Starch Utilization in Food Industries
|The food industries constitute 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
use. Cassava, sago, and other tropical starches were extensively used for
food before the Second World War but use declined owing to the disruption
of world trade. Attempts were made to develop waxy maize as a replacement
for normal non cereal starches; the production of cassava starch has increased
considerably in recent years.
High quality cassava flour
Livestock feed industry
Livestock feed products
in paper, etc.
|Unmodified starch, modified starch, and glucose
are used in the food industry for one or more of the following purposes:
as cooked starch food, custard, and other forms.
- As thickeners,
using the paste properties of starch (soups, baby foods,
sauces, and gravies, etc.).
- As fillers,
contributing to the solid content of soups, pills, and tablets, and
other pharmaceutical products,
face cream, etc.
- As binders,
to consolidate the mass and prevent it from drying out during cooking
(sausages and processed meats).
- As stabilizers,
owing to the high water holding capacity of starch (e.g., in ice cream).
|Functional properties of starch are important
for food applications (Table 1)
|Table 1. Functional Properties of Starches
|Specific viscosity (hot and cold)
|Thin boiling (faster canning heat transfer)
|Viscosity resistance acid/mechanical sheer
|Freeze-thaw stability (natural/ modified)
|Gel texture, body at various temperatures
|Processing conditions tolerance
|Oil retention, high or low
|Resistance to setback (gel formation)
swelling or dispersibility
and resistance to swelling
|Emulsion stabilizing capacity
|Source: Morton Satin (undated). Functional
properties of starches Chief, Agro-Industries and post-harvest management
service, FAO, Italy.
|Examples of the use of starch are given below
with various sub-themes of 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% to soften the texture, add taste, and render the biscuit
non sticky. The use of dextrose in some kinds of yeast-raised bread
and bakery products has certain advantages as it is readily available
to the yeast and the resulting fermentation is quick and complete.
It also imparts a golden brown color to the crust and permits longer
Dextrose and glucose syrup are widely used as sweetening agents in confectioneries.
In addition to this widespread use, 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. The principal use of starch in confectioneries is
in the manufacture of gums, pastes, and other types of sweets as an
ingredient and in the making of molds or for dusting sweets to prevent
them from sticking together. Dextrose prevents crystallization in boiled
sweets and reduces hygroscopicity in the finished product.
||Canned fruits, jams, and preserves
Recent advances in these industries include the partial replacement of
sucrose by dextrose or sulphur dioxide-free glucose syrup. This helps
to maintain the desired percentage of solids in the products without
giving excessive sweetness, thereby emphasizing the natural flavor of
the fruit. The tendency toward crystallization of sugars is also decreased.
Monosodium glutamate (MSG) and lysine
Monosodium glutamate (MSG) is used extensively in many parts of the
world in powder or crystal form as a flavoring agent in foods such
as meats, vegetables, soups, 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 sulphuric
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% pure. As at 2002, the highest consumption of native cassava
starch in Thailand was by the industries making MSG (four factories)
lysine (one factory) in the proportion or 80:20. The production
of MSG in Thailand utilizes only two sources of carbohydrates for
molasses and cassava starch. To produce one tonne of MSG, factories
need either about 2.4 t of cassava starch or 7.0 t of molasses.
There are two factories manufacturing citric acid in Thailand though
none in Nigeria. One uses cassava pulp from starch factories as the
raw material (about 5-6 t/day) for its solid-state (surface) fermentation.
The other, recently established, uses cassava chips as the raw material
for its submerged fermentation process. About 40 t of chips are needed
to produce 6 t/day of citric acid.
Caramel as a coloring 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 flavoring 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 color many foodstuffs
and beverages. Uniform and controlled heating with uniform agitation
is necessary to carry the caramelization to the point where all the
sugar has been destroyed without liberating the carbon.
Glucose from starch: starch hydrolysis
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
At present, glucose
is usually produced as syrup or as a solid. The physical properties
of the syrup vary with the dextrose
equivalent (DE) and the method of manufacture. Dextrose equivalent
is the total of reducing sugars expressed as dextrose and calculated
as a percentage of the total dry substance. Glucose is the common
name for the syrup and dextrose for the solid sugar. Dextrose,
sometimes called grape sugar, is the D-glucose produced by the complete
of starch. Today, two methods for starch hydrolysis are used for
the commercial production of glucose: acid hydrolysis and partial
acid hydrolysis followed by an enzyme conversion.
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