[Page 1]

Bulletin 192  November, 1913

The Agricultural Experiment Station

of the

Colorado Agricultural College



HOME-MADE CIDER VINEGAR

_By_ WALTER G. SACKETT



PUBLISHED BY THE EXPERIMENT STATION
FORT COLLINS, COLORADO
1913

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=The Agricultural Experiment Station=
Fort Collins, Colorado
                                              =Term=
  =The State Board of Agriculture             Expires=
HON. F.E. BROOKS           Colorado Springs,   1915
HON. J.S.CALKINS                Westminster,   1915
HON. J.C.BELL                      Montrose,   1917
HON. WILLIAM HARRISON               Clifton,   1917
HON. CHAS. PEARSON                  Durango,   1919
HON. R.W. CORWIN                     Pueblo,   1919
MRS. J.B. BELFORD                    Denver,   1921
HON. A.A. EDWARDS              Fort Collins,   1921
GOVERNOR E.M. AMMONS,    _Ex-Officio_
PRESIDENT CHAS. A. LORY, _Ex-Officio_
L.M. TAYLOR, SECRETARY        J.S. JONES, TREASURER

=EXECUTIVE COMMITTEE IN CHARGE=
A.A. EDWARDS,  _Chairman_
J.S.CALKINS    E.M. AMMONS

=STATION STAFF=
W.P. HEADDEN, A.M., Ph.D.                                   CHEMIST
C.P. GILLETTE, M.S., _Entomologist_                        DIRECTOR
G.H. GLOVER, M.S., D.V.M.                              VETERINARIAN
W.G. SACKETT, B.S.                                   BACTERIOLOGIST
ALVIN KEYSER, A.M.                                       AGRONOMIST
J.O. WILLIAMS, B.S.A., _U.S. expert-in-charge_       HORSE BREEDING
E.P. SANDSTEN, Ph.D.                                 HORTICULTURIST
B.O. LONGYEAR, B.S.                                        BOTANIST
G.E. MORTON M.L., B.S.A.                         ANIMAL HUSBANDSMAN
E.B. HOUSE, B.S. (E.E.), M.S.                   IRRIGATION ENGINEER
V.M. CONE, B.S.                           IRRIGATION INVESTIGATIONS
R.E. TRIMBLE, B.S.              ASSISTANT IRRIGATION INVESTIGATIONS
P.K. BLINN, B.S., ROCKY FORD                 ALFALFA INVESTIGATIONS
EARL DOUGLASS, M.S.                               ASSISTANT CHEMIST
S. ARTHUR JOHNSON, M.S.                      ASSISTANT ENTOMOLOGIST
L.C. BRAGG                                  ASSISTANT IN ENTOMOLOGY
J.W. ADAMS, B.S., _Cheyenne Wells_  AGRONOMY ASSISTANT, DRY FARMING
ELWOOD D. ROOD, A.B.                              ASSISTANT CHEMIST
W.W. ROBBINS, M.A.                               ASSISTANT BOTANIST
PAUL S. JONES, B.S.             ASSISTANT IRRIGATION INVESTIGATIONS
RALPH L. PARSHALL, B.S.         ASSISTANT IRRIGATION INVESTIGATIONS
JAMES D. BELL, B.S.             ASSISTANT IRRIGATION INVESTIGATIONS

=OFFICERS=
CHAS. A. LORY, LL.D.                                    _President_
C.P. GILLETTE, M.S.                                      _Director_
L.M. TAYLOR                                             _Secretary_
MARGARET MURRAY                                   _Executive Clerk_

[Page 3]

=HOME-MADE CIDER VINEGAR
By Walter G. Sackett.=

In driving through the fruit-growing sections of the United States, 
one cannot fail to be impressed with the fact that thousands of 
bushels of apples and other fruit are allowed to go to waste annually 
just because it is too much trouble to gather it up and make some use 
of it. This is particularly true during a season when prices are low 
owing to an overproduction. Such a practice would be condemned, most 
certainly, by any commercial firm, and rightfully so, as a most 
extravagant waste and far removed from any principle of scientific 
management. Talk with any captain of industry, and he will invariably 
tell you that the largest profits in his business accrue from the 
complete utilization of the waste products.

