Part 13

"COOKING."

After the cutting is done, if the whey is separating rapidly, the heat may be started at once. If the action of the rennet is rather slow, it is better to wait a few minutes for the curd to harden a little, while with your hand you carefully rub down the side of the vat, thus removing all the curd that may be adhering to it. Not over five minutes waiting, as a usual thing, is necessary, and generally there need be no waiting. But as soon as the heat is started, begin to gently stir the curd with a rake, by passing it down into the middle of the vat and gently raising the curd on each side. If uncut pieces appear, carefully separate them with the teeth of the rake. Keep up this stirring, which may be more violent after the curd hardens, until the whole is heated up to 98 or 100 degrees--or to blood heat. The reason for constant agitation is to keep an even temperature throughout the mass and prevent the curd from packing. This secures even action of the rennet. The reason for going to blood heat is because rennet is most active at this point. It is the temperature indicated by Nature. It is the one at which we digest our food, and the one at which the calf's stomach forms curd and afterwards digests it. The pepsin or gastric juice is more potent at blood heat, and this pepsin or rennet is what does the work. The heat does not cook the curd in the vat any more than it cooks the milk in the cow's udder. We choose 98 degrees as the proper temperature because the digestive or cheesing process of the rennet goes on faster at this point. To go above or below it is to lose instead of gain. This temperature should therefore be maintained until the curd is "cooked"--that is, until the action of the rennet has expelled the proper amount of whey and the curd is as firm as we want it. Anent the stirring of curds, use the hands as little as possible. There is nothing better for this purpose than the common hay rake with the handle shortened and one tooth cut off from each end by severing the rake-head within three quarters of an inch of the next tooth.

DRAWING THE WHEY.

We next draw the whey down to the curd--leaving enough to stir it in easily, and cool the whole mass down to 90 degrees, to avoid too much packing, and draw off the balance of the whey. The whey should be run off before the acid develops, because acid, formed from the milk in the sugar, dissolves the minerals and cuts some of the oils in the curd, and these run off in the whey. Many curds, by remaining in the whey too long, become whey-soaked, and make cheese that is soggy and hard, with a sour flavor. This kind of firmness is not desirable, notwithstanding it is called for by buyers, who seldom know anything about cheese making. If the acid develops before the whey is properly expelled, or the curd is "cooked," it carries off the minerals, which are in the form of phosphates, and this makes the cheese poor indeed. These phosphates are of lime, iron, magnesium, etc., but the principal is phosphate of lime. The affinity of these minerals for lactic acid is stronger than for phosphoric acid; so they let go of the latter and unite with the lactic acid, forming lactates and leaving the phosphoric acid free. But if we get all of the whey out of the curd that we desire, and then get the curd out of the whey--that is, draw off the whey--before the acid comes on, we retain the phosphates and fats in the cheese--all the goodness that belongs in it. The acid will come on afterward, but we have reduced the sugar to a minimum, and the amount of acid developed does no serious injury. As the whey is already expelled, of course it cannot wash out the minerals that are dissolved. These remain, and in the process of curing recombine with the phosphoric acid. We have left in the curd about 3-1/2 parts of the 87 parts in 100 parts of milk. The whey left in the curd contains, we will say, 1-10th of the sugar that was in the milk. The acid formed from this, though too small to do any known injury, is large enough to do all the good required, if it does any good at all. We are, therefore, safe when we get the whey out of the curd and the curd out of the whey before the development of the lactic acid.

SALTING.

When the whey is well out of the curd, so as not to waste the salt, the salt may be applied and stirred in. The salt does not stop the development of acid, as is popularly supposed. When applied, it aids in keeping the curd loose. Then the curd may stand, with occasional stirring, almost any length of time for the purpose of airing and cooling, of getting rid of any bad odors, of developing flavor by oxydation from contact with the atmosphere, and of letting the acid come on. It is safest not to put the curd to press until it has a positively clean sour smell. This shows that certain chemical changes have taken place, freeing the curd of the gases generated by this process, and prevents any huffing of the cheese on the shelf in the curing room. Where cheddaring and grinding are practiced, the salt is of course applied after the curd is ground. Cheddaring is the easier and safer method, as the whey can be drawn early, and there is no danger from the acid. Salting at the rate of 2-1/2 lbs. of salt to 1,000 lbs. of milk is the usual practice and not far from right. For long keeping, 3 lbs. of salt are not too much. Use none but the best dairy salt--the best of all the dairy salts, as well as the cheapest, being the Onondaga, F.F.

PUTTING TO PRESS.

After the acid fermentation is properly progressed, the curd should be put to press at a temperature not much below 80 degrees, nor much above 85. If higher, it is liable to heat and taint the cheese at the center; if lower it is difficult to face the cheese and press the curd together properly. But in warm weather, there is not much danger of getting the curd too cool.

ACID IN CHEESE MAKING.

