But the difficulty of preventing the cream from rising and forming a cream-curd, that will float on the whey, if it does not waste, needs to be overcome before we can allow the milk perfect rest after incorporating the rennet. We are not aware of any method for accomplishing this. Agitation of the surface, at least, seems necessary to retain the cream; but if the surface only is agitated, manifestly the cream will escape from the bottom of the mass and impoverish it while enriching the top. A thorough stirring of the whole mass, therefore, will keep the cream more equally distributed, and it will also secure a greater uniformity of temperature. The cheese must be of evener texture than if made of curd of different degrees of richness mixed together.
It is a question for debate as to whether the cream which rises on milk is thoroughly incorporated with it by stirring. That butter is wasted in making cheese, is a fact that cannot be denied. Some think that nearly all the cream that rises on the vat during the night is floated off in the whey. We cannot indorse this conclusion, although it is asserted that where agitators are used, and the cream is thus prevented from rising, there is a great saving of the butter. But one fact is worth a thousand fictions in the practical affairs of life, whatever it be in romance. Cream will mix with the milk by stirring, and go to enrich the cheese, as is proved in the manufacture of the English Stilton cheese. In the manufacture of this, the cream of the night's milk is taken off and added to the morning's milk, which is worked up separately. The cheese is greatly enriched thereby. How much the waste of butter is increased, we are unable to say. We know from our own experience, that skimming the night's milk, instead of stirring in the cream, makes a marked difference in the yield and quality of the make.
The first thing in setting, when a vat of milk is raised to the proper temperature, is to add the coloring. This is a strong alkaline preparation, and must have a tendency to retard the development of the lactic acid, if it does not combine with it in forming a neutral salt. If no effect is perceptible, beyond the color it imparts, it is simply because the quantity is so small. Probably the effect of the alkali in the annotto is more than counteracted by the acid in the rennet.
Nothing as good as clear whey has been found for soaking rennets. Some think the acid an advantage in the working of the milk, and others go so far as to add, in cold weather, a quantity of sharp whey to the milk along with that in the prepared rennet. This, of course, hastens the development of acid throughout the mass. But we cannot say that we approve of doing anything to change the milk, and thus sour the curd before cooking. We prefer to have the milk as sweet as possible when set, and to keep the curd sweet until it is cooked. Then we would develop the acid in the whey. For this reason, if sour whey is to be added, we should add it after the curd is cooked, for the purpose of hastening the development of the lactic acid in the whey. This seems to us to be the most rational course, from what our experience has taught us. If fair experiment should demonstrate that we are in error as to when and where the development of the acid should take place, we shall be willing to yield the point.
The amount of prepared rennet that it is necessary to add to the milk, depends upon its strength, which can be determined only by experiment. Sufficient should be used to coagulate the milk in ten or fifteen minutes, and render it fit to cut in thirty or forty minutes. If the milk is "old," the same quantity of rennet will cause it to work sooner, as it should. Some would add less rennet. We would not. The milk needs to work faster, and the acid, although it coagulates the milk, will not supply the place of the rennet. The rennet ought to be strong enough to require not more than a quart to a thousand pounds of milk.
CHAPTER XIV. CUTTING CURDS.
Cheese-making was once carried on without cutting the curd; and even since the introduction of the factory system, there have been those who denounced the idea of using a cutting instrument. Breaking up the curd with the hands was considered the better method as incurring less waste, both of butter and cheese. Such ideas, though entertained but a few years ago, are obsolete. Cutting curds is now universal, certainly in America. The only questions are as to the time, manner and extent of cutting.
When should the curd be cut? Practically, there is little difference of opinion on this question. Some may cut a little sooner or later than others, and even the same person may not always be precise as to the time of cutting. But all will agree that a curd should not be cut before it is firm enough to break square and smooth over the finger without whitening the whey; and they will also agree that it should be cut before it gets tough enough to drive along ahead of the knife. We would cut it as soon as it can be done without waste, while the curd is tender; and we would do all the cutting at once. There is no sense in running the knife through the curd one way, and then letting the curd stand and toughen before cross-cutting and completing the operation. If it is fit to partly cut, it is fit to wholly cut; and the sooner the cutting is done with, the better. Time for the separation of the whey can be given after the cutting is done, and before the heat is further raised.