Allen Paul W. Industrial Fermentations
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THE EQO INDUSTRY 355
The method of preserving eggs by packing them in water glass has
been successfully used for many years. The water glass sterilizes the
surface of the egg and hermetically seals the egg so that bacteria
cannot reach the interior of the egg.
Some other sealing methods have been employed in egg preservation
as wrapping eggs in waxed paper, coating with paraffin, varnishing
with collodion, etc., and coating with vaseline.
Of the methods tried out the use of a vaseline coating, packing in
lime water or water glass were the only ones which caused eggs to
remain unfermented according to the U. S. Dept. of Agriculture.
The use of vaseline was found to be too laborious and storage in
brae water gave a slight taste of lime water. It was found that the
use of water glass (solution of water glass in water 1:9) was most
efficient and practical; especially where a fairly low temperature of
storage is maintained and eggs are kept well covered with the solution.
The most satisfactory results are obtained when on]y the cleanest
eggs are used. Eggs which have been washed do not store well because
in washing the bacteria on the surface of the egg are carried into the
egg pores and readily find entrance into the egg. Eggs which are
cracked or have spots should also be eliminated as they have internal
contamination. Such eggs can be identified by candling. Infertile
eggs are better for storage than fertile ones.
REFERENCES ON EGG INDUSTRY.
Beckwith, T. D., and Hortoij, G. D., 1914. Is the poor hatching of normal eggs
due to the presence of microorganisms -within the egg? Science, N. S.. Vol.
40,
p. 240.
Bushnell, L. D., and Mauer, 0., 1914. Some factors influencing the bacterial con-
tent and keeping quality of eggs. Elan, Agr. Expt. Sta., Bui. 201.
Cao,
G., 1908. Su La Penneobilita della uova ai microorganismi ann. Inst.
lg.
Sper. Univ. Roma, Vol. 18, p. 39.
Ciuoa, M., 1908. Sur la culture du streptocoque dans les ouefs de poulea vac-
oine'ea contre ce microbe. Compt. Rendu. Soo. Biol. Paris, Vol. 86, p. 275.
Gage, G. E., 1911. Note on ovarian infection With Bact. pullorum
•
(Rettger)
in the domestic foul. Jour. Medical Research, Vol. 24. p. 491.
Hadley, Philip B., and Caldwell, Dorothy W., 1916. The bacterial infection
of fresh eggs. Rhode Island Agr. Exp. Sta., Bulletin No. 164, pp. 1-70.
Lameon, G. EL Jr., 1909. Infection and preservation of eggs. Storrs Agr.
Exp.
Sta., Bui. 66.
Mauer, O., 1911. Bacteriological study on eggs.
TTRTI
Agr. Expt. Sta., Bui.
180.
Pennington, Mary E., et al., 1914. A bacteriological and chemical study of com-
mercial eggs in the producing districts pf the Central West. U. S. Dept. of
Agr., Bur. Chem., Bui. 51.
Pennington, M. E., and Robertson, H. C, Jr., 1912. A study of the enzymes
of the egg of the common fowl. U. S. Dept. Agr, Bur. of Chemistry, Cir-
cular 104.
Pennington, M. E., et al., 1916. A study of the preparation of frozen and dried
eggs in the producing section. U. 8. D. A., Professional Paper No. 224.
Pennington, M. E., Jenkins, M. K., and Betta, H. M. P., 1918. How to candle
eggs.
U. S. D. A., Bui. 665.
Pemot, E. F., 1908. An investigation of the mortality of incubator chioka.
Oregon Expt. Sta., Bui. 103.
356 INDUSTRIAL FERMENTATIONS
Rettger, L. F., and Stonebum, F. H., 1909. Bacillaiy white diarrhoea of young
ahiaks. Storrs. Agr. Expt. Sta., Bui. 60.
Rettger, L. F, Kirkpatrick, W. F., and Stonebum, F. H., 1912. Bacillary white
diarrhoea of young chicks.
Rettger, L. F., 1913. The bacteriology of the hen's egg with epeoial reference
to ite freedom to micro-invasion. Storrs. Agr. Expt. Sta., Bui. 75.
Rettger, L. F., 1914. Ovarian infeotion in the domestic fowl and direct trans-
mission of disease to the offspring. Jour. Expt. Med., Vol. 19, No. 6, p. 662.
Rettger, L. F., Kirkpatrick, W. F., and Jonea, R. E., 1914. Baoillary white diar-
rhoBa of chicks (4th, Rpt.) Storrs. Agr. Expt. Sta., Bui. T7.
Sperry, J. A., 1913. On antifleptio andf bactericidal properties of egg white.
Science, N. 8., Vol. 38, p. 413.
Stiles,
G. W., and Bates, C, 1912. A bacteriological study of shell, frozen and
desicoated eggs made under laboratory conditions at Washington, D. C.
