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SUGAR AND SUGAR-MAKING
BY
JAMES B. McNAIR
Assistant Curator of Economic Botany
Botany
Leaflet 13
FIELD MUSEUM OF NATURAL HISTORY
CHICAGO
1927
J
LIST OF BOTANICAL LEAFLETS ISSUED TO DATE
No. 1. Figs $ .10
No. 2. The Coco Palm 10
No. 3. Wheat 10
No. 4. Cacao 10
No. 5. A Fossil Flower 10
No. 6. The Cannon Ball Tree 10
No. 7. Spring Wild Flowers 25
No. 8. Spring and Early Summer Wild Flowers . . .25
No. 9. Summer Wild Flowers 25
No. 10. Autumn Flowers and Fruits 25
No. 11. Common Trees 25
No. 12. Poison Ivy 25
No. 13. Sugar and Sugar- Making 60
D. C. DAVIES. Director
FIELD MUSEUM OF NATURAL HISTORY
CHICAGO, U.S.A.
Courtesy of the United Fruit Co.
SIXTEEN SUGAR CANES FROM ONE SEED IN CUBA.
Field Museum of Natural History
DEPARTMENT OF BOTANY
Chicago. 1927
Leaflet Number 13
Sugar and Sugar-Making
Sugar is manufactured by plants for their own
use. It is formed in their green parts from carbon
dioxide of the air and the water of the sap. Under the
influence of sunlight filtered by the green coloring
matter (chlorophyll) of the plant, the gas and water
combine to form formaldehyde which is later con-
verted into glucose and other sugars.
Sugar is soluble in the plant sap and is carried in
the sap to various parts of the plant to be transformed
where needed into other substances such as fiber.
Some plants store sugar for future use, e. g., for the
growth and seed-production of the following year, as
is the case with the sugar beet.
For storage, particles of sugar may unite with
each other to form larger, less soluble bodies such as
starch due to the union of glucose with glucose in
potatoes, the starchlike substance inulin from the sugar
levulose with levulose in dahlia tubers, cherry tree gum
from the sugar arabinose with arabinose in cherry
trees, and gum arabic from the sugar galactose, arabi-
nose, and arabinon in acacia trees.
Sugar may also join with other substances in
plants as when glucose unites with gallic acid to form
tannin in the oaks and sumacs, rhamnose with fisetin
to form the dye stuff fustic in the smoke-wood tree
(Rhus Cotinus), and mannose with cellulose to form
[181]
2 Field Museum of Natural History
"vegetable ivory" in the kernel of the ivory palm
(Phytelephas macrocarpa). Sometimes these com-
pounds are poisonous as in the cases of arbutin and
amygdalin. Arbutin is found in the trailing arbutus
and bearberry, while amygdalin is found in the seeds
of the bitter almond, apricot, and peach.
Besides its use as food for the plant, sugar manu-
factured by plants also serves a useful purpose in the
nectar of flowers by attracting insects for pollination
and in fruits by making these attractive to animals
that aid in seed dissemination. Nectar contains for the
most part cane sugar, glucose, and levulose, and is
taken by bees to form honey. Some flowers contain
sufficient nectar to be attractive to man as a source of
sugar. Among these are those of the Madhuca tree
(Madhuca latifolia), the Honey Flower (Melianthus
major), and the Boer Honey Pots (Protea mellifera
and Protea cynaroides) . W. Ferguson says that in the
time of Manu, about 4,000 years ago, the Hindus knew
how to make sugar from the flowers of the Madhuca
tree. The natives of Cape Colony collect the Honey
Flowers for the large quantity of sugar they contain,
and the Boers of South Africa make use of the Honey
Pot flowers for the same purpose.
Many different sugars occur in nature in plants
and animals. Other sugars not yet found in nature
are produced synthetically in the laboratory. The gen-
eral term "sugar" applies to a large number of sub-
stances composed of three elements, carbon, hydrogen,
and oxygen combined in certain proportions. Sugars
which possess distinct chemical and physical prop-
erties are distinguished by special names, e. g., sucrose.
The sugars belong to a much larger group of sub-
stances called carbohydrates, most of which conform to
the general formula Cm (H20)„, where m and n stand
for various multiples. See outline on page 4. The
[ 182 ]
Field Museum of Natural History
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Sugar and Sugar-Making 5
other plant substances of this group, cellulose, starch,
and gum, are more complex but may be decomposed
or broken down into various sugars.
Commercial sugars are named after the particular
plants from which they are extracted, for instance,
cane, beet, maple, sorghum, palm. The chief con-
stituent of all these is a single substance — sucrose or
saccharose. Corn and grape sugar on the contrary
consist of another chemical substance — glucose.
All sugars are not of equal sweetness. Corn sugar
(glucose) is only three-fifths as sweet as cane sugar,
while levulose is about equal to cane sugar in sweet-
ness.
CANE SUGAR
The sugar cane (Saccharum, officinale) belongs to
the grass family (Gramineae) which includes wheat,
oats, corn1 (maize) , sorghum, etc. ; but the sugar cane
towers above most of them, sometimes attaining a
height of twenty feet. Its native country is Southern
or Southeastern Asia. Being a plant of the moist
tropics and subtropics, it grows successfully only
where the average temperature does not fall much be-
low 80° Fahrenheit nor the rain below sixty inches a
year.
