** Made from firm or tough curd--Gorgonzola, Stilton and such French forms as Gex, Septmoncel 158

b. Curd cooked and ripened by bacteria,--brick, Munster, Port du Salut (Oka) 164

Subsection C. Hard cheeses, cooked and pressed (30 to 40% water).

a. Ripened without gas holes.

1. Dutch--Edam, Gouda 173 2. Danish.

3. The Cheddar group.

* English--Cheddar and numerous related forms known princ.i.p.ally in Great Britain 184 ** American--the factory Cheddar of United States and Canada 184

b. Ripened with the development of gas holes.

* Holes large--Swiss-Emmenthal, Gruyere, American Swiss 276

** Holes small--Parmesan and related varieties 288

Such a cla.s.sification brings together series of products in which there is essential similarity in the final output, however great the differences in manipulation. It does not consider all varieties and specialties. Some of these groups are important enough to demand special mention.

+105. Processed cheeses.+--Cheese of any group may be run through mixing and molding machines and repackaged in very different form from that characteristic of the variety. In such treatment, the texture and appearance may be so changed as to give the effect of a new product.

Substances (such as pimiento) are added to change the flavor. Or the product may be canned and sterilized with equally great change of flavor and texture. One thus finds Club made from Cheddar; Pimiento from Cream, Neufchatel or Cheddar; similarly olive, nut and other combinations are made. The possible variations are numerous.

+106. Whey cheeses.+--Several products bearing cheese names are made from whey. These take the forms of the recovery of the alb.u.min and casein separately or in a single product, and the recovery of the milk-sugar either alone or with the alb.u.min. Whey cheeses have been especially developed by the Scandinavian people, although some of them have their origin in the south of Europe. Certain of these varieties are produced on a limited scale in America.

There are a number of forms fairly widely known that are difficult to place in this scheme of groups. Among these are Caciocavallo, Sap Sago.

+107. Soft and hard cheeses.+--Another commonly used cla.s.sification makes two groups: (1) soft cheeses; (2) hard cheeses. In such a cla.s.sification the semi-hard group presented here is included with the soft cheeses. Some cheeses of this group are soft in texture. This is correlated with high water-content, high fat-content or both together.

+108. Relation of moisture to cla.s.ses.+--In this cla.s.sification the water-content reflected in the texture of the cheese a.s.sumes first place. To carry the a.n.a.lysis somewhat further by showing the correlation between water-content and certain factors, a tabulation of well-known varieties of typical groups is presented (Table III). In this table the series of typical dairy products are first arranged according to water-content of the final product. Approximate limits of percentages of milk-fat are also given, because milk-fat frequently affects texture to a degree almost equal to water. Column 4 gives the period within which the more quickly perishable cheeses are usable, and the length of the ripening for the more solid forms. The correlation between water-content, texture and the time of keeping is clearly shown for most varieties.

TABLE III

CORRELATION WATER- AND FAT-CONTENT WITH RIPENING

------------------+--------+--------+-------------+--------------

PER

PER

VARITY OF

CENT

CENT

PERIOD

RIPENING

WATER

FAT

REQUIRED

AGENT ------------------+--------+--------+-------------+-------------- Cheese: Soft,

Cottage

70

trace

a few days

Bacteria Skim Neufchatel

70

trace

a few days

Bacteria Neufchatel

50-60

12-28

a few days

Bacteria Camembert

50

22-30

3-5 weeks

Molds Cream cheese

40-50

35-45

a few days

Primarily

bacteria

Semi-hard:

Limburger

40-45

24-30

3-6 months

Bacteria Roquefort

38-40

31-34

3-6 months

Mold Brick

37-42

31-35

3-6 months

Bacteria

Hard:

Cheddar

30-39

32-36

6-12 months

Bacteria Swiss

31-34

28-31

9-18 months

Bacteria

and yeasts Parmesan

30-33

2-3 years

Bacteria ------------------+--------+--------+-------------+--------------

The soft cheeses are quickly perishable products. Bacteria and molds find favorable conditions for growth in products with 45 to 75 per cent of water. If such growth is permitted, enzymic activities follow quickly with resultant changes in appearance, texture, odor and taste.

