Allen Paul W. Industrial Fermentations

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MARINE PRODUCTS 291

be of small capacity and carried on a fishing boat or it may be a

freezer of large capacity at some central point convenient for receiving

the oatches. In this method a strong brine solution, cooled by circula-

tion through crushed ice is used for freezing" the fish. By this method

large fish may be frozen in from 1 to 3 hours, a great saving in time

as oompared with the method at present in use."

BEFERENCES ON SEA FOOD.

Clark, H. W., and Gage, S. Deam., 1904. American Pub. Health Assn. Rept.,

1904.

Clough, R. W., 1922. Wash, (state) Univ. Pugot Sound, Biol. Sta. Pubs., Vol.

8, No. 64067, pp. 196-272.

Cobb,

John N., 1921. U. S. Dept. of Commerce Bureau of Fisheries, Docu-

ment 902.

Cobb,

John N., 1917. U. S. Dept. of Commerce Bureau of Fisheries, Docu-

ment 839.

Cobb,

John N., 1911. U. S. Dept. of Commerce Bureau of Fisheries, Document

751.

Conn. H. W.

1894. Medical Record 46, 743; 746.

Crumbine, S. J., 1907. Kansas State Board of Health, Bui. 3 (2):

40-41.

Doane, R. W., 1904. Pacifio Fisherman, 2 (1): 42-44.

Field, C. W., 1902. N. Y. City Board of Health Ann. Rpt., 1904; 461-456.

Fuller, C A., 1904. U. S. Bureau of Fisheries. Report, 1904, pp. 189-238.

Gage, 8. Dem., 1910. Jour, of Inf. Diseases, 7 (1); 78-86.

Ham, G. C.,1905. 28th Ann. Rpt. Conn. State Board of Health, pp.

70-73.

Herdmann, W. A., and Boyoe, Rubert, 1899; Lancashire Sea Fisheries Memoir

No.

1, page 1.

Hill, G. E., 1906. Franklin Inst. Jour., 169 (1): 1.

Hill, H, W., 1900. 29th Ann. Rpt. Boston Health Dept., pp. 63-92.

Houston, A. C, 1904. Jour, of Hygiene, 4 (2): 173-200.

Moore, H. F., 1897. U. S. Com. of Fish, and Fisheries Rpt., 1897, pp. 260-320.

Savage. W. G., 1906. Jour, of Hygiene, 5 (2): 146-174.

Sofer, G. A;, 1906. Medioal News, 88 (6): 241-253.

Stevenson, C. EL 1898. U. S. Com. of Fish, and Fisheries, Bui. 1898, pp. 335-563

Turrentine, J. W., 1915. U. S. D. A., Bui. 150.

Wood, B. F., 1908. N. Y. Forest, Fish and Game Commission, Bui. 1906.

Chapter 22.

Vinegar Manufacture.

There are two fermentations involved in vinegar making, the

alcoholic, and the acetic fermentation. The alooholic fermentation

may be represented as follows:

CHuOa + yeast alcoholase = 2C

0H + 2CO,

dextrose ethyl alcohol carbon dioxide.

This reaction is the result of the action of alcoholic yeasts on dex-

trose sugar.

The acetio fermentation may be represented by the following

reaction:

2C,HBOH

+ O

+ bacterial oxidase = 2CH

CHO + 2H,0

ethyl alcohol acetic aldehyde

2CH»CH0 + 0, + bacterial oxidase = 2CH

COOH

acetic aldehyde acetio aoid

Raw Materials of Vinegar Making.

"Vinegar can be made from a wide variety of products, however the

most common sources of vinegar are cider, grape juice, and malt ex-

tracts of grains. Other products which have been used as sources of

vinegar are honey, beets, oranges, sugar cane, peaches, berries, pears,

watermelons, maple syrup, sorghum, glucose, molasses, eto. Some

of the sources of starches which may be treated with diastase or other-

wise converted into sugars for vinegar making are starohes of corn,

potatoes, wheat, arrowroot, etc.

Composition of Vinegar.

