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Cassava
uses
The
most important and obvious use of cassava is as a staple foodstuff,
but it is also ground into a type of flour and used as a thickener
in soups and puddings in the form of tapioca. It is used as
a base in canned foods, ice cream, biscuits, confectionary
and pharmaceuticals. Cassava is cultivated in the United States
but there it is used primarily as food for cattle and as an
industrial ingredient.
One of
the products of cassava is starch, which is used in food production,
pharmaceuticals, paper manufacturing and textile industries.
Other industrial uses of the tuber are in the production of
alcohols and manufacture of adhesives.
Other
species of Manihot have been grown for their rubber. This
has been successful but not widely utilised. The main use
of cassava remains as a versatile food.
The
flour produced from the cassava plant, which on account of
its low content of noncarbohydrate constituents might well
be called a starch, is known in world trade as tapioca flour.
It is used directly, made into a group of baked or gelatinized
products or manufactured into glucose, dextrins and other
products.
Starchy
foods have always been one of the staples of the human diet.
They are mostly consumed in starch-bearing plants or in foods
to which commercial starch or its derivatives have been added.
The first starch was probably obtained from wheat by the Egyptians
for food and for binding fibres to make papyrus paper as early
as 4000-3500 B.C.
Starches
are now made in many countries from many different starchy
raw materials, such as wheat, barley, maize, rice, white or
sweet potatoes, cassava, sago palm and waxy xaize. Althbugh
they have similar chemical reactions and are usually interchangeable,
starches from different sources have different granular structures
which affect their physical properties.
Starch
and starch products are used in many food and nonfood industries
and as chemical raw materials for many other purposes, as
in plastics and the tanning of leather. Nonfood use of starches
- such as coating, sizings and adhesives - accounts for about
75 percent of the output of the commercial starch industry.
In
many industrial applications, there is competition not only
among starches from various sources but also between starches
and many other products. Resin glue has largely replaced starch
in plywood because of its greater resistance to moisture;
resin finishes are used in the textile industry and natural
gums compete with starches in paper making. Nevertheless,
the continuous development of new products has enabled the
starch industry to continue its expansion. The growth of the
starch industry in the future appears to be very promising,
providing the quality of products and the development of new
products permit them to compete with the various substitutes.
FOOD
INDUSTRIES
The
food industries are one of the largest consumers of starch
and starch products. In addition, large quantities of starch
are sold in the form of products sold in small packages for
household cooking. Cassava, sago and other tropical starches
were extensively used for food prior to the Second World War,
but their volume declined owing to the disruption of world
trade caused by the war. Attempts were made to develop waxy
maize as a replacement for normal noncereal starches; but
the production of cassava starch has increased considerably
in recent years.
Unmodified
starch, modified starch and glucose are used in the food industry
for one or more of the following purposes:
(a)
directly as cooked starch food, custard and other forms;
(b)
thickener using the paste properties of starch (soups, baby
foods, sauces and gravies, etc.);
(c)
filler contributing to the solid content of soups, pills
and tablets and other pharmaceutical products, fee cream,
etc.;
(d)
binder, to consolidate the mass and prevent it from drying
out during cooking (sausages and processed meats);
(e)
stabilizer, owing to the high water-holding capacity of
starch (e.g., in fee cream).
Bakery
products
Although
starch is the major constituent of flours, the art of' bread
baking depends to a large extent on the selection of flour
with the proper gluten characteristics. Starch is used in
biscuit making, to increase volume and crispness. In Malaysia,
cassava starch is used in sweetened and unsweetened biscuits
and in cream sandwiches at the rate of 5-10 percent in order
to soften zyestexture. add taste and render the biscuit nonstickv.
The use of dextrose in some kinds of yeast-raised bread and
bakery products has certain advantages as it is readily available
lo the yeast and the resulting fermentation is quick and complete.
It also imparts a golden brown colour to the crust and permits
longer conservation.
