Application of Starch

By

Padraig Jordan ,Helen Jordan ,Mark Greally, Liz Cullivan

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Application of Starch

1 Introduction Starch is white in colour, odourless, tasteless and a carbohydrate powder. It plays

a vital role in the biochemistry of both plants and animals and has important commercial

uses. In green plants starch is produced by photosynthesis; it is one of the chief forms in

which plants store food. It is stored most abundantly in tubers (e.g., the white potato),

roots (e.g., the sweet potato), seeds, and fruits; it appears in the form of grains that differ

in size, shape, and markings in various plants.

Starch is both a major component of plant foods and an important ingredient for the food

industry. Starch in food reviews starch structure and functionality and the growing range

of starch ingredients used to improve the nutritional and sensory quality of food. Starch,

common name applied to a white, granular or powdery, odourless, tasteless, complex

carbohydrate, (C6H10O5)x, abundant in the seeds of cereal plants and in bulbs and tubers.

Molecules of starch are made of hundreds or thousands of atoms, corresponding to values

of x, as given in the formula above, that range from about 50 to many thousands.

Starch molecules are of two kinds. In the first kind, amylose, which constitutes about 20

per cent of ordinary starch, the C6H10O5 groups are arranged in a continuous but curled

chain somewhat like a coil of rope; in the second kind, amylopectin, considerable side-

branching of the molecule occurs.

Starch is manufactured by green plants during the process of photosynthesis. It forms part

of the cell walls in plants, constitutes part of rigid plant fibres, and serves as a kind of

energy storage for plants, because its oxidation to carbon dioxide and water releases

energy. The granules of starch present in any plant have size, shape, and markings

characteristic of the species of plant in which the starch is made.

Starch is almost insoluble in cold water and in alcohol, but with boiling water it gives a

colloidal suspension that may form a jelly on cooling. Hot water changes starch slowly

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into smaller molecules called dextrins. This reaction, an example of hydrolysis, is

catalyzed by acids and by some enzymes. Dextrins, like starch, react with water, giving

still simpler molecules, the ultimate products being maltose, C12H22O11, a disaccharide,

and glucose, C6H12O6, a monosaccharide.

The digestion of starch in the human body takes the following course:

the hydrolysis begins in the mouth under the action of salivary ptyalin, but is completed

in the small intestine. The body does not immediately use all the glucose absorbed from

the digestion of starch, but converts much of it to glycogen, which is stored in the liver.

(Glycogen, called animal starch, has a structure nearly identical with that of

amylopectin.) As the body requires glucose, hydrolysis of glycogen releases it into the

bloodstream. Glycogen provides an energy reserve for animals in the same way that

ordinary starch does for plants.

The two kinds of carbohydrates are starches, which are found mainly in grains, legumes,

and tubers, and sugars, which are found in plants and fruits. Carbohydrates are used by

the cells in the form of glucose, the body's main fuel.

After absorption from the small intestine, glucose is processed in the liver, which stores

some as glycogen, a starchlike substance, and passes the rest into the bloodstream.

In combination with fatty acids, glucose forms triglycerides, fat compounds that can

easily be broken down into combustible ketones. Glucose and triglycerides are carried by

the bloodstream to the muscles and organs to be oxidized, and excess quantities are

stored as fat in the adipose and other tissues, to be retrieved and burned at times of low

carbohydrate intake.

The carbohydrates containing the most nutrients are the complex carbohydrates, such as

unrefined grains, tubers, vegetables, and fruit, which also provide protein, vitamins,

minerals, and fats. A less beneficial source is foods made from refined sugar, such as

confectionery and soft drinks, which are high in calories but low in nutrients and fill the

body with what nutritionists call empty calories.

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2.1 Biochemistry

Biochemically, starch is a combination of two polymeric carbohydrates

(polysaccharides) called amylose and amylopectin. in which the monomers are glucose

units joined to one another head-to-tail forming alpha-1,4 linkages. These linearly

combined units constitute amylose. These linear molecules link together in an alpha 1-6

linkage as well, forming branch-like structures. The branched units constitute the

amylpectin content of starch. The overall structure of amylopectine is not a linear

polysaccharide chain since two glucose units are frequently forming a branch point.

Structurally, the starch forms clusters of linked linear polymers, where the alpha-1,4

linked chains form columns of glucose units which branch regularly at the alpha-1,6

links. The relative content of amylose and amylopectin varies between species, and

between different cultivars of the same species.

For example, high-amylose corn (maize) has starch consisting of about 85% amylose,

which is the linear constituent of starch, while waxy corn starch is more than 99%

amylopectin, or branched starch.

The primary function of starch in plants and animals, where it is called glycogen, is to act

as an energy storage molecule for the organism. In plants simple sugars are linked into

starch molecules by specialized cellular organs called amyloplasts.

Starches are insoluble in water. They can be digested by hydrolysis, catalyzed by

enzymes called amylases, which can break the glycosidic bonds between the 'alpha-

glucose' components of the starch polysaccharide. Humans and other animals have

amylases, so they can digest starch. Digestion of starches consists of the process of the

cleavage of the starch molecules back into their constituent simple sugar units by the

action of the amylases. The resulting sugars are then processed by further enzymes (such

as maltase) in the body, in the same manner as other sugars in the diet.

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2.2Applications

Starch was important for both sizing and coating of paper, when Gutenberg

invented his printing technique in 1450. The history of starch in papermaking is 6000

years old - as old as the printed word itself. Starch is used in papermaking from the wet

end to the size press. It is used in coating and as calendar starch. It is preferable used

because of tradition and the potential to reduce total costs significantly.

 In North America 1.7 million ton is used for papermaking. The large quantities require

bulk deliveries and we offer shipments in 20' IBC Intermediate Bulk Container with

plastic liner with no need for labour-intensive manual handling.

The following table shows the applications of starch in food and building materials

Food Beverage Animal Feed Plastic Pharmacy Building

Mayonnaise Soft drinks PelletsBiodegradable

plasticTablets

Mineral

fibre tiles

Baby food Beer By productsDusting

powder

Gypsum

board

Bread Alcohol Concrete

Buns CoffeeGypsum

plaster

Confectionery Agriculture Textile Paper Various

Meat sausages Jelly gums Seed coating WarpCorrugated

boardFoundries

Meat rolls and

loaves

High-boiled

sweetsFertiliser Fabrics

Water

treatment

Ketchup Jellies Yarns Cardboard Coal

Marchmallows

Soups Marmalade Paper Detergent

Snacks Jam Fermentation Non-WowenPrinting

paperOil drilling

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Pizza sauces Ice cream VinegarHygienic

diapers

Stain

remover

Sauces Dairy cream Enzymes Baby diapersPackaging

materialGlue

Low fat foods Fruit fillingsSanitary

napkins

Foamed

starch

Noodles

Starch has many uses, but in the wastewater treatment there are other factors of

extraction. Where some manufacturers accept the starch as part of the effluent, there are

several incentives to remove the starch before wastewater treatment for:

To sell the dewatered starch

To reduce effluent costs

Recycle centrate to the pre-wash area

Reduction of fresh water requirement

The Following Images are Centrifuged Potato Starch at 62% DS Recovered from Potato

Processing Factory

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Cake and Centrate Produced by Centrifuging Potato Effluent 35%

Potato starch is a pure renewable natural polymer that has a wide range of

industrial uses, including surface sizing in the textile industry, in adhesives, in

biodegradable plastics and in the pharmaceutical industry. Most potato starch is used for

industrial purposes. Special techniques are used to produce speciality products that are

named modified starches.

