END NOTES
1.From circular No. 85 of a series of statements prepared under the direction of the Secretary of Agriculture, covering the agricultural situation for 1918.
1.From circular No. 85 of a series of statements prepared under the direction of the Secretary of Agriculture, covering the agricultural situation for 1918.
2.The Babcock Testis operated as follows: When the milk has been thoroughly mixed and a true sample has been taken thepipetteis filled to the mark by sucking the milk into it until it stands a little above the mark on the stem, then quickly placing a dry finger over the end of the pipette and allowing the milk to escape until it just reaches the mark. The quantity thus measured off is 17.6 c.c. The pipette is then emptied into thetest bottleby placing the point in the neck and allowing the milk to flow slowly down the inside of the neck, taking care not to lose any of the milk. Blow the last drops out of the pipette into the bottle.Themeasuring glass, holding 17.5 c.c., is filled to the mark withsulphuric acidof a specific gravity of 1.82 to 1.83 and this is poured into the milk in the test bottle. The acid is a strong poison and must be handled with care. Pour it slowly down along the wall of the bottle which is held at an angle and turned slowly during the operation.Now give the bottle a rotary motion to thoroughly mix the milk and the acid, shaking vigorously towards the end of the operation so as to be sure not to leave any of the acid which is heavier than the milk at the bottom of the bottle.Whirling.—The bottles are then placed in the centrifugal machine and whirled for five minutes at the proper speed—from 600 to 1200 revolutions per minute—according to the diameter of the machine and as stated in the directions which come with the tester. The mixture of milk and acid is hot enough if the whirling is done at once, but if it is allowed to cool the bottles should be placed in hot water of 150 to 170° for about 15 minutes; whirling at full speed for 4 minutes brings all the fat to the top.Hot water is now added until the bottle is filled almost to the scale on the neck and the bottles are again placed in the machine and whirled at full speed for one minute. Hot water is then again added until the lower end of the fat column is within the scale, preferably at the 1% or 2% mark on the neck of the bottle. Whirl once more for one or two minutes and then read off the percentage of fat on the scale. Each division represents 0.2% fat. The fat column is measured from the lower line between the fat and the water to the point where the top of the fat column touches the wall of the neck. A pair of dividers are handy for measuring the fat column and reading off the percentage of fat in the milk. The bottle with contents should be warm—about 140°—when the measure is taken.For testing skim milk and cream special forms of test bottles are used—which are described in the circulars coming with the testers and students who desire fuller information are referred to Farrington and Woll’s “Testing Milk and its Products,” published by the Mendota Book Co., Madison, Wis.
2.The Babcock Testis operated as follows: When the milk has been thoroughly mixed and a true sample has been taken thepipetteis filled to the mark by sucking the milk into it until it stands a little above the mark on the stem, then quickly placing a dry finger over the end of the pipette and allowing the milk to escape until it just reaches the mark. The quantity thus measured off is 17.6 c.c. The pipette is then emptied into thetest bottleby placing the point in the neck and allowing the milk to flow slowly down the inside of the neck, taking care not to lose any of the milk. Blow the last drops out of the pipette into the bottle.
Themeasuring glass, holding 17.5 c.c., is filled to the mark withsulphuric acidof a specific gravity of 1.82 to 1.83 and this is poured into the milk in the test bottle. The acid is a strong poison and must be handled with care. Pour it slowly down along the wall of the bottle which is held at an angle and turned slowly during the operation.
Now give the bottle a rotary motion to thoroughly mix the milk and the acid, shaking vigorously towards the end of the operation so as to be sure not to leave any of the acid which is heavier than the milk at the bottom of the bottle.
Whirling.—The bottles are then placed in the centrifugal machine and whirled for five minutes at the proper speed—from 600 to 1200 revolutions per minute—according to the diameter of the machine and as stated in the directions which come with the tester. The mixture of milk and acid is hot enough if the whirling is done at once, but if it is allowed to cool the bottles should be placed in hot water of 150 to 170° for about 15 minutes; whirling at full speed for 4 minutes brings all the fat to the top.
Hot water is now added until the bottle is filled almost to the scale on the neck and the bottles are again placed in the machine and whirled at full speed for one minute. Hot water is then again added until the lower end of the fat column is within the scale, preferably at the 1% or 2% mark on the neck of the bottle. Whirl once more for one or two minutes and then read off the percentage of fat on the scale. Each division represents 0.2% fat. The fat column is measured from the lower line between the fat and the water to the point where the top of the fat column touches the wall of the neck. A pair of dividers are handy for measuring the fat column and reading off the percentage of fat in the milk. The bottle with contents should be warm—about 140°—when the measure is taken.
For testing skim milk and cream special forms of test bottles are used—which are described in the circulars coming with the testers and students who desire fuller information are referred to Farrington and Woll’s “Testing Milk and its Products,” published by the Mendota Book Co., Madison, Wis.
