ALL ABOUT CASEIN.

Kaipara and Waitemata Echo, 4 September 1914, Page 7

ALL ABOUT CASEIN.

Casein is the dried cheesy matter of the skim-milk. The cheesy matter can be precipitated from the milk either by rennet or by various acids, and is called accordingly rennet-casein or acid-casein. The acids used are lactic, sulphuric, muroatir, and acetic acids. The manufacture of casein by the addition of j rennet is carried out as follows :— | The milk which is to be used, and . which must be as fresh as possible, is set to curdle at a temperature , of 97deg. Fahr., and sufficient" • ren- '. net is added to give it a firm j curd in the course of twenty mm- , utes. The curd is then cut with ; a curd-knife, and it is stirred for ; 20 minutes, after which it is heated j to 162deg. Fahr. in the course of 20 I minutes. It is next stirred for ten ' to twenty minutes. The total i amount of stirring is about one ; hour. The whey is run off, and j the curd is rinsed well with water at a temperature of 140deg. Fahr. It is next filled into cheese hoops I and pressed • for about twenty mm- j utes with ten to twelve times the weight of the curd. Konsulent O. Wennevold, the ! Danish cheese and casein expert, ! gave a lecture in December, 1911, the following particulars of the pro- j cess in vogue in Denmark. The milk j is set at a temperature of 77deg. I to Sfideg. Fahr., and 1 to 2 per j cent, lactic acid (the same as is used in the ripening of the cream) is ad- j (led. It remains undisturbed for j about twenty hours, by which time | iit should be thick. It is next warmed to 131deg., when the curd is precipitated and remains in a layer floating on the whey. The curd is now very soft, and in order to dry it it is transferred to a rack covered with cheese-cloth, where the washing or rinsing with water is carried out. The quantity of water used should be at least 10 j per cent. of the quantity of milk. The heating of the milk, the placing of the curd on the rack, the drawing of the whey, and the cleaning of the cheese-vat should be done in the morning before separation '*of the milk commences. The curd remains on the rack for some hours until it is well drained, and in the afternoon it is put into cheesehoops- and pressed. Since jthe adoption of this method the reports from the German galelith manufacturers have been to the eflect that the quality of the casein is excellent. The precipitation of the curd by the ripening of the milk has not only the advantage of giving the finest quality of casein, but the whey is cleaner and more suitable as a food, and furthermore the process is much more preferable from a hygienic point of view than the process used in the earlier stages of the industry, when sour whey was used instead of lactic acid. In order to get '.he whey sour enough, it had to remain in a vessel for more than a week before it could be used. '! he stench and other . drawbacks can easily be imagined. Another advantage with the present process is that the quantity of the moisture in the curd can be reduced to about 50 per cent., which is a great advantage, partly because it canstand the journey to the drying establishments without getting fermented. When the ripening of the milk is adopted in order to precipitate the curd it is necessary for the factory to have a large cooler with which to reduce the temperature of the separated milk to the temperature at which the milk has to be set (77 deg.—B6 deg.) Good quality casein can be manufactured by the aid of the ripening process or acid process from milk pasteurised to 180 deg. to 185 deg. and rapidly cooled down, but pasteurised milk direct from the weighing, or measuring machine I must not be used, as this gives a poor quality casein. The drying of the curd to casein takes place in specially constructed drying factories. The curd is milled finely on a curd mill, and next placed in thin layers on trays made of wooden frames with bottoms of cheese cloth. The trays' are placed above each other with suitable spaces between them, and are exposed to warm currents of air. There are several different drying systems in use. The drying process can either take place in i small drying plants at the various factories or in large drying establishments in central positions treat- . ing the casein from a number of ; factories ; in this case the casein i must be sent to the drying establish- ! ment every second day. The ex" pense of drying casein in the large drying establishments works out at about |d. per pound dried casein. | The dried casein should contain j from 10 to 12 per cent, water. It can be kept for a practically unlimited time, provided it is not exposed to moisture. Certain properties are required to make casein a first-class article. The i casein must be as poor in fat as '■ possible ; of light, even colour; ab- i solutely free from dirt ; and of a clean, agreeable colour. These j points are the same in regard to both rennet and acid casein. In reference to the former, it is im- j portant that it should contain a i large percentage of ash. About 8 per cent, constitutes a good casein, while 6 per cent, a poor one. Acid casein must be easily dissoluble in ' water when 12 to 15 per cent, bo- ! rax is added. Twenty grams ca- j sein and 3 grams borax are mixed i well, after which 120 grams of water is added by degrees. In the course of two to five hours the ', casein should* be swollen and form'

a lough, sticky n\r,r.r-. The great pour. (■• are (1) easily dissoluble, (2) good stickiness, <8) good capaci'.y for swelling, (4) clean, clear solution. A hundred pounds of skim milk produces from 3 to 3-|lb. dry casein. The value of casein depends upon its quality and the demand for it. The very best quality casein'fetched lately over £.40 per ton. The casein industry has been in vogue for some ten or fifteen years. The chief producers have been till lately Argentine, France, and Italy. and during the past few years America, Canada, and Denmark. Casein is purchased by the large galalith manufacturers in America and Germany, and .it has been finding a steadily increasing demand in a great variety of industries. Ren-net-casein is used in the manufacture of galalith (milk-stone). Thin is a very hard and hornlike substance somewhat resembling celluloid, but is free from odour an^ not dangerous from fire. It is not affected by'metals, and it acts as a splendid insulation r.iaterial for electricity. It is manufactured into various articles, as combs, knife handles, cigar holders, pearls, paperknives, etc. One of the latest ey periments is to make an imitation silk from casein. Acid casein is used as a glue instead of glue and oil, as a paint (casein paint). Fluid casein glue and rubber paste is used in large quantities. In the paper mills casein is used in the manufacture of glcssy paper. Casein is also used largely in the textile manufactures, and last, but not least, in the preparation of artificial foods—amongst others, lactorin and galactogen. The present consumption of casein in Europe and America is roughly estimated at 15,000 tons a year. Seeing that the industry is a comparatively young one, and that it is chiefly during the past four or five years that its .many mercantile properties have been discovered, it is reasonable to expect that the demand will go on increasing even mure rapidly in the future, and that it will before long' become an important factor in connection with the dairy industry.—"N.Z. Dairyman."