Chapter IX: Bacteria in Market Milk

Within the last decade attention has been especially directed toward the quality of milk that is furnished to the people in the cities. This has come about, in part, in connection with the demands made for better and purer food of every kind. These demands are reflected in the pure-food laws enacted by the federal government, and by the various states and municipalities. Another factor that has focused attention on the milk supplies has been the belief that it plays an important role in the production and distribution of disease, especially among children. The rapid growth of cities in all of the great countries of the world, the higher standard of living, and the greater demand for milk and other dairy products, has, of necessity, widened the zone from which the milk supply of any particular city must be drawn. Milk is now an article of export and of import; some of the great cities draw a portion of their supply from farms hundreds of miles away. This means that a longer time must elapse between the time of production and consumption, necessitating the exercise of greater care in production and handling in order to preserve the milk until it reaches the consumer.

In the past in the cities, as in the smaller towns at present, the supply was largely furnished by the producer directly to the consumer. This direct contact afforded the consumer the opportunity of informing himself of the conditions under which his milk supply was produced if he desired. The advent of the middleman in the business, and the gathering of the milk from many hundreds of farms, and its redistribution to thousands of homes has made it impossible for the individual consumer to learn anything of the conditions surrounding production. When the individual cannot protect himself against fraud and unhealthful conditions, it is the duty of the government to protect him. This is the theory underlying the modern control of food supplies, water supplies, and of living conditions in general. Acting on this basis the cities are seeking to control, to an increasing degree, the healthfulness and cleanliness of the milk supply.

Formerly such control as was given was largely with reference to the composition of the milk, the regulations providing that it should contain not less than a minimum amount of fat and other solids, and be free from preservatives. The more modern regulations are much more complex and touch every phase of production and handling that can, in any way, affect the value of the milk as human food.

=Municipal regulations.= The different cities vary widely in the methods employed to secure a satisfactory milk supply. Rules and regulations are adopted to which the producer and dealer must conform. In order to ascertain whether the regulations are being obeyed, two types of examinations may be made: first the inspection of the farms and of the plants of the dealers; second the examination of the milk itself with reference to its chemical composition, bacterial content and temperature.

The city of New York is doing more to safeguard and to improve its milk supply than any other large city in this country. A brief summary of its regulations and methods follow. A copy of the rules is furnished to each dairyman and is supposed to be posted in the stable.

The Cows.

1. The cows must be kept clean, and manure must not be permitted to collect upon the tail, sides, udder and belly of any milch cow.

2. The cows should be groomed daily, and all collections of manure, mud or other filth must not be allowed to remain upon their flanks, udders or bellies during milking.

3. The clipping of long hairs from the udder and flanks of the cows is of assistance in preventing the collection of filth which may drop into the milk. The hair on the tails should be cut, so that the brush will be well above the ground.

4. The udders and teats of the cow should be thoroughly cleaned before milking; this to be done by thorough brushing and the use of a cloth and warm water.

5. To prevent the cows from lying down and getting dirty between cleaning and milking, a throat latch of rope or chain should be fastened across the stanchions under the cow's neck.

6. Only feed which is of good quality and only grain and coarse fodders which are free from dirt and mould should be used. Distillery waste or any substance in a state of fermentation or putrefaction must not be fed.

7. Cows which are not in good flesh and condition should be immediately removed and their milk kept separate until their health has been passed upon by a veterinarian.

8. An examination by a veterinary surgeon should be made at least once a year.

The Stable.

9. No stagnant water, hog-pen, privy or uncovered cesspool or manure pit should be maintained within 100 feet of the cow stable.

10. The cow stable should be provided with some adequate means of ventilation, either by the construction of sufficient air chutes extending from the room in which the cows are kept to the outside air, or by the installation of muslin stretched over the window openings.

11. Windows should be installed in the cow barn to provide sufficient light (2 sq. feet of window light to each 600 cubic feet of air space the minimum) and the window panes be washed and kept clean.

12. There should be at least 600 cubic feet of air space for each cow.

13. Milch Cows should be kept in a place which is used for no other purpose.

14. Stable floors should be made water-tight, be properly graded and well drained, and be of some non-absorbent material. Cement or brick floors are the best, as they can be more easily kept clean than those of wood or earth.

15. The feeding troughs and platforms should be well lighted and kept clean at all times.

16. The ceiling should be thoroughly swept down and kept free from hanging straw, dirt and cobwebs.

17. The ceiling must be so constructed that dust and dirt therefrom shall not readily fall to the floor or into the milk. If the space over the cows is used for storage of hay, the ceiling should be made tight to prevent chaff and dust from falling through.

18. The walls and ledges should be thoroughly swept down and kept free from dust, dirt, manure or cobwebs, and the floors and premises be kept free from dirt, rubbish and decaying animal or vegetable matter at all times.

19. The cow beds should be so graded and kept that they will be clean and sanitary at all times.

20. Stables should be whitewashed at least twice a year unless the walls are painted or are of smooth cement.

21. Manure must be removed from the stalls and gutters at least twice daily. This must not be done during milking, nor within one hour prior thereto.

22. Manure should be taken from the barn, preferably drawn to the field. When the weather is such that this cannot be done, it should be stored not nearer than 200 ft. from the stable and the manure pile should be so located that the cows cannot get at it.

23. The liquid matter should be absorbed and removed daily and at no time be allowed to overflow or saturate the ground under or around the cow barn.

24. Manure gutters should be from six to eight inches deep, and constructed of concrete, stone or some non-absorbent material.

25. The use of land plaster or lime is recommended upon the floors and gutters.

26. Only bedding which is clean, dry and absorbent should be used, preferably sawdust, shavings, dried leaves or straw. No horse manure should be used as bedding.

27. The flooring where the cows stand should be so constructed that all manure may drop into the gutter and not upon the floor itself.

28. The floor should be swept daily. This must not be done within one hour prior to milking time.

29. If individual drinking basins are used for the cows, they should be frequently drained and cleaned.

30. All live stock other than cows should be excluded from the room in which the milch cows are kept. (Calf or bull pens may be allowed in the same room if kept in the same clean and sanitary manner as the cow beds.)

