Although the work is not completed, the preliminary reports[69] have indicated the fundamental principles which must underlie such development.

+169. Outline of making Roquefort.+--Some of the results of these experiments are summarized in the following paragraphs:

_Milk._--Clean-flavored fresh milk testing 4-4.2 per cent fat and up to 2.8 per cent casein gives the best results. The milk with a high percentage of cheese-making solids forms a firmer curd, hence works up better in the process than milk of lower quality.

_Acidity._--The milk is ripened by lactic starter up to an acidity of 0.23 per cent t.i.trated as lactic acid at the time rennet is added. This gives a firm curd, which drains to the desired water-content but is low enough to prevent the toughening effect of too high acid. A very slight increase in initial acid--1 to 2 hundredths per cent--combined with the rate at which acidity is developing introduces such physical changes in texture as to make the final texture of Roquefort impossible.

_Temperature._--Rennet is added at or below 84 F. Every degree of heat adds definitely to the efficiency of rennet. Below 82 F., curdling becomes slower and the coagulum softer and more difficult to drain. The sheep's milk curd is made from 76 to 84 F. but sheep's milk has about twice the cheese solids found in cow's milk. It was found necessary to raise the temperature as high as texture would permit. However, at 86 F. the physical character of the curd tends to become tough or waxy in handling. At 84 F. the curd remains brittle and crumbly. It was, therefore, necessary to keep the curdling temperature down to 84 F.

_Renneting or setting._--Rennet at a rate of 3 to 4 ounces of standard liquid rennet to 1000 pounds (10 to 12 c.c. to 100 pounds) was found to give the best curd under experimental conditions.

_Curdling time._--One and one-half to two hours gave most satisfactory results in forming curd. This should be very firm and stand until it begins to "sweat," until beads of whey have begun to collect upon its surface.

_Cutting._--The cow's milk curd gave best results when cut in two directions with the half-inch curd knife. The resulting columns, a half inch square in cross-section, may be handled without excessive losses.

_Draining._--The cut curd is dipped to a draining rack covered with cloth with as little breaking as possible. During the draining process, a certain amount of turning is necessary to facilitate the separation and escape of the whey. If handled too much, losses of fat are increased and the curd becomes tough or waxy instead of remaining brittle or crumbly. When properly handled, not over 0.35 per cent of fat is lost.

Under favorable conditions, four-ninths to two-thirds of the original weight of curd will separate and run off as whey in twenty to thirty minutes. The curd meanwhile is exposed to the air of the room and cools toward room temperature. If cooling goes too far, further drainage is interfered with. Hence the curd is put into the hoop and the drainage completed while the cheese is reaching its final form.

_Hoop._--Hoops for cow's milk Roquefort must be 7 inches in diameter and about 5 inches high to hold curd enough to produce a cheese the size of the standard Roquefort when completely drained. Sheep's milk with its higher percentage of solids does not require such high hoops.

The curd as it goes into the hoop should be a soft, pulpy ma.s.s with no suggestion of toughness.

_Inoculation with mold._--The mold for Roquefort cheese (_Penicillium Roqueforti_[70]) is readily grown in pure culture in ordinary loaves of bread. For this purpose loaves hot from the oven are quickly drenched with or immersed in hot paraffine to form an impervious crust to retain moisture as well as to keep out contaminations. It is then allowed to cool. The interior of each loaf is inoculated by drawing a suspension of _P. Roqueforti_ spores in water into a sterile pipette (10 c.c.) which is then thrust through the paraffined crust to the center of the loaf of bread and allowed to empty there. The hole is sealed up with paraffine.

These loaves are incubated for about a month at room temperature. When cut, every open s.p.a.ce should be found lined with the green spores of the mold. When dry enough, the ma.s.s may be powdered, and put into an ordinary pepper box. When the curd is ready to go into the hoop, this mold powder is sprinkled upon it from the pepper box.