Wiley, H. W., et al., 1908. A preliminary etudy of the effects of cold storage
on eggs, quail; and chicken. IT. S. Dept. Agr., Bur. Chem., Bui. 115, p. 117.
Chapter 29.
Maple Sugar and Maple Syrup.
BUgar and syrup made from the maple tree are foods which
LOUS
for their delicacy of flavor. There are two members of
>le family (aceracese), the hard maple and the soft maple. Both
B
produce considerable amounts of maple syrup and maple
The hard maple or sugar maple produces the largest amount
h the soft maple also yields well. Early in the spring, in the
before the buds beoome green, the trees are tapped by boring
MI
in
Vermont.
Bulletin,
161.
EIG.
66.—A sugar orchard.
f-inch holes about two feet from the ground. These holes are
wo inches deep and three inches apart and spiles or spouts are
into them to carry the sap to buckets. The sap is boiled
D
a definite Sp. G. depending on the product to be made. The
'or sugar-making is boiled down further than that for maple
inking. The sap from a single tree may yield from 4 to 12 lbs.
e sugar per season. The most favorable weather is characterized
freezing nighte followed by rather warm days.
Drding to Edeon, the composition of average maple sap is
367
358 INDUSTRIAL FERMENTATIONS
about 3% saccharose with traces of other sugars as invert sugar. The
distinctive flavor of maple sap and the products made from it is due
no doubt to the small but important protein content. Maple sap also
contains some malic acid and salts of calcium and potassium.
The Department of Agriculture has denned maple syrup as a food
product containing not more than 35% water and weighing not less
than 11 lbs. to the gallon. Sucrose constitutes 95 to 97.5% of maple
syrup on dry basis.
Since the sap contains elements well suited for bacterial nutrition,
we readily conclude that as Boon as the weather becomes warm enough
for the rapid growth of germs in the sap, some change must normally
take place. Edson says that the appearance of the sap undergoes
a marked change as the sugar season progresses. The first sap is
clear and transparent and possesses a delicious sweet flavor but with
the advance of the Beason, as the days become warmer and the freezing
nights less severe and less frequent, the sap often becomes cloudy, and
discolored, while at the same time certain unpleasant flavors develop.
Such sap, while usudly free from acid, is popularly termed sour.
Several types of this sour sap are recognized by sugar makers. Milky
sap,
stringy sap, red sap, and particularly so-called "green sap" are
among the more common kinds. "Green sap" is almost always ob-
served just before the close of the season when the leaf buds are
ready to open. These occurrences are observed by all maple sugar
makers and this occurrence of "buddy" sap is often thought to be
directly connected with the appearance of buds on the trees. It is
always the case that the earlier "runs" of sap make the best syrup
and sugar. The later the "run," the poorer the flavor becomes aef a
usual thing.
*
With the above facts in mind, Edson conducted a set of experiments
to determine whether or not microorganisms are the real cause of
"buddy" sap, poor flavor and poor quality of the finished syrup and
sugar as the season develops. He showed that the sap within the
vascular bundles of the tree iB free from microorganisms' and that
when sap is drawn under aseptic conditions it keeps sweet without
being sterilized or chemically preserved, while s'ap drawn under the
ordinary conditions of tapped trees soon sours and becomes cloudy.
He found that such sap contains enormous numbers of bacteria yeasts
and molds, and that extensive decomposition changes have taken
place.
A table from Edson's work shows clearly the effect of micro-
organisms in maple sap. In one series, samples of sap were inoculated
with green fluorescent bacteria isolated from green sour sap and this
trouble was reproduced. In another series samples of sap were
inoculated with material obtained from cloudy sour sap and the
organism which caused this trouble was established. In a third series
aap was inoculated with an organism believed to be a new species
obtained from a milky type of stringy sap. Stringiness and sourness
developed in these samples. A fourth series was inoculated with
PLATE 14
After
Edam
and
Oarpmter
in
Vermont
Bulletin
167.
FLA.QHL.LA
STAINS
OF
MAPLE
SAP
Flagella preparations from 24-hour agar slants (Loeffler's stain) Figa 1-4 aho"w
capsulation.
Fia 1—B.
acerie
Fia 4—B. parallelus
FIG
2J—B.
parallelix Fia 5—Ps. fluore&oens
Fia 3.—B.
paraUelus
Fia. 6—Pa fluorescena
350
0 INDUSTRIAL FERMENTATIONS
jastfl and molds obtained from red sap and resulted in the reproduc-
Dn of this trouble.
As in the production of other foods, quality here depends con-
derably upon the amount of cleanliness practiced in manufacturing
le produot. Clean, boiled sap buckets mean much in producing
laple syrup and sugar of highest quality. New tap holes in the
itter part of the sap season improves the quality also.