Indifference to the needs of others and ignorance of the latent 
possibilities in this second grade fruit are largely responsible for 
the fruit grower’s short-sightedness. He is apt to forget that there 
are a few more than ninety-three million others in this country who 
are dependent upon him for orchard products such as cider, apple 
butter, jelly and vinegar, all of which could be made from this fruit 
which he permits to rot unnoticed under the trees. Could he only be 
shown the roll of greenbacks or catch the glitter of the gold which 
would represent his actual net return from the complete utilization 
of this unnecessary waste, rotten apples, wormy apples, green apples 
and everything would be cleaned up the next time we should pass by 
his orchard.

In spite of the fact that thousands of gallons of white wine vinegar, 
which has never been near a wine press, are produced yearly by a 
purely chemical process from alcohol, there is still a market for 
good, old-fashioned, apple cider vinegar. The genuine article will 
never be entirely replaced by the artificial product. But where is 
the public to obtain pure apple vinegar of acceptable quality? It is 
not for sale at the local groceries except in sealed bottles at 
twenty-five cents a quart. Beside it on the shelf may be found the 
distilled vinegar, artificially colored with caramel, and the white 
pickling vinegar at fifteen cents a bottle. In bulk the distilled 
vinegar can be bought for forty cents the gallon with a reliable 
guarantee behind it for strength and quality. But you say, [Page 4] 
"Surely you must be mistaken about not being able to get cider 
vinegar from your grocer in bulk." No, gentle reader, do not be 
deceived by the stencil mark on the end of the barrel. If, perchance, 
this particular lot came from a nearby ranch, the odds are in favor 
of its not being worth carrying home. Do not understand me to speak 
thus lightly of all home-made vinegar for there is some to be found 
of splendid quality, but it is the exception. As a rule the 
storekeeper will apologize to the customer for his farm vinegar, but 
with that which comes from the wholesale dealer it is different. Most 
certainly a sad condition, when the first and best vinegar that was 
ever made came from the farm home! What is more, it cannot be 
obtained from the farmer or apple grower today for most of them are 
buying all of the vinegar they use.

What has become of our apple vinegar industry, and why have the 
merchants turned their attention to the distilled article? The answer 
to this can be had without pursuing an extensive investigation into 
the economics of the question. It is simply this—the average run of 
farm vinegar is so inferior to the distilled product that the 
merchants cannot afford to handle it. The quality is so variable and 
the strength is so unreliable that the good housewife has learned 
through the repeated experience of having her pickles spoil not to 
ask for cider vinegar.

There is no good reason why this condition of affairs should exist 
which has resulted in placing a boycott on the farm product, but in 
the light of the facts as they actually exist, is not the consumer 
justified in taking this stand? There is no doubt that the synthetic 
article has come to stay, but this does not mean that genuine apple 
vinegar is a thing of the past. However, until we are able to produce 
as good or better vinegar on the farm and in the orchard and can 
guarantee its quality and strength to be reasonably constant, we have 
no right to ask or to expect the public to buy an inferior product or 
to help build up the industry by its patronage.

It is just as easy to make high-grade apple vinegar at home when one 
understands the different operations and principles involved as it is 
to make good butter or good bread. If the housewife knew as little 
about making butter and baking bread as the average farmer or 
orchardist knows about making vinegar, we should all forsake the 
staff of life and take refuge in the nearest sanitarium.

[Page 5]

_Selection of the Apples._

What has been said above concerning second grade fruit for cider and 
vinegar is not to be construed as meaning rotten, wormy, dirty, or 
unripe fruit. Nothing is gained by such a practice and often all is 
lost. In the first place, it is impossible to cover up the flavor of 
the spoiled apples in the vinegar, and in the second place, when 
decayed and dirty fruit is employed, it is practically out of the 
question to control the fermentations in the cider upon which the 
quality of the finished product depends almost entirely.

