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Sugars
Sugar Cane Sugar Beets
Maple Sugar Palm Sugar
Sorghum Syrup Misc. Sugars
Honey Starches and Starch Products
Sources of Commercial Starch Cornstarch
Potato Starch Wheat Starch
Rice Starch Cassava Starch Arrowroot Starch
Sago Starch Starch Products Soluble
Starch Dextrin
Glucose Industrial Alcohol Nitrostarch Cellulose Products
Paper and Paper Industry Raw Materials
Wood Fibers Cotton and Linen Minor
Paper Raw Materials Esparto Textile Fibers
Paper Mulberry Misc Paper Sources Synthetic Fibers From Plant Products Cellulose
Acetate Rayon Cuprammonium
Rayon
Nitrocellulose Rayon Viscose Rayon Cellulose
Acetate Products Viscose Products Products of Cellulose Hydrolysis Hemicellulose
Cellulose Nitrate
Products Vegetable Ivory Guncotton
Pyroxylin
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Green plants manufacture sugars so
that they all contain some quantity of sugar. However, much of the manufactured product is used directly in
plant metabolize that very little usually accumulates. Storage sugars are found in roots, as with
beets, carrots, parsnips; in stems as in sugar cane, sorghum, maize and the
sugar maple; in flowers, such as in palm trees; in bulbs like the onion; and
in many fruits. There are several
kinds of sugar, principal among which are sucrose or cane sugar, glucose or
grape sugar and fructose or fruit sugar.
They all seem to serve as a reserve food supply for the plant. Humans require sugar in their
diet. It constitutes a perfect food,
as it is a form that can be readily assimilated in the body. Its main value is as an energy producer,
and it is especially well adapted for use after heavy exercise. A large industry has developed in
connection with the extraction of sugar from plant tissues, purification and
refining. Additionally over 10
thousand different chemical derivatives have been made. Sugar is an especially valuable
product derived from the plant world.
Only wheat, maize, rice and potatoes surpass it in importance. Yet there are relatively few sources for
this industry. Only the sugar cane,
sugar beet, sugar maple, maize, sorghum and several palms are commercial
sources. Sucrose is the type of sugar
stored in all of these plant species. Most sugar is derived from sugar cane, Saccharum officinarum. It is a vigorous and rapid-growing
perennial grass reaching a height in cultivation of 8-12 ft and a diameter of
about 2 in. It grows in clumps with
bamboo like stems arising from large rootstalks and with very ornamental
feathery plumes of flowers. The stem
is solid with a tough rind and numerous fibrous strands, and contains about
80 percent juice, the sugar content of which varies considerably from area to
area and season to season.
Commercial sugar cane is a cultivar that is not known in the wild
state. The plant was most likely
first domesticated in Southeastern Asia or the East Indies from some wild
ancestor from that region. By 327
B.C. it had become an important crop in India. It reached Egypt in 641 A.D. and Spain in 755 A.D. Since that time sugarcane has gradually
been introduced into most humid tropical and semitropical regions. The Portuguese and Spaniards were great
disseminators of the plant into the New World. They carried it to Madeira in 1420 and to America by the
beginning of the 16th Century. Within
another 100 years it had spread all over the West Indies, Central and South
America. Sugar cane first arrived in
the United States in Louisiana in 1741.
The name “sugar” is derived from Sanskrit “sarkara,” meaning gravel,
and refers to the crude sugar, which was the only kind known for centuries. Sugar cane has been the principal
export crop of the tropics and is unaffected by many of the conditions that
influence the growing of other crops.
It will grow well in any moist hot region where the average rainfall
is 50 in. or more per year and where there is abundant sunshine and where
temperatures do not drop below 70 deg. Fahrenheit. Backyard stands of sugar cane are possible in colder climates,
however. Cultivation styles vary
considerably, but in general extensive, flat, low-lying fields are utilized
and these are plowed deeply. Cuttings
of varying length made from the upper joints of old canes propagate the sugar
cane. These cuttings, known as seed, are
placed in trenches and nearly covered with soil. They begin to sprout in about two weeks. When the cane is grown for human
consumption, the cuttings are usually placed in holes. The crop has to be cultivated, weeded and
fertilized extensively during the first few months. It is harvested from 10-20 months after sprouting. Harvest is 10-20 months after
sprouting. The sugar content is
carefully monitored and the canes are cut at just the right stage. This is usually when the flowers are
beginning to fade. The stems are cut
close to the ground because the lower end of the cane is richest in
sugar. Cane knives have been
ordinarily used in poorer countries.
