The book of cheese

There are three kinds of bottles employed in making the test, one with a very large neck which is used when testing materials high in fat-content such as cream, butter and cheese. This is generally called a cream-test bottle. It is graduated from 0 to 50 per cent. When testing materials with a small amount of fat such as whey, skim-milk and buttermilk, a test bottle with two necks is used, one with a small bore for the fat and the other neck with a larger bore to add the milk, acid, water. It is graduated from 0 to 0.5 of 1 per cent. There is a third bottle between the other two to test whole milk. This is known as a whole-milk bottle. It is graduated from 0 to 8 per cent. All of the glassware should comply with the laws.

309. Sampling the milk.—One of the most important parts of testing is to obtain a fair sample of the milk. The milk to be tested may be in a vat or in a farmer's can or a composite sample jar. If the milk is bought on the fat basis, that of each patron is not tested daily, but a small quantity, about half an ounce, is taken each day and placed in a jar; this is known as a composite sample. It is the usual practice to number the patrons and have a sample bottle for each patron with his number on it. Some substance must be added to preserve the milk and to keep it from souring or coagulating. It is difficult to secure a fair sample of sour milk. A wide-mouthed jar is preferred for keeping milk samples. This must be kept closed to prevent evaporation. Each day when milk is added to the composite sample, the bottles should be shaken to prevent the cream drying. Composite samples are tested at least twice a month. The milk may be mixed to obtain a fair sample, by stirring in the vat or by pouring from one bottle to another. Vigorous shaking should be avoided as this is likely to cause churning. One should see that all the cream is removed from the sides of the sample bottle and that it is evenly distributed through the milk. The sample of milk is now measured out with the pipette. This is graduated to deliver 18 grams of milk, and holds 17.6 c.c. Hold the pipette between the thumb and second finger of the right hand with the tip below the surface of the milk, draw the milk by suction with the lips until it is filled well above the graduation. Quickly place the forefinger over the opening and at right angles to the pipette. By gently and carefully raising the forefinger, allow the milk to run down until the surface is exactly level with the graduation. To obtain an accurate reading, the pipette should be on a level with the eye. Then with the left hand, hold the milk test bottle in a slanting position and place the tip of the pipette into it about one-third of an inch and at a slight angle. Now let the milk slowly flow down the side of the neck of the bottle, making certain that none is blown out by the escaping air. When all has run out of the pipette, blow out the drop which remains in the tip. Then measure out another sample in the same way, as the test should be made in duplicate.

310. Adding the acid.—The sulfuric acid should have a specific gravity between 1.82 and 1.83. It should be kept in glass-stoppered bottles or carboys to prevent the absorption of moisture from the air, which will reduce its strength. Acid that is too strong might burn the fat. The acid is a strong poison and will burn if it comes in contact with the flesh or the clothing. In such case, it should be removed by washing with plenty of water. An alkaline substance such as ammonia or bicarbonate of soda should be applied to remove any acid not washed away.

The acid measure holds 17.5 c.c. and it should be filled to the graduation. Then this acid should be added to the test bottle. The bottle should be held at an angle and slowly rotated so that the acid will rinse down any milk remaining in the neck of the bottle. Immediately mix the acid and milk by whirling the body of the bottle in a circle five or six inches in diameter. The mixture should not be allowed to go into the neck of the bottle while mixing. Continue shaking for about a minute after all the curd has disappeared. One should avoid pointing the neck of the bottle toward any person in the mixing operation. The acid unites with all the milk substances except the fat and generates much heat.