_Handling._--Freshly made cheeses are turned within the first hour to insure the proper smoothness of both sides. Further draining is best accomplished in a room at about 64 F. with a relative humidity of 85 to 90 per cent. If the surface of the cheese becomes too dry, a rind is formed. No real rind is permitted on Roquefort. If the temperature is too high, slime forms quickly and unfavorable fermentation may occur.

Slime (bacteria and _Oidium lactis_ usually) must be sc.r.a.ped when it becomes too heavy.

_Salting._[71]--Experimental cheeses were found to give the best results when at the end of about three days' drainage they contained about 50 per cent water. Such cheeses were salted by sprinkling the entire surface lightly, replaced upon the drain boards for one day, salted again and piled in two's. After another day they received the third salting and were piled in three's for two days longer. A total of about 10 per cent by weight of salt was used to secure an absorption of 4 per cent. At the same time the water-content dropped to 40 to 43 per cent.

After salting is completed, the cheeses are brushed and punched with holes to permit oxygen to enter.[72] They are then ready for ripening.

+170. Ripening of Roquefort.+--The ripening of experimental Roquefort has required four to six months at a relative humidity of 85 to 90 per cent. This relative humidity is just below the equilibrium relative humidity of the cheese, hence permits a shrinkage of 2 to 4 per cent in the water-content of the cheese. This makes it possible to control the amount of surface slime developed.

If the relative humidity goes too high, the surface slime of bacteria and yeasts becomes very heavy, soft and almost liquid, and follows the openings into the cheese with resultant damage to appearance and flavor.

Even under the conditions at Roquefort, this slime must be removed by rubbing or sc.r.a.ping several times to avoid injury to the cheeses, together with the production of bad odor and taste. If the humidity becomes too low, the surface becomes dry, hard and cracks open, the friable crumbly texture is injured, and there is considerable loss in weight. Salt forms about 4 per cent of the cheese. This is in solution in the water present, which is about 40 per cent, and makes a brine of about 10 per cent strength. This strength of brine does not prevent the growth of the Roquefort mold (_Penicillium Roqueforti_) but does hinder the development of _Oidium lactis_ in the open s.p.a.ces within the cheese.

Accurate adjustment of temperature and relative humidity in the ripening rooms to salt and water-content in the cheese is essential to proper ripening. These conditions are furnished by the unique natural conditions of the caves of Roquefort. The production of such cheeses elsewhere depends either on the discovery of another locality with closely similar conditions or on the artificial production and control of the necessary temperature and relative humidity. This has been done on an experimental basis by the use of cold storage apparatus combined with proper humidifiers.

The differences between working with sheep's and with cow's milk lie in the making process rather than in the ripening. Sheep's milk freshly drawn shows a higher acidity than cow's milk, probably on account of the acid reaction of its greater casein content. With nearly double the total solids of cow's milk, the yield to one hundred pounds is much greater, consequently the drainage of the curd is much more easily handled.

Once made and salted, the cheeses require very nearly the same conditions of ripening. The resultant products are alike in appearance and texture. In flavor, cow's milk Roquefort differs in character from sheep's milk cheese to such a degree as to be recognized by taste. The difference was found by Currie[73] to be due to an actual difference in the combination of fatty acids present.

Although these differences in character are recognizable by the expert in testing the cheese, as well as by chemical a.n.a.lysis, cow's milk Roquefort would satisfy that large proportion of consumers who use such cheese only in connection with other fairly high flavored foods. The demands for technical skill and factory equipment are not naturally greater than for many other lines of cheese-making. The gradual development of a cow's milk Roquefort may be antic.i.p.ated.

[Ill.u.s.tration: FIG. 24.--Gorgonzola ripening establishment in valley near Lecco.]