Refrigeration is necessary to transport such cheeses to the consumer, if properly ripened. Trade in these forms may continue throughout the year in cool climates and in places where adequate refrigeration is available. Practically, however, outside the large cities this trade in America is at present limited to the cold months; inside the large cities much reduced quant.i.ties of these cheeses continue to be handled through the year.

In the stricter sense, the soft group of cheeses falls naturally into two series: (1) the varieties eaten fresh; and (2) the ripened soft cheeses. Those eaten fresh have a making process which commonly involves the development of a lactic acid flavor by souring, but no ripening is contemplated after the product leaves the maker's hands. In the ripened series, after the making process is completed, the essential flavors and textures are developed by the activity of micro-organisms during ripening periods varying in length but fairly well-defined for each variety.

In contrast to the soft cheeses, the hard kinds are low in water-content, ripen more slowly and may be kept through much longer periods. They retain their form through a wider range of climatic conditions. They develop flavor slowly and correspondingly deteriorate much more slowly. Such cheeses are in marketable condition over longer periods. In their manufacture the cooking of the curd takes a prominent place.

+109. Relation of heat to cla.s.ses.+--The close relation between the heat applied and the product sought forms the basis of a striking series of graphs (Fig. 12, page 78). These show the changes hour by hour in the heat relation during the making process of a series of widely known forms, each of which is chosen as typical. In some of these forms, heat is applied but once to bring the milk to the renneting temperature typical for the variety. Subsequent manipulations are accompanied by a steady fall in temperature. In other forms, the curd when solid is specially heated or "cooked" to bring about the changes characteristic of the variety. These contrasts are clearly brought out by the graphs which represent practices well recognized for the varieties. The detailed process for these groups is considered in succeeding chapters.

CHAPTER VII

CHEESES WITH SOUR-MILK FLAVOR

The cheeses with flavor of sour milk are probably more widely used than any other group. Historically and to a very large degree at present, they are farm cheeses.[31] No estimate of volume of such production in the household has ever been made. The utilization of surplus milk in this way is of ancient origin.

With the introduction of the factory system of handling milk, the manufacture of such cheese in the household was largely dropped. The rise in price of all food substances and increasing appreciation of the food value of milk products have made the recovery of all surplus milk in some form very necessary. The manufacture of cottage, Neufchatel and cream cheese is one of the best forms of such recovery which may be adapted to utilize any grade from skimmed-milk to cream. Large quant.i.ties of skimmed-milk have frequently been lost from the total of human food by the manufacture of casein for industrial uses, and by use as stock feed.

+110. Skim series.+--The kinds of cheeses eaten fresh have in common a very soft texture and the flavor of sour milk, princ.i.p.ally lactic acid.

The group falls naturally into two sections: (1) the cheeses made from milk curdled by souring; (2) those for which the milk is curdled by souring and rennet. In the latter group both agencies are necessary to the resulting product. The time required to curdle by souring alone is longer than when rennet is used; this period is usually longer than necessary for the cream to rise by gravity; hence the cream is either skimmed off or removed with the separator beforehand. The curd, therefore, is essentially a skimmed-milk curd. Casein curdled in this way tends to become granular or "rough," to feel "sandy" when rubbed between the fingers. Heating is commonly necessary to lower the water-content of the ma.s.s even to 75 per cent. Such curd tends to become hard or rubbery when heat is applied. In this group, the best known form is variously called "cottage" cheese, "clabber" cheese, schmierkase.

+111. Cottage cheese+ is made from skimmed-milk, soured by lactic bacteria until a curd is formed. This is done preferably at about 20 C.

(70 F.), because at this temperature the purely lactic type of organism has been found to outgrow competing forms which may be present. Starter containing the desired culture, if properly used, saves much time in the curdling period. Such curdling requires at least twelve to twenty-four hours, frequently much longer unless abundant starter is introduced.

