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, NeufchÂtel 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 quantities 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, principally 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 mass 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, schmierkÄse.

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 butter-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 mass; (4) bagging and draining the mass until it reaches the desired texture; (5) the kneading of the mass 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 buttery consistency of NeufchÂtel to hard coarse 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 coarse 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 coarse 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 NeufchÂtel 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 mass and with it all forms of microbial contamination.

114. Buttermilk cheese.—A cheese closely resembling cottage may be made from buttermilk. If the buttermilk 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 buttermilk 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 pass 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 buttermilk may be mixed with sweet skimmed-milk; then as the latter coagulates, it locks in the casein of the buttermilk so that it can be collected. If buttermilk from soured cream is used alone, the casein may be collected34 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 buttermilk is sandy in texture and often not palatable. If the buttermilk with good flavor is mixed with skimmed-milk, it makes a good cheese closely resembling cottage.

115. NeufchÂtel group.35—The NeufchÂtel process originated in northern France where a number of varieties are included under this as a group name. Among these are Bondon, Malakoff, Petit Suisse, Petit CarrÉ. 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 NeufchÂtel 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 NeufchÂtel. (See Chapter VIII.)

116. Domestic or American NeufchÂtel 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 NeufchÂtel 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.—NeufchÂtel 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, NeufchÂtel 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.

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.

119. Draining racks.—A draining rack is required for each can of curd. These racks also are standardized units whose number draining rack. Fig. 14.—Detail of a NeufchÂtel draining rack. 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

121. Molding machinery.—For work on a large scale, special power machines37 are regularly used. These consist of a hopper and worm delivering a standard size stream of curd through a cream chwwsw molds. Fig. 15.—NeufchÂtel and cream cheese molds. proper size and shape of delivery tube. This curd stream is cut by an automatic device into the proper lengths to form the standard cheese. In this way a uniform size of cheeses is obtained. Experimental work with hand apparatus showed that a worm six inches in diameter is required to deliver curd in a smooth column one and one-half inches square. If the pressure is not sufficient, the column will frill at the edges. Such irregular surfaces cannot be wrapped smoothly enough to delay spoilage.

On a small scale, a fair grade of product can be molded through a tin tube (see Fig. 15) one and three-quarters inches in diameter and ten inches long in which the curd is compressed by a close fitting plunger operated by hand.

122. Milk for NeufchÂtel should be clean, free from gas and taint. Such milk should preferably be not more than twelve hours old when received and in no case show higher than 0.20 per cent lactic acid by titration. Milk testing 4 per cent fat or higher will produce a higher quality of product than lower grade milk, although every grade from skimmed-milk to cream is used in producing some form of NeufchÂtel. This milk should be pasteurized unless shown to be free from tuberculosis by proper test of the cattle. Evidence38 that the organism of tuberculosis will withstand the regular handling process for cheeses of this group and retain its ability to cause disease in experimental animals makes the introduction of pasteurization necessary in this whole group of cheeses. Any effective pasteurization may be used, but temperatures of 140-145° F. for thirty minutes have been effective with less changes in the milk than higher temperatures for shorter periods. The milk should be cooled to curdling temperature and the starter and rennet added and stirred into the milk in bulk. The milk may then be quickly distributed into the curdling cans with a hose or from the gate valve of the mixing vat.

123. Starter.—To insure the development of a clean acid flavor, a small amount of lactic starter should be used. The quantity to use depends on the quality of the milk. With skimmed-milk, a pint for each thirty-pound can is recommended by Matheson and Cammack39 and by Dahlberg. (See page 98.) For whole-milk NeufchÂtel, 2 c.c. to a thirty-pound can of milk commonly gives good results. On this basis 2 ounces of starter would be sufficient if properly stirred into about 1000 pounds of milk. Too slow development of acid is preferable to over-rapid souring.

124. Renneting or setting.—The milk should be cooled after pasteurizing to between 70° and 75° F. Rennet is added at the rate of ½ c.c. to a thirty-pound can (roughly ? ounce to 1000 pounds). This will thicken the milk sufficiently in the first few hours to reduce the separation of the cream. For completion of the curdling and souring process, twelve to eighteen hours are required. Usually the cans stand overnight at uniform temperature. When ready to drain, the curd should be firm, smooth and mildly acid. Whey separating from it should not titrate above 0.35 per cent titrated as lactic acid.