+171. Gorgonzola+[74] is a rennet cheese made from fresh whole cow's milk, in northern Italy. It takes its name from the village of Gorgonzola, a few miles from Milan, but the manufacture of the cheese has spread over a wide area. The cheeses are made on farms and in factories from which they are transported for ripening to cool valleys of the Alps, princ.i.p.ally near Lecco (Fig. 24). Boeggild introduced the making of a cheese after the Gorgonzola process into Denmark about 1885.

This industry has been successful on a small scale since that time.

Gorgonzola cheeses are about 30 cm. (12 inches) in diameter and 18 cm.

(7 inches) thick and weigh 15 to 20 pounds. As exported they are usually heavily coated[75] with a mixture usually barite, tallow and lard colored with annatto or other cheese color. This coating prevents shrinkage or mold on the surface of the cheese in transit. When cut these cheeses vary greatly. All show marbling with mold (Roquefort mold). During their ripening they become very slimy at the surface. To open up air s.p.a.ces for mold growth, this slime is sc.r.a.ped off and holes are punched into the cheeses. These holes are readily seen in the final product. Some show crumbly texture, well distributed mold, as in Roquefort, with flavor approaching that cheese; in others the texture is waxy rather than crumbly, a condition correlated regularly with different character in the flavor. Frequently in whole areas or in small pockets, slime consisting of bacteria and Oidium has followed the openings into the cheese and affects its odor and taste.

Experimental Gorgonzola cheeses comparable with the Italian product were made with cow's milk ripened as for Roquefort or higher, to 0.25-0.30 per cent (t.i.trated as lactic acid), curdled at 86 F. (30 C.), cut into cubes and slightly stirred, then dipped to a draining board for about one-half hour, and put into the hoop. The cheeses drained quickly to about 50 percent water and developed a surface rind as in the harder cheeses. Cut surfaces showed a fairly open cheese in which mold grew readily. These cheeses were salted to taste, not to a specified percentage. They ripened with the same irregular results and the characteristic range of flavors found in Gorgonzola. To avoid the rotting of the cheese by surface growths, they were exposed to low humidities for a time and cracks opened at the surfaces, as seen in the ripening rooms at Lecco (Fig. 24). The texture was more or less waxy or tough, which was correlated with the slightly higher heat at renneting together with the stirring or "working" of the curd. Comparative a.n.a.lyses of a series of imported cheeses confirm the interpretation that the salt-content of Roquefort, 4 per cent approximately, prevents the invasion of the interior of the cheese by Oidium. No complete study of the ripening of Gorgonzola has been made. As far as followed, it consists in an initial souring process followed by ripening by molds and slime organisms. At its best, Gorgonzola is nearly equal to Roquefort but the percentage of such quality is low. In spite of its irregular quality, England has used larger amounts of Gorgonzola than of Roquefort. Considerable quant.i.ties have been imported for the Italian trade in the United States.

[Ill.u.s.tration: FIG. 25.--Gorgonzola cheese curing-room.]

+172. Stilton cheese+ bears the name of an English village[76] in which it was first sold. It is made from cow's milk and is typically a whole milk cheese, although part skim cheeses are regularly made and sold as lower grades. In the Stilton-making counties, the milk from Shorthorn cattle testing about 3.5 to 4.0 per cent fat is preferred to richer or poorer grades. Such milk is curdled with rennet at about 86 F. in about one hour; the curd is cut, dipped to a draining table covered with cloth and drained slowly over a period of several hours, commonly overnight.

During this period considerable acidity is developed. The curd is then milled or broken by hand, salted, packed into hoops 15 to 16 inches high and 7 inches in diameter. These hoops are made from heavy tin (Fig. 26) with four rows of holes about 3/10 inch in diameter. The freshly filled hoops are allowed to stand and drain without pressure in a room at about 70 F. (Fig. 26). Such cheeses are turned every day for several days.