History. — Various classical writers of the first cen-
tury noticed the sweet sap of the Indian honey-bearing
reed or its granulated saltlike product. This product
was imported to Europe from India and from Arabia
and Opone (these being entrepots of Indian trade) un-
der the name of saccharum (<janxa.pi from Sanskrit
sarkara, gravel, sugar), for medical use.
Before the Middle Ages Europeans had no clear
idea of the origin of cane sugar. It was confounded
'The Aztecs in Mexico made use of the corn plant for sugar
in the same manner as sugar cane is used now.
[185]
6 Field Museum of Natural History
with manna or was thought to exude from the stem of
a plant, on which it dried into a kind of gum. The art
of boiling sugar was known in Gangetic India, from
which it was carried to China in the first half of the
seventh century ; but sugar refining cannot have been
known then, for the Chinese learned the use of ashes
for this purpose only in the Mongol period (600 A. D.) ,
from Egyptian visitors. The cultivation of the cane
in the West spread from Khuzistan in Persia. At
Gunde-Shapur in this region "sugar was prepared
with art" about the time of the Arab conquest, and
its manufacture on a large scale was carried on at
Shuster, Sus, and Askar-Mokram throughout the
Middle Ages. It has been plausibly conjectured that
the art of sugar refining, which the farther East
learned from the Arabs, was developed by the famous
physicians of this region, in whose pharmacopoeia
sugar had an important place. Under the Arabs, the
growth and manufacture of the cane spread far and
wide, from India to Sus in Morocco, and was also in-
troduced in Sicily and Andalusia.
In the age of discovery, the Portuguese and Span-
iards became the great disseminators of the cultiva-
tion of sugar; the cane was planted in Madeira in
1420; it was carried to San Domingo in 1494; and it
spread over and occupied portions of the West Indies
and South America early in the sixteenth century.
Within the first twenty years of the sixteenth century
the sugar trade of San Domingo expanded with great
rapidity, and it was from the dues levied on the im-
ports brought thence to Spain that Charles V obtained
funds for his palace-building at Madrid and Toledo.
In the Middle Ages, Venice was the great Europe-
an center of the sugar trade, and toward the end of the
fifteenth century a Venetian citizen received a reward
of 100,000 crowns for the invention of the art of mak-
[186]
8 Field Museum of Natural History
ing loaf sugar. One of the earliest references to sugar
in Great Britain is that of 100,000 pounds of sugar
being shipped to London in 1319 by Tomasso Lore-
dano, merchant of Venice, to be exchanged for wool.
In the same year there appears in the accounts of the
Chamberlain of Scotland a payment at the rate of
Is 9*4^ per pound for sugar. Throughout Europe it
continued to be a costly luxury and article of medicine
only, till the increasing use of tea and coffee in the
eighteenth century brought it into the list of prin-
cipal food staples. The increase in the consumption is
exemplified by the fact that, while in 1700 the amount
used in Great Britain was 10,000 tons, in 1800 it had
risen to 150,000 tons, and in 1885 the total quantity
used was almost 1,100,000 tons. In 1924-25 the
United States produced 88,483 of a world-production
of 17,649,000 short tons.
Sugar cane was introduced into Louisiana from
San Domingo by the Jesuits in 1751. Dubeuil built the
first cane-mill, and his efforts at manufacture failed.
The first refined sugar was made by Antonio Mendez
in 1792, but the first refined sugar on a commercial
scale was made in 1794 by Etienne de Bore. The
plantations of these two planters now form part of
the city of New Orleans.
The manufacture of sugar was very crude up to
1700. Inefficient mills operated by wind, water, or
oxen were used for extraction with lime, clay, and
ashes as purifying agents; the evaporation was ef-
fected in open copper or iron pans placed directly over
the fire, and the refining consisted in melting, boiling,
and recrystallizing. These crude methods still exist
in some countries, especially in districts where cane
is grown for making syrup and very crude sugar.
Extraction. — There are in practice two methods
of extracting the sugar from cane, namely, milling
[188]
Sugar and Sugar-Making 9
and diffusion. The older and more generally used is
milling, the diffusion being confined almost entirely to
manufacture of sugar from beets. A mill may consist
of two or three rollers, usually placed horizontally and
varying in length from eighteen to seventy-two inches,
and in diameter from twelve to thirty-two inches. If
the mill is to be operated by oxen or by horses the
rollers are set in an upright position. The most primi-
tive mill was the wooden roller. This has been used
in a small way in some of the southern states since
the Civil War, but there is at this time, perhaps, not
one in existence in this country. In most large
factories there are two of these three-roller mills and
in some three. The rollers are so arranged that two
are placed on a level and geared to move in the same
direction while the third moves in the opposite direc-
tion. If a factory operates two mills, the rollers of the
first are farther apart than those of the second, and if
three mills, the third has its rollers closer together
than the second. These rollers revolve very slowly
(one and a half to two and a half revolutions per min-
ute) and are operated under great pressure. To re-
lieve the strain upon the mill, a cane crusher or
shredder has come into general use. The cane enters
one of these as it leaves the cane carrier and is either
crushed or shredded into small pieces before reach-
ing the mill. This not only relieves the mill of the work
of crushing the whole cane, but increases its capacity.
