Cheddar is the best known cheese throughout the United States and the one most commonly made in factories. The Cheddar process was brought to America by English immigrants. Similar to Cheddar cheese are Pineapple, English Dairy, Sage cheese, skimmed-milk and California Jack cheese made in this country, and Derbyshire, Leicestershire, Wensleydale and Cheshire made in England. The Cheddar cheese process as employed in the factories to-day has been modified and improved since it was first introduced into this country by the early immigrants. The following description87 includes only the practices as found in the factories to-day if whole milk is used. Skimmed-milk Cheddar cheese is discussed later.

192. The lot-card.—The Cheddar process involves several hours of manipulation and includes many details which should be closely and accurately observed and recorded. The necessity of carrying observations of several different factors at the same time makes a scheme of recording data essential to convenient work. For this purpose, a lot-card for Cheddar cheese is introduced here and the pages given to particular factors are indicated in the space intended for the recording of observations. The manufacture of Cheddar cheese is a complicated process, because several factors must be given attention at the same time. A careful record of the observations of each step in the successive handling of each lot of milk puts the operator in possession of a permanent record of his experience. This record has several uses. It may help to convince patrons of the importance of eliminating faults in the milk; it furnishes the cheese-maker a cumulative record of his experiences in handling milk with special qualities, such as high or low fat-content, over-acidity or taints. Since Cheddar ripening covers a period of weeks and months, no operator can remember particular lots of milk sufficiently well to be able to use his experience on the interpretation of the qualities found in the ripened product.

193. The milk.—It is the usual practice to deliver the milk to the cheese factory each morning (Fig. 29). The night's milk is cooled and kept clean and cold until delivered at the factory. It is advisable not to mix the cold night's milk and the warm morning's milk, but to deliver them in separate cans to the cheese factory at the same time. The milk is weighed, sample for fat test taken and then run into the vat (Fig. 30). The receiving or taking in of the milk is one of the most important parts of the cheese factory work. It is practically as important as the actual manufacturing of the cheese.

Any milk high in acid or with a bad flavor should be avoided. It is often bad policy to reject the milk, for a neighboring factory will accept it and the factory not only loses the milk but also the patron. Factories should have an agreement to prevent this. The acidity can be determined by the acid test, but the detection of flavors must be made by the cheese-maker himself with the aid of smell and taste. Many of the bad flavors in the cheese can be traced to the poor quality of the milk. One of the worst qualities in milk and cheese is the presence of gas-producing organisms.88 Any milk which shows gassy fermentation should be rejected, for it is difficult to make cheese from this and at best there will be a large loss during the manufacturing process. The cheese may have a bad flavor and develop "pin-holes" and in extreme cases may puff up like a ball. The person receiving the milk should talk to the farmers or dairy-men about the proper care of the utensils and milk. He must see that the cans are kept clean. One very bad practice is to deliver milk and take home whey in the same cans. The cans, as they are brought back from the cheese factory full of whey, are often left in the barn or near a hog-pen until the whey is fed. Unless such cans are emptied immediately on returning to the farm and then rinsed out with cold water, thoroughly washed and scalded, bad flavors may develop in the cheese. It is thought that this causes "fruity" or sweet flavor, which resembles that of fruits such as raspberries, strawberries or pineapples.

194. Ripening the milk.—A slight development of acidity is required: (a) to obtain the formation of a firm curd; and (b) to establish immediate dominance of a desirable type of lactic organism which will produce the large amount of acid required later in the cheddaring process. The development of this acidification before the addition of rennet is known as the ripening of the milk. The extent of ripening advised by different schools of makers has varied from an acidity of 0.20 of 1 per cent or even slightly higher percentage titrated as lactic acid, to about 0.17 of 1 per cent as now preferred by some of the most successful groups of workers. The ripeness of the milk can also be determined by the use of the rennet test.

The milk may be ripened by allowing the lactic organisms already present in the milk to develop naturally. This requires considerable time and while the lactic acid-forming bacteria are developing, other and undesirable fermentations may be taking place, so that the good results which should follow the uninterrupted development of the lactic acid-forming organisms are lost. Starter is commonly used to produce the desired ripening of the milk. (For the preparation of starter see Chapter IV.)

