The process of preparing rennet for use is very simple, and so generally understood that we need not more than give a few hints on the subject. In putting rennets to soak, care should be taken not to allow any tainted ones to get into the batch. When they are packed in salt, it is not difficult to make a selection. If the poor rennet does not smell, it will be pretty likely to be discolored and unhealthful looking, instead of having a whitish, wholesome appearance. All rennets thus discolored should be thrown away as worse than useless—as positively injurious. If the rennets are dried, it may not be so easy to detect the poor ones before putting them to soak. After soaking, their quality will be quite apparent; but much of their injurious effect may be avoided by promptly rejecting them without rubbing. It is generally, and we believe correctly, understood that diseased or tainted rennets produce both huffy and bad-keeping cheese, by the introduction of decayed animal substances. It certainly cannot improve the quality of the cheese to mix with it the broth of carrion.
Clear whey is the common and best liquid for soaking rennets. Water was once and is now sometimes used, but it needs to be very soft and pure, and is improved by boiling. We have never tried water, but it is asserted by those who have used it for soaking rennets that a batch prepared with it will not keep sweet as long as one prepared with whey, but that boiling the water keeps it sweet longer than it will keep if not boiled. We think the purer the whey the better, and therefore prefer that which first separates from the curd after setting. Some are not particular, and some prefer the salt whey that runs from the presses. There is a saving of salt in this, but we think this liquid cannot be as good to introduce into milk as that containing less cheesy and buttery particles. Boiling the whey and skimming it, afterward allowing it to cool and settle, that the sediment may also be excluded, is said to be a great improvement, and we can easily believe this to be true. It is not only free from impurities, but it forms a sharp acid that acts readily upon the rennets and extracts more completely the pepsin, gastric juice, or whatever it may be that coagulates the milk. It is said that quite a saving in rennets can be effected by using scalded whey for soaking them.
Twenty or twenty-five prime rennets put into a half barrel of whey will make a good preparation. It can be made stronger, of course, by the addition of more rennets, or pouring in a less amount of whey; but it is questionable if the entire strength can be extracted by using a less quantity of whey in proportion to the number of rennets. They need to be rubbed at least three times, each time in a new batch of whey. The second time the preparation will be found about as strong as the first. The third rubbing and rinsing may be in fresh whey to be used for soaking a new batch of rennets. We like to have two tubs or jars for soaking the rennets, one for the first and the other for the second rubbing, alternately. After rubbing the second time, put the rennets in a sack made of strainer cloth, to keep them separate, and soak them with the batch intended for the next second rubbing. In this way the strength of the preparation from the batch may be kept equal to that from the first. Rub the third time, and rinse in fresh whey, as before indicated, when the strength will be found pretty completely extracted. If dried rennets are used, it will be necessary to add salt to the whey when the batch is put to soak. Every time new whey is added, more salt will be required. Where the rennets are packed in salt there will usually be salt enough for the first soaking adhering to them; if not, it may be increased in quantity by a few handfuls of that loose in the barrel in which they have been packed. As the rennets will float on the whey, they should be thoroughly stirred up as often as night and morning, and a little salt sprinkled over those left on the top.
We prefer stone jars, both for soaking rennets and to keep the prepared rennet in, because they are so much more easily kept sweet than wooden tubs can be. Of all things, we detest a stinking rennet tub or jar. Frequent scalding, when emptied, is necessary. When the preparation is kept in a tub, it will be advantageous to rub a little salt, each morning, on the sides of the tub left exposed to the air, after setting the milk, by the lowering of the liquid. By all means, do anything and everything that may be necessary to keep the rennet tubs or jars from stinking so badly that the stench will nearly suffocate one on uncovering them. A sweet rennet tub is the evidence of important qualities in a cheese-maker—care and cleanliness.
Of course, there are various ways of managing, as regards quantity, convenience's sake, and so on, but we do not believe the principles involved in the process of selecting and preparing rennets for use, as we have given it, can be violated or neglected without loss in some manner. The importance of properly-prepared rennet, and of keeping it sweet and clean, cannot be too highly estimated. "Bad luck" in cheese-making might not infrequently be traced to the rennet tub; while "good luck" may be as often traced to the same source. Look out for your rennets and take care of your rennet-tubs or jars. They may make or mar your fortune.
CHAPTER XIII. SETTING.
The temperature of 82° to 86° is generally considered the best for setting—the former in hot and the latter in cold weather. This gives an average of 84° for mild weather. Perhaps this point is as good as any for setting. But it is worth bearing in mind that the milk will coagulate sooner, after adding the rennet, at a high than at a low temperature. The same milk will set quicker at 86° than at 82°, and at the points in the vat where the heat is greatest, or the milk cools least by radiation, the curd will become tough and difficult to cut, while other parts of the mass will remain tender and cut easily. This not only demonstrates the greater activity of the rennet at a higher heat, but the importance of an even heat throughout, and of keeping it from falling. Some throw a cloth over the vat, after the milk begins to thicken and agitation is no longer necessary to keep the cream from rising. This is a good practice, we believe, as it retards the reduction of temperature by radiation, and keeps the heat more equalized. This will secure a more uniform action of the rennet, and render the cutting less difficult and less liable to cause waste.
When the rennet is once added and thoroughly incorporated with the milk, we believe it would be better if the mass could have perfect rest until the curd is ready to cut. We think the curd is more likely to be spongy in consequence of the continued or frequent agitation kept up to prevent the cream from rising. All know that a stir too much after the milk begins to look thick, and roll heavily, prevents the formation of a solid curd. It refuses to unite in one uniform mass, and remains in small, separate particles. But, when the milk is all right, observation will show that such a curd makes fine cheese, though there is great waste from the fine particles floating off with the whey. And why will it make fine cheese? Because it is in small particles, gets thoroughly and evenly cooked, and the butter is equally distributed through it.