Casein protein CAS# 9000-71-9

Acid casein is mainly used as a base material for paints, a binder for wood, paper, and cloth, an additive for food, etc. As a base material for paints, it accounts for about half of the total consumption, has excellent water resistance, disperses well in pigments, and improves the uniformity of paints. In addition, crude rennet protein is mainly used in the manufacture of plastic buttons because of its good fluidity and ease of coating construction. Compared with other resin buttons, casein buttons have good dyeability, processability, and brightness of color, and the quality is in the middle and upper level in buttons. Casein is evenly mixed with slaked lime, sodium fluoride, copper sulfate, and then with kerosene to get casein glue, which is a glue used in the aviation industry and wood processing sector. Casein is also used in medicine and biochemical reagents. Casein is the main protein in the milk of mammals including ewes, sheep, and humans.

Production method:

 (1) Fresh milk is skimmed and acid (lactic acid, acetic acid, hydrochloric acid, or sulfuric acid) is added to adjust the pH to 4.6 so that the microgel of casein loses its charge and coagulates and precipitates. The casein obtained by this method is called acid casein, but the acid casein obtained by adding different types of acid is almost indistinguishable. Casein is a white to yellowish powder or granule with a slightly milky and sour odor. It only swells in water but can be dispersed and dissolved in water if ammonia, alkali, and salt are added. It is soluble in strong acid, diethanolamine, morpholine, urea, formamide, hot phenol, and Turkish red oil.

 (2) Milk and crude rennet act to form a coagulated precipitate called crude rennet casein, which is white in granular form, almost tasteless and odorless, and produces a characteristic odor when heated and burned. The rennet casein has a higher ash content than acid casein.