Some makers put the starter into the empty vat (Fig. 31) and add the milk as it is received; others add it to the total volume of cold milk and then begin to heat it. Whenever the starter is used, it should be strained to remove lumps. These lumps might cause a mottled color in the cheese. The best practice calls for an acidity or a rennet test of the mixed milk after it has been brought to the setting temperature in the vat. With milk tested at this stage and the volume of milk in the vat known, the cheese-maker is able to calculate closely the amount of starter needed. When the quantity of starter to use is in doubt, the amount added should be under rather than over the estimate, since the need of more can be determined by making frequent rennet and acid tests in a very few minutes without damage to the cheese. If too much starter has been used, acid or sour cheese is usually obtained, with loss in market quality.

An over-development of acidity at any stage of the manufacturing process affects the flavor, body and texture, color and finish of the cheese. The product is known as a sour cheese, and can usually be identified by its sour taste and smell. A sour cheese while curing will seldom develop a normal Cheddar flavor and the texture will be hard and harsh and very brittle. The body will not be smooth but harsh and grainy. The over-development of acid will show by fading or bleaching the color. A sour cheese usually leaks whey for a few days after being placed on the curing-room shelves.

Ripening the milk is one of the most important parts of cheese-making. Proper ripening places the acid fermentations under the control of the cheese-maker so that he may know what results will follow his labors. The operator can control the acidity while ripening the milk, but after the rennet is added all control of the acidity is lost. From that time, the moisture must be regulated in proportion to the acidity.

Before setting, the milk should be ripened to such a point as to leave at least two and one-half hours from the time that the rennet extract is added until the acid development has reached the stage at which it is necessary to remove the whey. By the acid test the milk may vary from 0.16 to 0.18 of 1 per cent, but no definite statement can be given for the rennet test. This can be determined only by comparison from day to day. For operation of rennet test see Chapter V. During this period of two and one-half hours, the curd is formed, then cut, and the temperature is raised from 84° or 86° F. (the temperature at which the rennet extract is added) to about 98° to 100° F. The curd must be kept agitated so that the particles will not mat together; this is necessary to obtain sufficient contraction of the particles of curd with the proper reduction of water-content. If the milk becomes too ripe (too sour) before the rennet is added, there will not be sufficient time for these steps to take place naturally. In such cases special means are required to firm the curd. These result in a loss of both quality and quantity of cheese. On the other hand, if the milk is not ripened, but the rennet extract added, regardless of the acid development, one of the important natural forces for expelling the moisture is lost. The time required for the particles of curd to contract is much prolonged, the expulsion of whey is usually inadequate and the curd remains in a soft or wet condition. Using too much starter is almost equally bad, for although it hastens the making process, it produces a sour or acid cheese.

195. Setting or coagulating.—The milk for Cheddar cheese-making is heated to 86° to 88° F. or occasionally a slightly lower temperature. This temperature is found by experiment to give the texture of curd most favorable for the desired results. Although some cheese-makers work as low as 84° F., the texture of such curd is too soft and coagulates too slowly. The very slight change of 2° F. produces curd which coagulates more quickly and is tougher and firmer.If the cheeses are to be colored, the color should be added after all the starter. It should be thoroughly and evenly mixed with the milk to insure an even color in the cheese. If the color is added before the starter, there are likely to be white specks in the cheese, on account of the coagulated casein in the starter. The amount of color to use depends on the tint desired in the cheese. It varies from ? to ½ ounce to 1000 pounds of milk for a light straw color to 1½ to 2 ounces for 1000 pounds of milk for a deep red color.

Enough rennet should be used to produce a curd firm enough to cut in twenty-five to thirty-five minutes. The necessary amount will vary with the strength of the rennet extract itself, with the acidity, the temperature, the nature of the lot of milk, and with the individual aims of the maker in which he adjusts the other factors to his preferences as to rapidity of rennet action. With the usual commercial extract, the needed amount ranges from 2.5 to 4 ounces for 1000 pounds of milk. As for all varieties of cheese, the rennet extract should be diluted in cold water at about one part rennet to forty parts water and thoroughly stirred into the milk. (See Chapter V.)