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The EU has significantly increased its share of world starch production. Potato starch is a

major constituent of potatoes. Anybody who is used to peeling potatoes knows about the

sheer quantity of starch each contains. It is difficult not to come away coated in white

spray. For the food industry, potato starch poses quite a problem.

Already the potato starch industry uses a system of integrated processing – in several

European factories, denatured protein is being extracted from the waste stream. However,

harmful compounds still persist which have a negative environmental effect. Even so, this

waste stream can still be used for the production of valuable substances. Until recently, a

considerable loss of starch occurred in the process water and the starch waste was

collected in reservoirs for subsequent recovery. Today, separation is so efficient that

much less starch is lost.

The ultimate aim of this project is to develop a “closed cycle” industrial

production system. This means integration of potato starch production with energy

generating systems, recuperation and use of potato protein and higher added-value and, of

course, the recirculation of water. Specifically the project will endeavour to

achieve a 50% reduction in energyconsumption and a quality improvement by

moving from a conventional process to a membrane based one.

Environmentally-friendly or “green” chemicals will be adopted into the processing chain

along with a 50% fall in the amount of fresh water usage through the recirculation of

process water.

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3.1 Disposal of starch- Agricultural Disposal. Starch tubers contains 70-80% juice with a valuable content of nutrients, which maybe

utilized as a substitute to artificial fertilizers.

In Denmark landspreading is practiced both by road tankers and distributed by pipeline to

near by farmers for landspreading.

One pipeline method uses a flexible tube and another uses aluminium pipes. The flexible

tube is wound round a drum (picture) slowly pulling the distant nozzles home before the

system is moved.

Corn dominates as starch raw material (83%), followed by wheat (6%), potato (6%),

tapioca (4%), and other crops - mainly rice (1%). 

Composition of potato starch

Constituents Typical analysis

Starch, dry substance 80%Water 20%Ash 0.3%Sand 0.02%Protein 0.09%Phosphor, P 0.07%Calcium, Ca 0.03%Iron, Fe 3 ppmCold water soluble 0.1%

By-products:

The major constituents of the potato are:

Fibre (cell walls, peel)StarchJuice

3.2 Potato processing

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Potatoes contain approx. 70% of juice with approximately 5% of dry matter -

half of which is sugars and protein bringing about 30,000 ppm BOD5 in the

concentrated juice.

After Rasping & Extraction, crude starch milk and pulp are produced. Pulp is the residue

after starch extraction.

1. The pulp is an excellent cattle feed. Potato pulp is an excellent cattle feed.

Calculated on dry matter the feeding value is equivalent to barley.

The high digestibility of the fibre content makes potato pulp of particular advantage as a

roughage to high yielding dairy cattle. Potato pulp is improving the microbial activity in

the rumen.

2. The crude starch milk is concentrated and excess potato juice isolated.

Potato juice contains the soluble nutrients of the potato.

The juice is an excellent fertilizer and is recycled to farmland. The juice has also been

used for animal feeding. Potato juice is an excellent fertilizer. Calculated on nutrients it is

equivalent to an artificial fertilizer with same composition. Use of potato juice equivalent

to 100 kg nitrogen per ha  in the autumn on grass as a catch crop does not give any

significant leaching of nitrogen during the winter. The utilization of nitrogen the

following growing season is high.

The residual juice is removed from the concentrated crude starch milk by washing with

pure water. The residual juice is diluted with the washing water as "fruit water”. Fruit

water is an excellent fertilizer.

Dewatering & Drying

The purified starch milk is dewatered and dried ready for a multitude of application in

food and technical industries. Starch is a pure, renewable and versatile polymer.

3.3 Starch as animal feed.

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The above juice is the result of evaporation of fresh and untreated potato juice. The

evaporation was carried out in order to reduce volume and to improve keeping quality.

The juice was fed to porker (25 - 93 kg) in a mixed diet.

The diet comprises a dry feed in the form of pellets and a wet feed. Potato juice was

given as part of the wet feed with potassium as the constraining element. If potato juice is

the only component of the wet feed, it takes too long before the pigs adapt to the taste.

It works better with a wet feed of juice and whey - half and half calculated on dry matter.

The growth rate on this diet does not deviate from the growth rate on whey as the only

constituent of the wet diet.

The draw back of potato juice compared to whey is a brief refusal to eat before the pigs

adapt to the taste of the juice and a stronger urinating as a consequence of the high

content of inorganic salts in the juice.

Farmers are not keen to change pig diet - in particular not when the pigs hesitate to eat

the new diet. This "hesitation" combined with the high cost of storage in between

production campaigns and the distribution cost is in disfavor the use of potato juice as pig

feed.

3.4 Land spreading

Effluents from certain processes are not suitable for recycling to farmland by land

spreading. Effluents resulting from chemical modification of starch may require a

treatment before discharge. 

The traditional methods used for household sewage does not work for that simple reason

that effluents from a starch derivative plant are not a steady and proper balanced diet for

microbes. Constructed wetlands is an efficient, reliable and energy saving alternative of

particular advantage in the Tropics regarding cassava processing.

4 Major starch crops

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Corn dominates as the main starch raw material (83%)

Followed by wheat (6%)

Potato (6%),

Tapioca (4%)

Rice (1%). 

4.1 The Potato

By-products of potato are Fibre, Starch and Juice

In processing, after Rasping & Extraction, crude starch milk and pulp are produced

Potato pulp is an excellent cattle feed. Calculated on dry matter the feeding value is

equivalent to barley.

Crude starch milk is concentrated and excess potato juice isolated. The juice is an

excellent fertilizer and is recycled to farmland.It is also used for animal

feeding.Calculated on nutrients it is equivalent to an artificial fertilizer with same

composition.

Use of potato juice equivalent to 100 kg nitrogen per ha 

After Dewatering and Drying, the purified starch milk is dewatered and dried ready for a

multitude of application in food and technical industries. The above juice is the result of

evaporation of fresh and untreated potato juice.

The juice was fed to pigs (25 - 93 kg) in a mixed diet. Potato juice was given as part of

the wet feed with potassium as the constraining element. Effluent from chemical

modification of starch during processing needs treatment before discharge.

4.2 Corn (maize)

The crop value of corn was estimated to be $25 billion for 1997. Among all components

of the corn crop, corn fiber has the least value. The only major outlet for disposal of corn

fiber is animal feed. Unfortunately, corn fiber has poor nutritional value though interest

was expressed by industry in making value-added products from corn fiber.

The greatest use for corn is feed for livestock and poultry.

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Corn also goes into many everyday food items-corn oil for margarine; cornstarch for

gravy; and corn sweeteners for soft drinks, to name just a few. Non-food uses of corn

include alcohol for ethanol, absorbing agents for disposable diapers, and adhesives for

paper products.

Shelled corn is a fuel that can be produced within 180 days, compared to the millennia

needed to produce fossil fuels.

Corn ash has some modest value as a fertilizer and as a liming agent, with no evidence of

heavy metals or any other contaminants. The corn ash (after cooling) can be safely

applied to garden areas, flowerbeds, lawns, and fields.

The energy content of shelled corn is not a constant value because of biological

variability and management factors. Generally the energy content of corn is in the range

of 8,000 to 8,500 BTU per pound of dry matter.