31. The barnyard should be well drained and dry, and should be as much sheltered as possible from the wind and cold. Manure should not be allowed to collect therein.

32. A suitable place in some separate building should be provided for the use of the cows when sick, and separate quarters must be provided for the cows when calving.

33. There should be no direct opening from any silo or grain pit into the room in which the milch cows are kept.

The Milk House.

34. A milk house must be provided which is separated from the stable and dwelling. It should be located on elevated ground, with no hog-pen, privy or manure pile within 100 feet.

35. It must be kept clean and not used for any purpose except the handling of milk.

36. The milk house should be provided with sufficient light and ventilation, with floors properly graded and made water-tight.

37. It should be provided with adjustable sashes to furnish sufficient light and some proper method of ventilation should be installed.

38. The milk house should be provided with an ample supply of clean water for cooling the milk, and if it is not a running supply, the water should be changed twice daily. Also a supply of clean ice should be provided to be used for cooling the milk to 50 degrees within two hours after milking.

39. Suitable means should be provided within the milk house, to expose the milk pails, cans and utensils to the sun or to live steam.

40. Facilities consisting of wash basins, soap and towel should be provided for the use of milkers before and during milking. During the Summer Months the Milk House should be properly screened to exclude flies.

The Milkers and Milking.

41. Any person having any communicable or infectious disease, or one caring for persons having such disease, must not be allowed to handle the milk or milk utensils.

42. The hands of the milkers must be thoroughly washed with soap and water, and carefully dried on a clean towel before milking.

43. Clean overalls and jumpers should be worn during the milking of the cows. They should be used for no other purpose, and when not in use should be kept in a clean place protected from dust.

44. The hands and teats should be kept dry during milking. The practice of moistening the hands with milk is to be condemned.

45. The milking stools should be at all times kept clean, and iron stools are recommended.

46. The first streams from each teat should be rejected, as this fore milk contains more bacteria than the rest of the milk.

47. All milk drawn from the cows 15 days before, or 5 days after parturition should be rejected.

48. The pails in which the milk is drawn should have as small an opening at the top as can be used in milking; top opening preferably not to exceed 8 inches in diameter. This lessens the contamination by dust and dirt during milking.

49. The milking should be done rapidly and quietly, and the cows should be treated kindly.

50. Dry fodder should not be fed to the cows during or just before milking, as dust therefrom may fall into the milk.

51. All milk utensils, including pails, cans, strainers, and dippers, must be kept thoroughly clean and must be washed and scalded after each using, and all seams in these utensils should be cleaned, scraped and soldered flush.

The Milk.

52. Milk from diseased cows must not be shipped.

53. The milk must not be in any way adulterated.

54. The milk as soon as drawn should be removed to the milk house and immediately strained and cooled to the proper temperature.

55. All milk must be cooled to a temperature below 50 degrees F., within two hours after being drawn, and kept thereafter below that until delivered to the creamery.

56. The milk should be strained into cans which are standing in ice water which reaches the neck of the can. The more rapidly the milk is cooled, the safer it is, and longer it will keep sweet. Ice should be used in cooling milk, as very few springs are cold enough for the purpose.

57. If aerators are used, they should stand where the air is free from dust or odors, and on no account should they be used in the stable or out of doors.

58. Milk strainers should be kept clean; scalded a second time just before using, and if cloth strainers are used, several of them should be provided, in order that they may be frequently changed during the straining of the milk.

59. The use of any preservative or coloring matter is adulteration, and its use by a producer or shipper will be a sufficient cause for the exclusion of his product from the City of New York.

Water Supply.

60. The water supply used in the dairy and for washing utensils should be absolutely free from any contamination, sufficiently abundant for all purposes, and easy to access.

61. This supply should be protected against flood or surface drainage.

62. The privy should be located not nearer than 100 feet of the source of the water supply, or else be provided with a water-tight box that can be readily removed and cleaned, and so constructed that at no time will the contents overflow or saturate the surrounding ground.

63. The source of the water supply should be rendered safe against contamination by having no stable, barnyard, pile of manure or other source of contamination located within 200 feet of it.

In order that the farm inspection shall be as effective as possible, and to make the work of the several inspectors as uniform as may be, the dairies are scored. A copy of the score card follows.

DEPARTMENT OF HEALTH

The City of New York

=Division of General=
=Sanitary Inspection= =Dairy Report=

Inspection No. ... Time...... A. P. M. Date......191..

1 =Dairyman=.................. =Owner= .....................
2 =P. O. Address=............. =P.O. Address=.......State...
3 =County=..... State..... =Party Interviewed=............
4 Milk delivered to Creamery at.......... Formerly at.........
5 Operated by.................. Address.......................
6 Distance of farm from Creamery..... Occupied farm since.....
7 No. Cows....... No. Milking...... No. Qts. Produced.........
8 All persons in the households of those engaged in producing
or handling milk are............free from all infectious
disease. Weekly reports are..................being filed
..........................................................
9 Date and nature of last case on farm........................
10 =WATER SUPPLY= for utensils is from a............... located
.......... feet deep and apparently is............ pure and
wholesome............ State any possible contamination
located within 200 feet of source of water supply or
if water supply is not protected against surface drainage
...........................................................
...........................................................
11 Water supply on this farm analyzed.... 191.. Result........
12 Style of Cow Barn.... Length.... ft. Width.... ft. Height
of ceiling.... ft.
13 =Dairy Rules= of the Department of Health are........ posted
..................
14 =Dairy Herd= examined by............. on.............. 191..
Report............