196. Cutting.—The object of cutting is to obtain an even expulsion of the moisture from the curd. The curd is cut as soon as it becomes firm enough. To determine this, various tests may be used. Some operators test it by pressing it away from the side of the vat, considering it ready to cut when it separates cleanly from the metal. The test most commonly used is to insert the index finger obliquely into the curd, then to start to split the curd with the thumb and finally to raise the finger gently; if ready to cut, the curd will split cleanly over the finger and clear whey will separate to fill the opened crack. Another arbitrary but more or less satisfactory rule is that the time from adding the rennet until cutting should be two and one-half times that from the addition of rennet until the first sign of coagulation is observed.

The condition of the curd itself is the best guide to show when it is ready to cut. The condition of the curd is constantly changing, so that in a large vat, if the cutting is not begun until the curd is in the best condition, by the time the last of the curd is cut it will be too hard or firm. It is better to begin while the curd is a trifle too soft so that the cutting will be taking place while the curd is at the proper stage. At best the last of the curd may become too hard. If too hard, it will break ahead of the knife instead of cut. Breaking causes more fat loss than cutting because there is more surface exposed and hence more fat globules. The softer the curd when cut, the quicker and easier the moisture can be expelled.

If the curd is cut when soft, care must be exercised not to stir it too hard immediately after cutting. Soft curd breaks very easily. When the curd is cut soft and then stirred vigorously, there is a larger loss of fat than when the curd becomes hard before it is cut.

Two knives are used to cut the curd. (See Fig. 11.) These knives may have either wire or blades for cutting. The space between the wires or blades varies from 5/16 to ½ inch. Knives used should have blades or wires close enough together to cut the pieces as small as desired, without a second cutting. When the curd has to be cut a second time it usually results in pieces of uneven sizes, because the pieces already cut cannot be evenly split in two.One set of knives has horizontal and the other perpendicular blades or wires. The curd is cut the long way of the vat with the horizontal knife and lengthwise and crosswise with the perpendicular knife so that the result is small cubes or oblongs of curd. Some cheese-makers prefer to use one knife first and some the other, but the result should be a curd cut into pieces of uniform size. The smaller the particles of curd or cubes are cut, the quicker the curd will firm up or cook. If not cut uniformly, the changes taking place later in the curd particles will not be uniform,—the small pieces will be hard and dry while the large ones will be soft and mushy.

Care should be taken to let the knife cut its way into the curd (Fig. 32). If the knife is pushed into the curd, it will break it and cause a large loss of fat. The same is true when taking the knives out of the curd. The loss of fat due to cutting is very similar to the loss of sawdust when sawing a board. It may be considered a necessary evil. The loss due to cutting is about 0.3 of 1 per cent of fat in the whey and the loss of casein about 0.1 of 1 per cent in the whey.

197. Heating or "cooking" the curd.—After the curd is cut, the pieces (cubes) rapidly settle to the bottom of the vat and tend to mat together. To prevent this, the curd must be kept stirred. When stirring first begins, the curd is soft and very readily broken. Some cheese-makers prefer to stir by hand for the first few minutes Acme curd rake. Fig. 33.—Acme curd rake. after cutting, while the curd is soft. The importance of careful handling can hardly be over-emphasized. No matter how well the curd has been cut, if the stirring is performed in a careless manner in the early stages, it will be broken into uneven sized pieces and a considerable loss of fat will result. A wooden hay rake or a McPherson curd agitator (Figs. 33, 34) may be used to stir the curd. Mechanical curd agitators are used in some cheese factories. Edam cheese mold. Fig. 34.—McPherson curd agitator. There are several makes. (See Fig. 35.) These agitators save much hand labor, although some stirring by hand must be done in connection with them. The mechanical agitators do not stir the curd in the corners of the vat; this must be done with the hand rake. It is the usual practice to stir the curd immediately after cutting for five to ten minutes before the mechanical agitators are used. This is necessary to give the curd a slight chance to firm as the mechanical agitators tend to break it up. After cutting, a thin film forms on each piece of curd. This film holds the curd particles, especially the fat. Breaking the films on the cubes causes loss of fat. If lumps form at the early stage, by matting of the curd particles, violent stirring is required to separate them. When such lumps are broken up, new cleavage lines are formed with loss of fat, because the original films surrounding the soft curd fuse so firmly that the curd cubes do not separate but actually break. New surfaces are thus formed with consequent fat loss. Rapid shrinkage with expulsion of whey takes place during the first few minutes of gentle agitation. Before any heat is applied to the vat, sufficient whey should have separated or formed to float each piece of curd separately. This will require ten to fifteen minutes from the time of cutting.