[A BTU (British Thermal Unit) is a unit measure of energy. One BTU is the amount of

heat energy needed to heat one pound of water one degree Fahrenheit.]

The factors that may influence the energy content of corn include:

variety of corn

weather conditions during growing season

weather conditions at harvest

drying method

and storage conditions.

The term "dry matter" refers to material that is "bone dry." The standard moisture content

of shelled corn is 15.5 % moisture on a wet basis

http://burncorn.cas.psu.edu/disposal.html

4.3.1 Other uses of corn starch derivatives

From the corn processing, "new uses " are:

1. Vitamin C. Produced from a new two-stage fermentation based process to 2-keto-

gulonic acid, which is then chemically converted to vitamin C.

2. 2. Biotin. This is a new fermentation based product from a patented, genetically

engineered organism.

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3. 3. Astaxanthin. This is a pigment found in natural salmon and trout that give the

fish its pink color. In farmed salmon and trout it must be added to the diet or

produced by a yeast that contains the pigment. The yeast can be fed to the salmon

direct and provide part of the fishes protein needs also. The competitive

astaxanthin is produced synthetically.

4. Isoleucine. This is the next critical amino acid for feeds. A new genetically

engineered organism is nearing completion.

5. Zeaxanthin. Another pigment used in shrimp farming is in development

6. Lutein. Another neutriceutical to be produced by fermentation.

7. Ethyl lactate. This is an environmentally friendly solvent that can replace many

chlorinate hydrocarbons. Significant application work has been completed to

determine the industries where it can be cost effective. Other solvents are also

being developed from fermentation and chemical processing of glucose streams.

8. Organic acids. A number of organic acids are in development. These acids

currently have small markets now, which are limited by the high cost of the acids.

In the oilseed and corn areas significant increase in the grinding of these crops are

expected to come from industrial products that compete in the chemical and polymer

markets. The nutraceutical and pigment areas will provide higher margin products.

http://www.infinitytrading.com/grain_futures_options.html

4.3 Corn fiber

Corn fiber is a low-value byproduct of wet milling, the industrial process that produces

starch, sweeteners, fuel grade ethanol, and other products from corn.

The corn processing industry produces about 4 million tons of corn fiber each year,

which could yield about 80,000 tons of corn fiber oil. This fiber is now sold as corn

gluten feed, a low-cost ingredient in cattle rations.

Corn fiber is ideal because it is abundant and cheap. The U.S. ethanol industry generates

four million tons of the fiber annually, and sells it as livestock feed to avoid disposal fees.

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Corn gluten feed- is a by-product of corn wet milling which produces high fructose corn

syrup. A kernel of corn has 5 primary constituents: starch, gluten, hull, water, and germ.

Corn gluten feed is that portion of the corn kernel that remains after extraction of starch,

gluten and germ. The major constituent in CGF is the hull or bran, along with the gluten,

protein.

4.4 Wheat

In general, it takes less raw grain to produce a whole-grain product than a similar refined

product. Whole-grain products use most of the grain kernel while refined-grain products

lack most of the bran. For example, whole-wheat flour uses about 25 percent less wheat

than refined flour.

The primary use for wheat is flour, the key ingredient for breads, pastas, crackers, and

many other food products. Wheat by-products are used in livestock feeds. Wheat is also

used in industrial products such as starches, adhesives, and coatings.

The remaining byproducts from refined-flour milling are diverted to secondary uses.

Bran, for example, is used as an ingredient in food products and livestock feed.

A shift from refined-grain to whole-grain products could reduce the quantity of grain

milled and supplies of byproducts for secondary markets.

Wheat by-products are used in livestock feeds. Wheat is also used in industrial products

such as starches, adhesives, and coatings.

Approximately 25 % of total wheat milled is left as a byproduct and termed wheat

middlings or mill feed. Wheat Midds-Approximately 25 % of total wheat milled is left as

a byproduct, and termed wheat middlings or mill feed. This by-product feed has been

used in ruminant diets and is widely used in commercial supplements as a protein and

energy source. Wheat midds tends to vary in nutrient composition due to the varying

amount of flour.

This by-product feed has been used in ruminant diets and is widely used in commercial

supplements as a protein and energy source

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4.5 Tapioca

Cassava is the chief source of tapioca. Liquid waste is generated from extraction of

cassava pulp with solid waste is produced from peeling of cassava and extraction process

of cassava pulp as well.

Cassava processing plants produce not only tapioca starch and "polvilho", a naturally-

fermented cassava starch, typical products of Brazil, but also a solid, moist by-product,

the cassava solid waste, which represents an environmental problem. Drying cassava

waste, to produce bran/rough flour for animal feed is economically unfeasible, because of

low market prices.

Solid waste is mostly made use either for food additive or feedstock .The liquid waste is

the most important to be treated before discharging to the river. It is the most pollutant

substance generated from extraction of tapioca starch from cassava pulp. (see Wastewater

treatment from starch processing.)

Partially hydrolysed cassava waste (PHCW) prepared from industrial cassava solid waste

by an enzymatic process. Fed to model rats and both promoted digestive function effects.

Insoluble fibre constituent from PHCW promoted faecal bulking and faecal weight.

These findings indicate that PHCW presents digestive function properties that allow it to

be used as a functional food for human nutrition.

4.6 Rice

Rice is the primary food staple for 2.5 billion people It is an important ingredient in

processed foods such as breakfast cereals and snacks.

Rice by-products are used for brewing and distilling, fuel, fertilizers, packing material,

and industrial grinding.

Of the many possible uses for rice byproducts, the ones presently most likely to be

economic include:

Rice straw as an in-field means of maintaining soil organic matter levels,

Rice straw as a low grade animal feed in areas with no other feed options,

Rice straw as a mulch in high value crops,

Rice hulls as a fuel source, and

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Bran as a source of oil

Brewer’s rice and small broken as a source of flour.

There are many good reasons for using rice byproducts:  

they contain energy  

they are a renewable resource

their utilization can reduce waste problems and related environmental pollution   

they are carbon neutral i.e. no net emission of CO2 in the atmosphere   

http://www.knowledgebank.irri.org/troprice/Why_Use_Rice_Byproducts_.htm

http://www.knowledgebank.irri.org/troprice/whgdata/whlstt53.htm#53

4.7 Other grains

One of the primary uses for oats is for animal feed. As any trip down the cereal aisle of

your supermarket will demonstrate, oats are also the main ingredient in many hearty

break-fast foods. Additionally, oats are used in the manufacture of plastics, solvents, and

other industrial products.

Grains are a renewable resource, and the demand for them is great. Efficient trading of

grains, combined with effective business planning, helps to ensure relatively stable food

prices for consumers.

4.8 Starch in the human diet

Dietary fibers present carbohydrates that are not digested by the digestive enzymes in the

human body, but some can be hydrolyzed or degraded by natural microflora present

especially in the colon.

Pectins, mucilages and gums can be completely degraded, while hemicelluloses presents

a variable degree of degradation, and cellulose is only slightly degraded. The importance

of fibers is related to the physiological effect, both for digestive function regulation and

for controlling and/or preventing gastrointestinal diseases or related malfunctions, such as

constipation, diverticulitis, digestive cancer, cholesterolemia and glycemia.