The rhizomes normally give rise to two or three more crops, known as
ratoons, before another planting is required. There have been up to 20 ratoon crops obtained, however. Cultivated varieties today are
usually hybrids of Saccharum officinarum, the “noble cane,” with other
hardier species. Sometimes small owners of a stand
of sugar cane extracted their own sugar in a primitive mill, but more often
large “centrals” have been established which draw their supply from a wide
area. In the milling process the
canes are first carried to crushers where they are torn into small pieces. They are then passed through three sets of
rollers. In the first set 2/3rds of
the juice is expressed. They are then
sprayed with water to dilute what sugar remains, and are passed through the
second set. These rollers exerts a
very high pressure and remove nearly all of the moisture. After passing through the last set the
residue is almost dry. This bagasse,
as it has been named, can be used as a fuel for the mills, as a source of
paper or wallboard because of its fibrous nature. It also contains a wax with some commercial value. The juice that flows from the mill
is a dark-grayish sweet liquid full of impurities. It contains sucrose, and other sugars, together with proteins,
gums, acids, coloring materials, soil and pieces of cane. The purification of the sugar involves the
separation of the insoluble materials and the precipitation of the soluble
nonsugars. The juice is first
strained or filtered to remove the solid particles. It is then heated to coagulate the proteins, a process which is
aided by the addition of sulfur. Lime
is then added to neutralize the acids present, to prevent the conversion of
sucrose into lower carbon sugars and to precipitate some of the substances in
solution. These are removed by a
series of filter bags or a filter press.
Carbon dioxide may be added to aid in the process. The chemical processes involved in the
purification of sugar are under constant supervision. The juice is now clear and dark colored
and ready for concentration. It is
boiled down to a syrup of such density that the sugar crystallizes out. This operation is done in open kettles or
vacuum pans. The resulting sticky
mass is known as massecuite. It is
placed in hogsheads with perforated bottoms.
The juice slowly percolates through the holes leaving the crystals of
sugar behind. The juice constitutes
the familiar molasses of commerce. In
modern refineries the massecuite is centrifuged with the molasses passing out
through fine perforations. The raw or
crude sugar thus obtained is brown in color and 96 percent pure. Besides the bagasse, by-products
of value are molasses, which is used in cooking and candy making. It is also used in the manufacture of rum
and industrial alcohol. The better
grades of molasses are obtained when the cruder methods of sugar milling are
employed, for in such cases the sugar content of the molasses is higher. A mixture of bagasse and molasses, known
as molascuit, is a valuable cattle feed. Refining is the final stage of
sugar preparation for markets. This
is usually done in factories located in seacoast areas of the United States
and Europe. The process involves
washing to remove the film of dirt from around the crystals of crude sugar,
dissolving the sugar in hot water, the removal of any mechanical impurities
by filtering through cloth, decoloring by passing through bone black,
recrystallization by boiling, and the removal of the liquids from the
granulated sugar by centrifuging or other means. A hundred pounds of raw sugar usually yields 93 lb. of refined
sugar and three-quarter gallon of refined molasses. The granulated sugar is washed, dried, screened, and
packed. Loaf, cube and domino sugars
are made by treating granulated sugar with a warm concentrated sugar solution
and pressing it into molds. Loafsugar
is often sawed into blocks, strips or other forms. Powdered sugar is made from loafsugar or imperfect pieces of
other types by grinding, bolting and mixing with starch to prevent
lumping. The refining of sugar is a
very old process and was probably first done in North Africa. The first type of refined sugar was the
sugar loaf, which appeared in England in 1310 and was familiar in America
until late in the 19th Century. A marketable syrup has also been
made from sugar cane by clarifying the juice and merely evaporating it to a
consistency where the water content is 25-30 percent. This is sometimes called Golden Syrup. India led the production of cane
sugar in 1947, raising about 25 percent of the world’s crop. Cuba, Brazil, Puerto Rico and other
islands of the West Indies and Australia followed in the order names. In the United States Louisiana, Florida
and Texas produce most of the sugar.