The capacity of mills will vary from 200 to 1,400 tons
of cane per day and the extraction is 70-80 per cent
of the weight of cane and 90-95 per cent of the sugar
in the cane. Between the first and second mill the
juice receives a spray, through a perforated pipe, of
either hot or cold water, the object being to dilute the
sugar so that a large percentage will be crushed out
by the second mill. This addition of water is termed
[189]
10 Field Museum of Natural History
maceration, and the quantity of water added may vary
from 5 to 15 per cent of the weight of the cane and in
some cases as much as 20 per cent, the quantity de-
pending somewhat upon the value of fuel and the
capacity of the evaporating outfit. In some instances
the diluted juice from the third mill is returned and
used for macerating the crushed cane between the
first and second mill, and water is used between the
second and third.
Diffusion has been practiced at several factories in
Louisiana and some other countries, but it has not yet
met with very great favor.
Purification of the juice. — The juice as extracted
by the mill has a gray or dark-green color, an acid
reaction, and contains sucrose, glucose, perhaps a little
levulose, gum, protein, organic acids, pectin, ash or
mineral constituents, soil, coloring matter, fine par-
ticles of suspended cane, etc.
Primitive methods for purifying the juice do not
differ essentially from the practice of today. The
juice extracted in crude mills was heated in an iron
vessel over a wood fire. Ashes from the fire were
added to the hot juice. A dark scum was thus caused
to form and was removed. The juice was concentrated
by boiling to a thick syrup and slowly cooled. This
practice is still employed in China and India. The
chemical action of wood ashes is now easily explained
by its alkaline constituent, carbonate of potash, which
precipitates certain non-sugars in the juice and forms
a dark scum.
For large-scale manufacture more economical
methods of heating the juice were evolved. Steam
heat was first employed in 1785. Other alkalies soon
came into use, for instance, carbonate of soda, which is
used in India to the present day. The cheaper alkali,
[190]
Sugar and Sugar-Making
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12 Field Museum of Natural History
slaked lime, was first employed in addition to wood
ashes in 1750 and finally substituted for it.
In the modern factory, the object of the chemical
treatment is threefold:
1. Clarification by the precipitation of dissolved
non-sugars.
2. Defecation or the separation of insoluble solid
matter which has not been removed by the filter but
remains suspended in the juice.
3. Refining. This treatment is only adopted in
the manufacture of white and yellow sugars intended
for direct consumption.
The purpose of clarification is to remove the im-
purities as far as possible. This is accomplished by
chemicals and heat, causing the soluble impurities to
become insoluble so that they may be removed by
settling or filtration. The principal chemicals are
sulphur, lime, and phosphoric acid. Sulphur is ap-
plied as sulphur dioxide which bleaches, disinfects,
and coagulates some of the protein and prepares the
juice for taking more lime, thereby causing a heavier
precipitation which brings about a mechanical cleans-
ing. Sulphur is not much used in the tropical coun-
tries where the juice is of a high degree of purity, but
it is extensively used in Louisiana and other sections
where the juice contains large portions of impurities.
Lime is universally used and is the most important of
all the chemicals employed in a sugar factory. It
neutralizes acids, acts upon the gums, protein sub-
stances, coloring matters, and, if added in excess, upon
the glucose, converting it into organic acids. The lime
compounds thus formed are largely insoluble, the in-
soluble portion is removed by settling or filtration and
much of the soluble can be gotten rid of by the addi-
tion of phosphoric acid or sodium carbonate, to form
the insoluble lime salts. Phosphoric acid is also used
[192]
Sugar and Sugar-Making 13
to correct any alkalinity resulting from excessive lim-
ing, and sodium carbonate is very essential in prop-
erly correcting the acidity of sour juices. Lime salts,
if left in solution in any considerable quantity, give
trouble by depositing on the coils of the "effects" and
"pans," thereby reducing their efficiency in the evapo-
ration. Carbon dioxide is used to correct alkalinity
and remove excess of lime.
To carry out the process of clarification, the juice
is strained through a copper-wire gauze as it leaves
the mill, then drawn into a sulphur box or tank, if
sulphur is used, where it is thoroughly mixed with
sulphur dioxide which is produced by the burning of
sulphur in an appropriate oven near by. From the
sulphuring apparatus which may consist of a box in
which the juice and "sulphur gas" are mixed by a
pump, or of a cylindrical rotating and inclined vessel
in which the mixing takes place by rotation, the juice
is drawn into measuring tanks. The clarifiers are
large rectangular or circular metallic pans, provided
with a steam coil. In some cases the juice is heated be-
fore entering the clarifiers, in others it is heated in
them. Milk of lime, prepared by slaking and grinding,
is added to the juice in the clarifiers in sufficient quan-
tity to neutralize it, or leave it slightly acid or alkaline.