311. Centrifuging.—There are two machines in common use for centrifuging, one that runs by mechanical power and the other smaller and runs by hand. If the machine and atmosphere are very cold, the apparatus can be warmed by placing hot water in it. This is not necessary in a steam machine. In a factory where there are a number of samples to test, a power machine is usually employed. In this machine there are pockets or cups in which to set the test bottles. The machine or disk must be balanced by placing bottles in opposite pockets. These pockets are hinged so that when standing still the bottle is in an upright position and when the centrifuge is running, it is in a horizontal position. The machine should then be covered and started running. It should be run at the speed indicated. After five minutes, stop the machine and fill the bottles with boiling water up to the neck. This can be done without taking the bottles out of the machine. A pipette or slender-spouted vessel may be used to add the water. Whirl the bottles two minutes, then add more boiling water to bring the fat column into the graduated part of the neck of the bottle. Then whirl one minute. The test should be read at once or the bottles kept at a temperature of 130° to 140° F. until ready to read.

312. Reading the test.—To read the test, subtract the reading at the bottom of the fat column from that at the highest point. The curved meniscus which always forms at the top of the fat column should be included in the reading. Duplicate samples should not vary more than O.2 of 1 per cent. Standard Babcock test bottles and pipettes should always be used. In some states the agricultural experiment stations examine all glassware and mark it to make certain that it conforms to the requirements of the state law. In New York, glassware found to be correct is branded "S. B.," which means State Brand. In some states a person must have a license to test milk or cream, when it is paid for on the fat test. Such a person must pass an examination to show that he understands the test before a license, will be granted. The license may be revoked if the work is not honestly performed.

313. Testing whey for fat.—Because of the small amount of fat in whey, it is difficult to obtain a representative sample. The best way, if the entire amount cannot be placed in a vat and stirred, is to catch a little of the whey at intervals as it is being drawn from the vat. The sample to be tested is measured with the pipette the same as the milk and placed in the skimmed-milk test bottle. The same acid is used to test whey as to test milk but because there are not so many solids to destroy, not so much is used. If as much acid is used with whey as with milk, it will burn the fat and so interfere with the reading of the test. Just enough acid is added to destroy the milk substances except the fat, or enough to turn the contents of the test bottle dark brown. This usually requires filling the acid measure one-quarter of an inch under the graduation. The remainder of the test is the same as for whole milk.

314. Testing cheese for fat.—The sample of cheese to test for fat is obtained by removing the sample with a cheese-trier. This sample is called a "plug." Different plugs from the same cheese will test various percentages of fat so that it is difficult to secure a representative sample. The usual practice is to take three plugs, one near the center, another near the outside and the third between the first two. The plugs should be put into glass-stoppered bottles to prevent the evaporation of moisture. These plugs are then chopped up very fine. It is of course impossible to measure the cheese as with milk and whey, but it is weighed (Fig. 70). If the cheese is soft it can be stirred with a spatula until well mixed. A soft cheese usually sticks to the neck of the test bottle. After being weighed, it can be dissolved in a little sodium hydroxide and poured into the bottle. Different amounts may be used, commonly 4½ or 6 grams, but 6 grams is to be preferred. This is placed in the Babcock cream bottle since there will usually be more fat than can be read in a milk bottle. After the material has been placed in the test bottle, about two-thirds of an acid-measure of warm water is added to assist in dissolving the cheese.

The acid is added the same as with the milk. If all the cheese particles are not destroyed, and therefore do not disappear, a little more acid will complete the solution. Centrifuging is performed as with the milk.

315. Reading the test.—In a cream-test bottle the neck is so much wider that there is a much larger meniscus. In order to obtain an accurate result, the meniscus should be removed. This is done by carefully adding a substance called glymol, which is a mineral oil colored red. Usually about one-quarter of an inch of glymol is added to the fat column. This should not mix with the fat. The bottles should be placed in a hot water bath 135° to 140° F. for four minutes before reading. The temperature at reading should be 135° to 140° F. The reading is then taken from the bottom of the fat column to the line between this and the glymol. The bottle is graduated for 18 grams of material, but as only a part of 18 grams of cheese was used for the test, the reading should be multiplied by the part of 18 grams used. For example, suppose 6 grams of cheese were used and the test read 12 per cent fat. Since 6 is one third of 18, the actual percentage of fat is 3 times 12, or 36 per cent.