There is no reason why apples which have merely been bruised should 
not be used, and where they are not too badly rotted, the soft 
portion can be cut out. Children are always glad to have a hand in 
cider making and this is just where their services will fit in 
nicely. Remember that many hands make light work and likewise clean, 
acceptable cider, and you will be surprised to see in how short a 
time the spoiled parts can be removed from the bushels of otherwise 
worthless apples.

The importance of washing the apples thoroughly with clean water 
before they go to the mill to be ground cannot be overestimated. 
There is bound to be a quantity of soil and dust clinging to the 
outside, particularly where the orchards lie along a public road and 
are clean cultivated so that the apples fall on plowed ground. This 
can be carried out very conveniently in an ordinary washtub, after 
which the apples should be allowed to drain before they are ground. 
One is always astonished at the amount of mud in the water after such 
an operation, even when relatively clean, hand-picked fruit is 
employed.

Let us see next whether all varieties of apples are equally well 
suited to cider vinegar making; whether a good cider apple is 
necessarily a good vinegar apple; and what constituent or 
constituents of the apple determine its usefulness for these 
different purposes.

In answer to the first question, it may be said that apples differ 
very widely in their adaptability to cider and vinegar making; some 
appear to have been created for this very purpose, while others would 
not do at all.

Concerning the second point, we find it is quite often the case that 
an apple which makes an excellent cider to drink would not make good 
vinegar. This is due to the fact that most tastes demand a cider that 
is not too sweet and with a slight acidity. Such [Page 6] apple juice 
would be very apt to make weak vinegar because of the relatively 
small amount of sugar present.

This reference to sugar brings us to the third item, namely, the 
important constituents of the apple so far as cider and vinegar are 
concerned. Several years ago, Dr. Van Slyke of the Geneva, N. Y., 
Experiment Station, reported a series of analyses of apple juices 
representing eighty-three different American-grown varieties. He 
gives the average composition of these juices as follows:

Solids                            13.52 per cent
Total sugar as invert sugar       10.91 per cent
Ash                                 .29 per cent
Fixed acid (malic)                  .52 per cent

The sugar is unquestionably the most important of these substances so 
far as the part which it plays in the making of cider vinegar since 
the degree of sourness due to the vinegar acid (acetic) is directly 
proportional to the fermentable sugar present; in other words, all of 
the acid which was not originally present in the cider as natural 
apple acid, or malic acid, is produced from the sugar by processes 
which are soon to be described. Therefore, since from a given amount 
of sugar just so much acid and no more can be made, we can understand 
quite readily that for a high grade vinegar of maximum acidity the 
apple juice containing the most sugar will be the most desirable. The 
amount of natural acid present in the juice plays an insignificant 
part in the final acidity of the vinegar, since the small quantity 
that is present in the apple juice practically all disappears during 
the change into vinegar. From this it is clear that it is the sugar 
and not the natural apple acid that is to be considered in cider for 
vinegar.

Now, as has been stated above, cider for table use is usually more 
pleasant to drink when it is not too heavy and when the sugar is 
lower and the acid somewhat higher than the standard for vinegar 
cider requires.

The composition of the juice of some of our common commercial 
varieties, especially the sugar content, may be of interest at this 
time in connection with what has been said with reference to the 
suitability of different ciders for vinegar making. The [Page 7] 
analyses which I am submitting are those given by Dr. Van Slyke* for 
eastern apples.


*Van Slyke, L, L., Bulletin 258, Geneva, N, Y., Exp. Sta. "A Study of 
the Chemistry of Home-Made Cider Vinegar," 1904.