This is done in accordance with the practice of the
factory, acid juices being worked to produce high-
grade sugar and alkaline or neutral to produce low
grades. On heating the limed juice a portion of the
impurities rise to the surface, while others fall to the
bottom. It is the custom in some factories to filter
through heavy canvas bags (one folded within an-
other) the entire volume of juice, that is, the partial-
ly clarified juice, the muddy portion being conveyed
to filter presses, arranged with cloths that fit in be-
tween cast-iron plates. The juice is pumped into the
[193]
Sugar and Sugar-Making 15
filter press where these cloths retain all the solid
particles. In recent years there has been added to
the ordinary process a super-heating apparatus by
which some of the soluble material is converted into
insoluble material at a temperature 15-30° Fahrenheit
above boiling.
Evaporization and crystallization. — The evapora-
tion of sugar solutions or cane juice has for its object
a concentration of the liquid to such density as will
cause the sugar to crystallize out. To accomplish this
there are two methods, the "open kettle" and the
vacuum pan. The open-kettle process consists in boil-
ing the juice in open pans, either of circular or rec-
tangular form, provided with steam coils. The heat
is continued until the density indicates sufficient cook-
ing. When a density of 22° or 36° Baume is reached,
the liquid is termed a syrup, and when the syrup is
cooked to a stiff mass, massecuite. After allowing
crystallization to take place in wood or iron vats, the
massecuite is thrown into a hogshead and the molasses
percolates through a perforated bottom, or the sugar
and molasses may be separated in a centrifugal ma-
chine. The sugar thus made is termed open kettle,
and the process is not used in the up-to-date factory.
The vacuum apparatus for evaporating sugar
solutions consists of a dome-shaped vessel, provided
with coils of steam pipes and requires only about one-
third the fuel of the open-kettle process and reduces
to a minimum the loss by burning or inversion to
glucose and fructose.
The syrup is drawn from the syrup tank into the
vacuum pan until one, two, or three coils are covered,
and this definite quantity is heated until grains of
sugar may be seen on withdrawing a sample and
spreading it on a piece of glass. The formation of
crystals is sometimes brought about by permitting a
[195]
16 Field Museum of Natural History
little cold juice to enter the pan and suddenly cool it.
The object here is to form a crop of "seed crystals,"
and the remainder of the process has for its purpose
the increase in size of the crystals to a desired point.
This is accomplished by continuing the boiling and
adding, from time to time, small quantities of the
syrup, taking care that no more grains or crystals are
formed. In three to four hours the pan will be as full
as is convenient to cook it and the sugar crystals as
large as desired. If very large crystals are wanted,
as is sometimes the case with confectioners' sugar, a
"cut" strike is made. That is, one-third or one-half
the sugar in the pan is removed and the remaining
portion is built up in the same manner as already de-
scribed. On completing the boiling the second time
there are not so many crystals, but they are twice as
large. This process may be repeated, but it is very ex-
pensive. The cooking is continued until the concen-
trated mass contains 6-8 per cent of water. The
discharging of the pan is termed a "strike," and the
product discharged, massecuite. This is conveyed to
a mixer provided with a shaft carrying paddles or lin-
gers that keep the sugar and adhering molasses mixed.
The well-mixed massecuite is next conveyed to a cen-
trifugal machine, made to revolve 1,000 to 1,200 times
per minute, and in its rapid motion the sugar and
molasses are separated, the latter being ejected
through very small perforations, while the sugar re-
mains in the basket. The product thus obtained is
termed "first sugar," or "raw sugar," and is usually
of 96 per cent purity.
The utilization of bagasse. — The cane, after re-
ceiving its final crushing (bagasse), whether passed
through two or three mills, contains from 40 to 50 per
cent of water and is, therefore, a poor fuel if its value
be estimated on the weight of bagasse. Even though
[196]
- T r
Courtesy of the United Fruit Co.
CENTRIFUGAL MACHINES FOR CANE SUGAR IN CUBA.
18 Field Museum of Natural History
it is poor fuel it is used as such for if allowed to ac-
cumulate it would become a great nuisance about the
factory. If the ash contains silica and alkalies in pro-
portion to form a fusible mixture, a slag will result
and choke the furnace by forming a coating over the
gratings ; for this reason the burning of a mixture of
bagasse and molasses has not been satisfactory. Not-
withstanding its high water content, it supplies about
two-thirds of the fuel in the Louisiana sugar factory
and practically all of it in the tropical countries where
the bulk of fiber is from 2 to 3 per cent greater.
Bagasse can also be made into paper. The first
patent for paper manufacture from bagasse was issued
in 1838. The first large-scale experiment was carried
on in Texas in a sugar factory. This was a commercial
failure and was abandoned. The experiments on the
Tacarigua Estate, Trinidad, were more successful.
There bagasse was mixed with bamboo and Para grass
and made into paper. The manufacture of this paper
was carried on in 1915 by a sugar factory in Cuba. Im-
provements in the process have resulted in the making
of "wall board" and paper suitable for newspaper
and better grades of wrapping paper.