+112. Household practice.+--The details of cottage cheese making in the home differ widely in separate sections and even in different families in the same part of the country. The essentials of the practice, common to all, include: (1) curdling the whole milk by natural souring; (2) removing the sour cream which is usually used for b.u.t.ter-making; (3) scalding the curdled skimmed-milk either by slowly heating it in the original vessel surrounded by hot water or by actually pouring an approximately equal volume of boiling water into the curdled ma.s.s; (4) bagging and draining the ma.s.s until it reaches the desired texture; (5) the kneading of the ma.s.s with the addition of salt and cream. The resulting product varies greatly in quality. Unfavorable fermentations frequently affect the flavor.[32] The "scalding" varies from a temperature of 90 F. almost to boiling with a resultant texture varying from almost the smooth b.u.t.tery consistency of Neufchatel to hard coa.r.s.e granular lumps. The best practice, using clean well-cared-for milk and draining at low temperature, produces a very attractive cheese. Such cheese is heated to 90 to 100 F. on the maker's judgment, drained carefully, kneaded well by hand or by machine with the addition of cream to give it an attractive texture and flavor.

+113. Factory practice.+--When cottage cheese is made in the factory,[33] separated milk is taken; it should be pasteurized and then soured by a lactic starter. The souring can be accelerated by the use of a starter, which may be added at the rate of 0.5 to 5 per cent of the skimmed-milk used, depending on the amount of starter that can be made.

Generally, the more starter added, the more rapid will be the coagulation and the better will be the flavor of the cheese. As soon as the milk has thickened, the curd is ready to be broken up and separated from the whey. This separation is hastened by the application of heat.

Usually the temperature of the curd is raised slightly before it is broken up; since this makes the curd firmer, there will be a smaller loss of curd particles in the whey. The curd may be cut with coa.r.s.e Cheddar cheese knives or broken with a rake. The temperature of the curd should be raised very slowly, at least thirty minutes being taken to reach the desired final temperature. No set rule can be given as to the exact temperature to which the curd should be heated. The temperature should be raised until a point is reached at which the curd, when pressed between the thumb and the fingers, will stick together and not go back to the milky state. This temperature is usually from 94 to 100 F., but the cheese-maker must use his own judgment in this respect. If the curd is heated too much, it will be hard and dry; on the other hand, if it is not heated sufficiently, the whey will not separate from the curd and the latter will be very soft and mushy.

When the curd has been heated sufficiently and has become firmed in the whey, it should be removed from the whey. This may be done either by letting down one end of the vat and piling the curd in the upper end, or by dipping out the curd into a cloth bag and allowing the whey to drain, which it does very rapidly. No treatment can prevent the "roughness" of an acid curd (this is a fine gritty feeling when rubbed between the fingers), but the coa.r.s.e hard grainy texture and lumps characteristic of the highly heated curd do not develop. Experimental workers have agreed that to have the proper texture, such curd should contain when finished about 70 to 75 per cent of water. It should have a mild but clean acid flavor. Such a cheese will carry about 1 to 2 per cent of salt, without an objectionably salty taste. This cheese is commonly sold by measure, sometimes in molds or cartons. The manufacture of all forms of cottage cheese has been largely superseded by the making of skimmed-milk Neufchatel or Baker's cheese.

The yield from one hundred pounds of skimmed-milk runs up to fourteen to nineteen pounds of cheese, when made very wet or from pasteurized milk.

The yield varies with the moisture-content of the cheese, being greater for cheese with a high content. Too much moisture or whey should not be left in the curd, however, as this will render it too soft to be handled.

Cottage cheese made by either the home or factory practice is a quickly perishable article. Although the acid restrains bacteria at first, the high percentage of water favors the growth of molds which tolerate acidity, especially _Oidium (Oospora) lactis_ and the Mucors or black molds. These molds destroy acidity rapidly and thus permit the bacteria of decay to develop and to produce objectionable taste and odors.

Spoilage in these products is accelerated by the kneading process which distributes air throughout the ma.s.s and with it all forms of microbial contamination.

+114. b.u.t.termilk cheese.+--A cheese closely resembling cottage may be made from b.u.t.termilk. If the b.u.t.termilk came from cream which was churned before it became sour, the process is the same as that already described for the making of cottage cheese from skimmed-milk. If the b.u.t.termilk came from sour cream the process of manufacture is much more difficult. The casein of sour cream has already been coagulated with acid and broken during churning into very minute rather hard particles.

These fine particles are difficult to recover. They are so fine that they pa.s.s through the draining cloth or at other times clog it and prevent drainage. They do not stick together at ordinary temperatures.