_Table I —— Analyses of Apple Juice of Different Varieties of American 
Apples._
                     =Specific   Solids.  Equivalent of total    Fixed=
=Variety of Apple.    Gravity.              sugar in form of    acid as=
                                            =invert sugar.       malic.=
                               =Per cent.      Per cent.        Per cent.=
Baldwin               1.072      16.82         15.39             .67
Belleflower           1.061      14.09         12.82             .58
Ben Davis             1.052      12.77         10.60             .46
Ben Davis             1.046      10.69          6.74             .44
Gano                  1.046      10.16          8.61             .41
Gano                  1.056      13.92         11.32             .41
Grimes Golden         1.070      18.18         14.05             .74
Jonathan              1.056      14.62         11.60             .32
Maiden Blush          1.051      12.70          9.99             .67
Northern Spy          1.052      13.77          9.77             .69
Red Siberian Crab     1.070      17.34         11.83             .97
Rome Beauty           1.048      11.37          8.70             .37
Wealthy               1.057      15.26         11.64             .66
Whitney               1.060      14.16         11.39             .40
Winesap               1.065      16.45         13.34             .58
Yellow Transparent    1.049      11.71          9.76             .87

An examination of the above table shows us that there is a wide 
variation in the percentage of sugar in the apple juice of different 
varieties, varying from 6.74 per cent. in one sample of Ben Davis to 
15.39 per cent. in the Baldwin; that the quantity of sugar in any 
given variety may vary as much as 4 per cent. (Ben Davis 6.74-10.60).

The amount of sugar depends upon a number of factors such as soil, 
climate, culture, variety, and ripeness, unripe and over-ripe apples 
containing less sugar than ripe ones.

+ Browne has shown very clearly the changes that take place in the 
sugar content of apples at different periods of ripeness:


+ Browne, Annual Rept. Penn. Dept. Agr, 1899. p. 541.


_Table II —— Sugar in Baldwin Apple at Different Periods._

                                    =Equivalent of Total Sugar in=
        =Date            Condition.     Form of Invert Sugar.=
     Aug.   7, 1899     Very Green            8.11
     Sept. 13, 1899     Green                10.72
     Nov.  15, 1899     Ripe                 14.87
     Dec.  15, 1899     Over-ripe            14.85

The question is sometimes asked whether the so-called "sweet apples" 
will make as good vinegar as the tarter varieties. All things being 
equal, there is no reason why they should not, provided they contain 
as much sugar as the more acid kinds. This statement may seem 
somewhat paradoxical, but it should be remembered that [Page 8] it is 
the presence of acid rather than the absence of sugar that makes an 
apple taste sour. As a matter of fact, some of our very sourest sorts 
contain as much and more sugar than the sweetest sweet apples. Cider 
for vinegar should not contain less than 8.5 per cent. of sugar.

_Storage of the Cider._

The most satisfactory containers for both cider and vinegar are 
whisky and brandy barrels. Molasses barrels and old vinegar barrels 
should be used only when no others are available, and then not until 
they have been very carefully and thoroughly cleaned. Too much stress 
cannot be laid upon the necessity of scalding old vinegar barrels 
with either live steam or boiling water to remove the last trace of 
the old vinegar. There is, perhaps, no one factor which is 
responsible for more failures in farm vinegar making than the 
time-honored but pernicious custom of using old vinegar barrels for 
sweet cider without even rinsing out the dregs of former years. Mere 
rinsing is not sufficient. They must be scalded to make them fit for 
use. If this is not done in such a manner as to kill all of the 
organisms in the barrel, the probability is that the sweet cider which 
is put in them subsequently will never make vinegar. The reason for 
this will be given a little later. In a recent number of a certain 
farm journal, the following is given under directions for making 
apple vinegar:

"Get a barrel in which good vinegar has been made and use it, or get 
some of the scum off of the top of good vinegar and rinse out the new 
barrels with this as soon as they cool after having been thoroughly 
washed out with boiling water. Put fresh cider into these barrels."