Thus far the first of three distinct factors which expel the moisture from the curd has been considered: (1) the action of the rennet; (2) the development of the lactic acid; and (3) the application of heat. These forces must have time to act naturally. If heat is applied too soon after the curd is cut or if the temperature is raised too rapidly, it causes a thick film to form on the pieces of curd which interferes with the escape of the whey. The outside of the curd becomes firm but the inside remains very soft. A curd which is cooked on the outside only feels firm when stirred by hand in the whey, but when a handful is squeezed the soft centers are noticed. To firm such curd masses requires violent stirring, which will break the thick tough film. This allows the moisture to escape and also increases the fat loss. The rapidity of heating should depend on the condition of the curd and the amount of acid developed. The heat should keep pace with these. When ready to raise the temperature, the least amount of steam possible should be allowed to pass through the valve. This should raise the temperature very gradually. If heat is applied too quickly at first, it will cause the curd to lump. A safe rule is to raise the temperature one degree in the first five minutes after the steam has been turned on. The heating should progress slowly until the whole mass of curd in the vat has reached a temperature of 90° to 92° F. The usual temperature to which the curd is heated or cooked is 98° F. to 100° F. The lower the temperature that can be used and properly firm the curd, the better will be the body of the cheese. If the curd is heated too high, it will become hard, which causes a dry hard "corky" cheese. After this temperature has been reached, there is not such a tendency for the curd particles to stick together nor are they so easily broken in stirring. It should require, under normal conditions, not less than thirty to forty-five minutes, from the time the steam is turned on, to raise temperature of the curd from the setting temperature to that necessary to "firm" the curd. If a shorter time is allowed to raise the temperature, the curd will not have opportunity to contract naturally.

The temperature required to expel the moisture properly varies with the percentage of fat in the milk. If rich in fat (4.5 to 5.5 per cent) milk requires a temperature of 98° to 104° F. to firm the curd, while the same result can be accomplished with milk testing 3.0 to 3.5 per cent fat at a temperature of 94° to 96° F. A higher temperature is needed in winter than in summer because the milk is usually richer in fat. In a water-jacketed vat, allowance must always be made for the rise in temperature due to the water surrounding it. The water may be removed if there is danger of the temperature going too high. However, it is better to gauge the heat so that the water may be left, as this helps to hold the curd at an even temperature, especially in cold weather. In a steam-heated vat there is not so much danger of the temperature running up.

The stirring must be kept up after the steam has been turned off until the curd has reached such a stage of contraction that it will not readily pack or mat in the bottom of the vat. After the curd reaches this stage it may be allowed to settle to the bottom and stirred only occasionally until it is time to remove the whey. If the cheese room is not warm and there is danger of the curd cooling, a cover should be placed on the vat. The curd should not be allowed to settle for more than fifteen minutes without stirring to keep each piece separate. This is necessary to obtain uniform contraction of all curd masses.