This has been written on so much that the subject has become hackneyed. The acid seems to have eaten into the souls of some and turned them sour; but notwithstanding, the so-called "sweet curd" idea has made steady progress. Much of the opposition has come from buyers for export, who do not appear to be able to distinguish between a firm cheese and a hard cheese, and who ignore quality if they get a cheese hard enough to ship, without danger of breaking, by the time it is ten days old. This has been demonstrated by the fact that cheese condemned when green as too soft has been pronounced by the same buyers fine and all right, even endorsed with enthusiasm, when it was two or three months old, which is about as young as a first-class cheese should be shipped.

ANALYSIS OF MILK.

Of course, there would be no acid in milk if there were no sugar in it. The proportion of sugar is shown by the following analysis of an average sample of good milk made by Dr. Voelcker, the late chemist of the Royal Agricultural Society of Great Britain:

Water 87.30 Butter 3.75 Caseine 3.31 Milk-sugar and extractive matter 4.86 Mineral matter (ash) 0.78 ------ Total 100.00

It will be seen by this that the per cent. of sugar is at least 4.50, if we deduct the extractive matter, the proportion of which is not given. Numerous German analyses show it to range from 3.50 to 5.75 per cent. Henry and Chevalier put the average at 4.77, and Prof. L.B. Arnold says milk from cows in perfect health should contain, during the month of August, 4.30 to 5.50 per cent. We will call it 4.50 per cent. There is 87.30 per cent of water.

WHAT THE CHEESE MAKER DOES.

In separating the solids from the liquids, by the action of rennet, at the proper temperature, we expel, say 83.30 parts of the water, leaving 4 parts. We get rid of, say 4.20 parts of the sugar, which is held in perfect solution in the water. We lose, say .50 of one part of butter, .31 of one part of the caseine or albuminoids, and .13 of one part of ash. This leaves--

Water 4.00 Butter 3.25 Caseine 3.00 Sugar .30 Ash .65 ----- Total 11.20

We thus have 11.20 per cent. of the 100 parts out of which to get our cured cheese. A fair average is 10 lbs. of cheese for 100 pounds of milk. Some of the water evaporates in curing, say 1 part, leaving 3 parts. Our 10.20 parts of cheese is then composed of the following:

Water 3.00 Butter 3.25 Caseine 3.00 Sugar, or what results from decomposition .30 Ash .65 ----- Total 10.20

This is a little in excess of the general yield. The waste is usually in the greater amount of ash, sometimes nearly the whole of it, when the acid develops before the whey is expelled. In that case, the lactic acid dissolves the phosphates and they run out with the whey. This is so much loss of ingredients absolutely essential to digestion and assimilation.

WHAT OUGHT TO BE.

So far from this, there ought to be less loss of ingredients than we have supposed in our illustrative figures. But more of the butter is cut and runs off with the whey when the acid is developed before drawing the whey. The aim of the "sweet curd" system is to avoid this waste as much as possible, especially that of the butter and ash. To effect this, the whey is drawn sweet and the acid allowed to develop after the curd is cooked and the whey expelled. There need be no more water left in the curd, but more butter and ash, both of which tend to make the cheese softer. But with proper curing rooms, there is no trouble in making the cheese firm enough for all practical purposes, including shipping. It is better to use less rennet and not have coagulation begin under 25 minutes, cutting the curd about 15 or 20 minutes later, and to take more time for curing, at a lower temperature. We then have a firmer, more buttery, and better flavored cheese, which is a desideratum. But, with high and changing temperature in the curing room, no certain or satisfactory results can be counted on.

THEORY AND PRACTICE.

In theory, we ought to prevent the waste of butter and caseous matter altogether; but in practice, there is always a little loss of butter, and there are certain albuminous ingredients, called by the Germans ziega, which rennet will not coagulate. There is, of course, no means of saving this. The sugar we cannot and do not want to save in the cheese. If retained, it would be injurious and probably spoil the cheese, as the lactic acid in the small amount of sugar retained in the water is all that we can well manage. But all matter coagulable by rennet, all the butter, and all the ash, we ought to retain; and we cannot really call ourselves scientific cheese makers until we can do this. When accomplished, a greater weight of cheese will be the result.

There is no avoiding the acid resulting from the small amount of sugar retained in the curd; but, having expelled sufficient whey, if we keep the curd warm enough, and hold it in the vat or the sink long enough, the lactic acid will come on and we shall get rid of the bad results of putting a curd to press sweet. This acidity is absolutely necessary with the generality of curing rooms. But with low and steady temperature in the curing room, we can do about as we please.

RENNET.

Our recent observations more than ever convince us of the importance of good rennet in cheese making. Great evils and losses result from the use of bad rennet; and the great trouble is that many cheese makers do not know when rennet is bad. There is not only the evil of diseased and tainted rennets, to begin with, but the preparation from good rennets is often spoiled in the preparing. Frequently, in hot weather, they are allowed to taint while soaking; and when the liquid is prepared sweet, it is often allowed to ferment and taint for want of sufficient salt and from exposure in a high temperature.

SOAKING IN WHEY.