The highest yields per acre have been recorded in Mauritius. <bot335> Bananas (Musa sapientum ) (fruit; fiber) & Sugar
Cane (Saccharum officinarum) in northern Costa Rica Sugar beet, Beta vulgaris, is another important source
of sugar. It was derived from the
wild B. maritima, which is still found wild on European
seacoasts. There were times when beet
sugar equaled or even exceeded that of cane sugar. However, by the 21st Century only about one-third as much beet
sugar as cane sugar was being produced. Although sugar beet was known
since before the Christian era it was not used as a source of sugar until
modern times. The leaves are edible
as a substitute for spinach and the cooked beet serves as a delicious
vegetable. The occurrence of sugar in
the tubers was first noted in 1590 but Maregraf in 1747 first realized its
possibilities. The industry formally
began around 1800 in both Germany and France. Napoleon promoted the use of it as an embargo against British
importations. He was ridiculed
because of this and a famous cartoon pictured him dipping a sugar beet into
his coffee. Another cartoon showed
him offering one to his small son, the King of Rome, with the caption, “Suck
dear, suck, your father says it’s sugar” (Hill 1952). Subsequently interest in sugar beets
decreased, but it was again revived in France around 1829 and in Germany in
1935. Since then it has been a crop
of increasing importance in many European countries. Although earlier attempts were made, the
beet industry did not truly begin in the United States until 1879. Sugar beet is a white-rooted
biennial that grows best in regions where summer temperatures range around 70
deg. Fahrenheit. It produces well in
irrigated portions of the southwestern United States during winter
months. Almost any good soil is
suitable for this plant’s growth.
Plants are frown from seed and must be thinned until they are from
8-10 in. apart. Thorough weeding and
deep cultivation are required. The
crop is easily machine cultivated and harvesting, so is less expensive to
raise than sugar cane. In temperate
climates the seeds are sown inn April and the roots are allowed to remain in
the ground until October because the sugar content increases in that
position. The beets are pulled before
the ground hardens and the tops are removed to prevent loss of sugar after
which they are stored. The finest
plants are saved for seed, which has led to a gradual improvement, by
selection. Extraction of the juice is a
simpler process than for sugar cane because the roots are soft and
pulpy. Earlier they were rasped to a
pulp and the juice squeezed out in bags, but then a diffusion process was
used. The roots are cleaned, cut into
thin strips and heated in running water in a series of tanks. About 97 percent of the sugar can be
extracted in this manner. The waste
beet pulp is removed and a process known as carbonation precipitates the
insoluble impurities in the raw juice out.
For this the raw juice is treated with lime, which coagulates some of
the nonsugars, and carbon dioxide, which precipitates calcium carbonate. This settles out along with the impurities
and the purified juice is separated out by filtration. The process is repeated several times
during which sulfur dioxide is added to adjust the alkalinity. A clear liquid is left after filtration,
which is concentrated, crystallized and centrifuged just as with cane sugar. The massecuite is reboiled several
times. It is difficult to differentiate
between raw beet sugar and raw cane sugar for they are for all practical
purposes identical in composition and appearance. By-products of the industry include the green tops, which are
used for cattle feed and fertilizers; the wet or dried pulp, which is a
valuable cattle and sheep feed; the filter cake, which is used as a manure;
and the molasses, which is used for stock feeding or for industrial alcohol. Central Europe has produced most of
the beet sugar, while in the United States California, Colorado and Idaho are
the principal states that grow this crop.
It might be noted that in the manufacture of rum in Europe, the flavor
when the rum is derived from beet sugar differs substantially from that prepared
from sugar cane. The former tends to
be much more aromatic and has a distinctly unique taste <bot701>
Sugar beet roots (Beta vulgaris) [Mediterranean]
The sap of maple trees is used in making syrup and sugar. The area is confined to northeastern North
America and was discovered and developed by the Amerindians.
Although several species of maple have a sweet sap, the most important
is the sugar maple, Acer saccharum, and the black maple, A. nigrum. The sugar maple is a prominent tree in the
northern part of the eastern deciduous forest zone. It reproduces naturally and lives to an age of 300-400 years. The red and silver maples give a
comparatively small yield and are not of commercial interest. The sap begins to flow about the middle of
March and continues for about a month.
This is a period of warm, sunny days and cold nights. The best flow comes when the temperature
reaches 25 deg. Fahrenheit at night and 55 deg. Fahrenheit during the day. The preferred location for tapping is the
first three inches of sapwood, about 4.5 ft. above the ground.
Amerindians made incisions in the bark or large roots and conveyed the
sap by reeds or curved pieces of bark into clay or bark receptacles. They boiled down the sap by dropping hot
stones into it and converted the sap into sugar by letting it freeze and
skimming off the ice. European
settlers were quick to adopt the procedure and they added many improvements,
eventually tapping with a 1-inch auger and using spiles to convey the sap
into containers. They evaporated the
sap in the open in large kettles so the sugar had many impurities. The dark-brown sap was stored and later
converted into sugar. This involved
the famous sugaring-off, a process in which the syrup was boiled until it
became waxy and the container was then dropped into snow. It was then poured into molds, where it
immediately crystallized. Such simple
methods are persisted for domestic use.
Commercial production further advanced the technique. Modern evaporators have replaced the
furnaces and oiling pans of earlier times.