198. Removing the whey.—To permit the normal changes in the curd to take place naturally, two and one-half hours from the time the rennet extract is added is ordinarily required before the whey is drawn. The time of removing the whey is determined by two factors: one, the acid development, and the other, the firmness of the curd. For the best results, it is better to have the firmness of the curd a trifle ahead of the acid development. When the proper acid development has been reached, the whey must be removed, regardless of the firmness of the curd. If the curd has not become firm enough by natural forces, when the acid development has reached the proper stage to remove the whey, it must be firmed by other means. If it is not firm enough, either by natural or artificial means, when the whey is removed, a sour cheese is the result. The acid development should not be allowed to go beyond 0.16 to 0.19 of 1 per cent acidity in the whey by the acid test or ?16 to ?8 of an inch of acid on the hot-iron test, before the whey is removed.

199. Hot-iron test.89—This test is employed to determine the amount of acid in the curd. A piece of iron, such as an iron pipe two feet long, is heated in the fire to proper temperature. If the iron is too hot it will burn the curd, and if not hot enough the curd will not stick to the iron. When hot, it is taken from the fire and wiped clean with a cloth. A handful of curd is taken from the vat and squeezed dry, either in the hand or in a cloth. This curd is carefully pressed against the hot iron and drawn away. If the iron is at the right temperature and the curd has sufficient acid development, the curd will stick to the iron and when pulled away will form fine threads. The length of these threads determines the amount of acid in the curd. The acid is usually spoken of in terms of the length of threads, as ?8 inch of acid, ½ inch of acid and the like. The curd must have a slight development of acid before it will stick to the iron. This test takes advantage of the peculiar properties90 of curd which are produced by the action of the acid on the casein.

200. Firmness of the curd.—The cheese-maker must be able to judge the firmness of the curd by physical examination. The particles of curd should have shrunken to about one-half their original size and should be of uniform consistency throughout; they should not have any soft centers. The curd should be firm and springy. When a double handful is pressed and suddenly released, the curd particles should spring apart. The curd should have a "shotty" feeling when in the whey. If the curd has attained the proper firmness, and the acid has not reached the correct stage to remove the whey, it may be left in the whey until sufficient acid development has been attained. This is liable to cause the curd to become too firm and to result in a hard dry cheese. If Whey siphon with strainer. Fig. 36.—Whey siphon with strainer. there is no evidence of the presence of undesirable organisms, such as bad odors, or gas holes in the curd, it is better to remove the whey and develop the acid when the curd is in the "pack." The pack refers to the first piling of the curd.

The whey may be removed either by means of a faucet or gate in the vat or by a siphon (Fig. 36). With either form of removal a whey-strainer (Fig. 37) should be used to prevent loss of curd particles. It requires considerable time for the whey to escape from a large vat. After the curd has been heated to the proper temperature, it is well to remove a portion of the whey. In doing this the surface of the whey should not be drawn down quite to the top of the curd. When ready, the remaining whey can be quickly removed.

If it is decided that the curd is not firm enough, when the whey is drawn down to the surface of the curd and the acid has developed sufficiently, the curd should be firmed up in the whey by stirring it vigorously by hand before the remainder of the whey is removed. This is commonly called "hand stirring." This difficulty results Whey strainer with spout to fit into the gate in the vat. Fig. 37.—Whey strainer with spout to fit into the gate in the vat. either from the use of too much starter or from holding the milk until too much acid development has taken place before adding the rennet. Hand stirring accomplishes what natural forces would accomplish if given sufficient time. If the curd does not firm naturally in the whey, there is a large loss of fat and other solids, because the pieces of curd will have to be broken up to allow the water to escape from the soft centers of these masses. This loss can usually be reduced by firming the curd in the whey or adding water rather than by stirring without either water or whey. If the curd is not properly firmed, it carries extra whey into the cheese. With the increase in whey, the amount of milk-sugar carried into the cheese increases. This extra milk-sugar attacked by bacteria produces an excess of lactic acid, which results in "sour" cheeses. This explains why the curd is placed beyond the danger of over-development of acid by removing so large a portion of the whey. If the curd is properly firmed in the whey and the whey is removed before too much acid has developed, it is impossible to make a sour cheese.