=================================================================
|Perfect| Allow |
-----------------------------------------------------------------
EQUIPMENT | | |
| | |
15 =COW STABLE= is.......located on elevated | | |
ground with no stagnant water, hog-pen, | | |
privy, uncovered cesspool or manure pit | | |
within 100 feet | 1 | ..... |
| | |
16 =FLOORS=, other than cow beds, are | | |
of concrete or some non-absorbent material | 2 | ..... |
| | |
17 Floors are...properly graded and water-tight | 2 | ..... |
| | |
18 =Cow beds are=...of concrete or planks | | |
laid on concrete | 2 | ..... |
| | |
19 =DROPS= are.....constructed of concrete, | | |
stone or some non-absorbent material | 2 | ..... |
| | |
20 Drops are......water-tight and space beneath | | |
is clean and dry. | 2 | ..... |
| | |
21 =CEILING= is constructed of.......and is | | |
tight and dust proof | 2 | ..... |
| | |
22 =WINDOWS= No.......total square feet | | |
there is...........2 square feet of window | | |
light for each 600 cu. ft. air space (1 | | |
sq. ft. per each 600 cu. ft.--1) | 2 | ..... |
| | |
23 =VENTILATION= consists of ......sq. ft. muslin| | |
in ceiling or..........which is sufficient | | |
3, fair 2, poor 1, insufficient 0 | 3 | ..... |
| | |
24 =AIR SPACE= is......cu. ft. per cow (600 and | | |
over--3) (500 to 600--2) (400 to 500--1) | | |
(under 400--0) | 3 | ..... |
| | |
25 =LIVE STOCK=, other than cows, are....excluded| | |
from rooms in which milch cows | | |
are kept | 2 | ..... |
| | |
26 There is..........direct opening from stable | | |
into silo or grain pit | 1 | ..... |
| | |
27 Separate quarters are...........provided for | | |
cows when calving or sick | 1 | ..... |
| | |
28 =COW YARD= is..............properly graded and| | |
drained | 2 | ..... |
| | |
29 =WATER SUPPLY= for cows is..........unpolluted| | |
and plentiful | 1 | ..... |
| | |
30 =MILK HOUSE= has...........direct opening into| | |
cow barn or other building | 1 | ..... |
| | |
31 Milk house has..........sufficient light and | | |
ventilation | 1 | ..... |
| | |
32 Floor is.................properly graded and | | |
water-tight | 1 | ..... |
| | |
33 Milk house is...........properly screened to | | |
exclude flies | 1 | ..... |
| | |
34 Milk pails are............of smoothly tinned | | |
metal in good repair | 1 | ..... |
| | |
35 =MILK PAILS= have...........all seams soldered| | |
flush | 2 | ..... |
| | |
36 Milk pails are..........of the small mouthed | | |
design, top opening not exceeding 8 inches | | |
in diameter. Diameter | 2 | ..... |
| | |
37 =Racks are=........provided to hold milk pails| | |
and cans when not in use | 2 | ..... |
| | |
38 =Special milking suits= are......provided | 1 | ..... |
|-------|-------|
| 40 | |
| | |
=METHODS= | | |
| | |
39 =STABLE INTERIOR= painted or whitewashed | | |
on.......which is satisfactory 3, fair 2, | | |
unsatisfactory 1, never 0 | 3 | ..... |
| | |
40 =FEEDING TROUGHS=, platforms or cribs are | | |
......well lighted and clean | 1 | ..... |
| | |
41 =Celling= is..........free from hanging straw,| | |
dirt or cobwebs | 3 | ..... |
| | |
42 =Window panes= are.............washed and kept| | |
clean | 1 | ..... |
| | |
43 =WALLS AND LEDGES= are...............free from| | |
dirt, dust, manure or cobwebs | 2 | ..... |
| | |
44 =FLOORS AND PREMISES= are.......free from | | |
from dirt, rubbish or decayed animal or | | |
vegetable matter | 2 | ..... |
| | |
45 =COW BEDS= are.........clean, dry and no horse| | |
manure used thereon | 2 | ..... |
| | |
46 =Manure= is.......removed to field daily 4, | | |
to at least 100 feet from barn 2, stored | | |
less than 100 feet or where cows can get | | |
at it 0 | 4 | ..... |
| | |
47 =Liquid Matter= is....... allowed to saturate | | |
ground under or around cow barn | 2 | ..... |
| | |
48 =Milking stools= are.......clean | 1 | ..... |
| | |
49 =Cow Yard= is.......clean and free from | | |
manure | 2 | ..... |
| | |
50 =COWS= have......been tuberculin tested and | | |
all tuberculous cows removed | 7 | ..... |
| | |
51 Cows are.....all in good flesh and condition | | |
at time of inspection | 2 | ..... |
| | |
52 Cows are.....all free from clinging | | |
manure and dirt. (No. dirty.....) | 4 | ..... |
| | |
53 =LONG HAIRS= are.....kept short on belly, | | |
flanks, udder and tail | 1 | ..... |
| | |
54 =UDDER AND TEATS= of cows are...... | | |
thoroughly brushed and wiped with a | | |
clean damp cloth before milking | 3 | ..... |
| | |
55 =ALL FEED= is.....of good quality and | | |
distillery waste or any substance in a state | | |
of putrefaction is......fed | 2 | ..... |
| | |
56 =MILKING= is.....done with dry hands | 2 | ..... |
| | |
57 =FORE MILK= or first few streams from each | | |
teat is.....discarded | 2 | ..... |
| | |
58 =Clothing= of milkers is.....clean | 1 | ..... |
| | |
59 Facilities for washing hands of milkers are | | |
......provided in cow barn or milk | | |
house | 2 | ..... |
| | |
60 =Milk= is strained at.....and.....in | | |
clean atmosphere | 1 | ..... |
| | |
61 Milk is.....cooled within two hours after | | |
milking to 50 degrees F. 3, to 55 degrees | | |
F. 2 to 60 degrees F. 1 | 3 | ..... |
| | |
62 Ice is.....used for cooling milk | 1 | ..... |
| | |
63 =MILK HOUSE= is.....free from dirt, rubbish | | |
and all material not used in the | | |
handling and storage of milk | 1 | ..... |
| | |
64 =Milk utensils= are.....rinsed with cold | | |
water immediately after using and washed | | |
clean with hot water and washing solution | 2 | ..... |
| | |
65 Utensils are.....sterilized by steam or | | |
boiling water after each using | 2 | ..... |
| | |
66 =Privy= is.....in sanitary condition, with | | |
vault and seats.....covered and protected | 1 | ..... |
| | |
|-------|-------|
| 60 | |

Remarks

Equipment 40 per cent. Score .... per cent
Methods 60 per cent. Score .... per cent
Perfect Dairy 100 per cent. Score .... per cent

A copy of the completed report is left with the dairyman.