The ability many fibers have to bind to toxic compounds has not been sufficiently

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studied, although it is considered to be the reason for its protective action against

gastrointestinal cancer. The role of fibers such as those in some fruit and vegetables as

well as in wheat bran in stimulating peristaltic action, is another effect considered

protective.

Conversely, some products produced and released in the large bowel from the microbial

fermentation of dietary fiber constituents have been considered as carcinogenic. Because

viscous fibers slow down the food bolus and fecal matter movement, they stimulate the

establishment of constipation .

Despite the controversy, the beneficial effects of dietary fibers in human health are

clearly shown in most research. These results have, in recent years, awakened foodstuff

producers for the need of making available feeds containing dietary fibers in their

composition. Fibrous by-products, such as those from wheat mills, are no longer

discharged since their use is a well-established practice in human nutrition. A possible

exploitation alternative, both for the solid waste from starch factories and for the solid

bulky mass that results from its hydrolysis, would be its utilization as ingredient in the

formulation of fibrous food products. Therefore, this research was aimed at evaluating, in

model rats, the functional digestive properties of a concentrate foodstuff rich in insoluble

dietary fiber, the partially hydrolyzed cassava waste (PHCW), which was prepared from

cassava solid waste produced by a starch factory, against wheat bran, a dietary fiber

standard.

http://www.knowledgebank.irri.org/troprice/whgdata/whlstt53.htm#53

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5 Wastewater treatment from starch processing.

5.1 Modern starch production

The starch processing industry is characterized by streams that vary in diversity and

complexity and that require extensive processing to achieve high end product quality.

Historically, wet milling has provided pure (>99.5%) starch products for the paper and

corrugating industries, modified starches for food ingredients and high fructose corn

syrup HFCS.

In Europe the majority of starch used in processing is derived from root tuber crops such

as beet or potatoes. However in south and south-east Asia tapioca starch is extracted from

the cassava plant. Governments in the region see the potential for investment in adequate

and sustainable treatment facilities to protect the rural areas where most cassava

processing occurs with many new technologies being applied.

5.2 Tapioca(cassava) processing

Water removal and product separations are two fundamental processing steps that impact

both starch product quality, and starch processing economics.

Activities of a typical cassava-processing factory produce liquid, solid, and gas wastes.

Liquid waste is generated from extraction of cassava pulp.

Solid waste is produced from peeling of cassava and extraction process of cassava pulp as

well. While gas waste is generated from the biodegradation of organic material by

uncontrolled anaerobic process.

In an average factory, the solid waste is mostly made use either for food additive or

feedstock. Therefore, the liquid waste, with high COD loadings, needs to be treated

before discharging to the river.

The tapioca wastewater is:

Highly organic in nature with COD up to 25,000 mg/l.

High in Suspended Solids comprising starch granules in the range 3,000 to 15,000

mg/l COD, which are highly biodegradable by nature.

Anaerobic ponds also serve as a settling basin for starch granules.

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Tapioca wastewater has high cyanide content up to 10-15 mg/l, which is highly

toxic to aquatic life (cyanide conc. 0.3 mg/l have been reported as cause for

massive fish kill.)

For these reasons tapioca or cassava production is a good example of examining starch

waste production in industry, particularly liquid starch effluents.

To understand how the high organic waste loadings are generated one must first look at

the various stages involved in the starch extraction process from tapioca.

After weighing, usually women workers, peel the cassava roots. The peel is made

use by people locally for feeding of sheep.

Raw Material Transportation - After peeling, the cassava roots then transported

to the factory for subsequent processes.

Washing - Washing of peeled cassava roots is done in a rotating drum like. The

rotating drum is halving submerged in a basin, which contain wash water. The

water flow continually and it is typically discharged directly to a river nearby. The

rotating drum equipped with screw mechanism to draw up the cassava root to the

end part of the drum. Then simple bucket elevators usually transports the cassava

roots in to a concrete basin.

Grinding -Manually, cassava roots are pushed to the grinder. The grinder is

normally rotary type. Grinding process result cassava pulp, which should be

separated into tapioca starch and fibrous materials.

Separation -Separation of cassava pulp need fine screen and water. The screen is

‘vibrated’ by action of eccentric rotation, while water is used to dilute the cassava pulp to

make the separation process easier. Fibrous material will retained on the fine screen,

while mixed water and tapioca starch will pass the screen and it flows to the

sedimentation basin. The fibrous material flows to the basin, which is specially designed

to separate water, contain in the fibrous material. The basin equipped with ‘screen’ made

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of bamboo. In this basin, the de-watering process is occurred. The water produced is

typically directly discharged to the river, and the fiber is harvested and sold.

Sedimentation- The sedimentation basin in factories long. The basins are usually

made of concrete and glass laminated. The glass laminated purpose is to maintain

the cleanliness of product, especially in the harvesting process. The tapioca starch

will precipitate, and the wastewater is usually directly discharged in to the river.

Harvesting - Harvesting of tapioca starch is done manually using shovels. The

form of this wet tapioca starch is clump. Therefore, to reduce the size, they utilize

size reductor driven by fuel-engine. The result is finer tapioca, which is ready to

be dried.

Drying - Drying process is done by put the starch in winnowing tray (made of

matted bamboo). Every tray has about 1.5 – 2 kg starch. The trays then are laid on

the bamboo racks. The drying is totally depends on the sun. Usually the drying

period is approximately 2 – 3 days.

Fine grinding - After drying process, the starch is then milled. The grinder is

hammer mill typed.

Packaging Finely, the tapioca starch is packaged in 50 kg - plastic bag and sold.

The yield of the product in between 20% - 25% based on the raw material.

The process generates 20-60 m3/ton of wastewater with low pH in the range 3.8-5.2.

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5.3 Anaerobic DigestersAn Anaerobic Digester is a device for optimizing the anaerobic digestion of biomass, and

possibly to recover biogas also referred to as biomethane for energy production.

The process of anaerobic digestion consists of three steps. 

The hydrolysis of the starch.

The conversion of decomposed matter to organic acids during which bacteria

convert the sugars to acetic acid, carbon dioxide and hydrogen.

The acids are converted to methane gas.

Digester types include:

Batch-batch-type digesters are the simplest to build. Their operation consists of loading

the digester with organic materials and allowing it to digest. The retention time depends

on temperature and other factors. Once the digestion is complete, the effluent is removed

and the process is repeated.

Continuous flow-In a continuous digester, organic material is constantly or regularly fed

into the digester. The material moves through the digester either mechanically or by the

force of the new feed pushing out digested material. Unlike batch-type digesters,

continuous digesters produce biogas without the interruption of loading material and

unloading effluent. They may be better suited for large-scale operations.

There are three types of continuous digesters: vertical tank systems, horizontal tank or

plug-flow; systems, multiple tank systems.

Proper design, operation, and maintenance of continuous digesters produce a steady and

predictable supply of usable biogas.

5.4 Upward-flow anaerobic sludge blanket (UASB) reactors. 

Another growing method of starch wastewater treatment is the use of upward-flow

anaerobic sludge blanket (UASB) reactors.

UASB reactors are based on the principle that inert support material for biomass

attachment is not necessary to retain high levels of active sludge in the reactor.

22

The UASB reactor relies on high levels of biomass retention through the formation of

sludge granules.

5.4.1 How the upward-flow anaerobic sludge blanket (UASB) reactor works.

Starch wastewater is distributed evenly into the tank at even-spaced intervals.