When solid enough to stand the hoops are removed, the cheeses are sc.r.a.ped or rubbed with a knife until the surface is smooth, and commonly wrapped with a cloth bandage to maintain the shape, if the cheese is still too soft to stand firmly. In the factories, several rooms are used with varying temperature and relative humidities, which makes it possible to place each cheese under the condition best suited to its texture and condition of ripeness. In general, the dairy sections of England are much more humid than those of America and there are less violent changes in temperature. Stilton cheese-making has grown up to take advantage of this climatic factor in handling the product.

Transplantation of such an industry necessitates a mastery not only of the manipulations but a grasp of the fundamental principles underlying the process and a readjustment of practices to preserve those principles.

[Ill.u.s.tration: FIG. 26.--Stilton cheeses in hoops, draining.]

Stilton is, then, a soured curd cheese in whose ripening a very prominent part is played by the green mold (usually some strain of _P.

Roqueforti_) which grows throughout the cavities of its ma.s.s[77]. At its best, it has attractive texture and flavor. Much of it fails to reach high quality on account of the invasion of bacteria, _Oidium lactis_, and very frequently myriads of cheese mites. The following a.n.a.lysis was furnished as typical for ripe cheese by Miles Benson,[78]

late professor of dairying at Reading, England: Water 31 per cent, fat 36 per cent, casein 29 per cent, mineral const.i.tuents including salt about 4 per cent. Approximately the same figures are given by Primrose McConnell (Agricultural Note Book). The low percentage of salt is another factor of uncertainty in the control of this Stilton product, as in Gorgonzola, since these cheeses are commonly high in water-content at first and are thus subject to invasion by Oidium.

Stilton has been made on a small scale in Canada[79] and occasionally attempted in the United States. No serious effort to develop an industry of commercial importance has been made in America. Comparative study of the cheeses ripened by green mold tends to the conviction that the adaptation of the Roquefort practice to the use of cow's milk offers a more satisfactory basis for experiment than efforts to establish a Stilton or a Gorgonzola industry.

+173. Gex.+--A cheese under this name made in southern France resembles, in its general character as a ripened cheese, the English Stilton and Italian Gorgonzola. Although it has no commercial importance, reference is made to this cheese to show that mold-ripened cheeses have been developed entirely independently in different countries to bring about the same general character of product.

+174. Bacterially ripened series.+--The semi-hard cheeses ripened by bacteria stand half-way between true Limburger and the hard forms. In fact, brands of Limburger are readily found which approach the texture and ripening of Brick cheese. In the same way, Brick cheeses are often found which have the appearance, texture and much of the flavor of the Cheddars with only a trace of the taste of Limburger. Port du Salut, Oka, Munster, in France Livarot, in the Balkan regions Kascoval, belong in this series.

+175. Brick cheese.+--The name of this cheese is probably due to the finished product being about the size and shape of a brick. It is similar to the German cheese Backstein and may have been developed from it. It is typically a sweet-curd cheese, made from milk freshly drawn, without permitting the development of appreciable quant.i.ties of acidity until after the curd has been put into the hoop. In the making process, it is intermediate between Limburger and the cheeses of the Cheddar group. Some cheese-makers use an ordinary cheese vat, others a copper kettle in manufacturing.

It is the usual practice to deliver the milk to the cheese factory both morning and evening, without cooling. Cheese is made twice a day. In some cases the milk is delivered only once a day, and extra precautions must then be taken to care for the milk properly.

The discussion of the care of milk in Chapter II applies to that for Brick cheese. For the best quality of cheese, the milk in the vat should show about 0.15 of 1 per cent acidity and never above 0.18 of 1 per cent.[80]