Before the farm inspection is carried out the creameries to which the milk is delivered by the farmers are inspected at the time the milk is being delivered. The temperature of the milk and its cleanliness are noted. In the creamery the straining, cooling and handling of the milk are observed as well as the washing of the milk cans and other utensils, and the construction and condition of the creamery, the opportunity for the water supply to become contaminated, and the presence of infectious diseases among the employees.

=Grades of milk.= Three grades of milk have been established. Each dealer is required to state which grade or grades he expects to handle. The specifications for the different grades are as follows.

_Grade A. Guaranteed Milk._ Guaranteed milk is that produced at farms holding permits therefor from the Department of Health and produced and handled in accordance with the following minimum requirements, rules and regulations:

1. Only such cows shall be admitted to the herd as have not re-acted to a diagnostic injection of tuberculin.

2. All cows shall be annually tested with tuberculin, and all re-acting animals shall be excluded from the herd.

3. No milk from re-acting animals shall be shipped to the City of New York for any purpose whatever.

4. The milk shall not contain more than 30,000 bacteria per c. c. when delivered to the consumer, or at any time prior to such delivery.

5. The milk shall be delivered to the consumer only in sealed bottles, which have been sealed at the dairy.

6. The milk shall be delivered to the consumer within 30 hours of the time at which it was drawn.

_Grade A. Certified Milk._ Certified milk is milk certified by a milk commission appointed by the Medical Society of the County of New York, or the Medical Society of the County of Kings, as being produced under the supervision and in conformity with the requirements of that commission as laid down for certified milk, and sold under a permit therefor issued by the Board of Health.

No milk shall be held, kept, offered for sale, or sold and delivered as certified milk in the City of New York which is produced under requirements less than those for guaranteed milk.

_Grade A. Inspected Milk--Raw._ Inspected milk (raw) is milk produced at farms holding permits therefor from the Board of Health, and produced and handled in accordance with the following minimum requirements, rules and regulations:

1. Only such cows shall be admitted to the herd as have not re-acted to a diagnostic injection of tuberculin.

2. All cows shall be tested annually with tuberculin, and all re-acting animals shall be excluded from the herd.

3. No milk from re-acting animals shall be shipped to the City of New York for any purpose whatsoever.

4. The farms at which the milk is produced must obtain at least 75 points in an official score of the Department of Health. These 75 points shall be made up as follows: A minimum of 25 points for equipment, and 50 points for method.

5. The milk shall not contain more than an average of 60,000 bacteria per c. c. when delivered to the consumer, or at any time prior thereto.

6. Unless otherwise specified in the permit, the milk shall be delivered to the consumer only in bottles.

_Grade A. Selected Milk--Pasteurized._ Selected milk (pasteurized) is milk produced at farms holding permits therefor from the Board of Health, and produced and handled in accordance with the following requirements, rules and regulations:

1. The farms at which the milk is produced must obtain at least 60 points in an official score of the Department of Health. Of these 60 points, a minimum of 20 points shall be required for equipment and a minimum of 40 points for method.

2. All milk of this grade shall be pasteurized, and said pasteurization shall be carried on under a special permit issued therefor by the Board of Health, in addition to the permit for "Selected Milk (Pasteurized.)"

3. The milk shall not contain more than an average of 50,000 bacteria per c. c. when delivered to the consumer, or at any time after pasteurization and prior to such delivery.

4. Unless otherwise specified in the permit, the milk shall be delivered to the consumer only in bottles.

5. All containers in which pasteurized milk is delivered to the consumer shall be plainly labeled "Pasteurized." Labels must also bear the date and hour when pasteurization was completed, the place where pasteurization was performed, and the name of the person, firm or corporation performing the pasteurization.

6. The milk must be delivered to the consumers within 30 hours after the completion of the process of pasteurization.

7. No milk shall be pasteurized more than once.

8. No milk containing in excess of 200,000 bacteria per c. c. shall be pasteurized.

_General Regulations for Grade A_--

1. The caps of all bottles containing milk of Grade A shall be white, and shall contain the words "Grade A" in black letters, in large type.

2. If cans are used for the delivery of milk for Grade A, the said cans shall have affixed to them white tags, with the words "Grade A" printed thereon in black letters, in large type, together with the designation "Inspected Milk (Raw)" or "Selected Milk (Pasteurized)," as the quality of the contents may require.

_Grade B. Selected Milk--Raw._ Selected milk (raw) is milk produced at farms holding permits therefor from the Board of Health, and produced and handled in accordance with the following minimum requirements, rules and regulations:

1. Only such cows shall be admitted to the herd as have been physically examined by a regularly qualified veterinarian and declared by him to be healthy, and free from tuberculosis in so far as a physical examination may determine that fact.

2. The farms at which the milk is produced must obtain at least 68 points in an official score of the Department of Health. These 68 points shall be made up as follows: A minimum of 25 points for equipment, and a minimum of 43 points for method.

3. The milk shall not contain an excessive number of bacteria when delivered to the consumer, or at any time prior thereto.

_Grade B. Pasteurized Milk._ Pasteurized milk (Grade B) is milk produced under a permit issued therefor by the Board of Health, and produced and handled in accordance with the following minimum requirements, rules and regulations and in further accordance with the special rules and regulations relating to the pasteurization of milk.

1. The milk after pasteurization must be at once cooled and placed in sterilized containers, and the containers immediately closed.

2. All containers in which pasteurized milk is delivered to the consumer shall be plainly labeled "Pasteurized". Labels must also bear the date and hour when the pasteurization was completed, the place where pasteurization was performed, and the name of the person, firm or corporation performing the pasteurization.

3. The milk must be delivered to the consumer within 36 hours after the completion of the process of pasteurization.

4. No milk shall be pasteurized more than once.

5. No milk containing an excessive number of bacteria shall be pasteurized.

_General Regulations for Grade B_--

1. Caps of bottles containing milk of grade B shall be white and marked "Grade B" in bright green letters of large type.

2. The necks and shoulders of cans containing grade B milk shall be painted bright green, and a metal tag shall be attached to each can with the words "Grade B" in large type, and the words of the subdivision to which the quality of the milk in said can conforms.