Confectioneries
In
addition to the widespread use of dextrose and glucose syrup
as sweetening agents in confectioneries. starch and modified
starches are also used in the manufacture of many types of
candies such as jellybeans. toffee. hard and soft gums, boiled
sweets (hard candy). fondants and Turkish delight. In confectioneries.
starch is used principally in the manufacture of gums. pastes
and other types of sweets as an ingredient, in the making
of moulds or for dusting sweets to prevent them from sticking
together. Dextrose prevents crystallization in boiled sweets
and reduces hvdroscopicity in the finished product.
Canned
fruits, jams and prederves
Recent
advances in these industries include the partial replacement
of sucrose by dextrose or sulfur-dioxide-free glucose syrup.
This helps to maintain the desired percentage of solids in
the products without giving excessive sweetness, thereby emphasizing
the natural flavour of the fruit. The tendency toward crystallization
of sugars is also decreased.
Monosodium
glutamate (MSG)
This
product is used extensively in many parts of the world in
powder or crystal form as a flavouring agent in foods such
as meats, vegetables, sauces and gravies. Cassava starch and
molasses are the major raw materials used in the manufacture
of MSG in the Far East and Latin American countries. The starch
is usually hydrolyzed into glucose by boiling with hydrochloric
or sulfuric acid solutions in closed converters under pressure.
The glucose is filtered and converted into glutamic acid by
bacterial fermentation. The resulting glutamic acid is refined,
filtered and treated with caustic soda to produce monosodium
glutamate, which is then centrifuged and dried in drum driers.
The finished product is usually at least 99 percent pure.
The
production of commercial caramel
Caramel
as a colouring agent for food, confectionery and liquor is
extensively made of glucose rather than sucrose because of
its lower cost. If invert sugar, dextrose or glucose is heated
alone, a material is formed that is used for flavouring purposes;
but if heated in the presence of certain catalysts, the coloration
is greatly heightened, and the darker brown products formed
can be used to colour many foodstuffs and beverages.
Uniform
and controlled heating with uniform agitation is necessary
to carry the caramellization to the point where all the sugar
has been destroyed without liberating the carbon.
THE
GLUCOSE INDUSTRY
According
to Whistler and Paschell, Abu Mansur, an Arabian teacher and
pharmacologist, about 975 A.D. described the conversion of
starch with saliva into an artificial honey. In 1811 Kirchoff
discovered that sugar could be produced by the acid hydrolysis
of starch. Glucose, or dextrose sugar, is found in nature
in sweet fruits such as grapes and in honey. It is less sweet
than sucrose (cane or beet sugar) and also less soluble in
water; however, when used in combination with sucrose, the
resulting sweetness is often greater than expected.
The
commercial manufacture of glucose sugars from starch began
during the Napoleonic Wars with England, when suppliers of
sucrose sugar were cut off from France by sea blockade. Rapid
progress was made in its production in the United States about
the middle of the nineteenth century.
NUTRITIONAL
VALUE OF COMPOSITE FLOURS
The
nutritional value of bakery products made from composite flours
was assessed in 1965 by the Central Institute for Nutrition
and Food Research, (Utrecht, Zeist), where the nutritional
value of cassava/soya bread and cassava/groundnut bread was
compared with the protein quality of common wheat bread. It
was concluded that the protein quality of both breads was
higher than that of common wheat bread. The cassava/soya bread
topped the other two breads in protein quality, while the
cassava/groundnut bread was slightly superior to common wheat
bread.
In
1969 at the Queen Elizabeth College, London, breads produced
at the British Arkady Co. Ltd. were assessed. They were made
from various composite flour mixtures consisting of wheat
flour, cassava starch, soya flour, millet and sorghum flour
and fish-protein concentrate in various proportions with mechanical
leavening. Results indicated that the protein value of the
original bread had not been impaired by supplementation, but
showed improvement.
Prospects
for commercial production and widespread consumption of bread
made of composite flours in different countries will depend
upon local acceptance (taste and characteristics of the bread)
and the price at which the bread will be available to the
public.
Food
habits are primarily based on socioeconomic and other conditions
rather than on scientific considerations. Changes in established
habits can take place gradually through public education and
the spread of knowledge.
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