The starch wastewater passes upwards through an anaerobic sludge bed where the

microorganisms in the sludge come into contact with starch synthesize starch

anaerobically.

The sludge bed is composed of microorganisms that naturally form granules (pellets) of

0.5 to 2 mm diameter

These granules have a naturally affinity towards high sedimentation and thus resist wash-

out from the system even at high hydraulic loads.

23

The anaerobic degradation of starch by the microorganisms releases an upward flow of

biogas (CH4 and CO2) bubbles that creates hydraulic turbulence, mixing the liquor

without mechanical aid.

Starch processing wastewater is highly organic in nature COD up to 25,000 mg/l and it

is recommended to have a sludge layer height 5 – 7 m at > 3000 mg/l COD .

At the top of the reactor, the water phase, sludge solids and gas are separated in a three-

phase separator (also known the gas-liquid-solids separator).

24

5.4.2 Anaerobic Processes in the UASB Reactor

There are 4 phases of anaerobic digestion in an UASB reactor

Hydrolysis, where enzymes excreted by fermentative bacteria convert, un-

dissolved starch molecules, amylase and amylopectin that form starch granules,

along with other complex, heavy molecules, to smaller sized sugar molecules

amino acids and alcohols.

Acidogenesis, where dissolved compounds are converted into simple compounds,

(volatile fatty-acids, alcohols, lactic acid, CO2, H2, NH3, H2S ) and new cell-

matter.

Acetogenesis, where digestion products are converted into acetate, CO2, H2 and

new cell-matter.

Methanogenesis, where acetate, hydrogen plus carbonate, formate or methanol

are converted into CH4, CO2 and new cell-matter

5.4.3 Optimum conditions in the UASB Reactor

The optimum pH range is from 6.6 to 7.6

The wastewater temperatures should not be < 5 °C because low temperatures can impede

the hydrolysis rate of phase 1 and the activity of methanogenic bacteria.

To optimize the digestion process, the digester must be kept at a consistent temperature,

as rapid changes will upset bacterial activity.

For optimal performance it is also important to maintain the ratio of COD : N : P = 350 :

5 : 1

If there is a deficiency of some of these nutrients in the wastewater nutrient addition

must be made to sustain the micro-organisms. Chemicals that are frequently used to add

nutrients (N, P) are NH4H2PO4, KH2PO4, (NH4)2CO3.

Digestion vessels require some level of insulation and/or heating depending on location.

This can be achieved in some systems by circulating the coolant from the biogas-powered

engines in or around the digester to keep it warm, while others burn part of the biogas to

heat the digester.

25

Some factors that affect the rate and amount of biogas output are:

pH

water/solids ratio

carbon/nitrogen ratio,

mixing of the digesting material,

the particle size of the material being digested,

and retention time

Anaerobic digestion is a biological process that produces a gas principally composed of

methane (CH4) and carbon dioxide (CO2) otherwise known as biogas.

Biogas produced in anaerobic digesters consists of methane (50%-80%), carbon dioxide

(20%-50%), and trace levels of other gases such as hydrogen, carbon monoxide, nitrogen,

oxygen, and hydrogen sulfide.

5.5 Biomethane

Biomethane is a renewable energy/fuel, with properties similar to natural gas, produced

from ‘biomass’. Unlike natural gas, biomethane is a renewable energy. 

‘Biomass gasification’ is the process in which is biomethane produced in the biomass

gasification process. The biomethane is then used like any other fuel, such as natural gas,

which is not a renewable fuel.

Methane (CH4) is the main component in "natural" gas. It is odorless, colorless and has

energy applications such as domestic use for cooking and heating. and to operate an

internal combustion engine for mechanical and electric power.

Methane (CH4) yields about 252 kilocalories (kcal) [1,000 British Thermal Units (Btu)]

of heat energy per cubic foot (0.028m3) when burned.

26

5.6 Biomass

Historically, biomass use has been characterized by low Btu (British Thermal Units) and

low efficiencies. However, today biomass gasification is gaining worldwide recognition

and favor due to the economic and environmental benefits. In terms of economic benefits,

the cost of the biomethane is essentially free, after the cost of the equipment is installed.

5.6.1 Starch biomass

Starch is a biomass fuel. Under controlled conditions, characterized by low oxygen

supply and high temperatures, most biomass materials can be converted into a gaseous

fuel known as producer gas, which consists of carbon monoxide, hydrogen, carbon

dioxide, methane and nitrogen.

This thermo-chemical conversion of solid biomass into gaseous fuel is called biomass

gasification.

5.6.2 Biogas applications

Biomass gasification technology has the potential to replace diesel and other petroleum

products in several applications:

Thermal applications: cooking, water boiling, steam generation, drying etc.

Motive power applications: Using producer gas as a fuel in IC engines for applications

such as water pumping .

Electricity generation: Using producer gas in dual-fuel mode in diesel engines/as the only

fuel in spark ignition engines/in gas turbines.

Commercial electricity generation systems that use biogas typically consist of an internal

combustion (IC) engine, a generator, a control system and an optional heat recovery

system. IC engines designed to burn propane or natural gas are easily converted to burn

biogas by adjusting carburation and ignition systems.

Such engines are available in nearly any capacity, but the most successful varieties are

industrial engines that are designed to work with wellhead natural gas.

27

A biogas-fueled engine will normally convert 18 to 25 percent of the biogas Btu value to

electricity. Biogas engines reject approximately 75 to 82 percent of the energy input as

waste heat. This waste heat can be used to heat the digester and/or provide water or space

heat to the facility

5.7 Membrane technology

Many uses have been found for membrane technology in the starch processing industry;

these include pretreatment of freshwater, recovery of solids and wastewater treatment.

Membranes can be used to filter many types of fluids in potato, wheat and corn starch

isolation processes with varying degrees of success.

Application of membrane technology has several advantages for the starch processing

industry:

Costs of removing water to concentrate starch and coproducts can be reduced. Up

to 90% savings in energy have been reported using membranes compared to

evaporation.

Membranes can be used to allow recovery and recirculation of water used in

processes, reducing water needs.

Waste treatment costs could be reduced by using membranes to recover solids

from a process stream that would otherwise enter the wastewater treatment

facility. This results in twofold savings for the processor, as costs could be

reduced in waste treatment as well as more solids could be recovered in

coproducts that can be marketed.

Manufacturers developed materials for microfiltration (MF), ultrafiltration (UF),

nanofiltration (NF) and reverse osmosis (RO), initially thought to be suitable for starch

processing.

UF and RO membranes are used to recover solubles from wheat starch process water.

They compared costs of evaporating process water to costs for membrane filtration in

combination with evaporation and found that UF and RO membranes could be used to

filter process water to reduce water pollution.

28

The ability of an acid-thermal process has been compared to that of a UF process to

recover and concentrate potato process water.

The acid-thermal process- involved coagulation with acid, followed by centrifugation to

remove precipitate and evaporation of the centrifuge supernatant to recover a powdered

product.

The UF process-included membrane filtration followed by evaporation and drying of UF

filtrate to recover product. Energy needed for the acid-thermal process was nearly twice

that required for the UF process.

UF and RO membranes to recover solubles from wheat starch process water. Compared

costs of evaporating process water to costs for membrane filtration in combination with

evaporation and found that UF and RO membranes could be used to filter process water

to reduce water pollution

5.8 Anaerobic ponds

Anaerobic ponds (AP) are popularly employed for treatment of organic wastewater

emanating from variety of industries including those with high starch content in

wastewater; such as food, pulp and paper, sugar and distillery processes.