Vinegar as it usually comes on the market contains 3 to 6 per cent

acetic aoid, 2.5 per cent total solids and .3 per cent ash (mainly

potassium salts). In addition there are other important chemical

substances which give to vinegar its desirable flavor and aroma. These

substances differ according to the methods and care of manufacture,

also according to the source of the sugary extract which has been

fermented,' Chemically, acetic acid is the oxidation product of ethyl

alcohol and is the second member of the fatty acid series.

Acetic acid is not only a fermentation product but can also be

produced by the destructive distillation of wood..

292

VINEGAR MANUFACTURE 293

Spontaneous Fermentations.

The fermentations in vinegar-making are best carried out by the

use of "starters," but the custom of using pure cultures is not very

well established in home or commercial vinegar-making. When fruit

juices are left exposed to the atmosphere, alcoholic fermentation usually

gets in, followed some weeks later by acetio acid fermentation. This

means that alcoholic yeasts and acetic acid bacteria are normally

present almost everywhere. Under certain conditions, however,

vinegar-making does not proceed spontaneously. This has been found

by the author to be the case where vinegar-making is attempted with

apples grown under irrigation conditions and sprayed with certain

arsenio sprays.

The Alcoholic Fermentation.

The alcoholic yeast, Saocharomyces ellipsoideus, is well suited to

carry on the alcoholic fermentation in vinegar-making. Jorgensen

describes this species as a bottom-fermentation yeaBt, producing mostly

oval and round cells in wort, seldom producing sausage-shaped cells.

It fennente dextrose, lfflvulose, and saccharose but does not ferment

lactose. Further Jorgenefen says, "At temperatures above 13° C. the

film of S. ellipsoideus II develops so rapidly and vigorously that

flasks containing this yeast can be recognized by this feature alone.

Thus,

at 22°-23° C. the film had completely covered the surface in six

to twelve days." He says that when streak cultures of S. eUipsoideus

are grown for eleven to fourteen days at 26° C. in wort containing

5.5 per cent of gelatin, it produces a characteristic net-like structure

which differentiates it from other species.

LaFar (1910) gives the following description of S. ellipsoideus:

"Saccharomyoes ellipsoideus, E. C. Hansen. Synonyms: Sacch. ellip-

soideus I., E. C. Hansen = Sacch. ellipsoideus, E. C. Hansen = Sacon.

ellipsoideus, Rees. The cells are ellipsoidal, though they may also

be sausage-shaped. The limits of budding temperature in wort are

40°-41° C. and 0.6° C. The spores are 3-4 \i, seldom 3.5-4 \i in

diameter. Limits of sporulation temperature on gypsum blocks,

30.5°-32.5° C. and 6?-7° C. The cells of the young film, grown at

13°-15° C. differ from those of Sacch. turbidans (which are round

and oval) by consisting largely of long, sausage-shaped forms. At

the end of eleven to fourteen days the streak cultures on wort gelatin

at 25° C. exhibit a peculiar reticulated structure, differentiating them

from the preceding species and Sacch. turbidans. This species is

generally a bottom yeast. It was discovered on the surface of ripe

grapes in the Vosges district and is one of the numerous species that

play an active part in the fermentation of wine."

The temperature for best work with many strains of this organism

is between 75° and 80° F.

The place of Saccharomyces in the classification of the true yeasts

is given in the following key by Hansen after Buchanan:

294 INDUSTRIAL, FERMENTATIONS

Family I. Vegetative reproduction by budding—Saccharomycetaceffl.

A. Cells do not form a surface membrane at once on sugar media,

i.e., do not grow exclusively at the top of the medium.

Spores having a single membrane.

a. Cells fusing in pairs before spore formation—zygooacoh-

aromycete.

Cells not fusing in pairs before spore formation.

(1).

Spores germinate by ordinary budding—Saooharomy-

ces.

(2).

Spores germinate by means of promycelium—

SaooharomycodeB.

Spores having two membranes—Saccharomyoopsis.

Cells forming a surface membrane at once by sugar media.

Spores spherical, hemispherical, or irregular—Pichia.

Spores lemon-shaped with pointed ends—Willia.