The kind of organisms found by Edson in the sap coming from
ifferent trees were yeasts and bacteria. The number of organisms
loreased in general as the sap season progressed. Late run sap was
ften sour. It was found that whereas late in the season the sap
owing from old holes and through old spiles was "bitter," "buddy"
nd cloudy, by boring new holes' and using sterile spiles and utensils,
ap could be obtained which was clear and free from "buddy" and off
astes.
This fact indioates that late-made syrup and maple sugar is
iften faulty due to baoterial infection of the sap.
Edson gives the following summary of the conclusions reached as
v result of his investigations:
"Maple sap as it occurs within the tree is free from bacteria and
)ther microorganisms.
"As the sap flows from the tree it becomes infected in the taphole,
ipouts and buckets, with wild yeasts, spores of molds, and countless
lumbers of bacteria. This infection becomes increasingly heavy with
he advance of the sugar season and is the cause of the 'souring' of
iap.
"Some of the types of hurt sap are caused by the action of specific
groups of organisms, others may be caused by the collective action of
many of the common forms.
"Green sap and the resulting red syrup are not to be attributed
bo the swelling of the buds, but are caused by the development of a
particular group of bacteria characterized by green fluorescence.
"The dark color of the late run syrup is due entirely to the action
of microorganisms. If these are eliminated, as light colored syrup
may be made from the last run as from the first run.
"The flavor of the syrups is-also seriously' impaired by these
agents. This injury often becomes pronounced before marked change
in color is produced. 'Buddy' flavors also appear to be due, at least
in part, to the action of microorganisms.
"The quality of the product may be improved by: (1) keeping the
spouts and buckets thoroughly olean; (2) using metal utensils in lieu
of wooden ones; (3) gathering the sap at short intervals and boiling
it at once.
"In the canning, storage, and marketing of syrups, Langlade em-
phasizes the great importance of using sterile bottles and containers
thereby preventing molds and bacteria."
Jones gives the following remedial measures concerning the difficul-
ties in the manufacturing of high grade maple symp and maple
sugar:
MAPLE SUGAR AND MAPLE SYRUP 361
"Practical remedial measures must be based upon efforts to mini-
mize the contamination with microorganisms and to restrict the period
of their action to the shortest possible time. The lower their content
and "the shorter their period of growth, the better the product. As in
dairying, cleanliness muBt be the watchword of the producer of
superior goods. Clean spouts, clean covered buckets and clean holders
are necessities. The use of metal utensils is to be preferred to the
employment of wooden ones, because the latter material affords organic
matter upon which organisms may develop. Moreover, wooden utensils
are less readily cleaned. Covered buckete are preferable to open ones,
not only because they keep out rain and snow, but because they pre-
vent the entrance of bits of falling bark, decayed wood, and other
inert matter. Such material is always heavily charged with bacteria
and other organisms, so that in addition to the coloring matter carried
in the refuse
itself,
agents are introduced which further discolor the
product through their vital activities.
"The practice of storing gap is one to be avoided whenever possible.
Modern evaporators not only make long periods of boiling unnecessary,
but they make it possible to concentrate the runs day by day as they
ooour, They are doubtless important factors contributing to the im-
proved quality of evaporator syrup as compared with that produced
by older methods. When storage is resorted to, the temperature 6f
the tank should be kept as
1
low as possible, because the lower the
temperature the slower the microtirganic development. Holders should
be located without rather than within the boiling house, where the
heat of the pans will not influence their temperature.
"The evidence obtained indicates that the sugar-maker cannot
expect to produce a high quality of syrup at the close of the season in
average years, because there is no known means by which the physio-
logically induced
f
buddy
J
flavor may be avoided. So long as the
depreciation is caused solely by bacteria, cleanly methods will enable
the producer to maintain a high standard of excellency in his product;
but if the physiological activity of the tree begins to be manifest, the
producer will find himself unable to manufacture an article of high
excellency as regards flavor. The light color can be maintained
indefinitely, but the 'buddy' flavor is so objectionable that the market
value of the syrup is insufficient to render its production profitable."
C. H. Jones says: "The conditions are more favorable to bacterial,
yeast and mold contamination in the sap toward the close of the
sugar season than earlier because of the higher temperatures, bare
ground, rain, interrupted runs, less cleanly utensils, etc., which then
obtain."
Jones describes standard maple syrup as follows: "Standard
maple syrup Bhould weigh 11 pounder to the gallon, should carry be-
tween 34 and 35% of water, should give a Baum6 reading of 35% to
36 at 60 degrees F., and should contain calculated to a moisture-free
basis,
a total (maple syrup) ash of 0.77%
x
an insoluble ash of 0.23%
and a malic acid value of 0.60%. These figures constitute the standard
362 INDUSTRIAL FERMENTATIONS
now in use for determining purity. They are none too low, should be
considered collectively, and when properly interpreted, should enable
certain differentiation between pure and adulterated maple products."