316. The Hart134 casein test was devised to determine the percentage of casein in milk. A special test bottle and centrifuge are necessary. The method of making the test is as follows: Place 2 c.c. of chloroform in the casein test tube, add 20 c.c. of a 0.25 of 1 per cent solution of acetic acid at a temperature of 65° to 75° F. This solution of acetic acid is made by diluting 10 c.c of glacial acetic acid with 100 c.c. of water, then dilute 25 c.c. of this solution to 1000 c.c. with water; 5 c.c. of milk at a temperature of 65° to 75° F. is then run into the bottle. The bottle is then covered with the thumb and inverted and the mixture shaken vigorously for exactly twenty seconds. It is then centrifuged within twenty minutes at a speed of Fig. 71.—A Quevenne lactometer. 2000 revolutions a minute. The bottle should stand ten minutes before reading the percentage of casein. There are other tests for casein but they are very complicated.

317. Solids in the milk.—Because not only the fat but all the solids are utilized in cheese-making, it is important to know the amount of the solids in the milk. This is ascertained by determining the specific gravity of the milk and knowing the fat-content; the solids not fat can then be calculated.

318. The lactometer.—The specific gravity of liquids is measured by an instrument called a hydrometer. Its use is based on the fact that when a solid body floats in a liquid, it displaces a volume of liquid equal in weight to its own. Hydrometers are in many cases so made that the specific gravity can be read at the point where the scale is even with the upper surface of the liquid. A hydrometer that is especially adapted to milk is called a lactometer. There are two lactometers in common use, the Quevenne and the Board of Health.

The Quevenne lactometer.—This is a long slender hollow piece of glass weighted at the bottom to make it float in the milk in an upright position (Fig. 71). The upper end is slender and contains the scale. This scale is graduated from 15 at the top to 40 at the bottom. Each reading on the scale corresponds to the point marked specific gravity on a hydrometer, except that the figures are not complete. For example, 15 on the Quevenne scale means a specific gravity Fig. 72.—A Board of Health lactometer. of 1.015; a reading of 30 on the Quevenne scale means a specific gravity of 1.030, and so on. The Quevenne lactometer is graduated to give correct results at a temperature of 60° F. The milk should be at this temperature. If the temperature is below or above this, a correction must be made to the reading. The temperature should not be more than 10 degrees above or below 60° F. The correction for each degree in variation of temperature can be made by adding 0.1 or subtracting 0.1 from the lactometer reading, as the case may be. If the temperature is above 60° F., the correction is added to the lactometer and if it is below 60° F., the correction is subtracted from the lactometer reading. The reading should be taken when the lactometer is floating free in the milk. The scale is read exactly at the surface of the milk. The better lactometers have a thermometer with the scale just above or opposite the lactometer scale.

The Board of Health lactometer.—This is very similar to the Quevenne lactometer except that the scale is graduated from 0 to 120 (Fig. 72). The point on the scale of the lactometer that floats at the surface in water is represented by 0, and 100 represents the specific gravity of 1.029. On the Board of Health lactometer, the 100 degrees or divisions from 0 to 100 equal 29 divisions on the Quevenne. Therefore, one division on the Board of Health equals 0.29 of a division on the Quevenne. To convert Board of Health reading to Quevenne, multiply by 0.29 and to convert Quevenne to Board of Health, divide by 0.29. The correction for temperatures above or below 60° F. is made the same as with the Quevenne, except 0.3 is added or subtracted from the reading instead of 0.1 as with the Quevenne.