_Grade C._ Grade C is to be used for cooking and manufacturing purposes only. It includes all raw milk that does not conform to the requirements of any of the subdivisions of grade A or grade B.

1. The caps of all bottles containing milk of grade C shall be white and shall contain in red the words "Grade C" in large type and "for cooking" in plainly visible type.

2. Cans containing milk of grade C shall be painted red on necks and shoulders and shall have in red the words "Grade C" in large type and the words "for cooking" in plainly visible type affixed to each can.

All creameries handling milk of different grades will be required to demonstrate to the Department of Health that they are capable of keeping the grades separate, and must keep records satisfactory to the Department of Health concerning the amount of milk of each grade handled each day.

It is to be noted that the grades of milk are based on the bacterial content of the milk and on the opportunity for the milk to become contaminated with pathogenic organisms. From the statements made in a previous chapter it is evident that the number of bacteria in any sample of milk is dependent upon (1) the original amount of contamination, (2) the age of the milk, and (3) the temperature at which it has been held. A high bacterial content is indicative of poor milk, while a low bacterial content can be obtained, in the case of raw milk, only where due attention is paid to cleanliness and cooling. This relation between the quality of milk and its bacterial content has led many cities to adopt numerical bacterial standards, even when grades of milk have not been established. Boston requires that the milk shall not contain more than 500,000 bacteria per cubic centimeter. Rochester, N. Y., has a standard of 100,000 per cubic centimeter, while Chicago requires that the milk on arrival in the city shall not contain more than 1,000,000 per cubic centimeter from May first to September thirtieth, and not over 500,000 between October first and April thirtieth. The sale of milk containing more than 3,000,000 bacteria per cubic centimeter is prohibited.

It has been urged that bacterial standards are not of value since the healthfulness of milk depends on the kind of bacteria present rather than on the number. It is well recognized that milk containing millions of acid-forming organisms, butter milk, is a healthful food, while that containing many less bacteria may contain some disease-producing organisms. It has been urged that a qualitative standard should supplant the quantitative. The consumer desires milk that has been produced under clean conditions, and which has good keeping qualities. The harmless forms of bacteria exert the greatest influence on the keeping quality. Experience has shown that the quantitative examination of the milk supply as it comes from the farm is the most feasible method of determining, in the laboratory, whether the farmer has obeyed the rules with reference to cleanliness and cooling of the milk. The bacteriological examination also gives an indication as to whether the large number of bacteria is due to gross contamination of the milk with mud and manure, or actual growth of bacteria as in old milk. In the latter case the ordinary acid-forming bacteria will usually predominate in the milk, while in the former, the number of kinds of bacteria and the proportion between the kinds will be changed. It is of course evident that the quantitative standards should be applied with judgment.

It is also claimed that the delay in securing the results in the quantitative examination of milk is an objection to the bacterial standard, since the milk is consumed before the laboratory findings can be obtained. It is true that it does not protect the community as far as the particular sample is concerned, but it is also true that the examination is not made for the purpose of determining the condition of the particular sample, so much as it is to determine the methods that are employed on any particular farm, and these do not vary widely from day to day. Thus, if a number of samples give high results, it is evident that conditions surrounding production need investigation.

If the milk is well cooled on the farm, and kept cold while being shipped, the growth of bacteria will be slow, and the condition of the milk as far as keeping quality is concerned, much better than if less care is used. Some cities have temperature standards; New York requires that the milk shall be cooled to 50 deg. F. on the farm, and shall not be above 50 deg. F. on arrival in the city. Others require that it shall not be above 50 deg. F. on delivery to the consumer.

=Certified milk.= In many cities the Medical Societies have appointed Milk Commissions, that adopt rules and regulations, concerning the production of milk that shall receive the certificate of the commission. Producers, who desire to have their milk thus certified, must satisfy the commission that they are able to conform to the rules. The commission appoints a physician to examine the personnel of the farm, a veterinarian to make frequent examinations of the herd, a chemist to examine the milk as to its contents in fat and other solids, and a bacteriologist to determine the bacterial content of the milk. The rules are very stringent and cover every point that may influence, in any way, the value of the milk as human food. In order to conform to these requirements, a heavy expenditure must be incurred, and the business must pay for such expert service; hence, certified milk must be sold at high prices, twelve to twenty-five cents per quart. This price makes it a special product and its use is confined mainly to infant feeding.

The bacterial standard for certified milk is usually 10,000 bacteria per cubic centimeter. It is only by the exercise of the greatest care at every point that the bacterial content can be kept below this maximum.

The term "certified milk" has been registered by Mr. Francisco of New Jersey, who was the first to engage in the production of such milk under the direction of the Medical Milk Commission of Essex County, New Jersey. The use of the term is allowed when the milk is produced under the regulation of any Medical Milk Commission.

Most certified milk is now produced on fancy dairy farms conducted by wealthy men. The barns and other equipment are the best that can be obtained, and the methods employed, as far as cleanliness is concerned, are extreme. In some of the dairies the bacterial content is reduced to a few hundred per cubic centimeter, or to that which is derived from the interior of the udder. Such milk will, when well refrigerated, keep for long periods of time. It is a not uncommon thing for such milk to keep perfectly sweet for ten to fifteen days.

=Tests for the quality of milk.= At the milk depot and elsewhere, it is frequently desired to determine the bacterial condition of the milk in a less refined manner than by the plate cultures of the bacteriologist, which require a large amount of time for their preparation and do not yield any positive information for at least twenty-four hours. There are a number of such tests that may be applied.

In the use of the apparatus on the right, increased air pressure is used to hasten the filtering process; the same is accomplished in the apparatus shown in the center by warming the milk by the injection of steam between the walls of the double jacket.]

1. _Dirt or sediment test._ This is made by filtering a pint of the mixed milk through a small disc of absorbent cotton. The insoluble dirt is retained and imparts a color to the cotton, the shade of which is dependent on the amount of dirt (P. 45). Since it is impossible to have dirt without bacteria, it is evident that milks containing a large amount of dirt will be high in bacteria. The reverse, however, is not necessarily true.