+176. Making of Brick cheese.+[81]--The milk is received at the cheese factory at a temperature of about 92 to 96 F. For the best results, the acidity should be determined (by the acid test) to decide on the amount of starter to use. Few Brick cheese-makers use an acid test or a starter but these precautions would improve the product of many factories. For method of using the acid test, see Chapter V. Chapter IV discusses the preparation and use of starter. Usually 0.25 to 0.50 of 1 per cent of starter is the amount required. A small amount of starter is used to aid the development of lactic acid and for the beneficial effect it has on the flavor. A very small development of acid is desired after adding the starter; therefore the change in acidity should be very carefully watched with the acid test. The vat is usually set when the acid test shows 0.16 of 1 per cent acidity. The more acid in the milk, the less starter should be employed. Sufficient rennet extract should be used to give a coagulation suitable for cutting in thirty to thirty-five minutes. For method of adding the rennet extract, see Chapter V. When the coagulum is firm enough for the curd to break clean over the finger, it is ready to cut. The curd is cut with coa.r.s.e knives into 3/8- or -inch cubes. After cutting, the curd is let stand three to five minutes, then stirred with the hands for a few minutes until the whey begins to separate and then stirred with the rake. Some makers do not stir by hand but use the rake directly after cutting. When this is done, great care must be exercised to stir the curd without breaking up the pieces, because this causes a loss of fat. After cutting the curd is stirred for twenty to thirty minutes before the steam is turned on. The curd is heated very slowly at first and more rapidly during the last stages of cooking. The curd is cooked to a temperature of 110 to 115 F. The lower the temperature that can be used to produce firm curd, the better the texture of the cheese. After cutting and during the cooking, the curd must be constantly stirred so that lumps will not form. When the curd forms lumps, the moisture is not evenly expelled. This results in uneven texture and curing. Sometimes some salt is added to the curd in the vat to restrain souring. The curd is stirred after cooking until it is sufficiently firm. It remains usually in the whey for a total period of one and one-fourth to one and one-half hours from the time of cutting. It is then dipped into forms 10 inches long by 5 inches wide by 8 inches deep. The forms are without top or bottom and are placed on a draining table. This table is so constructed that the whey can be saved for stock feed. When ready to "dip," the whey is drawn down to the surface of the curd in the vat, then the curd is dipped into the forms or hoops. Care must be taken to get the same amount of curd into each form to produce the cheeses of uniform size. Each cheese is turned several times to insure even draining and even reduction of the temperature. While draining, a follower is placed in each hoop and a weight placed on each cheese. Usually a brick is used for this weight. A cheese is allowed to drain or press for ten to fifteen hours. It is then placed on the salting table and rubbed with coa.r.s.e salt. While on the salting table, a cheese is placed on its broad side. Some cheese-makers prefer to salt their cheeses by soaking them in a salt brine. This brine should be strong enough to float an egg. Salting requires three days. The cheeses are then brushed free from excess salt and taken to the cellar to cure or ripen.

+177. Ripening Brick cheese.+--For this process, the cellars are kept at about 90 percent relative humidity and a temperature of 60 to 65 F.

Some prefer a temperature for curing as high as 68 F. During the curing, the surfaces of the cheese are kept moist and mold growths kept down by rubbing or brushing the cheese with pure water or salt and water. In the curing cellars the cheeses are placed on shelves; at first they are set close together and as they cure, they are separated. During curing, the color changes from a whitish to a reddish brown. The cheese cures from the outside toward the center. When first made, the product is harsh and hard in texture but during the ripening process it becomes mellow and smooth. The cheeses remain on the curing shelves for four to six weeks, after which they are wrapped in heavy waxed paper and boxed.

A cheese ready for market usually weighs about five pounds. A Brick cheese box is 5 inches deep by 20 inches wide by 3 feet long, and holds 110 to 115 pounds of cheese.