They cannot be collected by the use of acid because they have already been coagulated with acid. After casein has been coagulated with acid, rennet extract will not recoagulate the particles. The b.u.t.termilk may be mixed with sweet skimmed-milk; then as the latter coagulates, it locks in the casein of the b.u.t.termilk so that it can be collected. If b.u.t.termilk from soured cream is used alone, the casein may be collected[34] by neutralizing and heating to 130 to 150 F., and holding until the casein gathers together. The whey can then be drawn off. Often there is further difficulty in getting the casein to collect, since the pieces remain so small that they go through the strainer.

Cheese made entirely from b.u.t.termilk is sandy in texture and often not palatable. If the b.u.t.termilk with good flavor is mixed with skimmed-milk, it makes a good cheese closely resembling cottage.

+115. Neufchatel group.+[35]--The Neufchatel process originated in northern France where a number of varieties are included under this as a group name. Among these are Bondon, Malakoff, Pet.i.t Suisse, Pet.i.t Carre.

The name designates a general process of curd-making which is applied to skimmed-milk, whole milk or cream. Some of the resultant cheeses are ripened; some are eaten fresh. The Neufchatel cheeses of France gained such wide recognition for quality that the process of making has become widely known. In America the manipulations of the French process were early dropped. The essentials were made the basis of a successful factory practice which has been widely adopted. The American factory practice is discussed here and the French process briefly considered under the heading Ripened Neufchatel. (See Chapter VIII.)

+116. Domestic or American Neufchatel cheeses+ are soft, have clean sour milk (lactic acid) flavor and are quickly perishable. In all but the coldest weather, they require refrigeration to reduce deterioration and loss. They range in fat-content from traces only to 50 per cent and more; in water from 40 to 75 per cent, according to the milk used. In texture Neufchatel is smooth, free from gas, free from lumps or roughness when rubbed between the fingers. This flavor and texture is obtained by a combination of slow rennet curdling with developing acidity. No further ripening is permitted.

+117. The factory.+--Neufchatel factories require the standard dairy equipment for receiving, weighing, testing, separating, heating, pasteurizing and cooling the milk. Since many factories produce several products, the same general dairy equipment may serve for all. In addition to such equipment, Neufchatel requires a curdling apparatus which can be held at 70-75 F. This may be a room properly controlled, or a tank where temperature control is obtained by water and steam. For draining, a room kept at 60 F. gives nearly the ideal temperature, which must be supplemented by relative humidity high enough to prevent the exposed surface of curd from drying during periods of twelve to twenty-four hours. This requires almost a saturated atmosphere. A room with special molding machinery is required and tables for wrapping, labeling and boxing the product are necessary. Box-making machinery is usually an economic necessity for work on a large scale. Adequate refrigeration is requisite both to chill the curd before molding and to preserve it after packaging.

[Ill.u.s.tration: FIG. 13.--Neufchatel draining racks.]

+118. Cans.+--For curdling, the "shot-gun" can, about nine inches in diameter and twenty inches deep, is generally used. This holds thirty to forty pounds of milk. Increased capacity is dependent, therefore, on the number of units installed, not on changes in the units themselves.

[Ill.u.s.tration: FIG. 14.--Detail of a Neufchatel draining rack.]

+119. Draining racks.+--A draining rack is required for each can of curd. These racks also are standardized units whose number limits the capacity of the factory. The design of these racks (Figs. 13, 14) and their arrangement in the draining room are taken from Bulletin 78 of the Storrs Agricultural Experiment Station: "The racks are rectangular, thirteen inches wide, thirty-six inches long and ten inches deep. The corner posts extend one and one-half inches beyond the strips at top and bottom with the tops rounded as a rule as seen in the photograph. The bottom slats fit loosely into notches, hence are removable for washing purposes. The materials required are four corner posts one and one-half by one and one-half inches; nine strips one by three-eighths by thirty-six inches; six strips one by three-eighths by thirteen inches, two strips one by three-eighths by twelve and a quarter inches, notched to receive the bottom slats; all made from pine."

+120. Cloths.+--For each draining rack, a cloth one yard wide and one and one-half yards long is required. Cotton sheeting is satisfactory for the purpose; "even-count, round-thread, unmercerized voile" is suggested by Dahlberg.[36]

[Ill.u.s.tration: FIG. 15.--Neufchatel and cream cheese molds.]