These are able to convert from 25-400 gallons of sap into syrup in one
hour. Great improvements have also
been made in cleanliness and in the methods of collecting and transporting
the sap. Such large operations
involve from 100-1,000 trees. A
well-managed sugarbush has about 70 trees to the acre, which allows room for
the development of individual trees.
The maple-sugar industry reached its peak in 1869 when 45-million
pounds were produced. With the advent
of cane sugar it ceased to be an important commodity. Today the product is very pure and the demand
is increasing for the syrup especially.
Southeastern Canada is the leading producer while in the United States
Vermont, New York, Ohio, Michigan and Wisconsin produce small amounts. <bot700> Maple (Acer saccharum) tapping in
February [NE North America]
Several species of palm
provide a fourth source of commercial sugar all of which is only available in
the tropics and subtropics. The
species utilized are the wild date, Phoenix sylvestris, the palmyra
palm, Borassus flabellifer, the coconut, Cocos nucifera, the
toddy palm, Caryota urens, and the gomuti palm, Arenya pinnata. Some of the oil palms also yield
sugar. The date palm is tapped
similar to that of a maple and the sap is obtained from the tender upper
portion of the stem. In the other palm
species the sap is secured from the unopened inflorescences. Usually the tip of these is cut off and
the sap oozes out and is collected in various containers. The yield of this sweet juice, known as
toddy, amounts to 3-4 quarts per day for a period of several months. The sap has a sugar content of about 14
percent. It is boiled down to a
syrupy consistency and poured into leaves to cool and then hardens into the
crude sugar known as jaggary. Some of
this has reached European markets.
Three quarts of juice yield about one pound of sugar. The toddy is often fermented to make the
beverage known as arrack. The palm
sugar industry is very old in India where over 100,000 tons were still being
produced yearly by the mid 1900’s. The stem of the sweet sorghum, Sorghum vulgare var.
saccharatum, contains a juice that is used in making syrup. To differentiate between a true syrup and
a molasses it is necessary to realize that syrup is the product obtained by
merely evaporating the original plant juice so that all the sugar is
present. On the other hand, molasses
is the residue left after a juice has been concentrated to a point where much
of the sugar has crystallized out and been removed. The sweet sorghum or sorgo is a wild plant of the tropics and
subtropics which ahs long been cultivated in many parts of the world. The juice is a poor source of sugar, but
yields nutritious and wholesome syrup.
The stems are easily crushed and the juice is evaporated in shallow
pans. On the average about 11-million
gallons were being made in the United States by the mid 1950’s. Similar syrup has also been made from
sugar cane by clarifying the juice and evaporating it to a consistency where
the water content is 25-30 percent. This sugar is also known as dextrose or grape
sugar. It is present in small
amounts in many of the organs of higher plants and is especially
characteristic of fruits. However,
commercial glucose is prepared from starch. Also known as levulose, this fruit sugar is
present in many fruits together with glucose. It is somewhat sweeter than cane sugar and is valuable because
diabetics can consume it. Commercial
fructose is prepared from inulin, a polysaccharide that occurs in the tubers
of the dahlia, Dahlia pinnata, the Jerusalem artichoke (= sunchoke), Helianthus
tuberosus, and some other plants Mannose does not occur free in nature so that it must
be obtained by hydrolysis from several complex compounds. It is readily oxidized from the juice of
the manna ash, Fraxinus ornus, a tree in Sicily and southern
Europe. The juice oozes from slits
made in the bark and dries into a very sweet flakelike material known as
manna. Its use is primarily in
medicine. Maltose is also rarely found in a
free state in plants, but is easily produced from starch through the activity
of the enzyme diastase. It is used
primarily in the brewing industry.
Maltose syrup is sometimes used as a substitute for glucose and in
medicine. Maltose that is obtained
from rice starch has been used in Japan as a flavoring for over 2,000 years. Flowers that are attractive, such as roses, hibiscus, etc.,
usually produce a sweet substance called nectar. This serves to attract various insects that are necessary for
pollination of the plant. Nectar is
composed mainly of sucrose with some fructose and glucose. It is used as food by bees, and some of it,
after partial digestion, is converted into honey and stored for future
use. During this process the sucrose
is changed to an invert sugar, which is a mixture of fructose and glucose. Honey contains 70-75 percent invert sugar
along with proteins, mineral salts and water. The sugar has a tendency to crystallize out. Honey was most likely the first sweetening
substance used by humans. Beekeeping
is one of the very oldest industries.