+178. Qualities of Brick cheese.+--The cheeses should be neat and attractive and the rind not cracked or broken. The sides should be square and not bulged. The cheese should have a clean, characteristic Brick cheese flavor. The body and texture should be mellow and smooth and when rubbed between the thumb and forefinger, should break down like cold b.u.t.ter. The color should be uniform. The cheese should contain the proper amount of salt and moisture. One of the worst faults with Brick cheese is bad flavor. This is many times due to the cheese-maker not using clean flavored starter. It may also be due to bad flavored milk. A Brick cheese-maker has no means of controlling ga.s.sy fermentations. These show themselves in the bad flavor of the cheese and in the porous body. They also cause the cheese to bulge. If detected, ga.s.sy milk should be rejected. If too much acid is developed, a sour cheese is the result. This will not cure normally and usually has a sour flavor. The body will be brittle and mealy. If too much salt is used, the cheese may have a salty taste and it will cure very slowly. If not enough salt is used, the cheese may cure too rapidly and undesirable flavors and fermentations develop. The cheese must have the proper moisture-content; if too much moisture is present, the cheese cures too fast and is soft and pasty in body; if not enough moisture, then the reverse is true. Tabulation of cheeses of special quality, as submitted in scoring contests, show an average water-content of 37 to 38 per cent, with occasional cheeses verging toward Limburger in texture and flavor with 40 to 42 per cent water, and others indistinguishable from Cheddar, with water-content as low as 34 per cent.

The Wisconsin Cheese-makers a.s.sociation uses the following score-card for the judging of Brick cheese on a scale of 100:

Flavor 40 Texture 40 Color 10 Salt 5 Style 5 --- 100

+179. Composition and yield.+--The composition of Brick cheese varies within wide limits. The average cheese probably contains from 37 to 39 per cent of water, although many cheeses are above and below this average; Doane and Lawson[82] give the fat as 28.86 per cent, proteins 23.8 per cent and total ash 4.20 per cent.

The composition and yield are both affected by: (1) the moisture-content of the cheese; (2) composition of the milk from which made; and (3) losses during the manufacturing process. The average yield of Brick cheese is 11 to 13 pounds to 100 pounds of milk.

+180. Port du Salut cheese.+--The Trappist monks originated this type of cheese in their monasteries in France. Under the name of their community Oka, it has been made and sold widely by the Trappist Fathers of Quebec.

In recent years, factories independent of the order have made such cheese both in America and in Europe.

The following outline of the making process indicates the close relationship between Port du Salut and Brick cheeses. Whole milk or milk not over one-fifth skimmed is ripened to medium acidity, then heated to 90 to 95 F. according to season and acidity. Rennet enough is added (see Chapter V) to curdle in thirty to forty minutes, although some makers shorten the time to twenty minutes. When formed, the curd is cut into small cubes and excess of whey is dipped away. The constantly stirred ma.s.s is then heated or cooked to 100 to 105 F. within a period of ten to twelve minutes or according to some makers twenty to thirty minutes. It is allowed to stand a few minutes to settle. Most of the whey is then drawn and the ma.s.s is stirred vigorously to prevent fusion of the curd granules. The curd is ready for the hoop when the particles are about the size of grains of wheat and do not stick together when squeezed with the hand. The individual grains of curd should crumble easily between the fingers. The hot curd is transferred directly to the hoops without cooling. For this purpose, a hoop is set upon the table covered with a cloth and the curd dipped into the cloth. The edges of the cloth are then folded over. In this condition the cheese is transferred to the press where gradually increasing pressure begins with 3 to 4 pounds and reaches about 70 pounds. To insure proper shape, cheeses are turned and put into fresh cloths at the end of the first hour and turned subsequently several times during the pressing period of about twelve hours.[83]

Port du Salut cheeses are salted by rubbing fine salt on the surface by hand at the rate of 1.2 to 2 per cent of the weight of the cheese. After about two days in the salting process, they are put into the ripening cellars. The cellars are wet, since they reach 90 to 95 per cent relative humidity at a temperature of about 55 F. After two days in the cellar, the cheeses are plunged into a tank of saturated brine to which a trace of cheese color has been added. As they come out of these tanks, they are yellowish and greasy or slimy. They are returned to the shelves where they are rubbed every day with a cloth or by hands wet in brine. After about one week they are again plunged in the brine.

Treatment with brine tends to insure a firm rind. The cheeses are rubbed more or less regularly with brine through the whole ripening period.