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.