319. Calculating the solids not fat in the milk.—When the lactometer reading and fat-content of the milk are known, there are several formulas for calculating the solids not fat. In the following formulas, L equals Quevenne lactometer reading at 60° F., and F equals the percentage of fat in the milk:

320. Testing cheese for moisture.135—There are two methods of testing cheese for moisture. The following is a simple test devised by H. C. Troy:

The ordinary butter moisture test, in which a metal cup is heated over a flame, cannot be used for determining the percentage of water in cheese because the high temperature developed in operating that test drives from the cheese other substances with the water. Also, particles are lost by spattering when the cheese is heated with any degree of rapidity in the shallow butter-moisture cups. To overcome these difficulties, the new method here described has been developed for the purpose of determining the percentage of moisture in cheese. The apparatus consists of:

1 double-walled copper drying cup

1 centigrade thermometer registering to 200°

1 alcohol lamp

1 tripod

1 special flask

1 scales sensitive to 0.01 gram

1 set of weights, 0.01 to 100 grams

The body of the copper drying cup may be made in two parts. One of the parts is a jacket that forms the outer wall of the apparatus. It has a flat bottom 4½ inches in diameter, and the perpendicular wall is 4½ inches in height. The inner part of the cup must have a flat bottom 2¾ inches in diameter and a side wall 3¾ inches high. A flange attached to the upper rim of the inner part extends out at right angles to the cup wall and forms a cover for the space between the walls when the two parts are put together. The flange is bent down around its outer edge to make it fit snugly over the upper rim of the outer jacket. It thus holds the inner cup securely in place, leaving a space about ¾ inch wide for oil between the walls and bottoms, and permits the apparatus to be taken apart readily. A circular opening about ½ inch in diameter is made through the flange to permit the insertion of a thermometer for taking the temperature of the oil or the melted fat which is used in the space between the walls. Lard or tallow serves best for use in this space; a readily inflammable oil should not be employed. The thermometer may be permanently held in place by passing it snugly through a hole bored in a cork, the cork being then fitted into the hole through the flange. A flat metal cover is placed on the cup when making a test. This cover has a hole through the center just large enough to permit the neck of the drying flask to extend up through it. The cover assists in keeping the body of the flask at a constant temperature by preventing the entrance of cold air currents. The thermometer should register changes in temperature between zero and 200° C. The alcohol lamp should yield a flame about ¼ inch in diameter and ¾ inch high. The tripod should be about 6 inches high and of proper diameter at the top to support the oil bath.

An ordinary flat-bottom glass Erlenmeyer flask, of such a diameter as to fit neatly into the oil-bath cup, may be used to hold the cheese during the drying operation; but a special glass flask serves better. It is made with a flat bottom 2½ inches in diameter, which will fit into the cup of the drying apparatus. The side walls of this flask should be perpendicular for about 1 inch, when they should begin to slope in toward the base of the neck, which should be located about 2 inches above the bottom. The neck of the flask should be 1 inch in diameter, with perpendicular walls, and its length should give the flask a total height of 4¾ inches. When the apparatus (Fig. 73) is put together for the first time, the melted fat or oil may be placed in the outer jacket and the inner cup may then be fitted into position, or the parts may be put together first and the oil then poured into the space between the cup walls through the opening where the thermometer is to be placed. The oil should fill the space to within an inch of the top. The cork through which the thermometer has been passed is then fitted into the opening. The thermometer bulb should be placed in the oil about half an inch above the bottom of the outer jacket. The apparatus is then placed on the tripod over the alcohol lamp. A flame ½ inch in diameter and ¾ inch high will give sufficient heat to hold the bath at the proper temperature. The temperature may be regulated by raising or lowering the lamp or by changing the size of the flame by adjusting the wick. Hundreds of tests may be run without taking the apparatus apart or changing the oil. The copper drying cup can be made by any tinsmith. The other parts may be ordered through any dairy or chemical supply company.

Answer: 5.00 - 3.15 = 1.85
1.85 ÷ 5      = 0.37
0.37 ✕ 100 = 37 (percentage of water in cheese)

A butter-moisture scales with an extra 5-gram weight may be used for weighing out the 5 grams of cheese. If the scales indicates the amount of moisture in 10 grams of butter by percentage graduations on its beam or by percentage weights, then it will be necessary to multiply by 2 the percentage indicated by such scales or percentage weights when only 5 grams of cheese is used.