The flavor and quality of honey vary depending on the source of the nectar. Flowers that contain essential oils impart
a typical taste. The bees favor
certain plants and these are often cultivated near the apiaries. Clover, Alfalfa, buckwheat, lindens and
some of the mints and citrus are among the favorites. Honey is an excellent food for it is
almost pure sugar. It is also used in
medicine, in the tobacco industry and in the manufacture of a fermented
beverage called mead. <bot750>
Sea Grape
(Coccoloba uvifera Jacq.) (fruit; ornamental; wood
products; red dye; honey; treat fevers)
[Neotropics]
One of the most important and widely available vegetable products,
starch constitutes the principal type of reserve food for green plants. It is a complex carbohydrate. It is stored in thin-walled cells in the
form of grains. There are several
types of starch that differ in the size and shape of the grains and other
physical and microscopic characteristics.
Important sources of starch are the cereal grains and underground
tubers, although nuts, legumes and other plant organs may contain substantial
amounts. Besides being a staple food
for animals and humans, it also has many industrial applications. Soluble starch is a form that is used in the textile
industry to strengthen the fibers and cement the loose ends thus making a
thread that is smoother and easier to weave.
It also gives a finish to the end product. It serves as a mordant in calico printing, a thickener for the
colors. Starch is also used as a
sizing agent in paper industry, in laundry work, in medicine, in the
preparation of toilet powders, as a binding for china clay and as a source of
many other products. Relatively few plants are used for
the commercial production of starch.
The main ones are potato, maize, wheat, rice, cassava, arrowroot and
sago. Maize or Indian corn is the source
of over 80 percent of the starch that is made in the United States. The grains are soaked in warm water with a
small amount of sulfurous acid to loosen the intercellular tissue and prevent
fermentation. Then the corn is ground
so as not to injure the embryos. The
ground material is placed in germ separators where the embryos are
removed. The starch material is then
ground very fine and is either passed through sieves of bolting cloth or is
washed in perforated cylinders to remove the bran. The resulting milky liquid is run onto slightly inclined tables
where the starch grains settle out and the remaining material flows off. The starch is later collected and dried in
kilns and is then ready for the market.
The best grades of cornstarch are used for food while inferior grades
are for laundry starch and sizing and as a basis for glucose. Cull potatoes are utilized for making starch. These are washed and reduced to a pulp in
graters or rasping machines. The resulting
paste is passed through sieves to remove fibrous matter. After washing the solid starch is
separated by sedimentation, the use of inclined tables, or centrifuging, and
is then dried. Potato starch finds
uses in the textile industry and as a source of glucose, dextrin and industrial
alcohol. Europe is the principal producer. The oldest commercial sources of
starch were from wheat. It was known
to the Greeks and was widely used in Europe in the 16th Century in connection
with the linen industry. The gluten in
wheat makes the removal of the starch a difficult process. It is accomplished by extraction with
water or by the partial fermentation of the grain. Wheat starch is used mostly in the textile industry. Rice grains that are broken or
imperfect are used for making rice starch.
These are softened by treating with caustic soda and are then washed,
ground and passed through fine sieves.
More alkali is added and after a time the starch settles out as a
sediment. This is removed, washed and
dried. Occasionally dilute
hydrochloric acid is used to free the grains. Rice starch has found use in laundry and for sizing. Cassava flour and tapioca are used in industry mainly
as sizing materials and as the source of certain starch products. The tubers of several tropical plants provide a source
for arrowroot starch. West Indian
arrowroot is from Maranta arundinacea. Florida arrowroot is from Zamia floridana. Queensland arrowroot is from Canna
edulis, and East Indian arrowroot from Curcuma angustifolia. The tubers of these plants are peeled,
washed and crushed and the pulp passed through perforated cylinders. A stream of water carries the starch into
tanks where it settles out. Arrowroot
starch is easily digested and thus is valuable as a food for children and
invalids. There is little use in
industry. The stems of the sago palm, Metoxylon sagu,
contain starch. Cultivation is in
Malaya and Indonesia. The flowers
appear when the trees are about 15 years old and just prior to this time the
stems store up a large amount of starch.
The trees are felled and the starch pith is removed. This is ground up, mixed with water and
strained through a coarse sieve. The starch
is freed from the water by sedimentation and washed and dried. This is known as sago flour. Commercial sago is prepared from this by
making a paste and rubbing it through a sieve in order to cause
granulation. The product is dried in
the sun or in ovens and appears as hard shiny grains, known as pearl
sago. Both sago starch and pearl sago
are used almost entirely for human consumption.
Starch grains are insoluble in cold water but they readily swell in hot
water until they burst to form a thin, almost clear solution or paste. This soluble starch has been used for
finishing textiles and in the paper industry. When starch is heated or treated with dilute acids or
enzymes it becomes converted into a tasteless, white, amorphous solid known
as dextrin or British Gum.
Dextrin possesses adhesive properties and has been used as substitutes
for mucilage, glue and natural gums.