125. Draining.—A cloth is spread over a draining rack and the contents of one "shot-gun" can poured upon the cloth with as little breaking as possible. In this way a large surface is exposed. The room must be kept wet to prevent the surface of the curd drying to form crusts which stop draining. A temperature of 60° F. is favorable to the maintenance of proper texture and humidity without the development of objectionable organisms, especially Oidium lactis, which tends to cover every exposed surface in such rooms. Draining may be hastened by turning the curd or changing the position of the cloth. In factory practice, the large draining surface reduces the necessity of handling the curd and reduces the loss of fat. About twelve hours are required upon the draining racks.

On a small scale with a few cans of curd in the home, any form of draining rack may be used, such as a potato or berry crate, or the corners of the cloth may be brought together, tied and the mass hung up. The curd must be turned by pulling up the corners of the cloth to prevent drying at the edges and stoppage of draining from the center of the mass. Such treatment produces much more rapid drainage than the factory practice and involves proportionately more labor and larger fat losses.

126. Cooling NeufchÂtel.—When whey ceases to separate readily, the corners of the cloth are loosed from the rack, folded diagonally or tied, and the curd cooled on ice or in refrigerators. When thoroughly chilled the bags of curd are put into presses, where light but increasing pressure forces more whey out of the mass. Tests at this time should show about 0.60 per cent acid in the whey. With low-fat curd every step of the process may be hastened, but with high-fat care must be exercised to prevent loss of fat during pressing especially. Any pressing device permitting continuous pressure with ease of manipulation may be used.

127. Pressing.—The ideals of the maker must determine the extent of pressing. A high yield is obtained by leaving whey in the curd. If immediate consumption is certain, such cheese may be satisfactory, but if the cheese is to be held some days the extra whey carrying more milk-sugar favors increased acid development. This produces very sour cheese with much more danger of other fermentations which cause objectionable flavor. Too much water favors more active bacterial growth as well as produces cheese too soft for the necessary handling in the market.

In the press, several bags of curd may be piled together. The press should be released and the bags turned from time to time to insure even drainage. Several hours of pressing are usually required. The danger of insufficient pressing is due to the difference of texture between the worked and unworked curd. Before working, curd carrying 10 per cent excess moisture resembles the finished product sufficiently to deceive any but the experienced maker. But if this curd is transferred to the worker and to the molding machine, it is found to become soft, cream chwwsw molds. Fig. 16.—Working NeufchÂtel. pasty and sticky, to lack "body," hence to make very unsatisfactory packages and to spoil very quickly. The masses of curd should come out of the press as dry and hard flat cakes.

128. Working and salting NeufchÂtel.—The cakes of curd go from the press to the working table. Here they are broken by hand or by a butter-worker or kneading machine (Fig. 16). Salt at the rate of one and one-half pounds to 100 pounds of curd is added. If the curd is not sufficiently pressed, the masses become mushy or pasty during the working process. The working is continued until the whole mass is uniformly smooth and buttery.

129. Storage.—The draining and working processes permit the contamination of the curd with organisms from the air and from the apparatus. These are distributed throughout the mass. Air is also worked thoroughly into the curd. Such a product spoils quickly. Distributing houses find the NeufchÂtel trade uncertain in volume from day to day, hence many of them store the cheese in bulk and package only fast enough to fill orders. This minimizes the loss due to spoilage. Such curd may be packed into tubs and kept for considerable time in cold storage. If molded for the retail trade, it is more quickly perishable. When packed solidly in mass, curd is largely protected from spoilage by the exclusion of air and perhaps the quick exhaustion of free oxygen through the respiration of the micro-organisms present and by its acidity. This must be supplemented by low temperature to reduce the loss to a minimum. Even when spoilage begins, it is easily confined to the slight growth of Oidium lactis or green mold and bacteria on exposed areas. These can be removed with minimum loss and damage to the mass. On the other hand, such curd molded into the commercial package of 3 to 6 ounces and wrapped in paper, with tin-foil or carton for protection, still presents enormously increased surface for the growth of aerobic forms—especially Oidium lactis, green mold (Roquefort mold is the usual green species) and accompanying bacteria. Curd in tubs may be kept some days; in commercial packages lowering of quality (flavor) begins almost at once.130. Molding.—When the standard molding machine (Fig. 17) is provided, curd is brought directly from the refrigerator to the machine. If permitted to become warm, the mass becomes sticky; when cold it is more readily handled. The machine is fitted with the special delivery tube for the variety to be handled, cylindrical for NeufchÂtel in its various forms, rectangular in section for cream. Enough workers should be provided to wrap and label the cheese without leaving it exposed to contamination or heat. Parchment paper and tin-foil cut the proper size for each variety and bearing printed labels are readily obtainable. Each cheese should be wrapped with paper and tin-foil and put directly into a flat box which holds a standard number (usually 12 or 24) of the special product.

Fig. 17.—Molding NeufchÂtel.