201. Gathering the curd together.—Before the last of the whey has been removed, the curd should be pushed back from the faucet into the upper two-thirds of the vat and spread in an even layer. This layer should be six to eight inches thick. The curd can be pushed back with the rake or a board which will fit crosswise in the vat, in which are many holes. As soon as the whey has been removed so that there is not enough to wash the curd into the lower part of the vat, the vat should be tilted and a ditch eight to ten inches wide cut in the curd through the center. The curd from the ditch should be removed to either side and spread evenly. As soon as all the whey has been removed, the pieces of curd scattered about in the vat should be gathered up and placed with the remainder.

In some factories, instead of matting the curd in the vat, a curd sink is used. This is a wooden receptacle about the size of the vat but not so deep, with a slatted false bottom. It is fitted with castors so that it can be easily moved about. A cloth is placed in the sink and the curd and whey are dipped upon the cloth. The whey escapes very rapidly through the cloth. The curd sink is an advantage in those cases in which it is desirable to remove the whey from the curd quickly, such as high acid curds which have to be hand stirred to firm the curd. The disadvantage lies in the work required to keep the sink and the large cloth clean.

202. Matting or cheddaring is the distinctive feature of the Cheddar process. It is the piling and matting of the curd. Whether the curd is matted in the vat or in the curd sink, the process is practically the same. The object of cheddaring is three-fold: (1) to control the incorporation of moisture; (2) to control undesirable ferments, if present in the curd; (3) to develop the texture desired in the cheeses.

After the curd in the vat has become matted so that the particles stick together, the masses on either side of the central channel are cut crosswise into strips with a cheese knife (Fig. 38). The width of the strip depends on the water-content of the curd at this stage. The more water, the smaller should be the pieces of curd. This allows the whey to drain away much more rapidly. As soon as the strips of curd are cut, they should be turned over or stood on edge. A drain should be left along the A cheese knife. Fig. 38.—A cheese knife. middle line of the vat and on each side. This permits the whey to run away freely. If, on the other hand, the outlet is dammed up, the curd may become "whey-soaked." This produces a soft mushy cheese which sometimes is "acidy" or sour. After the curd is turned each time, all crumbs of curd broken off should be brushed underneath the masses of curd so that they will mat with it. They should never be placed on top of the curd because they will not unite but will become dry and hard. If the crumbs are not kept brushed up, they become dry and will cause an open textured granular cheese and possibly lumps in the cheese. After the pieces of curd have been turned several times, and the whey has fairly completely drained away, they may be piled first two deep, then three deep and so on, the depth of the piling being gauged by the softness or amount of water in the curd and the temperature. The higher the curd is piled, the more water it will retain (assimilate), so that the amount of moisture in the curd is regulated by the size of the pieces into which it is cut and the rapidity and depth to which it is piled.

The curd should not be left too long from the time it is turned until it is turned again. This period is usually about ten to fifteen minutes. The moister the curd, the more often it should be turned. In turning, care should be taken to keep the ends at the same temperature as the remainder. This can be done by piling them inside, thereby keeping them warm. There is a tendency for the ends of the pieces of curd to remain granular and so cause an open-textured cheese.

During the cheddaring process, the temperature should be reduced uniformly and gradually. If there is danger of the curd becoming too cold, the vat should be covered and a pail of hot water may be placed inside, if it is deemed necessary. The temperature of the curd should not be allowed to go below 85° to 90° F. If kept too warm, the curd will become soft and plastic, and if too cold, it will not mat together.

While the curd is being turned and piled, its physical properties are changing. The acid develops. When the cheddaring process is completed, the curd should be elastic, smooth and fibrous. The curd should have the close meaty texture desired in the cheese. If this step in the process is neglected, defects may appear later in the body, texture and flavor of the cheese. Attempts to pile the curd too fast result in a soft, mushy, open-textured product. Such cheese has mechanical holes, in which moisture collects, and so is likely to cause rot while curing. If gas is detected either before or during the cheddaring process, the curd should be piled until the gas holes are no longer round but flat. If the gas holes are not flattened or obliterated during this process, the cheeses will be very liable to puff on the shelves in the curing-room. The curd should be handled until the gas holes flatten out evenly, although this may require considerable time. At best, gassy curd will never produce the highest grade of cheese.