No procedure more absurd and dangerous to the success of apple 
vinegar could possibly be undertaken than is contained in this 
recommendation. In fact, it would be difficult to find a better 
recipe for vinegar failures than this. Never, under, any 
consideration, put either "mother" or old vinegar into sweet cider. 
It is never safe to use metallic containers for holding cider even 
for an interval of a few hours, since the acid of the juice attacks 
the metal, dissolving a portion of it. Such cider, because of the 
metal in solution, might produce metallic poisoning in the person 
drinking it.

The sweet cider as it comes from the press may either be placed at 
once in barrels, which should not be filled more than two-thirds to 
three-fourths full, or if one has suitable wooden tubs or vats in a 
clean, cool place, it may be stored there for twelve to [Page 9] 
twenty-four hours to permit settling, after which it should be 
transferred to barrels. The bung should be left out and a loose 
stopper of cotton batting inserted in the hole to decrease 
evaporation and prevent dirt from falling in. The barrels should not 
be tightly stoppered until the vinegar contains at least 4.5 to 5.0 
per cent. of acetic acid, at which time they should be filled 
entirely full and securely bunged. Throughout the entire period of 
vinegar making, the casks should be placed on their side and not on 
the end. This gives the cider a larger free surface exposed to the 
air, which is quite essential to rapid vinegar formation. It may be 
of some advantage in admitting air to bore a one and one-half inch 
hole in each end of the barrel along the upper edge. If this is done, 
the holes should be covered with fine wire gauze or two thicknesses 
of cheese cloth to exclude small vinegar flies.

_The Alcoholic Fermentation._

A few days after the cider is put into the barrels, the 
characteristic frothing appears at the bung-hole. To use a common 
expression, "It is beginning to work." This indicates that the 
alcoholic fermentation, the first step in the vinegar making process, 
has begun, and the sugar of the apple juice is being converted into 
alcohol and carbon dioxide gas.

The first of these substances is too well known to need any further 
comment other than to state that it is this element of "hard" cider 
that gives it its intoxicating property. With carbon dioxide, many of 
us are not as well acquainted. It is this gas escaping from the 
fermenting cider that causes the frothing and likewise the foamy 
appearance of the bread sponge. It is this gas dissolved in the cider 
or in the carbonated drinks at the soda-water fountains that imparts 
to them the characteristic bite or tingle, and upon escaping from the 
stomach produces that peculiar sensation in the head and nose. 
Strangely enough, this same gas is the active principle of 
practically all chemical fire extinguishers.

Now, what is the exciting agent which starts up the fermentation in 
the bread sponge and in the sweet cider? In both cases it is the 
same: a microscopic organism, the yeast plant. In the one instance we 
add a yeast cake to the bread mixture; in the other we either trust 
to the wild yeasts of the air and the skin of the apples or following 
the more recent, approved method, we add a yeast cake or a pure 
culture of a yeast selected especially for this purpose.

To depend upon the wild yeasts of the air to accomplish the 
fermentation is too uncertain since many of them are able to 
[Page 10] convert only a small part of the sugar into alcohol, while 
others act so slowly that they are impracticable. Inasmuch as the 
percentage of acetic acid in the vinegar depends directly upon the 
amount of alcohol produced, it is very essential to secure as large a 
yield of alcohol as possible from the sugar present. This means 
converting all of the sugar into alcohol in the shortest time 
possible. The most satisfactory way of doing this is to add one cake 
of compressed yeast, stirred up in a little cooled, boiled water, to 
each five gallons of sweet cider. In place of this, one quart of 
liquid wine yeast, propagated from a pure culture, may be used for 
each thirty gallons of cider.

During the alcoholic fermentation, the cider should be kept at a 
temperature of 65 to 80 degrees F. Here is where many make the very 
serious mistake of putting their fresh cider into a cool cellar where 
the fermentation takes place entirely too slowly. If the cider is 
made in the fall, the barrels should be left out of doors for a while 
on the protected, sunny side of a building and kept warm, unless a 
regular vinegar-cellar, artificially heated, is at hand.