Anaerobic ponds are particularly effective in treating high-strength wastewaters

containing biodegradable suspended solids (SS).

5.8.1 Advanced Integrated Wastewater Pond System (AIWPS)

AIWPS facilities are designed to minimize the accumulation of sludge and to maximize

the production of oxygen through algal photosynthesis. Algal biomass is produced and

can be used as a nitrogen-rich fertilizer, or as protein-rich animal or fish feed (for further

cultivation of high protein foodstuffs), modern medicine and even cosmetics for the idle.

AIWPS require similar land area to conventional lagoons, virtually eliminate sludge

disposal, produce less odor, and may be adapted to energy (methane) recovery.

Constructed wetlands are another technology that may be used to replace maturation

29

ponds. . Constructed wetland systems are designed to simulate and optimize filtering and

biodegradation processes that occur in natural wetlands. They are a possible solution to

improve the performance of pond systems, as they can "polish" wastewater effluent

before its discharge to a waterway.

6 Starch plastic applications

6.1 The Plastic Age

The last half of the twentieth century has been called the Plastic Age. Plastics are used to

make garbage bags, plastic wrap, pop bottles, food containers, insulation, water pipes,

bullet-proof vests, polyester and nylon clothing, latex paint, rechargeable batteries,

automobile bodies, teflon cookware, cement, adhesives, panty hose, shoes, computers,

furniture and many other useful products.

Plastics do not easily decompose in water, air, or sunlight – a great advantage if you do

not want your plastic dishes to dissolve in water or your computer or radio to crumble

when exposed to sunlight.

Generally, plastics are not biodegradable (they don't rot or break down like paper or food

into smaller molecules). The plastic bottles, bags, containers, cups, car parts that we use

today can be around for decades.

Plastics are now made from oil and natural gas. These fossil fuels are expensive to find

and are a non-renewable resource — that is — there is a limited supply available on the

planet.

6.2 Environmentally-Friendly Plastics

Biotechnology researchers are developing new ways to create plastics from plants and

plant oils.

These environmentally-friendly plastics have several advantages over their conventional

counterparts. They are made from renewable resources rather than fossil fuels so a farmer

30

can grow new material (such as a crop of wheat or canola) every year. Some of the new

plastics are formulated to be biodegradable and many of them are made from byproducts

of agriculture and industry that we now throw away or burn as garbage.

6.3 Polymers

Plastics are one class of the chemical group called polymers. Polymers are giant

molecules made up of long chains of simple molecules. Some polymers look like box

cars in a train while others are more complex and look like branches or nets.

Many important substances found in nature are polymers. Proteins are polymers. Proteins

carry smaller, vital molecules around your body, are necessary for digestion, and are

major components in skin, bones and muscles.

Another polymer, cellulose, is the primary component in plant cell walls. Starch, another

polymer, is a food source that most plants store in their cells. Lignin is another naturally

occurring polymer. It gives plants strength and breaks down very slowly. When you look

at plant fossils, what you see is an imprint of leftover lignin.

6.4.1 BioPlastics

One of the natural sources of plastic that biotechnology is taking advantage of is bacteria.

Many species of bacteria make plastics very similar to the polyester out of which we

make everything from snow tires to underwear.

The chemicals that are used to make bioplastics are themselves made through a process

called fermentation. Fermentation occurs when a microscopic organism like yeast or

bacteria is added to an energy-rich solution containing sugars or starch. The

microorganisms break down the sugars into carbon dioxide and alcohol. Bread and beer

are made this way.

31

Huge vats of fermented agricultural products such as sugarcane are used to produce these

"plastic ingredients". These chemicals are processed into plastic for shampoo bottles,

disposable razor holders and other goods.

Biotechnology has given researchers the tools to take the process a step further. They

have recently succeeded in transferring plastic-producing genes from bacteria into oil

seed rape plants.

Rape seed plants store their energy in the form of oil. However, these genetically

engineered plants store energy in a type of plastic polymer called polyhydroxybutyrate

(PHB). The crop is harvested, the seeds crushed to extract the oil, then the oil is treated to

remove the PHB.

6.4.2 Edible Dinnerware

Researchers have developed biodegradable plastic containers made from starch. This

plastic is used to make bowls, plates, coffee cups, egg trays, packaging and plastic films

for wrapping material.

The plastic can be made from barley, corn, oats, rice, soy, or wheat. When you're finished

using it, you can eat it, feed it to animals, or put it in your compost pile.

The nutritional content of the plastic can be varied according to the use. For example,

animal food manufacturers might want a high-protein package that animals can eat.

These plastics can be coloured or flavoured – scientist have already made chocolate,

orange, and vanilla-flavoured cups and bowls.

Another type of edible plastic is being made from starch and protein. The nutritional

content of this plastic is ideal for farm animals. In the future, we could collect plastic

garbage from fast food restaurants and grind it for animal feed.

This type of bioplastic has another useful characteristic – it dissolves in water – not right

away but after being submerged for a period of time. This plastic could be used to make a

straw that won't melt in your milkshake, but will dissolve after it was thrown into the

32

ocean, providing food energy for microorganisms rather than being a hazard to marine

animals.

By using different amounts of lactic acid in the plastic, researchers can increase or

decrease the rate at which the plastic biodegrades

Starch in cereals is found as granules ranging from 2 to 50 microns in diameter. The

starch polymer present in the granules exists as a mixture of amylose and amylopectin.

Depending upon the origin and nature of the starch, the relative ratios of amylose and

amylopectin vary. The amylose and amylopectin molecules are in an ordered

arrangement within the granule and gives crystallinity to the granule.

    Starch granules exhibit hydrophilic properties and strong inter-molecular association

via hydrogen bonding due to the hydroxyl groups on the granule surface. This strong

hydrogen bonding association and crystallization leads to poor thermal processing since

the Tm is higher than the thermal decomposition temperature, and degradation sets in

before thermal melting. The hydrophilicity and thermal sensitivity renders the starch

molecule unsuitable for thermoplastic applications.

6.5 Thermoplastic Starch

    The first starch plastics in the marketplace were starch filled polyethylene. They were

only bio-disintegradable and not completely biodegradable in practical time frames. Data

showed that only the surface starch biodegraded leaving behind a recalcitrant

polyethylene material. Products made from these resins do not meet the criteria of

complete biodegradability in defined disposal systems (like composting) and within the

operational time frames of the disposal system.

6.6 Starch Ester Technology

    Modification of the starch -OH groups by esterification chemistry to form starch esters

of appropriate degree of substitution (1.5 to 3.0 ds) imparts thermoplasticity and water

resistance. Unmodified starch shows no thermal transitions except the onset of thermal

33

degradation at around 260 0C. Starch acetate of ds 1.5 shows a sharp glass transition at

1550C and starch propionate of same ds had a Tg of 1280C. Plasticizers like glycerol

triacetate and diethyl succinate are completely miscible with starch esters and can be used

to improve processability. Water resistance of the starch esters is greatly improved over

the unmodified starch. The starch ester resin reinforced with biofibers has properties

comparable to general purpose polystyrene.