Bread loaves brushed with dextrin aids in crust formation. In steel manufacture, the sand for the
cores used in casting is held together with dextrin. Other uses include cloth printing, glazing
cards and paper and making pasteboard. When starch is treated with dilute
acids for a long time it becomes more completely hydrolyzed and is converted
into glucose sugar. Often the same
factory that extracts the starch also converts it into glucose. This operation is done in large copper
boilers under pressure. About six
pounds of dilute hydrochloric or sulfuric acid are used for each 10,000
pounds of starch. After all the
starch has been converted, the free acids are neutralized with caustic
soda. The liquid is then decolorized
with boneblack and concentrated into thick syrup. One of the common brands of corn syrup is “Karo.” Glucose may be considered as an inferior
substitute for cane sugar. However,
it is an excellent food material. Its
use is in table syrup, for sweetening, in candies, jellies and other kinds of
cooking. It is often mixed with maple
syrup, brown sugar, honey or molasses it is used for making vinegar and in
brewing. Starch is the source of an
enormous quantity of industrial alcohol.
Maize and potatoes constitute the chief sources, although the other starches
and even cellulose, various products of the sugar industry and fruit juice
may be utilized. The process converts
the starch into sugar by means of diastase and the fermentation of the sugar
by yeasts to yield alcohol. The
operations are carried out under different conditions from those followed in
making alcoholic beverages. When
fermentation has stopped, the alcohol is extracted from the mash by
fractional distillation. The alcohol
thus formed as a result of the fermentation of sugar is known as ethyl
alcohol, as distinguished from methyl or wood alcohol, a product of the
destructive distillation of wood. To
render it unpalatable, ethyl alcohol is often “denatured:” by adding methyl
alcohol or other substances.
Industrial alcohol is the most important and most widely used solvent
and is the basic material in the manufacture of hundreds of products. It is also used in medicine, pharmacy and
other industries.
Starch and cellulose are chemically very similar products. Cellulose reacts with nitric acid to form
nitrocellulose while starch yields nitro starch. Nitrostarch is a very safe explosive if the ingredients are
absolutely pure. Tapioca starch was
originally imported for this purpose but during World War I cornstarch was
used as a source. The most complex of the
carbohydrates, cellulose is present in the cell walls of all plants. Because of their strength, cells with
thick walls have been used in various industries. Besides the natural product being used in the textile industry,
artificial fibers are derived directly from cellulose as well as countless
other products. Cellulose chemistry
is an important phase of organic chemistry. Cotton, a very pure form of cellulose, has been used
for a very long time in the production of artificial fibers and other
cellulose products. Wood is another
very available source. When certain
woods are treated with concentrated acids or alkalis, the bond between the
wood fibers and the lignin, which cements them together, is broken, and the
fibers, which are pure cellulose, can be removed. These fibers may then be reorganized as paper, or they may be
treated further chemically. If the
chemical treatment merely causes the dissolution of the fiber into its
component molecules, these molecules may be synthesized into artificial
fibers or converted into cellulose plastics.
But if the molecules themselves are broken down, their component
elements, carbon, hydrogen and oxygen, may be recombined to form wood
sugar. Thereafter the wood sugar may
be transformed into yeast or alcohol and thus become available for food or as
the raw material for numerous industrial products. A very important use of cellulose is
in the manufacture of paper, a very old industry. The word “paper” comes from the Latin “papyrus” the name of a
sedge, the pith of which was used for paper in 2400 B.C. Egypt. However paper was first made in
China. The industry spread from China
to India, Persia and Arabia and then through Spain to other European
countries. The first paper mill in
the United States was in 1690 at Philadelphia. The papermaking value of the
various fibers depends on the amount, nature, softness and pliability of the
cellulose present in the cell walls.
This cellulose may occur alone or in combination with lignin or
pectin. Wood fibers, cotton and linen
are the principal raw materials.
Wood began being used in the paper industry from about 1850. Today wood has largely replaced the other
fibers and furnishes over 90 percent of all the paper manufactured in the
Untied States. Spruce is a very important source of wood pulp and has
furnished about 30 percent of the total supply. It is ideal because it has all the requirements of a good
pulpwood. The fibers are long and
strong with a maximum content of cellulose.
The wood is almost free from resins, gums and tannins; and it is light
colored, sound and usually free from defects. Red spruce, Picea rubens, white spruce, P. glauca
and Sitka spruce, P. sitchensis, are the main species The southern yellow pine, Pinus australis, is
another important pulpwood. The
eastern hemlock, Tsuga canadensis, is a main species in the Lake
States while the western hemlock, T. heterophylla is important on the
Pacific Coast. Other species include aspen, Populus grandidentata
and P. tremuloides, and balsam fir, Abies balsamea. Of lesser importance are jack pine, Pinus
banksiana, tamarack, Larix laricina, white fir, Abies
concolor, and several hardwoods among which are the beech, Fagus
grandifolia, sugar maple, Acer saccharum, and birch, Betula
lutea. Sawmill waste is also an
increasingly valuable source of wood pulp. Up to the middle of the 19th
Century rags of cotton and linen were the only source of paper, and they are
still used for making the finest grades.