Family II. Vegetative reproduction by fission—Schizosaccharomycetes

Wyant of Michigan Agr. Experiment Station says that in the

alcoholic fermentation there should result about 60% as much alcohol

as there was sugar in the unfermented solution. She says, "100 parts

of sugar in the juice should produce theoretically about,51 parts of

alcohol, that is, about half as much alcohol by weight should be

obtained as there was sugar in the juice. In actual practice only

from 46 to 47 per cent is obtained because some of the sugar is used

by Saccharomyces ellipsoideus and other microorganisms for purposes

other than alcohol production.

"In the conversion of alcohol into acetio acid 100 parts of al-

cohol should yield theoretically 130 parts of acetio acid, but leBB

than 120 parts' are actually obtained because certain other yeasts

and bacteria, whioh are quite sure to be present, also use aloohol as

food.

"Thus for every 100 parts of sugar present in the original sugary

solution, under favorable conditions, 60 to 55 parts of acetic acid

should be obtained. So if a vinegar containing 5 per cent acetic add

is desired, the fermentation should be started with at least a 10 per

cent sugar solution, while for a 4 per cent, acetic acid content

(Michigan standard) the sugar solution (fruit juice, etc.) must con-

tain at least 8 per cent sugar."

In the manufacture of vinegar from alcoholic solutions produced

from fruit or grain extracts, there is sufficient nitrogenous material

and phosphate salts so that the acetio acid bacteria do not lack for

these fundamental elements of nutrition.

If an alcoholic liquor has been produced from fruit or grain ex-

tracts which have been the seat of growth of foreign bacteria, neither

the alcoholic fermentation nor the acetic acid fermentation can be

normal and a satisfactory vinegar cannot be made because of the off-

flavors produced by abnormal fermentation.

The importance of the use of pure cultures as "starters" in making

VINEGAR MANUFACTURE 295

vinegar is very evident from the large number of abnormal fermenta-

tions which are possible.

The alcoholic fermentation of a single sugar as dextrose, naturally

results in ethyl alcohol and carbon dioxide, however, there is a large

number of bacterial fermentations whioh may go on along with the

yeast fermentation and use up enough of the sugars so that the final

vinegar is low in aoid. Some of these bacterial fermentations which

may attack dextrose, according to Erase, are as follows:

(1).

CeHuOa = 2C

lactio acid

(2).

CeHx.0, = 3C

H<O

acetic aoid

(3).

= C

+ 2CO

-f 2H

butyric acid

(4).

CH^Oe = C,H

O + 2CO, + H

butyl alcohol

(5).

70^0,, + 6H

O = 12C

Ha0

+ 6CO

glycerin

(6).

+ 6H

O = l^C^HaO* + 6H

succinic acid

(7).

+ 6H

O = 6CO

+ 12H

Use of Sulphurous Acid and Pure Cultures.

Cruess, Zion and Sefredi investigated the value of the use of sul-

phurous acid and pure cultures in vinegar making and found that a

large loss was being suffered due to the presence of foreign organisms

which could be largely eliminated by the proper use of sulphurous aoid

and a pure culture system. They describe the conditions in a typical

vinegar factory as follows: "In one of the largest factories, the cull

apples and peels and cores from apple driers are ground or 'grated' in

an Ohio apple grater as soon as received. The juice is pressed out

with heavy screw presses driven by a motor and cog gearing with a

capacity of 60 tons per day. The juice goes to 20,000 gallon tanks.

The first tank of the season is started with a large starter of com-

pressed yeast. When this tank is in fermentation, about one third of

its contents is used to start the next tank. The third tank is started

from the second, and so on through the whole series of tanks. Over

500,000 gallons are made in this way during a season. Examination of

the fermented juice showed it to be 'dry,' that is practically free from

unfennented sugar, but it was shown by microscopical examination

to contain large numbers of lactic acid bacteria and the large tanks

soon developed a heavy growth of mycoderma (wine flowers) often

alcoholic fermentation. The lactic acid bacteria develop a 'mousey'