BEET SUGAR
Sugar was noticed in the ordinary beet in 1590 by
Oliver des Serres, but received no further attention as
a source of sugar until Margraff, a member of the
Berlin Academy of Science, in 1747, conducted an in-
vestigation of the sugar content of various plants.
The sugar content of the common garden beet is very
small, being from 2 to 4 per cent. The sugar beet is
a variety of this derived by selection and cultivation
from the wild beet of the coast of Europe.
Great interest in both Germany and France fol-
lowed the investigation of Achard in 1799 and by
[ 198 ]
Sugar and Sugar-Making 19
1812 there were many factories established. Napoleon
added greatly to the progress of this industry by gov-
ernment aid and by the establishment of sugar schools.
After the new industry had become well established,
it was almost obliterated by destructive wars. It was,
however, soon revived in France and by 1829 a yield
of 4,000 tons of sugar was made, but Germany's in-
terest was not resumed until 1835. From these coun-
tries the industry has spread throughout Europe until
the production for 1924-25 has been estimated at
8,957,289 short tons for the world of which the United
States produced 1,172,000.
The first experiments with sugar beets in the
United States were made by two Philadelphians in
1830. About ten years later David Lee Child, North-
ampton, Massachusetts, attempted beet culture and
the manufacture of beet sugar. He produced 1,300
pounds at a cost of eleven cents per pound. These en-
terprises failed and seem to have discouraged fur-
ther efforts until Gennert Brothers, natives of Bruns-
wick, Germany, inaugurated a plant at Chatsworth,
Illinois, in 1863, which failed, and it may be said that
this industry was not permanently established until
between 1875 and 1880. From this time sugar beet
culture has been successfully conducted in the United
States.
Extraction. — The beets are first washed in tanks.
From the washing tanks, the beets are carried to a
slicing machine, where they are cut into very thin,
narrow pieces so that when the chips fall they will not
lie too compactly one upon the other. The chips are
conveyed from the slicing machine to a hopper feeding
a battery of twelve to fourteen cast-iron cylindrical
cells connected with each other by a system of pipes
with cocks between, so that one may empty and fill
without interfering with the operation of the rest.
[199]
Sugar and Sugar-Making 21
The extraction of the sugar consists in washing the
chipped beets with hot water. When the sugar has
been extracted from the beets, the bottom of the cell
is opened and the beets discharged and led to a press
where most of the remaining water and sugar are
pressed out. The pulp cake is used in the wet condition
for cattle food or it may be dried by means of the ex-
haust steam so it can be preserved for the same pur-
pose. It may also be used as a fertilizer.
The purification of the extracted sugar solution
consists of the application of lime, carbon dioxide, and
sulphur, together with settling and filtering. The use
of the lime followed by carbon dioxide is termed
carbonation. These two materials, lime and carbon
dioxide, are obtained by burning limestone in a kiln
constructed for that purpose at the factory. The
limestone is decomposed and the lime, mixed with
water, is added to the sugar solution in a quantity
equal to 2 or 3 per cent. The gas is led from the lime
kiln through water to wash it and admitted into a
large cell provided with coils of steam pipes so the
solution may be heated. The temperature at which
the carbonation is carried on is 176-94° Fahrenheit.
This process of adding lime, then charging with car-
bon dioxide, is repeated two or three times, depending
upon the quality of the juice, but after the first treat-
ment the juice is filtered each time before repeating
the carbonation. Finally the juice is treated with
sulphur dioxide, which is used to bleach the solution,
and then the excess of this gas or acid is removed by
the addition of lime and the juice is again treated with
carbon dioxide. Before filtering, the juice is allowed
to settle so that the impurities may collect at the
bottom of the settling tank. The clear liquid is drawn
off and filtered through bags. The clarified juice is
treated the same as that of cane sugar.
[201]
22 Field Museum of Natural History
The molasses containing 40-50 per cent of sugar,
discharged by the centrifugal, must be treated for the
sugar which it contains, though some of the cane
sugar molasses is sold to merchants for direct con-
sumption as table molasses, or to confectioners and to
glucose mixers for the preparation of glucose syrup.
Generally, this molasses is recooked over and over
again until all of the crystallizable sugar has been
separated. The first reboiling yields "second sugar"
and "second molasses," the second reboiling "third
sugar" and "third molasses," etc. The massecuite is
returned to the centrifugal, and the crystals separated
from the molasses. The second sugar may be sold
to the refineries, but as it falls below the 96 per cent
sugar (probably the most profitable grade), it is melt-
ed in hot sugar juice and turned out as first sugar.
The second molasses is reboiled to "string proof," put
into large tanks and allowed to remain at rest from
four to six months, when the crystallized mass is sub-
jected to centrifuging. The third molasses usually
contains a large portion of impurities which may make
it unprofitable to reboil it further, though some work
this molasses for fourth sugar. All of the foregoing
grades of sugar recovered by reboiling may be worked
back into a first sugar or sold to the refineries.
The refuse or exhausted molasses, which amounts
to from four to five gallons per ton of cane and carries
25-40 per cent sugar, has increased very much in
value in recent years, selling at six to ten cents per
gallon. Some of it is fed to stock and some consumed
by distillers.