Cotton fibers have a high felting power and a high cellulose content
of about 91 percent. Rags and raw
cotton in the form of fuzz or linters are utilized. Flax fibers, that comprise linen, contain 82 percent of
pectocellulose and yield a paper of great strength, closeness of texture and
durability. Textile waste may also be
used. In the preparation of rag pulp
the material is sorted, cut into small pieces and freed from dust. It is then boiled in caustic soda to
remove the grease, dyes and other impurities and it is washed until perfectly
clean. The resulting pulp is used directly
in papermaking. Esparto grass, Stipa tenacissima, is important
in Great Britain. The plant is native
to Northern Africa where it flourishes in dry, sandy and rocky coastal
regions. The tufted wiry stems are
plucked and pressed into bales for shipment.
Esparto is converted into pulp by heating in a caustic coda solution
under pressure. Although the cellulose
content is only 48 percent, the fiber has great flexibility and felting power. It yields an opaque, soft, light paper of
uniform grade. The finest printing
papers in England have been made from esparto, either entirely or in a
mixture. Another grass, Lygeum
spartum, is also used. There are other textile fibers
other than cotton and flax that have been used as sources for paper. The waste material of the jute and hemp
industry, in the form of old ropes, sacking, sailcloth, etc. was once used
extensively for making strong and tough papers. Jute and jute butts were used mainly for wrapping paper,
envelopes, cable insulation, while hemp, after bleaching, yielded ledger and
bank-note paper. Manila hemp was an
important source of envelopes and wrapping paper. Ramie, sisal, sunn hemp, New Zealand hemp, coir and other
fibers have been utilized. The bast fibers of the paper mulberry are very strong
and have been used in Japan for paper lanterns and umbrellas and as paper for
writing. The fiber is scraped, soaked
and beaten, after which it is mixed with mucilage and spread on frames to
dry. When treated with oil this paper
becomes strong enough to serve as a substitute for leather or cloth.
There are many other sources for making paper than what has been noted
previously. For example, stems of
rye, barley, wheat, oats, rice and other grasses are used for low-grade
paper, strawboard, pasteboard and cardboard.
These plants have fibers with low cellulose content and are too short
and small to have much tensile strength.
Thus, they are mixed with other fibers. Sugarcane bagasse, cornstalks, and waste paper have been
developed as sources of paper. Banana
fiber, tree bark, rushes, weeds, broomroot, licorice, cotton and tobacco
stalks, beet pulp waste and peat have been used somewhat. Recycled paper is extensively used to make
other paper products. In the Orient bamboo fiber is an important source of
paper. The papyrus, Cyperus
papyrus, baobab, Adansonia digitata, and Daphne cannobina
are used in Africa and India. Rice
paper of Japan and China is made principally from Tetrapanax papyriferum,
Edgeworthia tomentosa or Wickstroemia canescens. Synthetic Fibers From Plant Products Hill (1952) writes that since the
Middle Ages until modern time there have been many schemes to make artificial
silk and other fabrics. In 1880 Count
de Chardonnet made the first artificial fiber, and a few years later the
first artificial silk. Later
factories were established for making the product. At the outset this new material was handicapped by its name for
the public considered it only as an imitation or a substitute. This condition existed as late as
1908. Today it is understood that all
the artificial fibers constitute entirely new products with valuable
characteristics and properties of their own. The raw material of the rayon industry is high-polymer
alpha cellulose, prepared in a pure form from wood pulp or cotton
linters. Purification is accomplished
by the elimination of mechanical impurities through air separation and then
cooking in a 3.5 percent sodium hydroxide solution. This removes all the other organic substances. The pure cellulose fibers that remain are
bleached, washed and dried. The next
step is to dissolve the cellulose by various solvents thus rendering it
sufficiently liquid so that it can be squirted in a fine jet. The solution is then forced by pressure
through minute perforations in glass or platinum, and emerges from these
“spinnerets” in thin streams. The streams
are coagulated into fine, almost invisible filaments in different ways. The solvents are removed and the filaments
are caught up by revolving reels and twisted into threads suitable for
spinning. The threads are washed,
bleached and dried. In the viscose,
nitrocellulosee, and euprammonium processes the final product is an almost
pure cellulose fiber known as regenerated cellulose. This is chemically identical with the
cellulose in cotton, but it differs in itss mechanical properties. The product of the acetate process is a
cellulose ester , cellulose acetate.