The moisture may be determined by weighing out a small sample of cheese and drying it in an oven and calling the loss moisture. Many such ovens have been devised.

New York and Wisconsin have laws limiting the amount of water which may be incorporated in Cheddar cheese. New York places the limit at 39 per cent and Wisconsin at 40 per cent. If the moisture-content is above this, the cheese must be branded adulterated.

CHAPTER XX

MARKETING

Marketing is related to cheese in two ways: First, the purchase of the raw material, the milk; and secondly the sale of the finished product, the cheese.

321. Buying milk.—The method of paying for the milk differs in the various cheese sections and factories. At some factories a stated price is paid for the milk or the fat. This is usually in terms of 100 pounds of milk or for each pound of fat. This is the practice with concerns possessing large capital. Other factories make the milk into cheese and after each sale, the expenses necessary for operating the factory are deducted and the remainder of the money divided among the patrons. This money is divided either on the basis of the number of pounds of milk or of fat delivered. The question arises as to which is the better method to buy milk for cheese-making, or the fairest way to divide the money received from a sale of cheese.

322. Cheese yield basis of buying milk.—Let us suppose that at a cheese factory there were five patrons: (A) delivered 100 pounds of milk testing 3 per cent fat; (B) 100 pounds of milk testing 3.5 per cent fat; (C) 100 pounds of milk testing 4.0 per cent fat; (D) 100 pounds of milk testing 4.5 per cent fat; and (E) 100 pounds of milk testing 5.0 per cent fat. Table XXVI shows the actual number of pounds of cheese containing 37 per cent moisture which 100 pounds of milk containing different percentages of fat will produce. The cheese sold net for 20 cents a pound.

TABLE XXVI

This table shows the amount of money each patron should receive if the money were divided on the basis of the actual yield of cheese.

323. Fat basis for payment of milk.—Let us suppose that the same five patrons delivered the same quantity of milk testing the same percentages of fat and that the cheese sold for the same price. A total of 20 pounds of fat was delivered and the cheese sold for $10.598; by dividing this amount by the pounds of fat delivered, the price or value of one pound of fat is found to be $.5299. Multiplying the pounds of fat each patron delivered by the price a pound would give the amount of money due each patron.

TABLE XXVII

324. Weight basis or pooling method for payment of milk.—By this system, each patron would receive an equal price for 100 pounds of milk. If the same supposition is taken as before, there would be 500 pounds of milk delivered and the cheese sold for $10.59; each 100 pounds of milk would be worth $2.12. As each patron delivered an equal weight of milk, each would receive an equal amount of money, or $2.12.

325. Fat-plus-two method for payment of milk.—Some workers have thought that by adding two to the fat test, the division of money would be more nearly the true cheese-producing value of the milk. The amount due each patron is figured as in the fat basis, except that two is added to the fat test and this is used as the basis of division. If the same suppositions were used as before, each patron would receive the amount shown in Table XXVIII.

326. Comparison of methods.—The best way to judge the different methods of paying for milk is to compare them with the true value based on the actual cheese yield as shown in Table XXIX.

TABLE XXVIII

TABLE XXIX

A careful study of the above table shows that the pooling system is in favor of the dairy-man with the poor milk, and that the fat basis favors the dairy-man with the rich milk. This is due, of course, to the fact that the casein does not increase in the milk quite in proportion to the fat. With the pooling system or fat basis of payment, no account is taken of the casein; but the fat-plus-two system is an attempt to recognize the casein, but considers the percentage of casein in all milk to be the same. This method is in favor of the dairy-man with milk low in fat, but not to the extent of the pooling system. The latter system considers the cheese-producing power of all milk to be the same. It favors the dairy-man with low-testing milk. The fat basis for payment recognizes only the fat and is an advantage to the dairy-man with the high-testing milk but not to the extent that the pooling system is in favor of the low-testing milk. The fat-plus-two method recognizes 2 per cent of casein in the milk. This favors the dairy-men with low-testing milk. Other methods136 of paying for milk have been devised. Because the actual yield of cheese from the milk of different herds cannot be easily determined at the cheese factory, this method of payment cannot be employed. In localities in which all the dairy-men have the same breed of cattle and there is not a wide variation in the fat percentage, the fat basis is usually found to be the most satisfactory way to pay for the milk.