REFINING OF CANE AND BEET SUGAR
White-sugar loaves were first manufactured from
cane sugar many centuries before the introduction of
the present refining process which was probably de-
[202]
Sugar and Sugar-Making 23
rived from the Arabs. Boiled sap was allowed to
crystallize in conical molds, and the mother-liquor
drained through a hole in the point. Such sugar
loaves were first imported to Great Britain in 1319,
and appeared at the coronation banquet of Henry V in
1413.
In 1812 Howard, the inventor of the vacuum pan,
patented the use of saturated sugar solutions for
washing the sugar loaves in place of the old process of
claying. Purification by recrystallization was adopt-
ed as early as the thirteenth century. Some of these
recrystallized loaves were exported from Cypress,
Rhodes, Syria, and Alexandria between 1250 and
1400. The present system of refining is based on this
principle, but with the addition of a decolorizing proc-
ess applied to the solution of raw sugar before re-
crystallization. The bleaching agent — bone char — first
used for decolorizing vinegar in 1810 was later ap-
plied to sugar. The next improvement was carbona-
tion which the cane sugar refiners borrowed from the
beet sugar manufacturers.
COMPARISON OF CANE AND BEET SUGAR
No one can distinguish between highly refined
cane and beet sugar, as they are one and the same
thing. Between the crude or raw beet and cane sugar
there is a great difference, the latter being edible
whereas the former is not, as it possesses a very
disagreeable odor and taste. Cane sugar molasses
is good for culinary purposes, beet sugar molasses is
unsuitable.
MAPLE SUGAR'
Maple sugar production is an industry almost en-
tirely confined to Northeastern North America. The
'Other deciduous trees have been tapped for sugar. The
butternuts and birches were made use of in this way by some
of the early American colonists.
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24 Field Museum of Natural History
manufacture of this sugar was known to the Indians,
for Jeffreys, 1760, says that in Canada "this tree af-
fords great quantities of a cooling and wholesome
liquor from which they make a sort of sugar," and
Jonathan Carver, in 1784, says the Nandowessie In-
dians of the West "consume the sugar which they have
extracted from the maple tree." In 1870, the Winne-
bagoes and Chippewas are said to often sell to the
Northwest Fur Company 15,000 pounds of sugar a
year. The sugar season among the Indians is a sort
of carnival, and boiling candy and pouring it out on
the snow to cool is the pastime of the children.
The following paragraph is from a book written
by the eminent Robert Boyle (the discoverer of Boyle's
Law) and printed at Oxford in 1663:
There is in some parts of New England a kind of tree . . .
. . . whose juice that weeps out of its incisions, if it be permitted
slowly to exhale away the superfluous moisture, doth congeal
into a sweet and saccharin substance, and the like was con-
firmed to me by the agent of the great and populous colony of
Massachusetts.
Maple sap contains 2-6 per cent of sugar and aver-
ages about 3 per cent. Eighty to 90 per cent of all
maple sugar is made from the sap of four species:
the sugar maple (Acer saccharum), the black maple
(Acer nigrum), the red maple (Acer rubrum), and
the silver maple (Acer saccharinum) .
From nine to fifty-seven days of the year are used
in gathering maple sap with an average of thirty-
four days per year. The season lasts from the middle
of March to the middle of April from Vermont to
New York. In Ohio and western New York it extends
from late February to early April.
The yield of sap varies considerably with the sea-
son, size of tree, character of tapping, and many other
conditions. A tree averages a yield of three pounds
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26 Field Museum of Natural History
of sugar per season and may vary from one to seven
pounds per tree. From five to forty gallons of sap
may be had yearly from each tree. Thirty-two gal-
lons of sap are made into one gallon of syrup and four
and a quarter gallons of sap contain one pound of
sugar.
To make the sugar, the syrup is heated until it is
so thick that it pours slowly or becomes waxy in the
snow or in cold water or reaches a temperature of
230° Fahrenheit. It is then poured into molds. The
first run of sap always makes the best sugar and the
last of the season sometimes fails to "cake." During
the heating, scum is taken off the surface by skim-
ming; the sap gradually turns to an amber color as
it reaches the syrupy stage and deposits malate of lime
(called "niter" in Vermont and "silica" in Ohio) .
In 1860 the total production of maple sugar and
syrup in the United States reached its height. It fell
heavily in 1870, arose again to large proportions in
1880, remained stationary in 1890, and then suddenly
fell almost 50 per cent in 1900, when the total amount
produced was nearly one-third less than in 1850. The
quantity produced in 1923 was about one-half that of
1900 and amounted to 4,685,000 pounds of sugar and
3,605,000 gallons of syrup. This reduction has been
caused in part by the felling of the trees for lumber,
etc., insect attacks, adulteration, and the decrease in
the price of cane sugar.
COMPARISON OF CANE AND MAPLE SUGAR
By 1875 cane sugar became cheap enough to
undersell that of maple. Since 1885 maple sugar has
been a luxury only. In this capacity its prospects are
much better than formerly although the adulteration
of maple syrup with glucose and cane sugar has tended
to keep down the price of maple sugar.
