity of the starting materials in the process can be increased by nanofiltration and decalcium phosphatization before the evaporation stage. The yield depends primarily on the raw material used, on crystallization and on the process technology. However, the yield can still be significantly increased by integrating nanofiltration, decalcium phosphatization together with electrodialysis and ion exchange in the conventional process. The raw material is normally evaporated to a dry substance. The concentrate is subsequently crystallized in special crystallization tanks. The crystallized whey concentrate is now passed to a first decanter which separates the lactose crystals. After the separated lactose has been diluted with washing water to reduce the dry substance, a second decanter increases the dry substance. The wash water is separated. The concentrate is subsequently crushed when dry, screened and packed in sacks.
Concentration of cheese fines
The mix of cheese fines, whey and water produced when whey-fines removing and skimming separators are used may be processed into concentrated valuable cheese masses. Special decanters that considerably increase the dry mass of such mixes of cheese fines, whey and water may be employed in this task.
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