If yeast is added and the proper temperature is maintained, the 
alcoholic fermentation should be completed in six weeks to three 
months in place of seven to ten months as in the old fashioned way. 
Experiments along this line have shown that when yeast is added and a 
temperature of 70 degrees F. is held, the cider at the end of one 
month contained 7.25 per cent. of alcohol as against .11 per cent. 
when no yeast was used and the temperature was between 45 and 55 
degrees F. Cider kept in a cellar at 45 to 55 degrees with no yeast 
added required seven months to make 6.79 per cent. of alcohol.

Temperature, alone, is an important factor as shown by an experiment 
wherein cider to which no yeast was added was held for three months 
at 70 degrees F. and yielded 6.41 per cent. of alcohol.

There is no question but that the time required for completing the 
alcoholic fermentation can be reduced at least one half by adding 
yeast and by maintaining the proper temperatures. By hastening this 
operation, the loss of alcohol by evaporation is reduced, and the 
acetic fermentation can be started that much sooner.

Theoretically, 100 parts of sugar should give 51 parts of alcohol and 
49 parts of carbon dioxide gas. This figure has been shown by Browne 
to be a little high. In actual practice, 45-47 parts of alcohol from 
100 parts of sugar is a fair average.

But why not add "mother" or vinegar to sweet cider or put [Page 11] 
sweet cider into an old vinegar barrel? Here is the reason: We have 
seen from what has gone before that alcohol is produced from the 
fermentation of the sugar. We shall soon learn that the acetic acid 
of the vinegar is formed from this alcohol. Now, in order to obtain 
the maximum amount of acetic acid, it is necessary to have as much 
alcohol as possible in the hard cider, and this can be obtained only 
by the complete conversion of all the sugar into alcohol and carbon 
dioxide gas. The complete destruction of the sugar can be 
accomplished only by the uninterrupted action of the yeast, and the 
presence of "mother" of vinegar by producing acetic acid interferes 
seriously with this fermentation. The yeast cells are either killed 
or their useful activity is checked long before all of the sugar has 
been changed into alcohol. This is the condition of a very large 
percentage of farm vinegar—just hard cider that will not and never 
will make vinegar. It means just this:

A small part of the sugar was made into alcohol and this alcohol was 
at once changed to acetic acid by the "mother" present; this acetic 
acid killed the yeast so that no more sugar could be changed to 
alcohol and no more alcohol being found, no more acetic acid could be 
made by the "mother." We have a weak, worthless something neither 
vinegar nor hard cider with considerable unfermented sugar still 
present and incapable of further fermentation because no yeast can 
develop in the weak acetic acid solution.

_The Acetic Acid Fermentation._

The second step in vinegar making is the change of the alcohol of the 
hard cider into the acetic acid of the finished product. This is 
accomplished by the acetic acid germ, another microscopic plant still 
smaller than the yeast. In some peculiar way it is able to bring 
about a union between the alcohol of the hard cider and the oxygen of 
the air so that the alcohol is transformed into acetic acid and water.

As soon as the alcoholic fermentation, described in the preceding 
section, is completed, draw off the clear liquid, being very careful 
not to disturb the sediment in the barrel. Wash out the barrel 
thoroughly and replace the hard cider. It is believed that removing 
this sediment permits the acetic acid to form somewhat more quickly, 
and furthermore, the sediment may undergo decomposition and impart a 
disagreeable flavor to the cider. Again, these dregs may harbor 
living bacteria which either destroy acetic acid or interfere with 
its formation.