Cheddaring or piling the curd is not thoroughly understood by most cheese-makers. Because the moisture contains the milk-sugar, there is danger of having so much moisture present in the cheese that it will become sour from the action of the lactic acid-forming bacteria on the milk-sugar. A cheese may be sweet when made and later become sour because it contains too much moisture or milk-sugar. This is known as "shelf souring." For the proper cheddaring of a curd, it is necessary that it be properly firmed in the whey. If the moisture is not evenly incorporated, the cheese will have a mottled color. The pieces that have the more moisture will be lighter colored. If the proper amount of moisture is not incorporated, the cheese will be dry and hard, and if too much, soft and pasty.

203. Milling the curd.—The large pieces formed by the cheddaring process must be cut into small ones before the curd can be easily put into the hoop. This is called "milling." Properly milled curd can be salted evenly, cools more quickly and uniformly and can be distributed evenly in the hoops.

The proper time to "mill" the curd is determined by its physical condition. Some curds will cheddar much more rapidly than others, hence no definite length of time can be given. Curd, when ready to mill, should have a fibrous texture somewhat like the white meat of a chicken breast. The pieces of curd should split very easily. When cut, the curd should show a close, solid, smooth interior. The amount of lactic acid developed may vary within rather wide limits. The hot iron may show strings ½ to 1 inch long. The acidity (by titration of the freshly separating whey) may be 0.45 to 0.65 of 1 per cent. If the curd has been properly made, that is, firmed up in the whey with the proper acidity so far, acid development during the cheddaring process will take care of itself. The physical condition remains the principal means of determining the time when the curd should be milled.

There are many kinds and styles of curd-mills on the market. Gosselin, Barnard, Pohl, Junker, Victor, Harris are well-known kinds (Figs. 39-42). Some are hand, others power mills. Some of these tear the curd into pieces of unequal size, others cut it into uniform pieces. A mill that will do the work with the least possible pressure on the curd and which will cut it into small uniform-sized pieces is most desirable. The ideal mill should release the least fat and leave the curd in the best condition to receive the salt. It is impossible to run curd through any mill without exposing some fat on the freshly cut surfaces, and if the curd is put under pressure, more fat will be pressed out and lost. Cutting in the mill, like cutting the curd after coagulation by rennet, may be called a necessary evil. There is an unavoidable mechanical loss which may be greater or less according to the mill used. If the curd has been properly handled so that the water in it has become thoroughly assimilated (properly incorporated), this loss will be reduced to the minimum. If the curd contains free moisture and many of the particles have soft interiors, a stream of white whey will run down the vat as the curd masses are cut. Some samples of such white whey will test as high as 15 per cent fat. This not only causes a loss in yield but in quality of cheese, according to the amount of fat lost. White whey is an indication of loss of fat. If the proper amount of A curd fork. Fig. 43.—A curd fork. moisture is present and is so thoroughly incorporated in the curd that it can be separated only by evaporation, the ideal condition has been reached. While milling, the cut curd should be stirred as fast as milled to prevent matting again and to allow odors to escape. This stirring is usually performed with a curd fork (Fig. 43). At the same time the temperature will be lowered. The milled curd should be spread evenly over the upper three-quarters of the bottom of the vat. The flavor of the curd that has been made from tainted milk can be very much improved by stirring at this time so that air can enter.

A gassy curd, which has been held until the holes have become flattened, should be stirred very frequently during this stage to allow the gas to escape, thereby improving the flavor. 204. Salting.—Salt is added to Cheddar curd for several purposes: (1) for its taste; (2) to aid in the removal of the whey and to harden and shrink the curd; (3) to influence the fermentation by slowing down acidification, checking the growth of unfavorable organisms and delaying ripening. The salt should be pure. It should be coarse-grained, because the large grains dissolve more slowly and permit its absorption to a much larger extent than the fine-grained salt. Salt that dissolves slowly is, therefore, to be sought for this purpose.

