Agriculture. THE CHEMIST IN THE DAIRY.—No. VII. By R. W. Emerson Macivor, F.I.C.,F.C.S.,&c. AUTHOR OF " THK CHEMISTRY OF AGRICULTURE."

Waikato Times, Volume XIX, Issue 1604, 14 October 1882, Page 2 (Supplement)

Agriculture. THE CHEMIST IN THE DAIRY.— No. VII. By R. W. Emerson Macivor, F.1.C.,F.C.5.,&c. AUTHOR OF " THK CHEMISTRY OF AGRICULTURE."

When prepared for use, rennets are steeped either in a soltition of salt, or in whey. If in the former, the brine need not be stronger than is required to protect them from tainting, as too much salt is detrimental to their action. In America, whey, both sweet and sour, is extensively employed. It is generally boiled, previous to the introduction o£ the rennets, in order that taints may «ot be conveyed into the cheese. Sweet whey has a good effect on ' the cheese. Of whatever liquid is used, two quarts are sufficient for each rennet. The first soakings from the rennet are better than the last ; they are not merely stronger, but act much more effectively on the milk. Arnold recommends the distribution of the first soakings through the whole of the steepings so as ' to have them of uniform strength from first to last, in order to insure equality of results^ in curding. Care should be exercised in selecting rennets; those which are and " strong-smelling should be rejected. The steepings of rennet contain extremely minute globular bodies, and when examined by aid of the microscope are found to be full of them. Arnold observed by actual counting over 1000 of them in one five hundredth part of a single drop taken from a gallon of water in which a rennet had been soaked, and says that, at this rate, a good rennet would contain some 200,000,000,000 of them. These globular bodies are the vegetable fungus, micrococclis, already mentioned. In character they closely resemble yeast cells, and "may be multiplied and carried from batch to batch, the same as the leaven in panary fermentation, and they therefore are a true yeast and should be regarded as such in the principles of cheese-making." Milk becomes sour when curdled by rennet, but the formation of lactic acid is now held to be unessential to the curdling. There is no strong reason why the active principle of rennet should not be extracted cheaply, in a condition of purity, _ and of a uniform strength. Such preparations are now largely employed in Europe, particularly in Denmark, Switzerland, and France, and doubtless they will some day be introduced into these colonies. The action of rennet on cold milk is very blow, but becomes more vigorous as the temperature rises until at 135 deg. Fahrenheit it altogether stops. The temperature at which rennet is added to milk is of importance. If it be too low the curd is very tender, and the whey does not readily separate ; if, on the other hand, it be too high the curd shrinks a good deal and becomes hard and dry. It is the custom to effect the curdling at about 7-1 deg. Fahrenheit for thin cheeses and 80 to 85 deg. for thick ones. (b.) VARIETIES OF CHEESE. The quality of cheese depends chiefly on that of the milk used for its production. Itich cheese is made from fresh milk, cream being sometimes added to the milk to produce the richest sorts. The poorer varieties of cheese are manufactured from milk which has been wholly or partially skimmed. 1. Cream Cheeses are made from cream alone. The cream is put into vats and allowed to coagulate and drain of its own accord and without pressure, or, as in Italy, by heating the cream and curdling it with sour whey or with tartaric acid. Owing to their richness, these cheeses do not keep for any length of time. 2. Cream and Milk cheeses are made by mixing the cream of the preceding night's milking with the fresh milk of the morning, and then adding the rennet. English Sttlton cheeses '•.and the French Biie cheeses belong to this olass.