This done, we are now ready to introduce the acetic acid [Page 12] 
germs. This may be carried out in a number of different ways, but 
preferably by means of a pure culture of a desirable organism which 
has been selected because of its ability to produce strong acetic 
acid and to impart an agreeable flavor to the vinegar. In place of 
the pure culture starter, one may add two to four quarts of good 
cider vinegar containing more or less "mother" for each barrel. The 
introduction of a desirable organism is left to chance in this case. 
A serious objection to this latter method is that sometimes one 
introduces foreign organisms with the "mother" which may prove 
detrimental to the vinegar. The pure culture starter is free from 
this objection. On the whole, the indiscriminate use of "mother" 
alone is to be discouraged, since the popular idea of what 
constitutes "mother" is apt to be wrong. Pure "mother" is made up 
exclusively of acetic acid bacteria and is recognized as the thin, 
white, glistening, gelatinous membrane that forms on the surface of 
vinegar. It seldom becomes one sixteenth of an inch in thickness and 
should be translucent or white in color, It is entirely distinct from 
the thick, tough, dark brown, slipping, leathery masses which form in 
vinegar and are usually regarded as "mothy of vinegar." Such 
accumulations contain the acetic acid germ, in all probability, but 
in an impure state. In addition to this organism there may be present 
yeast cells and numerous bacteria which are positively harmful to the 
vinegar. Often these growths undergo decomposition and give the 
vinegar a flavor of rotten oranges. Again the germs present may cause 
the partial or complete loss of the acid, particularly if the barrels 
are not full and tightly stoppered. All things taken into 
consideration, the use of this sort of "mother" is a rather dangerous 
procedure.

With the acetic fermentation, as with the alcoholic, the higher 
temperatures favor the changes. Experimental work shows that hard 
cider to which no acetic acid bacteria were added other than those 
that came from the air, and kept at 65 degrees F., when six months 
old, contained 7.03 per cent. of acetic acid, while that held at 55 
degrees F. showed only 3.63 per cent.

The addition of some kind of an acetic acid starter, either as a pure 
culture of the acetic organism or as good vinegar, hastens the 
fermentation and reduces appreciably the time required for making 
marketable vinegar.

For most satisfactory results we would recommend using the pure 
cultures and holding the vinegar at a temperature of 65 to 75 degrees 
F. Under these conditions, salable vinegar can be obtained in three 
to six months in place of two to three years, as is often [Page 13] 
the case. Theoretically, 100 parts of alcohol should give about 130 
parts of acetic acid, but in actual practice this will probably fall 
below 120.

When the acetic acid has reached 4.5 to 5 per cent., fill the barrels 
as full as possible and cork tightly. In this way, contact of the air 
with the vinegar is cut off and the acetic acid organisms soon cease 
their activity. If this is not done and the acetic and other bacteria 
are allowed to develop indefinitely, there is apt to be a reverse 
reaction resulting in a partial or complete loss of the acetic acid. 
Such vinegar is, of course, worthless.

_Clarification of Vinegar._

For those who desire an extra fancy product of extraordinary 
brightness, suitable for bottling, it will be necessary to subject 
the vinegar to a special process of clarification known as fining. 
According to Bioletti*, the best results are obtained by using 
isinglass. This is employed at the rate of from one-half to 
three-fourths of an ounce of isinglass to each one hundred gallons of 
vinegar.


* Bioletti, Frederic T., Grape Vinegar, Bull. 227, California Exp. 
Sta., 1912.


"The isinglass is cut into small pieces and soaked for twelve to 
twenty-four hours in a little water containing acetic or tartaric 
acid equal in weight to the isinglass used. When thoroughly soft it 
is then rubbed several times through a fine sieve, gradually adding a 
little more water until a perfectly fluid liquid is obtained. This 
fluid is then well mixed with a little vinegar and thoroughly stirred 
into the cask. With some vinegars it is necessary to add a little 
tannin, from one-half to one-seventh the amount of the isinglass 
used. This tannin should be added at least twenty-four hours before 
the finings.

When the finings have settled and the vinegar is perfectly bright it 
is ready for bottling."