    Appropriately formulated starch esters with plasticizers and other additives provide

resin compositions that can be used to make injection molded products and for direct

lamination onto Kraft paper. Starch acetates up to ds=2.5 undergo complete and rapid

biodegradation. In the case of starch triacetates, 70% of the carbon is converted to CO2 at

580C in 45 days. National Starch & Chemical offer intermediate ds starch esters for

biodegradable plastics applications. 

    Although properties of the starch ester resin are comparable to polystyrene, and can be

injection-molded in cycle times comparable to polystyrene, two problems surface: cost,

and in some applications, weight because of its higher density. If one could effectively

foam the product in an extrusion or injection molding operation, less material will be

required and so the cost per article would be less. This would be true for all

biodegradable plastics. Therefore, generic process technology to make biodegradable

foam plastics would be very useful in the effort to successfully commercialize

biodegradable plastic products. This will be a major focus of SINAS

http://www.msu.edu/user/narayan/researchareas.htm#Biodegradable%20Plastics

Starch-poly(-caprolactone) blend technology

    This reactive blend technology was developed for biodegradable film applications like

lawn & leaf collection compost bags, agricultural mulch film etc. The technology

involves the following steps:

34

    Preparation of thermoplastic starch -- Plasticization of the starch in a twin

screw extruder with appropriate screw elements using glycerol as the plasticizer

with little or no water in a co-rotating twin screw extruder.

    Polymerization (REX) of epsilon caprolactone directly in an extruder with

residence times of 2-3 minutes, to provide a novel, multi-arm, branched

polycaprolactone polymer having Mn values greater than 100,000 and Mw values

around 300 to 400,000 using Aluminium trialkoxides as catalyst. Commercially,

PCL is produced using a batch process with a residence time of around 4 hours.

    Down stream compounding of the new, branched polymer by reactive blending

with thermoplastic starch during the extrusion polymerization operation. Some

grafting of the PCL chains on to the starch occurs during this step, and the in situ

generated graft copolymer is able to compatibilize the two phases giving better

properties to the resulting blend.

    Finally, a one step continuous process to prepare compatibilized poly(-caprolactone)-

thermoplastic starch blends from caprolactone monomer and starch using two extruders

in a T configuration has been developed.

    By controlling the rheology in the extruder, one can obtain a morphology in which the

plastic starch is dispersed in a continuous PCL matrix phase. Good adhesion and

compatibilization is promoted between the plastic-starch phase and the modified PCL

phase to obtain enhanced mechanical properties. Some of the advantages of using

plasticized starch instead of granular starch are:

    smaller domain size is possible by controlling rheological characteristics

improved strength and processing characteristics

reduced macroscopic dimensions in certain applications , i.e. film thickness

    All of the operations can be performed in the extruder. This eliminates the use of

solvent, reduces the number of steps and simplifies the process. From a Life-cycle

perspective, the biodegradable product reduces waste and energy consumption and

conserves resources. This new starch-PCL resin is being marketed under the name

35

ENVAR for film applications like compost, trash and retail carryout bags. Table 1 shows

the properties of the film, and it can be readily seen that the properties are comparable to

low density polyethylene film (LDPE) and better than pure polycaprolactone film.

    Two other companies, Novamont (Italy), and Milleta (Biotech Division, Germany), are

manufacturing and selling starch-PCL blends for film applications (compost bags, trash

bags). Starch is plasticized using water or hydroxy solvents and blended with a

commercial poly caprolactone (Tone 787) polymer from Union carbide.

 

6.7 Biodegradable plastics

New environmental regulations, societal concerns, and a growing environmental

awareness throughout the world have triggered the search for new products and processes

that are compatible with the environment. Thus, new products have to be designed and

engineered from cradle to grave incorporating a holistic "life cycle thinking" approach.

The impact of raw material resources used in the manufacture of a product and the

ultimate fate (disposal) of the product when it enters the waste stream have to be factored

into the design of the product. The use of annually renewable resources and the

biodegradability or recyclability of the product are becoming important design criteria.

This has opened up new market opportunities for developing biodegradable products.

Currently, most products are designed with limited consideration of its ultimate

disposability. Of particular concern are plastics used in single-use disposable packaging.

Designing these materials to be biodegradable and ensuring that they end up in an

appropriate disposal system is environmentally and ecologically sound. For example, by

composting our biodegradable plastic and paper waste along with other "organic"

compostable materials like yard, food, and agricultural wastes, we can generate much-

needed carbon-rich compost (humic material). Compost amended soil has beneficial

effects by increasing soil organic carbon, increasing water and nutrient retention,

reducing chemical inputs, and suppressing plant disease. Composting infrastructures, so

important for the use and disposal of biodegradable plastics, are growing in the U.S. and

36

are in part being regulatory driven on the state level.

The following biodegradable polymer resins are under extensive investigation:

Thermoplastic starch-polyester reactive blends

Soy protein/oil-polyester reactive blends

Starch esters and starch derivatives as biodegradable thermoplastics.

6.8 Engineering and Design of Natural-Synthetic Polymer Composite Systems

New approaches to tailor-made cellulose/starch/lignin-synthetic polymer graft

copolymers with precise control over molecular weight, degree of substitution, backbone-

graft linkage, and the overall grafting process are being studied. Cross-linked graft

copolymers with exactly defined polymer chain segments between cross link points have

been prepared. The graft copolymers exhibit a two-phase morphology and can function

effectively as compatibilizers/interfacial agents to alloy cellulosic and lignocellulosic

materials with synthetic polymers. This approach opens up new opportunities for

economically combining lignocellulosic materials with plastics to engineer new materials

with unique balance of properties targeted for precise end-use applications. Structure-

property relationship, morphological studies, processability and potential applications of

such binary and ternary blend systems are under intense study. Some exciting

applications are in the preparation of biodegradable plastics for packaging applications

6.9 Biodegradation and Composting Studies

Biodegradation studies on plastics and other biodegradable polymers using National

(ASTM) and International (ISO) Standards protocols are under study. Basic mechanisms

for biodegradation are being elucidated and a structure-biodegradability relationship is

being developed.

Fundamental studies and field trials are being conducted on composting selective waste

streams, which includes the new biodegradable materials, and plastics to quality, humic-

rich compost. Effect of process parameters and reactor configurations on the composting

process, microbial populations developed during composting, and the characteristics of

the resultant compost are being evaluated.

37

6.10 Plastics Recycling & Polymer Matrix Composites

Polymer recycling, polymer modification chemistry, polymer blends, polymer alloying,

reactive polymer, compatibilizing agent, Fiber reinforced composite.

Design and engineering of biofiber-polypropylene composites with properties

comparable to that of glass fiber reinforced PP composites and can be recycled unlike its

glass fiber analog.  Expertise in reactive extrusion processing, including polymer

modification such as maleation and sulfonation.  Experience in carrying out polymer

modifications in the extruder to enhance compatibility with other polymers. 

Have done a lot of work on blending and alloying of natural - synthetic polymers,

including detailed morphological characterization using electron microscopy (SEM,

TEM, and confocal microscopy).  Compatibilization of the blends done by generating the

graft copolymer (compatibilizing agent) in-situ in the extruder.  Used these concepts to

utilize recycled/reclaimed thermoplastics in engineering higher-value composite

materials.

6.11 Natural Polymers

Amylose, amylopectin, cellulose, cellophane, cellulose acetate, cellulose ester, cellulosic

polymer, cellulosic resin.