This differs from regenerated cellulose in both its chemical and
physical properties. Several kinds of rayon are Viscose
Rayon, Cellulose Acetate Rayon,
Cuprammonium Rayon and Nitrocellulose Rayon. Treatment with concentrated nitric
acid in the presence of sulfuric acid causes cellulose to change into several
types of cellulose nitrate. These differ
according to which concentration of nitric acid was used and the consequent
degree of nitration as well as the temperature and the duration of the
action. The higher cellulose nitrates
are called guncotton, or in error nitrocellulose. The lower nitrates constitute pyroxylin, or collodion cotton. This is made from cotton linters
during which process the cellulose is completely nitrated. It is used as an ingredient of many high
explosives. Cordite, e.g., is a
combination of guncottton and nitroglycerin, while smokeless powder is made
from a mixture of guncotton and the lower nitrates. Guncotton is one of the safest of explosives to handle when
properly manufactured. A partial nitration of cellulose
produces pyroxylin. This is carried
out under different conditions from those, which result in the formation of
guncotton. In modern photography the
films often consist of pyroxylin coated with gelatin. It is used in the rayon industry. However, its chief value is that it is
soluble in a variety of solvents and yields many useful products, such as
celluloid and other plastics, collodion, artificial fabrics and varnishes. Industrial uses include as a
substitute for cellulose nitrate in the film industry because it is not very
flammable. Resultant films are more
brittle and expensive, however. It is
also used for goggles, gas masks, automobile windows, artificial fabrics,
index cards, airplane varnish, etc. Cellophane is a viscose
product. Forcing crude viscose
through tiny slits rather than perforations makes this. It coagulates into a thin transparent film
only one-thousandths of an inch in thickness. Such viscose files are used for numerous poses even for sausage
casings. Viscose fibers have replaced
cotton in Welsbach mantles. Products of
Cellulose Hydrolysis When cellulose is completely
hydrolyzed in a process of saccharification this ultimately results in the
conversion of the cellulose into wood sugar that in its turn yields alcohol
and yeast. It is a complement to the
manufacture of paper pulp from wood. Under usual processes of pulp
making one ton of wood is converted to one-half ton of pulp and enough wood sugar
to yield 10-12 gallons of alcohol.
Doubling the cooking time produces an edible starchy material that is
an excellent cattle feed, and sufficient sugar to furnish 20 gal. of alcohol
is obtained. Under a still longer
cooking time all of the cellulose can be converted into sugar with an
eventual production of 60-80 gal. of alcohol. Regarding the kinds of wood sugar
that are produced, conifers yield glucose, pentose, and mannose; hardwoods
glucose and pentose. These sugars are
useful because they can be readily fermented. Glucose and mannose, which
comprise about 2/3rds of the wood sugar, are converted into ethyl alcohol by
the action of ordinary yeast. This
industrial alcohol has a wide range of uses.
Pentose sugars are not fermentable into alcohol, but they can be
converted, through the activity of a bacterium, Torulopsis utilis,
into Torula yeast, and edible substance with a 50 percent protein
content. One ton of pulp will yield
from 40-100 lbs. of yeast. Cellulose hydrolysis can play an
increasing role in a well-organized system of forest utilization as it
eliminates much of the waste. Small
pieces of wood, chips, sawdust, wood flour and sawmill waste can all be used
effectively Many
tropical plants have seeds that are very thick, hard and have heavy walls
consisting of hemicellulose. This is
a modification of ordinary cellulose and constitutes a supply of reserve food
for the plant. In young seeds the
endosperm consists of a milky juice, but as the seeds mature this fluid is
replaced by the harder material.
hemicellulose cannot be used by animals as food. However, it does provide vegetable ivory
of commerce.
The Ivory-nut or Tagua Palm, Phytelephas macrocarpa, of the
Neotropics is the main source of vegetable ivory. The palm is a low0-growing tree typically on riverbanks from
Panama to Peru. The drupes like
fruits have from 6-9 bony seeds with a thin brown layer on the outside and a
very hard and durable endosperm. The
natives collect the seeds that are shipped to Europe and the United
States. Ecuador is the main
exporter. This ivory may be carved
and shaped into various objects, so it serves as a substitute for true ivory
in the manufacture of buttons, poker chips, knobs, chessmen, dice, inlays,
etc. Several species of palms in Africa and Polynesia and
Neotropical America have seeds of similar constituency. With the exception of Metroxylon
amicarum of the Caroline Islands, these are not important in commerce. |