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 Hart[134] 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 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.

[Ill.u.s.tration: FIG. 71.--A Quevenne lactometer.]

_The Quevenne lactometer._--This is a long slender hollow piece of gla.s.s 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 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.

[Ill.u.s.tration: FIG. 72.--A Board of Health lactometer.]

_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:

L + 0.7 F --------- = S.N.F 3.8

L + F ----- = S.N.F.

4

L - + 0.2 F + 0.14 = S.N.F.

4

+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 b.u.t.ter 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 he 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 b.u.t.ter-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 4 inches in diameter, and the perpendicular wall is 4 inches in height. The inner part of the cup must have a flat bottom 2 inches in diameter and a side wall 3 inches high. A f.l.a.n.g.e attached to the upper rim of the inner part extends out at right angles to the cup wall and forms a cover for the s.p.a.ce between the walls when the two parts are put together. The f.l.a.n.g.e 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 s.p.a.ce about inch wide for oil between the walls and bottoms, and permits the apparatus to be taken apart readily. A circular opening about inch in diameter is made through the f.l.a.n.g.e to permit the insertion of a thermometer for taking the temperature of the oil or the melted fat which is used in the s.p.a.ce between the walls. Lard or tallow serves best for use in this s.p.a.ce; a readily inflammable oil should not be employed.

The thermometer may be permanently held in place by pa.s.sing it snugly through a hole bored in a cork, the cork being then fitted into the hole through the f.l.a.n.g.e. 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 a.s.sists 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 inch in diameter and 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 gla.s.s 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 gla.s.s flask serves better. It is made with a flat bottom 2 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 4 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 s.p.a.ce between the cup walls through the opening where the thermometer is to be placed. The oil should fill the s.p.a.ce to within an inch of the top. The cork through which the thermometer has been pa.s.sed 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 inch in diameter and 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.

[Ill.u.s.tration: FIG. 73.--Apparatus necessary to test cheese for moisture.]

In operating the test, the alcohol lamp is first lighted, so that the oil bath may be warming while the test sample is under preparation. A representative sample of the cheese, which may be taken with a cheese-trier and held in a gla.s.s-stoppered sample jar, is then cut into particles about the size of kernels of wheat without removing it from the jar. This may be accomplished with an ordinary table knife that has had the end squared and sharpened. The clean dry flask is then accurately balanced on the scales and a 5-gram weight is placed in the opposite scale pan. Particles of cheese from the prepared sample are put into the flask until the scales comes to an exact balance. Great care should be taken to avoid loss of moisture from the cheese in the preparation of the sample.

With the thermometer in the oil bath registering between 140 and 145 C. (or between 284 and 293 F.), the flask is placed in the cup of the oil bath and the flat disk-shaped cover is adjusted over the apparatus.

The flask should remain in the bath for fifty minutes, the temperature being kept between 140 and 145 C. all the time. The flask is then removed, covered and allowed to cool to room temperature in a dry place.

It is then weighed, and the quotient obtained by dividing the loss in weight by the original weight, multiplied by 100, gives the percentage of water in the cheese. The following shows the method of computation:

Problem: Five grams of cheese was heated until the water contained in it was evaporated. The remaining substance weighed 3.15 grams. What percentage of water did the cheese contain?

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

A b.u.t.ter-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 b.u.t.ter 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

SHOWING PAYMENTS FOR MILK BASED ON THE ACTUAL YIELD OF CHEESE

===================================================================== PATRON

POUNDS

PER CENT

YIELD OF CHEESE

PRICE A

AMOUNT

OF MILK

OF FAT IN

CONTAINING

POUND

DUE EACH

DELIVERED

MILK

37% MOISTURE

PATRON -------+-----------+-----------+-----------------+---------+--------- A

100

3.0

8.30

$.20

$1.66 B

100

3.5

9.45

.20

1.89 C

100

4.0

10.60

.20

2.12 D

100

4.5

11.74

.20

2.348 E

100

5.0

12.90

.20

2.58 -------+-----------+-----------+-----------------+---------+--------- Total

500

20

52.99

.20

10.598 =====================================================================

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 quant.i.ty 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

SHOWING PAYMENTS FOR MILK BASED ON FAT-CONTENT OF MILK

===================================================================

POUNDS

PER CENT

POUNDS OF

VALUE OF

PATRON

OF MILK

OF FAT IN

FAT

POUND OF

AMOUNT DUE

DELIVERED

MILK

DELIVERED

FAT

EACH PATRON -------+-----------+-----------+-----------+----------+------------ A

100

3.0

3.0

$.5299

$1.58 B

100

3.5

3.5

.5299

1.85 C

100

4.0

4.0

.5299

2.12 D

100

4.5

4.5

.5299

2.38 E

100

5.0

5.0

.5299

2.65 ===================================================================

+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.