CHAPTER XVI. ACID.
Another important agent in cheese-making is acid. This you are pretty sure to have, at some stage of the process, and the chief question seems to be as to when you will have it. It is said that milk fresh from the cow manifests the presence of lactic acid. The quantity is very slight, however, and under favorable circumstances the development is slow. Where milk is properly cooled immediately after being taken from the cow, and the factoryman has good facilities for keeping it cool, it will be found, when the time comes to begin the process of working up, what is called "sweet." It will not taste as fresh and clean as when first cooled after milking; but no acid will be perceptible to either taste or smell—not even enough to make it what is termed "old."
Some think age makes the milk all the better for cheese-making, and we believe it is generally understood that milk fresh from the cow does not work quite satisfactorily. However, we place no great stress on this opinion. Old milk will work quicker than new milk; the acid will develop sooner to the point desired by the cheese-maker, and this saving of time doubtless has something to do with the decision in favor of age in milk for the purpose of cheese-making.
Our impression is, that milk cannot be too sweet when the rennet is added, and that if sufficient time is taken to develop the acid in the whey before dipping, the fresh milk will be found to turn out the finest-flavored and best-keeping cheese. The acid is not wanted in the curd, but in the whey. If the milk is sour, to begin with, or quite advanced toward sourness, the lactic acid must pervade every particle of the whole mass. Now, it strikes us that the correct idea is to expel the whey from the curd, as far as possible, before the acid makes its appearance, and let the acid develop in the whey afterward, so as to furnish a sort of pickle. The acid will develop sharply at some stage in the process; and, as we have before said, the question to be decided seems to be as to what point it is best to have it develop at.
We say, with the light we at present have before us, we think the acid should never be allowed to develop much before the curd is cooked and the whey is properly expelled; then let the whey take on acid to quite a perceptible degree before dipping the curd. We doubt if it makes much difference whether the acidulation takes place while the curd is floating in the whey, or after the whey is drawn off and while the curd stands and drains. There is rather more convenience in handling to leave the whey on and stir the curd sufficiently to keep it from packing; but the "cheddar" cheese, which is generally considered the best of any, is made by stacking the curd, after cooking, and allowing the whey that clings to it to take on acid. But where the milk is all right, to begin with, and the curd is properly managed and cooked, we doubt if it makes any material difference which process is adopted for allowing the acid to develop. With such a curd, there is little danger of its being injured by the acid, as any one can demonstrate by allowing curd to stand unpressed over night, as is often done with small remnants, when the pieces will be found covered with an almost vinegar-sour acid. Grind this curd and put it to press, and there will be no signs of sour cheese.
The development of the acid is absolutely necessary to secure good keeping qualities and a mild, clean flavor. Dip a curd before the whey has become perceptibly acid, or is on the verge of "changing," and we think that a rank, bitter flavor will be sure to follow. The absence of sufficient lactic acid leaves the albumen in a condition likely to decompose, while the butyric acid develops itself, as in rancid butter, and the two combine to make a very unpalatable flavor to one nice about the taste of his cheese. Some prefer strong cheese. To such, the nearer the flavor approaches that of smoked herring and tobacco, the greater the gustatory gratification.
The principal difficulty in working up sour milk is to get sufficient action of the rennet and heat on the curd to properly condense it and expel the whey. It is a mistake, therefore, to dip a curd soft because it is sour. Run your heat up to 104° or even 106°, as soon as possible, and keep it there until your curd is cooked. It is sour, and nothing but cooking will save it, if anything will. The whey must and will come out. If you do not expel it from the particles of curd in the vat, you will not be able to press it out sufficiently to keep it from working and leaking out while the cheese stands on the ranges.
If anything will prevent sour milk from making leaky cheese, it is thorough cooking. This process you should hurry up as much as possible—always having an eye to keeping the heat even, and preventing waste of butter. The acid, acting on the butter globules, makes their coatings tender. Therefore, handle the curd as carefully as possible, cool well before putting to press, and press gently, increasing the pressure gradually. But, if you have succeeded in getting your curd properly cooked, you have done one of the best things possible to retain the butter. If, when you put the curd to press, you find you have more than the usual bulk of curd, filling the hoops fuller and refusing to yield readily to the pressure of the screw—as is generally the case with sour milk, as managed in most factories—you may know that you have not done your work thoroughly, and therefore look out for leaky, sour, poor cheese. On the other hand, if you have condensed the curd to the usual bulk, so that it works well under the screw, you may hope for a fair cheese, that may pass muster when the buyer comes along.
We often hear the remark, when anything is said about developing the acid, "No sour cheese for me; I prefer to dip my curd sweet." People who talk in this way either make bitter, bad-flavored cheese, or else get on more acid than they are aware of, in consequence of having dull taste and smell. They judge by the appearance and feel of the curd when it is in condition to dip, and may succeed in hitting the right point. In hot weather, it is hardly possible not to develop the acid sufficiently. But if they really dip the curd sweet, we do not believe it possible that their cheese can be up to the standard demanded by the best markets, though they may succeed in getting a fair price for it. Not all buyers are really good judges, and fewer still know what the matter is with a cheese that is imperfectly made. They know, perhaps, that there is something wrong about it; but what, they are unable to say. Further, we believe the average price of American cheese lower than it should be, in consequence of so little really prime cheese, and of the large amount of second-rate; and that, as yet, our buyers are not sufficiently discriminating in their purchases and prices, though they are yearly growing more so. Both buyers and cheese-makers need more experience and a better understanding of what is requisite in the manufacture of a prime article.