3.TheAcid Testdepends upon what in the laboratory is called “titration” and makes use of a “burette,” a long, graduated measuring tube provided with a pinch-cock. This burette is filled with an alkali solution of known strength, usually a “tenth normal” solution of caustic soda. A certain amount of the milk to be tested is measured off into a glass or a white porcelain cup. As a 17.6 c.c. pipette belonging to the Babcock test usually is at hand, that may be used for this purpose. A few drops of anIndicatoris added to the milk and under constant stirring the soda solution is allowed to drip into it until suddenly it turns pink. The color will quickly disappear, however, and a few more drops of the alkali are added and stirred in several times until a faint but distinct pink color remains for some time. That indicates that the acid in the milk has been neutralized and the amount of the soda solution consumed is then read off on the scale on the burette. By dividing the number of c.c. of the soda solution used by two, the tenths per cent of lactic acid in the milk is found. For example, if it takes 4 c.c. of the soda solution to neutralize 17.6 c.c. milk, the acidity is .2%. This depends upon the fact that 1 c.c. of a tenth normal soda neutralizes .009 gram of lactic acid and that therefore the per cent of acid in the milk is equal to .009 multiplied by the number of c.c. of soda solution used, divided by the number of c.c. of milk and multiplied by 100.If 50 c.c. of milk is taken instead of 17.6 the calculation is changed accordingly.
3.TheAcid Testdepends upon what in the laboratory is called “titration” and makes use of a “burette,” a long, graduated measuring tube provided with a pinch-cock. This burette is filled with an alkali solution of known strength, usually a “tenth normal” solution of caustic soda. A certain amount of the milk to be tested is measured off into a glass or a white porcelain cup. As a 17.6 c.c. pipette belonging to the Babcock test usually is at hand, that may be used for this purpose. A few drops of anIndicatoris added to the milk and under constant stirring the soda solution is allowed to drip into it until suddenly it turns pink. The color will quickly disappear, however, and a few more drops of the alkali are added and stirred in several times until a faint but distinct pink color remains for some time. That indicates that the acid in the milk has been neutralized and the amount of the soda solution consumed is then read off on the scale on the burette. By dividing the number of c.c. of the soda solution used by two, the tenths per cent of lactic acid in the milk is found. For example, if it takes 4 c.c. of the soda solution to neutralize 17.6 c.c. milk, the acidity is .2%. This depends upon the fact that 1 c.c. of a tenth normal soda neutralizes .009 gram of lactic acid and that therefore the per cent of acid in the milk is equal to .009 multiplied by the number of c.c. of soda solution used, divided by the number of c.c. of milk and multiplied by 100.
If 50 c.c. of milk is taken instead of 17.6 the calculation is changed accordingly.
4.Farmers’ Bulletin No. 602, U. S. Dept. of Agriculture.
4.Farmers’ Bulletin No. 602, U. S. Dept. of Agriculture.
5.Butter Coloris made of the coloring matter of “Annatto” dissolved in a refined vegetable (salad) oil. The Annatto tree (Bixa Orelana) grows in the tropics and the seed which has a thin coating of this beautiful coloring matter comes mostly from the West Indian Islands, Jamaica, Porto Rico and Guadeloupe. It is perfectly harmless and is used by the natives to flavor and color soup and other foods much as we use tomatoes.
5.Butter Coloris made of the coloring matter of “Annatto” dissolved in a refined vegetable (salad) oil. The Annatto tree (Bixa Orelana) grows in the tropics and the seed which has a thin coating of this beautiful coloring matter comes mostly from the West Indian Islands, Jamaica, Porto Rico and Guadeloupe. It is perfectly harmless and is used by the natives to flavor and color soup and other foods much as we use tomatoes.
6.The Marschall Rennet Test consists of a graduated cup (a) with a fine hole for an outlet in the bottom. One cubic centimeter of a standard rennet extract is diluted with water in the glass bottle (c). The cup is filled with milk and placed on the corner of the cheese vat, the milk being allowed to run through the fine hole in the bottom of the cup. The moment the surface of the milk reaches the upper mark of the graduation in the cup the diluted rennet extract is added and quickly stirred into the milk with the spattle (d).When the milk begins to curdle it stops running out. The sweeter the milk is the more will run out before coagulation stops it and the mark on the scale at which it stops indicates the degree of acidity or ripening. The point is to have the milk alike every day and if, for instance, the cheesemaker has found that his cheese is best if he adds the rennet to the milk in the vat when the test shows 2½, he wants to ripen the milk to that degree every day. So, if the test shows 3 or 4, it indicates that the milk is not sufficiently ripened and it should be allowed to stand warm for a longer time before it is set with rennet.