_Pure Cultures for Vinegar Making._

Reference has been made above to the use of pure cultures, both yeast 
and acetic acid bacteria, for vinegar making. For a little more than 
one year, the Bacteriological Laboratory of the Colorado Experiment 
Station has been supplying these at fifty cents (50c) per set, post 
paid, sufficient for one barrel, to those who care to give them a 
trial. Full printed directions for their use are included. These 
cultures have been selected because of certain properties which they 
possess which make them especially suited to the vinegar industry. No 
guarantee, either expressed or [Page 14] implied, goes with the 
cultures, since it is not the purpose of the Experiment Station to 
exploit these products, but rather to distribute them at the cost of 
production for experimental purposes. Inasmuch as one of the cultures 
is to be added to the sweet cider, the set should be obtained a few 
days, not longer, before the cider is to be made.

Requests for cultures should be addressed to the Bacteriological 
Laboratory, Colorado Experiment Station, Fort Collins, Colorado, and 
should be accompanied by a remittance of fifty cents (50c).

_Directions For Using Pure Cultures in Making Vinegar Preparation of 
Yeast Culture._

1. For each barrel of sweet cider, sterilize one two-quart Mason jar 
by washing thoroughly and boiling for five minutes in clean water.

2. Cover the top of the jar with a single layer of clean muslin or 
cheese cloth just removed from boiling water and secure it in place 
by a string tied about the neck of the can.

3. Select 6 or 8 medium sized _ripe_ apples; pare and quarter or slice 
them; add one quart of water and boil till soft; strain liquid 
through clean cloth while hot into Mason jar, first removing the 
cloth covering from the top.

4. Make up the volume of liquid to approximately one quart with 
boiling water; add 4 tablespoonfuls of sugar and replace the cloth 
immediately.

5. When the liquid has cooled thoroughly, partly remove the cloth 
covering and add the contents of the culture bottle marked "Yeast." 
Replace the cloth. Just previous to opening the culture bottle, shake 
thoroughly and immerse the lip and cork only, ten second in boiling 
water. Do not touch the lip while removing cork.

6. Keep the jar in subdued light at a temperature of 75 degrees F. to 
90 degrees F. After two to four days the foaming characteristic of 
alcoholic fermentation should appear.

7. After four to six days, add the entire contents of the _yeast_ jar 
to the barrel of freshly made _sweet_ cider. _The barrel must not be 
more than two-thirds full;_ it should be placed on its side, and the 
bung-hole be left open, or, better, plugged loosely with a tuft of 
clean cotton batting.

8. Keep the barrel at 75 degrees F. to 85 degrees F.

[Page 15]

_Preparation of Acetic Culture._

1. Three to four weeks after the yeast culture has been added to the 
cider prepare the Acetic Culture in precisely the same manner as 
described for the yeast in paragraphs 1 to 6 above. See that all of 
the culture is removed from the bottle; rinse with a little cooled 
boiled water if necessary. Do not shake the jar while the culture is 
developing.

2. By the end of one to two weeks, a white, gelatinous film or 
membrane should be visible on the surface of the liquid. This is a 
growth of acetic acid bacteria and constitutes the "Mother of 
Vinegar."

3. When this acetic membrane is well formed, which will require about 
two weeks, with a clean sliver of wood, previously dipped into 
boiling water, remove the membrane from the jar, but do not lay it 
down; pour the contents of the jar into the barrel of cider, now 
fermented, to which the yeast was added some five or six weeks 
before; next drop the sliver with the attached acetic film into the 
barrel through the bung-hole. The wood will serve to float the acetic 
membrane on the surface of the hard cider and thereby hasten its 
development by keeping it in contact with the air.

4. Keep the barrel at 65 degrees F. to 75 degrees F. till the vinegar 
has formed.

5. When vinegar of satisfactory quality has been obtained, in three 
to six months, draw off and store at a cool, even temperature in 
casks which are kept full and tightly bunged.

6. Both of these cultures can be propagated indefinitely by employing 
a small portion of the jar cultures in the same manner as the 
original bottle starters.


TRANSCRIBER'S NOTES:

1.  Italics in the original text have been indicated by underscores
at the beginning and end of the italicized text, for example, 
"_italicized text_".
2.  Bold face in the original text has been indicated by equals signs 
at the beginning and end of the bold face text, for example, "=bold 
face text=".