The following factors must be considered in determining the amount of salt to be used: (1) the amount of curd from the milk; (2) the percentage of water in the curd; (3) the acidity of the curd; (4) the particular market form of cheese desired. The custom of determining the quantity of salt by the weight of milk is an inaccurate practice. The amount of salt should be based on the amount of curd. If the amount of fat in the milk is known, a fairly accurate estimate of the amount of curd can be made. It would be more accurate to weigh the curd before salting, but this is not practicable or necessary to insure a good quality of cheese. The amount of salt varies from 1½ to 2½ pounds of salt to the curd from each 1000 pounds of milk.

The salt should not be added directly after milling because, at that time, it would cause a large loss of fat. After milling there should be time before salting for the freshly cut surfaces to dry or "heal over." When first milled the curd has a dry harsh feeling; when ready to salt it will feel soft and mellow and some moisture can usually be squeezed out easily. Fifteen to twenty minutes from the time of milling are required before the curd is ready for the salt. When ready, the curd should be spread evenly over the bottom of the vat. The salt should be carefully weighed, and then applied, evenly, over the surface of the curd, in two or three applications. The curd should be thoroughly stirred after each application Wilson press hoop. Fig. 44.—Wilson press hoop. A,complete hoop; B,bottom cover with wide flange; C,top cover with narrow flange; D,closed body; E, bandager. of salt. While the salt is being dissolved and absorbed, the curd should be stirred occasionally to prevent lumps from forming.

205. Hooping the curd.—When the salt has become dissolved and the curd as soft and mellow as before the salt was added, it is ready to be put into the hoop. Various sized hoops may be used, depending on the desired size of the cheese. Two types are the Wilson and the Fraser (Figs. 44, 45). With either type, a dampened press cloth should be cut just Fraser press. Fig. 45.—Fraser press hoop. A,complete hoop; B,bandager; C,follower; D,fibrous press ring. to fit the bottom of the hoop. A starched circle may or may not be used; if used, it should be placed on top of the press cloth. The bandage now commonly employed is the seamless one which comes in the form of a tube of various sizes for different sized hoops. The lengths of bandage cut for each hoop or cheese depend on the height of the cheese plus about one and one-half inches' lap on each end. The bandage, after being cut the desired length, is placed on the part of the hoop made to hold it, so that it is suspended about the side of the hoop and laps about one and one-half inches on the bottom. The bandage should be free from ravelings and placed squarely in the hoop.

The hoop is now ready to fill with curd. Enough hoops should be prepared to hold all the day's curd as fast as it is ready. In order to have all the cheeses as nearly as possible of the same size, it is advisable to weigh the curd into the hoops. The curd may be measured into the hoops, but this is not so accurate. The curd may be Curd scoop and pail. Fig. 46.—Curd scoop and pail. dipped with a flat-sided curd pail or a curd scoop into the hoops (Fig. 46).

206. Pressing the curd.—The natural changes sought in the curd require a period of at least five hours between the time of setting (addition of the rennet) and the pressing of the curd. Less time than this involves loss in yield and quality of the cheese. In other words, the time requirement for these changes cannot be ignored. The object of pressing is not primarily to remove whey but to produce the physical conditions essential to ripening the cheese in a mass and put it in convenient form for handling. The whey should have been removed during the cooking and cheddaring. When ready for the press, the temperature of the curd should be about 80° to 85° F.; it should be brought down to this point during the milling, salting and hooping processes. If the curd is put to press too warm or too cold, the following results may be expected:

Too high temperature during pressing produces several faults, as:

(1) Favors the development of undesirable ferments.

(2) Causes excessive loss of fat.

(3) Gives the curd pieces a greasy surface so that they will not readily pass into a compact cheese. If a cheese is greasy, the bandages will not stick.

(4) Favors the formation of mechanical holes in the cheese.

(5) Causes "seamy" color in the cheese by the collection of fat between pieces of curd.

Too low temperature has its difficulties, such as:

(1) The pieces of curd will not fuse together.

(2) The rind does not form properly.

(3) It appears to cause mottled cheese.

Fig. 47.—Continuous pressure gang cheese-press.