flavor and the mycoderma rapidly oxidizes alcohol to CO

and H

without forming any corresponding amount of acetic acid. Laboratory

testa demonstrated that mycodenna isolated from cider was capable of

296 INDUSTRIAL FERMENTATIONS

destroying all of the alcohol of a fermented orange juice containing

4.5 per cent alcohol in three weeks. The gravity of heavy mycoderma

growth may be seen from these figures." ,

They say, "The use of pure yeast and sulphurous acid in barrel

fermentations gave increased yield of alcohol, more complete fermenta-

tion of the sugar, a better flavor, more rapid clearing, a fermented

liquid praotioally free from lactic bacteria and mycoderma vim, and

a more rapid change of alcohol to acetio acid after alcohoho fermen-

tation. This indicates the disappearance of practically all of the

active sulphur dioxide because acetic bacteria have been shown to be

very sensitive to it. Large scale fermentations with pure yeast and

sulphurous acid gave an increased yield of alcohol and a cleaner

fermentation. Examination of several factories shows the extreme

need of some method of control of alcoholic fermentation, and to supply

this need, the use of small amounts of sulphurous acid to eliminate

wild yeast and the addition of pure selected yeast to give a rapid

and complete fermentation seems the most practical means of produc-

ing the desired results."

The Acetic Acid Fermentation.

It was shown by Hansen that the organisms causing acetio aoid

fermentation of alcoholic solutions consist of several speoies as follows:

Bacterium aceti (Kutzing)

Bacterium pasteurianum (Hansen)

Bacterium kutzingianum (Hansen)

Bacterium xylinum (Brown)

Bacterium acetigenus

Bacterium oxydans

Bacterium industrius

The vinegar bacteria if undisturbed form a film on the surface of

alcoholic solutions. This is often called "Mother of vinegar." As

the conversion of alcohol into acetic acid is purely an oxidation, it is

obvious that the organisms causing this oxidation must remain on the

surface and have a liberal supply of oxygen. When Pasteur investi-

gated the troubles of the vinegar makers of Orleans, he found that

they did not appreciate the great importance of supplying their fer-

menting vats with plenty of air and of the prevention of the sub-

mergence of the film of acetic bacteria. He devised a method of using

a raft of slats on the surface of the alcoholic solutions to prevent the

film of acetic acid bacteria from sinking.

In the manufacture of vinegar in barrels, the barrels are left partly

full, with vents open so that there will be a considerable surface

of liquid exposed to the air.

It has been calculated that-one vinegar bacterium is capable in a

single fermentation, of forming hundreds of times its own weight of

VINEGAR MANUFACTURE

297

acetio acid. The organism causes this oxidation reaction because it

needs the energy thus obtained for its life processes.

Because of the limited amount of sugar in fruit juices and the

limite of alcoholic fermentation by yeasts, the amount of acetic acid

in ordinary vinegar is kept down to from four to seven per cent.

After Eansm.

Fia. 43.—Bacterium aceti.

X 1000. 24-hour-old culture in "dopple-bier" at

However, acetic acid fermentation has its limits also. When the

concentration of acetic acid in fermenting liquor has reached eight

per cent the activity of the acetio acid forming organisms becomes

slower and slower and ceases almost altogether when 12 to 14 per

cent acid content is reached.

The amounts of different sugar and the total amount of sugar in

the juice of some common apples are given by GofE as follows:

298 INDUSTRIAL FERMENTATIONS

ANALYSES OF APPLE JTJTCB.

Sucrose Lavulose Dextrose Total

(o) (d) (e) (d) (e) (d)

Mother 25 65 6.4 1.7 22 9.7

Grimes 3.9 53 6.4 0.5 12 9.9

Arkansas 1.5 53 62 2.6 3.0 9.9

Limbertwig 0.7 5.0 5.4 3.5 2.3 93

York Imperial 12 63 6.6 2.5 2.7 9.9

Lankford 2.6 .. 63 .. 22 ..

Gano 13 6.9 6.0 35 2.6 104

Peok 63 62 33 23 12.0

Northern Spy 3.7 62 IX 1.7 1.7 10.4

White Pippin 2.7 5.9 63 22 13 10.5

Plumb Cider QA 5.9 6.7 1.4 1J6 7.9

Rome (Beauty).... 1.9 6.1 63 1.4 IS 9.7

Yellow Neuton.... 3JL 5.9 63 13 2.4 112

Stayman Winesap.. 31 63 63 2.1 2.4 11.8

Ben Davis 1J0 5.9 6.5 2.5 2.7 9J8

(o) Add inversion, ou reduction.

(d) Optically.

(e) Broune.