6.The Marschall Rennet Test consists of a graduated cup (a) with a fine hole for an outlet in the bottom. One cubic centimeter of a standard rennet extract is diluted with water in the glass bottle (c). The cup is filled with milk and placed on the corner of the cheese vat, the milk being allowed to run through the fine hole in the bottom of the cup. The moment the surface of the milk reaches the upper mark of the graduation in the cup the diluted rennet extract is added and quickly stirred into the milk with the spattle (d).
When the milk begins to curdle it stops running out. The sweeter the milk is the more will run out before coagulation stops it and the mark on the scale at which it stops indicates the degree of acidity or ripening. The point is to have the milk alike every day and if, for instance, the cheesemaker has found that his cheese is best if he adds the rennet to the milk in the vat when the test shows 2½, he wants to ripen the milk to that degree every day. So, if the test shows 3 or 4, it indicates that the milk is not sufficiently ripened and it should be allowed to stand warm for a longer time before it is set with rennet.
7.The Acidemeter for making an Acid Test is described in ChapterI.
7.The Acidemeter for making an Acid Test is described in ChapterI.
8.Rennet (see under “Ferments” in ChapterI) is prepared from the third division of the stomach of the suckling or milk-fed calf. Fifty years ago cheesemakers used to make their own rennet by soaking salted calves’ stomachs in sour whey, and our grandmothers used a piece of a dry, salted stomach to make Junket or “Curds and Whey.” About 1868, Christian Hansen, of Copenhagen, Denmark, began the preparation of Commercial Rennet Extract which soon supplanted the home-made rennet in all countries wherever cheese was made. Nowadays rennet in liquid or powder or tablet form for cheesemaking, and Junket Tablets for milk puddings, are prepared pure and of known strength in laboratories and handled by druggists and dealers in dairy supplies.The fresh stomachs are saved by the farmers or butchers and are either blown up and dried in the air protected from sunlight and rain, or split lengthwise and spread out flat and salted on both sides.In the laboratory the ferment is extracted by chemicals and a pure, clear liquid extract is prepared, of uniform strength and good keeping quality. Or the extract is condensed into a powder which again is compressed into tablets of great strength.The ferment acts best when the milk is lukewarm, but it will do the work at temperatures ranging from 50°, or even lower, to 120° F. Strongly pasteurized or sterilized milk will not curdle with rennet, but milk pasteurized at a low temperature is not changed enough to prevent it from making a firm curd. More rennet does not make a firmer curd but causes the milk to curdle quicker; less rennet makes the process slower. Diluted milk will not curdle firmly, and the failure of milk to make a smooth coagulum of the usual consistency and in the usual time, the temperature being right and the regular amount of a standard rennet being used, is a never-failing proof that something is the matter with the milk. It has been changed from its natural condition by over-heating in pasteurization or by watering or doctoring, or it has not been properly ripened.
8.Rennet (see under “Ferments” in ChapterI) is prepared from the third division of the stomach of the suckling or milk-fed calf. Fifty years ago cheesemakers used to make their own rennet by soaking salted calves’ stomachs in sour whey, and our grandmothers used a piece of a dry, salted stomach to make Junket or “Curds and Whey.” About 1868, Christian Hansen, of Copenhagen, Denmark, began the preparation of Commercial Rennet Extract which soon supplanted the home-made rennet in all countries wherever cheese was made. Nowadays rennet in liquid or powder or tablet form for cheesemaking, and Junket Tablets for milk puddings, are prepared pure and of known strength in laboratories and handled by druggists and dealers in dairy supplies.
The fresh stomachs are saved by the farmers or butchers and are either blown up and dried in the air protected from sunlight and rain, or split lengthwise and spread out flat and salted on both sides.
In the laboratory the ferment is extracted by chemicals and a pure, clear liquid extract is prepared, of uniform strength and good keeping quality. Or the extract is condensed into a powder which again is compressed into tablets of great strength.
The ferment acts best when the milk is lukewarm, but it will do the work at temperatures ranging from 50°, or even lower, to 120° F. Strongly pasteurized or sterilized milk will not curdle with rennet, but milk pasteurized at a low temperature is not changed enough to prevent it from making a firm curd. More rennet does not make a firmer curd but causes the milk to curdle quicker; less rennet makes the process slower. Diluted milk will not curdle firmly, and the failure of milk to make a smooth coagulum of the usual consistency and in the usual time, the temperature being right and the regular amount of a standard rennet being used, is a never-failing proof that something is the matter with the milk. It has been changed from its natural condition by over-heating in pasteurization or by watering or doctoring, or it has not been properly ripened.
9.W. O. Atwater, Farmers’ Bulletin No. 142.
9.W. O. Atwater, Farmers’ Bulletin No. 142.
10.Dr. E. V. McCollum in “Hoard’s Dairyman.”
10.Dr. E. V. McCollum in “Hoard’s Dairyman.”
11.Prepared for “The Story of Milk” by A. Louise Andrea.
11.Prepared for “The Story of Milk” by A. Louise Andrea.