A plate culture inoculated with 1/100 of a cubic centimeter of milk containing 67 colonies, which equals 6,700 bacteria per cubic centimeter of milk. Such milk will keep well.]

2. _Acidity test._ The acidity of the milk is also an indication of its bacterial content. If the acidity has increased, above the normal for fresh milk, the bacterial content is certain to be high, and the keeping quality poor. An acidity above 0.2 per cent in market milk is to be avoided, as an increase in acidity is always preceded by a great increase of bacteria.

Whether the acidity is above or below this point can be rapidly and easily determined at the receiving station by a modification of the Farrington acid test. Dissolve one alkaline tablet in an ounce of water. A unit volume of this solution added to a unit volume of milk is equal to 0.1 per cent of acidity. If two measures are provided,--one for the alkaline solution holding just twice as much as that used for the milk, the approximate acidity can be quickly determined by mixing a measure of each in a common white cup. If the acidity is above 0.2 per cent the color will remain white; if a pink color develops, it indicates an acidity less than this amount. This test is also useful in the selection of milk or cream that is to be used for special purposes, such as pasteurization.

A plate culture inoculated with 1/1000 of a cubic centimeter of market milk containing 1,680 colonies, which equals 1,680,000 bacteria per cubic centimeter. Such milk has poor keeping qualities.]

3. _Alcohol test._ A test giving similar information is made by adding two parts of 70 per cent alcohol to one part of milk, and noting whether curdling occurs.

4. _Curd test._ The curd test described on p. 100 gives no indication of the number of bacteria present, only concerning the types present. It has been proposed to combine the fermentation test with the reduction test referred to below and thus gain some idea of, not only the number, but the kinds of bacteria present.

5. _Reduction test._ The reduction test is made by adding to twenty cubic centimeters of milk, one-half cubic centimeter of a solution of methylene blue, a coal tar dye. A saturated solution of the dye is made in alcohol, and 2.5 per cent of this solution added to water. The time required for the reduction of the dye or the change of the color from blue to white when the samples are placed in tubes and kept at 98 to 100 deg. F., is dependent upon the number of bacteria present. By allowing the tubes to stand until curdling occurs, and noting the nature of the curd, whether the solid curd of the desirable acid-forming bacteria or the gassy curd of the harmful types is produced, knowledge is gained of the kinds of bacteria present.

According to Barthel, milks that reduce the methylene blue within fifteen minutes contain hundreds of thousands of bacteria per cubic centimeter. Those that require from fifteen minutes to one hour for the disappearance of the color are also high in bacteria, and are to be classed as a poor grade of market milk. If one to three hours is required, the milk is comparatively low in bacteria, and is to be classed as a good grade of market milk. When more than three hours elapse before the disappearance of the blue color, the bacterial content is low and the milk is to be placed in the highest grade.

The time of reduction is only a rough index of the number of bacteria present, but it gives a good idea of the keeping quality of the milk, and of the conditions of production and handling. Of the above tests the sediment and acid tests are more frequently used.

=Examination of milk sediments.= In the modern municipal laboratory, efforts are made to determine, as far as possible, the conditions of production on the farms, by an examination of the milk in the laboratory. The samples of milk are sedimented in a small centrifuge, and an examination of the sediment made with the microscope. The types of bacteria and the number of body cells found is an indication as to whether any of the animals of the herd are suffering from inflammation of the udder. The test also gives information similar to the dirt test since the insoluble dirt will be thrown down and will impart a color to the sediment.

=Pasteurization of market milk.=.The spread of the pasteurizing process as applied to market milk has been rapid. This has been due to the recognition of the fact that only by this process can a safe milk _i.e._, one free from pathogenic bacteria, be obtained. As previously mentioned a small proportion of all human beings that have suffered from typhoid fever become bacillus carriers. It is impossible to examine all persons who may be concerned in the handling of milk in order to ascertain whether they belong to this dangerous and unfortunate class of people.

The larger cities have also recognized the impossibility of requiring the tuberculin test of all cattle furnishing milk. Pasteurization remains the only safeguard, and it is probable that within a short time all the larger cities will require the pasteurization of all milk, except that produced under strict supervision.

As previously mentioned heating causes certain changes in milk. In the treatment of market milk it is desirable to use as low temperatures as will suffice to destroy the disease-producing bacteria. It is fortunate that temperatures that will insure this result have little effect on the milk. The temperatures now recommended for pasteurization are as follows:

158 degrees F. for 3 minutes.
155 degrees F. for 5 minutes.
152 degrees F. for 10 minutes.
148 degrees F. for 15 minutes.
145 degrees F. for 18 minutes.
140 degrees F. for 20 minutes.

In actual practice the milk is heated to 145 degrees for 25 to 30 minutes. The acid-forming bacteria are not completely destroyed and the pasteurized milk as a rule will undergo the same type of fermentation as raw milk. It is, however, deemed essential that all pasteurized milk be sold as such; that it be delivered to the consumer within twenty-four hours after pasteurization and that no milk be pasteurized a second time.

The continuous pasteurizing machines have the disadvantage that a small portion of the milk passes through so quickly that all pathogenic bacteria therein might not be destroyed, (p. 131). This has led to the use of the "holding" process in which the milk is heated to the desired temperature and then placed in tanks where it remains at this temperature for any desired time. Every portion is thus treated in a uniform manner.

If the milk is bottled after pasteurization, there remains opportunity for reinfection, possibly with typhoid bacilli. Pasteurization in the final container, the bottle, is being recommended. This is possible only when a special bottle is used with a metal cap lined with paper.

=Milk distribution.= Until within recent years in the cities and at present in smaller towns, milk is largely retailed from cans which are carried on the wagons or are kept in stores. This exposes the milk to contamination from street dust and from the container furnished by the consumer. It is well recognized that every utensil with which milk is brought in contact adds more or less bacteria to it, and the less milk is handled, the better will be its condition when it reaches the consumer. Milk is now largely retailed in glass bottles which are closed with pulp caps. In some cities the bottling is mainly done in the country at the bottling station to which the milk is brought by the farmers; or it may be shipped by the producer to a distributing company, and all subsequent treatment, as pasteurization and bottling done in the city.

Milk plants are now generally equipped for the rapid and economical handling of large quantities of milk in a most sanitary manner. The bottles as they are returned from the consumer are washed in a continuously-acting automatic washer which washes, rinses and sterilizes the bottles without their being removed from the cases in which they are carried on the wagons. These machines are effective, if not run at too rapid a rate, so that the bottles are not exposed for a sufficiently long period of time to sterilize them. The bottles are then filled and the paper caps inserted by machinery. The caps can now be obtained from the manufacturers in sealed tubes in which they have been sterilized so that the contamination from this source is avoided. The shipping cans are washed and sterilized with live steam, and in many plants are thoroughly dried, by passing hot air into them. Under these conditions they then reach the farmer with none of the musty and disagreeable odor that frequently is present when the can contains a small quantity of water, condensed from steam.

The top of the milk bottle over which the milk is poured is exposed to contamination from the hands of the deliveryman. Trouble from this source can be avoided if the consumer cleans the lip of the bottle before removing the cap. The better grades of milk are dispensed in bottles, the top of which is protected by an additional cover of paper or tin foil which reaches to the neck of the bottle and is held in place by a crimped metal band.

=Milk supply of the small cities.= It is true that the quality of milk supplied to the large cities by the great milk companies is generally much superior to that sold in the smaller cities and villages. Many of the smaller places are however, attempting in various ways to improve their supply. It is evident that methods will be successful here that can not be employed in the larger places. A detailed and careful farm inspection by a tactful, capable inspector, coupled with proper publicity will do much to improve conditions. The publication of the scores of the different farms, and the demonstration of the sediment test as applied to their product attracts favorable attention to the good dairies and unfavorable attention to the poor. This usually has an effect on the trade sufficient to cause the negligent producer and dealer to improve.

It is also becoming recognized that high grade milk can be produced with very simple equipment. In fact the small farm is often more successful in producing high grade milk than is the large farm on which the work must be done by hired help for here the personality of the owner can not make itself felt as where the producer is doing a portion of the work about the barn and dairy himself. It is becoming more and more evident that the chief factor in the production of clean milk is the personality of the producer; he should be one who gets enjoyment out of his clean stables and cows and his high grade product.

The man who is producing milk for the city market is but one of many and his individual efforts can not make themselves felt. The dairyman who is marketing his own product is in a position where his efforts to produce a fine product should prove of distinct advantage to him in enabling him to sell it for a higher price than that obtained for ordinary milk.

It should be remembered that the production of clean, healthful milk is not a question of equipment, but of methods and of additional work. The cows must be fed, the stables must be cleaned, the cows milked, and the milk delivered to the consumer. If beyond this unavoidable labor a small additional amount is expended, the improvement in the product will be great. It is necessary that the additional work be placed where it will do the most good, in keeping the cows clean both summer and winter so that little need be done in cleaning them before milking, the pails and other utensils kept clean and sterilized, and the milk cooled as soon as possible and kept cold until delivered to the consumer. The delivery should be made within the shortest practicable time after the milk is drawn. In order that the healthfulness of the milk may be beyond question, the herd must be kept free from tuberculosis and some attention should be paid to the health of the men, especially with reference to whether they may be typhoid carriers or not. The necessary labor should not increase the cost of the milk over one cent per quart. It has been shown in many cases that such a product can be marketed at a price that will more than compensate for the additional cost. Clean, fresh, rich milk is being sold in villages and small cities located in the great butter and cheese producing sections of the country for eight to ten cents per quart.

=The duty of the consumer.= The educational campaign that has been carried on by the health departments with reference to farm conditions and methods of handling has been most effective in improving the milk supply. Many cities are now extending this to the consumer, recognizing that as much harm may be done in the home as on the farm. The importance of keeping the milk cold, of not allowing it to stand exposed in open vessels, of thoroughly cleaning the vessel in which it is kept, or the milk bottle before returning it to the milkman are especially emphasized.

Moreover, it must be impressed upon the consumer that all of these improvements, not only on the farm where the milk is produced, but in the hands of the distributing companies in the cities, involve much expense, and cannot be carried out, unless the consumer is willing to pay their cost. More objection seems to be raised over an increase in the price of milk than any other food stuff. The consumer therefore needs education along the line of higher prices for milk. Dairy products of all types have increased much in value in recent years, so that at present prices milk, sold directly as milk, is relatively cheaper than in any form, when prevailing prices are compared with those that obtained a decade ago.

INDEX.

Abnormal fermentations, overcoming of, 108.

Abortion, contagious, 75.

Acid, amount of formed in milk, 84.

Acidity test, 211.

Actinomycosis, 75.

Aeration of milk, 55.

Aerobic bacteria, 13.

Air, contamination of milk from, 51.

Alcohol test, 213.

Alcoholic fermentation, 96.

Anaerobic bacteria, 13.

Animal, contamination of milk from, 42.

Anthrax, 75.

Antiseptics, 16, 117.

B.

Bacillus Bulgaricus, 89, 101.

Bacillus lactis acidi, 86.

Bacteria, aerobic, 13;
anaerobic, 13;
culture media for, 20;
desirable acid-forming, 86;
determining number of, 22;
distribution of, 18;
effect of cold on, 14;
effect of heat on, 15;
food of, 12;
forms of, 8;
manner of growth of, 9;
movement of, 11;
nature of, 8;
parasitic, 11;
products of, 17;
pure cultures of, 25;
rate of growth of, 13;
relation to air, 13;
relation to chemicals, 16;
relation to drying, 15;
relation to light, 16;
relation to temperature, 12;
size of, 9;
saprophytic, 11;
spores of, 10;
types of acid-forming, 86;
undesirable acid-forming, 90.

Bedding, 47.

Bitter fermentation, 97.

Bleaching powder, 112.

Bloody milk, 99.

Butter, bacteria in, 154;
bacterial defects in, 156;
cowy odor in, 157;
deterioration of, 155;
fishy, 157;
metallic, 157;
molding of, 157;
preservatives in, 155;
putrid, 156;
source of flavor, 140;
turnip flavored, 156;
types of, 137.

Butter-milk, 100.

Butyric fermentation, 93.

Boric acid, 117.

Borax, 117.

C.

Carbolic acid, 111.

Cheese, abnormal fermentations of, 174;
bitter, 177;
Camembert, 186;
Cheddar, 164;
colored, 178;
flavor production in, 172;
gassy, 174;
Gorgonzola, 185;
Limburger, 187;
moldy, 179;
preservation of by acid, 171;
putrid, 178;
quality of milk for, 162;
ripening of, 169;
Roquefort, 184;
Stilton, 185;
Swiss, 180;
temperature of ripening, 173;
types of, 161.

Children, diseases of, 80.

Chloride of lime, 112.

Cholera, 80.

Cleaning utensils, 39.

Clean milk, production of, 53.

Cold, effect of, on bacteria, 14.

Colored milk, 98.

Condensed milk, 135.

Contagious abortion, 75.

Contamination of milk, from milking machine, 50;
in factory, 59.

Cooling of milk, 54.

Corrosive sublimate, 111.

Cream, control of fermentation of, 142;
pasteurization of, 146;
ripening of, 138;
separators, 36.

Cresol, 111.

Curd test, 104.

Cycle of fermentations, 99.

D.

Deodorants, 109.

Digestive fermentation, 93.

Diphtheria, 79.

Dirt, exclusion of, 44;
removal of from milk, 53.

Disinfectants, 16, 109.

Disinfection, 109.

Distribution of bacteria, 18.

Dried milk, 135.

Drugs, excretion of in milk, 58.

Drying, effect of on bacteria, 15.

E.

Emmenthaler cheese, 180.

Evaporated milk, 134.

F.

Factory by-products, 36;
treatment of, 38.

Feeds, effect of on milk, 57.

Fermentation test, 104.

Fermented milks, 100.

Fly, contamination of milk by, 60;
means of spreading typhoid fever, 78.

Foot and mouth disease, 74.

Fore milk, 31; rejection of, 34.

Formalin, 112.

G.

Galactase, 172.

Garget, 75.

Germicidal action of milk, 33.

Gorgonzola cheese, 185.

H.

Hairs, bacteria on, 43.

Heat, effect on bacteria, 15.

Heated milk, detection of, 39.

Hydrogen peroxide, 118.

K.

Kefir, 102.

Koumiss, 102.

L.

Lange Wei, 95.

Light, effect on bacteria, 16.

Limburger cheese, 187.

Lime, 110.

Lumpy jaw, 75.

M.

Malta fever, 75.

Market milk, municipal regulations concerning, 190;
pasteurization of, 214.

Milk, acid fermentation of, 83;
aeration of, 55;
affected by feed, 57;
alcoholic fermentation of, 96;
bacterial standards for, 206;
bitter fermentation of, 93;
certified, 202;
butyric fermentation of, 93;
certified, 202, 208;
clarifying of, 115;
condition of when secreted, 29;
contamination of from animal, 42;
from by-products, 36;
from utensils, 34;
contamination of with tubercle bacilli, 67;
cooling of, 54;
creaming of, 136;
culture medium for bacteria, 28;
cycle of fermentation in, 99;
distribution of, 216;
digestive fermentation of, 93;
dirt in, 44;
effect of heat on, 119;
filtration of, 114;
germicidal action of, 33;
grades of, 201;
guaranteed, 201;
inspected, 202;
miscellaneous fermentations of, 98;
pasteurization of, 120;
pasteurization of in home, 131;
preservation of by antiseptics, 117;
preservation of by cold, 116;
relation to children's diseases, 80;
ropy fermentation, 94;
sediments, examination of, 214;
selected, 203;
slimy, 94;
spontaneous fermentation of, 91;
sterilization of, 134;
straining of, 153;
supply of small cities, 217;
sweet curdling fermentation of, 92;
tainted, 56, 58;
temperature standards for, 208;
tests for quality of, 209.

Milk pails, sanitary, 48;
small topped, 48.

Milker, factor in contamination of milk, 51.

Milking-machines, 36, 50.

Mold on butter, 177;
on cheese, 179.

O.

Odors, absorption of, 56, 58.

Oidium lactis, 186.

Oleomargarine, 152.

P.

Pasteurization, 120;
efficiency of, 133;
purpose of, 123;
methods of, 125.

Pasteurized milk, fermentations in, 124.

Pasteurizing machines, tests of, 130.

Process butter, 152.

Ptomaine poisoning, 81.

Pure cultures, 25.

R.

Rabies, 75.

Reduction test, 213.

Rennet, 170.

Ropy fermentation, 94.

Roquefort cheese, 184.

Rusty spot in cheese, 178.

S.

Salicylic acid, 117.

Scarlet fever, 79.

Score card for dairies, 198.

Sediment test, 210.

Skim milk, heating of, 38.

Slimy fermentation, 94.

Spores of bacteria, 10.

Stalls, 46.

Starters, 143;
for cheese, 167;
propagation of, 146.

Sterilization, 21, 134.

Stilton cheese, 185.

Storch test, 39.

Straining of milk, 33.

Sulphur, 111.

Sweet curdling of milk, 92.

Swiss cheese, 180.

T.

Taints, determination of cause of, 58, 103.

Temperature effect on growth, 12.

Tubercle bacilli, destruction of, 71;
in butter, 70;
in cheese, 70;
in milk, 67.

Tuberculin test, 73.

Tuberculosis, 64;
closed, 70;
distribution of disease in animal, 66;
economic aspects of, 72;
open, 70.

Typhoid fever, 76.

U.

Udder, inflammation, 75;
invasion of by bacteria, 30;
number and kind of bacteria from, 32;
structure of, 30;
washing of, 47;
cleaning of, 39.

Utensils, contamination from, 34.

W.

Water, effect on butter, 153;
supply, 59;
testing of, 60.

Whey, heating of, 38.

Wisconsin curd test, 104.

Y.

Yeast fermentation, 96.

Yoghurt, 101.