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Sugar and Sugar-Making 27
SORGHUM SUGAR
The stem of the Guinea corn, or sorghum (Sorg-
hum saccharatum) , has long been known in China as
a source of sugar. The sorghum is hardier than the
sugar cane; it comes to maturity in a season; and it
retains its maximum sugar content a considerable
time, giving opportunity for leisurely harvesting.
The sugar is obtained by the same method as cane
sugar.
Many experiments have been made to produce
sugar from sorghum on a commercial scale but the re-
sults have not been profitable. There is now very little,
if any, sugar made from sorghum, although there is
considerable syrup.
PALM SUGAR
Palm sugar which comes into the European markets
as jaggery or khaur is obtained from the sap of sev-
eral palms, the wild date (Phoenix sylvestris) , the
palmyra (Borassus flabellifer) , the cocoanut (Cocos
nucifera) , the gomuti (Arenga saccharif era) , and
others.
The palm sugar industry of India is a very old
one, but insignificant compared with the sugar-cane
industry of that country. A fair estimate places the
annual production of Indian palm sugar at about
100,000 tons.
The sap of the palmyra and cocoanut palms is ob-
tained from their young flowering branches. These
palms do not bloom until they are from twelve to fif-
teen years old. The sugar-gathering season which lasts
for several months commences with the appearance of
these branches or spadices in November or December.
The spathes are bruised and cut, and their juice or
toddy caught in a suspended chatty or toddy receiver.
A spadix continues to give toddy for about five months,
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Sugar and Sugar-Making 29
at the rate of three or four quarts a day. Seldom more
than three spadices yield toddy on the cocoanut tree
at the same time, but seven or eight will yield juice at
once on the palmyra palm. An expert climber can
draw toddy from about forty trees in a few hours. It
is said that if the operation be repeated on the same
tree for three successive years, without allowing any
of the buds to bloom, the tree will die.
To obtain sugar from the sap, the "toddy" is
boiled until it becomes a thick syrup. It may then be
poured into small baskets of palmyra leaf to cool and
harden into "jaggery," or it is formed into round cakes
and wrapped in pieces of dried banana leaves. About
three quarts of toddy are sufficient to make one pound
of crude sugar or jaggery.
Other palms of which the juice of the spadices
is a source of sugar are: the fish-tail palm (Caryota
urens), the gomuti palm (Arenga saccharifera) , and
the African oil palm (Elaeis guineensis).
The wild date palm (Phoenix sylvestris) is tapped
for its sap as a source of sugar quite similarly
to the maple tree. In many localities, especially in
Jessore and other districts of Bengal, the wild date
palm is of importance in this regard. In 1889, some
168,262 acres were under cultivation here. The fol-
lowing account of the process of tapping the trees
and of the manufacture of sugar from the sap comes
from Sir James Westland.
When the tree becomes six or seven years old
tapping begins and is continued each year there-
after. When the rainy season has completely passed,
the cultivator cuts off the lateral leaves of one-half
of the circumference, and in this manner leaves bare
a surface measuring about 10 or 12 inches square.
After the tree has remained in this condition for
a few days, the tapping is performed by making a cut
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30 Field Museum of Natural History
into this exposed surface, in the shape of a very broad
V, about three inches wide and a quarter or half inch
deep. Then the portion inside the angle of the V is
cut deeper, so that a triangular surface is cut into the
tree. From this the sap exudes. Caught by the sides
of the V, it runs down to the angle, where a bamboo
of the size of a lead pencil is inserted in the tree to
catch the dropping sap and carry it out as by a spout.
The tapping is arranged throughout the season
in periods of six days each. On the first evening a
cut is made as just described, and the juice is al-
lowed to run during the night. This juice is the
strongest and best, and is called jiran juice. In the
morning the juice collected in a pot hanging beneath
the bamboo spout is removed. The flow of juice stops
during the day. So in the evening a new cut is made,
not nearly as deep as the last, but rather a mere par-
ing, and for a second night the juice is allowed to run.
This juice is termed do-kat and is not quite so abund-
ant or so good as the jiran. The third night no new
cutting is made, but the exuding surface is merely
made quite clean, and the juice which then runs is
called jarra. It is still less abundant and less rich
than the do-kat, and toward the end of the season,
when the weather is getting hot, it is unfit even for
sugar manufacture, the gur (molasses) made from it
being sold simply as "droppings." These three nights
are the periods of activity in the tree, and after these
three it is allowed to remain for three nights at rest,
when the same process is repeated. Of course,
every tree in the same grove does not run in the same
cycle, some are at their first, some at their second
night, and so on; and thus the owner is always busy.
Since every sixth day a new cut is made over the
previous one, the tree gets more and more hewed into
as the season progresses, and toward the end of the
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Sugar and Sugar-Making 31
season the exuding surface may be, and often is, as
much as four inches deep. The cuts during the whole
of one season are made about the same place, but in
alternate seasons alternate sides of the tree are used
for the tapping; and as each season's cutting is thus
above the previous season's and on the opposite side,
the stem of the tree has a curious zigzag appearance.