The following conclusions were given by Edson and Carpenter
concerning the strains of fluorescent bacteria which they found as
factors in maple syrup and maple sugar making:
"Among the 42 strains of green fluorescent bacteria, selected from
several hundred strains which had been isolated from maple sap, there
were 32 strains of the liquefaciens and 9 strains of the non-liquefaciens
varieties of Ps. fluorescens. The studies included one strain which
was never more than doubtfully fluorescent, which, for this and other
reasons, should not properly be regarded as a member of the fluorescent
group. The 9 strains of the non-liquefaciens variety showed a delayed
liquefaction of gelatin in from 50 days to 5 months when cultivated
in a moist chamber at 20 degrees C. Peptonization of milk by these
strains was also long delayed commencing in from 30 days to 3 months.
From
UJ3J)A.
Bulletin
1389.
Fia. 66.—Pan evaporator.
"Critical comparative studies of 7 representative strains of green
fluorescent sap bacteria and 6 so-called species Ps. alba, Ps. fluorescens,
Ps.
longa, Ps. mesenterica, Ps. tenuis, and Ps. putrida show that no
sharp line of differentiation can be drawn between these forms. Of
the known 'species/ Ps. alba, Ps. longa, and Ps. putrida fail to liquefy
gelatin in 6 months time, while in the case of Ps. mesenterica and Ps.
tenuis a delayed liquefaction occurs. In the latter named strain
liquefaction first appears 4 months after inoculation.
"It is believed that the fluorescent sap bacteria as well as the so-
called species, Ps. alba, Ps. longa, Ps. mesenterica, Ps. tenuis, and Ps.
putrida should properly be recognized as" strains of the liquefaciens
and non-liquefaciens varieties of Ps. fluorescens."
REFERENCES ON MAPLE SUGAR AND SYRUP.
Brown, A. E. U. S. Patent, 1,245,669.
Bryan, A. H. U. S. D. A., Bureau of Chem., Bui. 134.
Edson, H. A., 1910. Vermont Agr. Expt. Sta. Bui. 151.
Edson, H. A. Jour, of Ind. and Eng. Chem., Vol. 2, No. 7, pp 326-327
Harrison, F. C, 1898. Botanical Gazette, XXVI, pp. 211-214
MAPLE SUGAR AND MAPLE SYRUP 363
Jordan,'E. 0., 1899. Botanical Gazette, XXYIE, pp. 19-36.
Langlade, M., 1909. Bui. Aesoo. Chem., siicr. dist., 26, pp. 592-593.
McGill, A. Inland Rev. Dept., Ottawa, Canada, Bui. 228.
Ruajcka, 8., 1898. Centralb. F. Bakt., XXIV Bd., pp. 11-17.
Sherwood, Setal, 1917. U. S. D. A., Bui. 466.
Warren, W. H. Jour. Am. Chem. Soc.,
1
3, pp, 1201-1211.
Chapter 30.
Dairy Products.
The original dairy products were milk, butter and chees
production, manufacture and marketing of these products up
or even 1890 was very simple. At about this time, however, 1
fessional dairyman appeared, ideas of sanitation m towns grew
the family or neighborhood oow disappeared. About this sai
the results of bacteriological study of milk and dairy produ
taken seriously by the public. There was a wave of interest
foods,
and milk and dairy products of higher quality were del
In 1893, Dr. Henry L. Coit initiated the idea of certified milk,
idea of having milk that had been certified by a medical mi
mission spread. Sedgwick and Batchelder, early in the deve]
of market milk, made a bacteriological and quality survey
milk of the city of Boston.. Conn at Connecticut Experiment
and Russell at Wisconsin made reports on milk quality. The
of pure cultures as starters in the manufacture of butter and
was also extensively studied.
Market Milk.
Milk is such an important food, especially for infants, 1
quality should be the highest of all foods. Still the nature
and its' production are such that it may be the dirtiest of al
Not only is this true but it also happens that milk is a food y
difficult to keep or transport in good condition.
Quality in market milk is hard to define. Many attemp
been made to tell what is meant by quality in market millr, bi
has been much difference of opinion. Dr. E. 0. Jordan says,
the exhaustively studied and relatively simple water standa
subject to such exceptions and reservations, it is certainly no
expected that bacterial standards for food will be any moon
factory." H. A. Harding says, "Many factors combine to de
the quality of milk, apparently thus far, no one has succeede
fully analyzing the city milk situation as to formulate a ci
expression for milk quality."
There are certain methods which have been used in gaining
of the sanitary quality of the milk produced by a dairyman,
cards as illustrated on opposite page for scoring the dairy ha
1
used quite extensively. The score card was used on the bas
364