He remarks concerning figures in above table that in every case

the amount of lavulose exceeds the combined amounts of the other

sugars present.

Acetic fermentation is carried on at different temperatures depend-

ing upon the particular organism employed and the process of manu-

facture. The English vinegar makers' hold their acetio aoid fermenta-

tion at between 40° and 43° C. while American manufacturers use

a much lower temperature usually about 32° G.

Care must be taken that the alcoholic content of the solution

being fermented to vinegar does not drop below two per cent alcohol

as at this point the vinegar bacteria begin to respire and destroy some

of the acetio acid -already formed aocording to the following reaction:

CHaCOOH + 40 = 2CO

+ 2H

Not only is this oxidation of acetio acid accompanied by commercial

loss of strength but also loss of flavor and aroma.

Before the acetic acid bacteria are allowed to start their fermenta-

tion of the alcoholic solutions, it is important that the yeasts should

have nearly completed their alcoholic fermentation as yeasts do not

work so well in the presence of acetic acid. This is because of the

poisonous effect which acetic acid has on alcoholic yeasts.

In starting the acetic acid fermentation it is usual to add a certain

amount of "starter," that is, a culture of acetic acid bacteria. This

insures a rapid film production on the surface of the liquid.

Concerning the subject LeFevre says, "Sometimes failure occurs

during the acetic fermentation. Acetification may be slow in starting

or may stop entirely, owing to the fact that the aoetic bacteria are

present only in small numbers or that those present are of a weak

After Hantm.

Fia. 44.—Baoterium paateurianum. X 1000. Culture on "doppel-bier" agar

a Bottcher chamber at 34° C.

(a ) Long thread of early oulture.

(a' ) After five and a half hours' oulture.

(a" ) After seven hours' culture.

(b ) Long thread showing bends.

(b ) Long thread after four hours' oulture.

\ T

300 INDUSTRIAL FERMENTATIONS

erf.TftiTi or of an objectionable type, like the Bacterium xylinum. In

most cases failure is due to the fact that the medium is unfavorable

to the growth of the acetic bacteria or that the temperature and air

conditions are not favorable. As a rule acetic bacteria will grow in a

medium which is only weakly acid or even slightly alkaline, but a more

prompt and vigorous growth can usually be obtained in a decidedly

acid medium. For thia reason the addition of vinegar iB always ad-

visable, especially in the case of juices or solutions which are normally

low in acid. The addition of vinegar also is. a protection, against the

growth of undesirable organisms until enough acid is formed by

oxidation of the alcohol present."

Pasteur Method.

Pasteur used a shallow vat with regulated air vents near top for

alcoholic fermentation. Four parts of high grade vinegar from a

previous fermentation and six parts of filtered pasteurized wine was

placed in the vat. A film of acetic acid bacteria was added to the top

of the vat and a perforated wooden float was placed on the top of the

liquor to keep the film from sinking. Each day a definite amount

of vinegar was withdrawn and an equal amount of wine was added.

The vinegar was filtered, pasteurized, and then stored. Some of the

advantages of this method over the Orleans method is that it makes

vinegar faster and therefore at less cost.

The "Quick Vinegar Process."

The rapidity with which vinegar is

made from alcoholic solutions

depends very largely upon the amount of film exposed to the air.

Working on this prinoiple, it became the custom in Europe to build

a tall wooden tank (vinegar generator), with false head and false

bottom. The tank was filled with washed beech-wood shavings over

which the wine or alcohol containing liquor, was allowed to trickle.

Air forced its way up through the porous mass of beech shavings while

the alcoholic liquor traveled down through the shavings. Due to the

great surface thus exposed, vinegar making took place very rapidly in

these generators. Small amounts of wine were added intermittently.

The vinegar was too weak as it came through the first time and

had to be repassed several times through one tank or through several,

lined up as a battery. The temperature was not allowed to go above

30 degrees C. because of considerable loss due to volatilization of

alcohol and acetic acid. There is enough heat of fermentation gen-

erated by the acetic acid bacteria on the shavings to insure air circu-

lation from the vente, in the lower false head, upward. The disad-

vantages of the "quick vinegar process" are the high loss of acetic

acid due to volatilization, and the loss of other volatile products

related to the flavor and aroma.