The age of a tree can of course be at once counted up
by enumerating the notches and adding six or seven,
the number of years passed before the first year's
notch. More than forty notches have been counted on
a tree, but one rarely sees them so old. When they are
forty-six years old they are worth little as sugar-pro-
ducing trees. It is somewhat remarkable that the
notches are almost always on the east and west sides
of the tree and very rarely on the north and south
sides; also that the first notch appears to be made on
the east side in by far the majority of instances.
One may expect from a good tree a regular aver-
age of five pints of sap per night (excluding the
quiescent nights) . The colder and clearer the weather,
the more copious and rich the juice. In the beginning
of November tapping begins. In December and Jan-
uary the juice flows best, beginning sometimes as early
as 3 P.M., and decreasing with the coming of the warm
days of March. If the cultivator begins too early, or
continues too late, he will lose in quality and quantity
as much as he will gain by extending the tapping
season.
The next process is the boiling, and this every
rayat does for himself, and usually within the limits
of the grove. Without boiling, the juice speedily
ferments and becomes useless; but once boiled down
into gur, it may be kept for very long periods. The
juice which was at first brilliant and limpid, becomes
now a dark-brown, half-viscid, half-solid mass, and
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32 Field Museum of Natural History
when it is still warm, it is easily poured from the
boiling-pan into the earthenware pots in which it is
ordinarily kept. As it takes from seven to ten pints
of juice to produce one pint of gur or molasses, one
can calculate the amount of gur which a good tree can
produce in a season. One may count four and a half
months for the tapping season, or about sixty-seven
tapping nights. These, at five pints each, produce
335 pints of juice, which will give about forty pounds
of gur.
After the juice is boiled down into gur it is then
sold to the sugar-refiners and by them is manufac-
tured in various ways into different grades of sugar.
The best known is called dhulva, a soft, moist, powdery
sugar, used largely in the manufacture of native can-
dies. Another kind, termed pucka, is purer, granular,
and more expensive. The waste molasses, collected
during the preparation of sugar, is called chitiya gur.
When boiled for a longer time, it becomes a black,
sticky treacle, which is largely utilized for mixing
with tobacco for the native hookah, and also for mak-
ing cheap candy. A small proportion of the juice is
consumed as a drink either fermented or unfermented,
under the name of tari, or is converted into vinegar.
OTHER SUGARS
Malt sugar preparations. — A sweet material called
"ame" has been made in Japan since early times
from glutinous rice or glutinous millet, sometimes from
common rice and rarely from Indian corn or sweet po-
tatoes. Ame is made from these by converting their
starch into maltose by the action of an enzyme called
diastase. Sprouted barley is generally used to furnish
the enzyme. In making ame the grains or potatoes
are first cleaned, then soaked in water and steamed
until the starch grains are broken and made easily ac-
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Sugar and Sugar- Making 33
cessible to the enzyme. Powdered malt and water in
proper proportions are now added, and in six or eight
hours the diastase converts most of the starch into
dextrin and maltose. The liquid is then filtered and
evaporated to the desired consistency. One of the
forms is a dense, clear, light-colored amber liquid.
Another form is hard and quite similar to white candy
in appearance. Ame has been made in Japan for at
least two thousand years, and long before cane sugar
was known it was a favorite flavoring. Even at the
present time it is sometimes used instead of sugar in
cooking and it also makes a favorite addition to the
food of invalids.
Several malt preparations, some of them thick like
syrup and others more of the consistency of candy, are
on the market. These are mixtures of dextrin and
maltose coming from the action of diastase on starchy
materials. Many commercial products, such as those
called "predigested" and "malted," have this material
as their basis.
Glucose. — Glucose is manufactured in large
amounts in the United States from corn-starch, and is
sold for table syrup and other purposes. It is prepared
by a chemical process which consists of hydrolyzing
the starch into glucose by means of dilute acid and
pressure. Frequently part of the output of a glucose
plant is blended with maple syrup or other flavoring
material. The resulting mixtures are palatable and
nutritious but do not have the body-heating value nor
the sweetness of syrups having the same percentage of
cane, maple, and sorghum sugar.
Miscellaneous sugars. — Other sugars which before
1914 were largely or entirely imported, but which are
now made in the United States in amounts sufficient
for local needs, are lactose (milk sugar) used in the
preparation of infant foods, etc. ; levulose, used in place
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34 Field Museum op Natural History
of cane sugar in the foods of persons suffering from
diabetes, etc. ; and the so-called "rare" sugars, such as
maltose, mannose, xylose, melezitose, melibiose, treha-
lose, rhamnose, etc., used almost solely in chemical
and bacteriological investigations. The production of
these sugars varies from about 6,000,000 pounds in the
case of lactose to possibly less than one ounce in the
case of some of the rare sugars, and the price varies
from about twenty cents per pound in the case of lac-
tose to twenty-five dollars or more an ounce in the case
of certain of the rare sugars.
James B. McNair
Exhibits illustrating the processes of cane and beet sugar-
making, together with specimens of various sugars, are to be
found in the economic exhibits of the Department of Botany on
the south side of Hall 25 in the Museum. The various palms
mentioned are on the north side of the same Hall. A flower of
the "Boer Honey Pot" may be seen in the Hall of Plant Life
(Hall 29).
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