327. Laws governing the production and sale of milk.—Many states have laws regulating the sanitary conditions under which the milk may be produced. These laws relate principally to the condition of the stables, the health of the cow, the food given the cow, and the care of the milk. The following law137 of Wisconsin is a good example:

Most states have laws which determine the legal standard of milk. Any one selling milk which does not meet this standard is liable to be fined. The laws of most states prohibit the taking of anything from the milk or the adding of anything to it. This prohibits the skimming and watering. Skimmed-milk must be sold as such.

328. Marketing of cheese.—There are many different methods138 of selling cheese. Each is adapted to certain conditions and each has its advantages and disadvantages. In cheese sections, the customary method of selling is on the board of trade, which is the meeting of the cheese-buyers and factory salesmen. They meet at a given place at a certain day and hour each week. Every board has its officers. There are different ways in which a board of trade may be operated. In some cases there is a large blackboard divided into columns. In the first column, the salesman writes the name of the factory and the number and kind of cheese offered for sale. At the top of the other columns are the names of the different cheese-buyers. The president usually opens the sale at a stated time and asks that all cheese be placed on the blackboard. When this is done he states that they are ready to receive bids on the cheese. The buyers then write the price a pound they wish to pay opposite each lot of cheese and in the column headed by their names. After all the bids have been received and placed on the board, the presiding officer states that a certain length of time, usually fifteen minutes, will be given the salesman to withdraw his cheese if he does not think a high enough price has been offered; this is indicated by the salesman stepping to the blackboard and erasing the factory name and number of boxes. At the close of the stated time, the presiding officer declares the cheese offered on the board sold to the highest bidder. The purchaser then gives the salesman directions for shipping.

Sometimes a board of trade has a committee of one member elected by the factory salesmen and one elected by the cheese-buyers. These two members elect a third and these three constitute the price committee. This committee meets each week and determines what the price shall be. This is known as the ruling. The factory salesmen and cheese-buyers then try to make private sales. By this method no one, except the persons concerned, knows exactly what price is paid for the cheese. Usually, a price above the ruling is paid.

At Quebec, Canada, there is a cheese-selling organization with government assistance. On paying a certain fee, any cheese factory may join. All the factories belonging to the organization ship their cheese to a central cold storage where the cheeses are examined and graded by a government inspector. A cheese from each vat is tried. These cheeses are separated into white and colored lots, then graded according to quality. When the total number of cheeses in each lot is known, the lots are sold at auction. The purchaser must accept the cheese as graded. The better grades of cheese bring about the same price as on the market, but the advantage lies in the selling of the lower grades. Ordinarily, the purchaser takes advantage of the salesman when the cheeses are undergrade. The success of this plan depends on the accuracy of the person grading the cheese. This method seems to be growing in popularity, because the cheese-buyer can purchase large amounts of cheese at one time and be sure of the quality. A small fee, about one-twelfth of a cent a pound, is charged for handling the cheese. Similar organizations are in operation in Wisconsin. The boards of trade and selling organizations deal almost entirely in Cheddar cheese.

329. Mercantile exchanges.—In the larger cities are exchanges where cheese is bought and sold by jobbers. This cheese is mostly Cheddar. The prices paid these jobbers tend to fix the daily price of cheese. These prices are published daily, for example, in New York Price Current. Some factories ship their cheese directly to these jobbers. The following are the cheese rules of the New York Mercantile Exchange adopted May 4, 1915: