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.
[Illustration: Fig. 39.--Sediment Testers.
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.
[Illustration: Fig. 40.--Good Milk.
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.
[Illustration: Fig. 41.--Poor Milk.
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.