Have worked extensively on cellulosic graft copolymers, and blends & alloys of cellulose

acetate with synthetic and natural polymers, including biofiber-based composites. 

Recently edited a book on "Emerging Technologies for Materials and Chemicals from

Biomass", and contributed two chapters to the book.  National Technical Program

Chairperson for the American Chemical Society's Cellulose, Paper & Textile Division.

38

Commercial Pathways

Corn

Starch Synthesis Genes

Dextrose

Sugar

Immobilized Enzymes and Genetically Modified

Micro Organisms

Bioreactor /

Fermentor

Extrusion SINAS is utilizing the tools of molecular biology to

produce new types of starches with altered chain

lengths and degrees of branching. In addition, organic

modifications of starch in extruder based reactions are

resulting in new types of starch with different physical

properties. This flow chart demonstrates the types of

approaches that are presently being pursued to make

new types of starch.

Bioplastics and Associated Bioproducts

39

Industrial

Automotive

Packaging

Biomedical

Implants, Cell

Culture,

and Hydrogels

Consumer

Toys, Films, and

Molded Products

Computers

Biochips and

Computers

Peripherals

   

http://gaea.bch.msu.edu/~sinas/biodeg.html

 During the past ten years, considerable research and commercial efforts have been made

to introduce starch, particularly cornstarch, as an alternative polymer for the production

of bioplastic materials. Because of its relatively low cost and abundance, starch is an

attractive alternative to oil based plastics.

More importantly, starch polymers provide an alternative and safe structural material

that can be incorporated into a variety of consumer products that are ecologically

friendly, nontoxic, biodegradable or water soluble; all properties that are uniquely absent

from oil based plastics.

In economic terms, the strategies for bringing such "Green" products to the market can,

for the most part, be considered a failure. This lack of commercial success and the

concomitant public unawareness of these materials and their advantages to society are

predominantly related to the following issues:

Expense- the starch based products such as compost bags and picnic utensils that have

been proposed for commercialization are considerably more expensive

than the oil based plastic alternatives limiting their public acceptance (cost

sensitivity)

Esthetics- products made from starch have not attained required levels of esthetic appeal,

i.e. rough or uneven surfaces on starch sheets, non-isotropic cell

distribution within starch foam resulting in brittleness

40

Manufacturing- the relatively unsuccessful efforts to manufacture starch based products

utilizing injection and compression molding equipment and extruders/die

configurations whose performance is optimized for oil based plastics or

food production rather than the different process requirements of thermoplastic

starch

Chemistry- unavailability of starch based materials whose resistance to water can be

regulated from completely water soluble to water resistant,

Density- the absence of extrusion based methods for the manufacture of starch foam

products whose density more closely approaches Styrofoam.

Marketing- the absence of a variety of highly visible starch based products that highlight,

promote and educate the public to the particular advantages of using starch,

e.g. renewal resource, water solubility/biodegradability, non-toxicity,

volatility to nontoxic components (CO2 and water).

6.12 Composting .

The mere production of biodegradable materials does not ensure market, environmental,

or regulatory acceptance of these products.  The ultimate disposability of these materials

and the environmental benefits that accrue from the use and disposal of these materials,

as opposed to today's non-biodegradable synthetic based materials are currently being

demonstrated with the support of an industrial consortium, and the U.S. Government.

Both fundamental studies and field trials on composting selective waste streams, which

includes the new biodegradable materials, and plastics to quality, humic-rich compost is

underway. 

Biodegrading just means breaking the material up into smaller units, but it is all still there

- we are aiming to go one better and leave absolutely no trace."

http://www.leeds.ac.uk/reporter/440/s5.htm

41

Plastics now account for a fifth of the rubbish dumped in landfill sites. Environmental

concerns are driving the global search for green alternatives. Last month biotechnology

company Monsanto announced they had genetically engineered plants to produce a

plastic that can be broken down more easily. University researchers in chemistry and

physics aim to go one better and develop a polymer plastic that will rot away completely.

http://www.potatoplates.com/

6.13 Potatoes to Plastic

Researchers have discovered how to make plastic from the potato waste produced by

processing plants that make french fries, mashed potatoes or hash browns.In the past, the

waste was either sold as cattle food, treated and dumped into water systems, or spread

over large areas of land.

Potato waste is high in starch. The starch is broken down into glucose and then bacteria

are added, causing the glucose to ferment into lactic acid. The lactic acid is dried and

powdered and used to make plastic.

Potatopak NZ Ltd is a multi-award winning Blenheim (New Zealand) based company

that manufactures innovative 100% Biodegradable food serving and packaging products

out of Potato-starch.They are a good example of a business involved reducing and

replacing toxic undesirable, un-biodegradable Polystyrene and other plastics from the

global ecosystem. The perfect replacement being the 100% safe, 100% biodegradable

equivalents made from potato starch waste.

Such treatment processes help clean up the environment with a dual approach by utilizing

the starch from potato processing plants waste water and converting the waste starch into

a product that will help reduce landfill with its biodegradable qualities.

Waste from packaging is a global problem, such technology takes waste and use it to

create something that alleviates waste. Unlike the manufacturing process that is used to

create plastics and polystyrene, the manufacturing process for such biodegradable

products emits no noxious fumes to the atmosphere or toxic liquid waste.

42

Plastics come from oil -- a limited natural resource -- we use a renewable resource -

potatoes - in such a manufacturing process. The process occurs as follows:

Potatoes, on their journey from potato farm to dinner plate, are blasted with water -

washed, scrubbed and, at 120 kph, pushed through a tube outfitted with a set of knives.

The water, full of starch from the cut surfaces, is processed through a starch extractor.

What comes out is potato starch, a valuable by-product, and another valuable resource,

clean, re-usable water.

All waste from the manufacturing is fed to livestock, fish or worms. Starch may also be

used that has been reclaimed from local food processing waste streams. In locations that

do not have starch extraction facilities, reclaimed starch may be imported from other

locations that do.

Potatopak NZ Ltd manufactures Plates, Trays, Bowls and Punnets out of 100%

Biodegradable Potato starch. These items are designed primarily for the serving of Food

on, also be used in Food Retails, for Takeaways, and Gift Packaging.

Once the dried starch is recieved, it is processed it in a high-speed pressure

thermoforming machine that inserts the powdered starch between a set of moulds of the

desired shape. The mould closes and the starch is pressurised and 'cooked' into the rigid

and strong shape. An automated handling system then extracts the tray ready for the next

cycle.

43

REFERENCES

http://burncorn.cas.psu.edu/disposal.html

http://gaea.bch.msu.edu/~sinas/biodeg.html

http://www.infinitytrading.com/grain_futures_options.html

http://www.knowledgebank.irri.org/troprice/whgdata/whlstt53.htm#53

http://www.knowledgebank.irri.org/troprice/Why_Use_Rice_Byproducts_.htm

http://www.leeds.ac.uk/reporter/440/s5.htm

http://www.potatoplates.com/

http://www.uasb.org/discover/agsb.htm

Implementation of anaerobic process on wastewater from tapioca starch industries

Adi Mulyanto and Titiresmi Institute for Environmental Technology, Agency for

the Assessment and Application of Technology Building 412, Puspiptek Serpong,

Tangerang, Indonesia

Rausch Kent D. Front End to Backpipe: Membrane Technology in the Starch

Processing Industry Agricultural Engineering Department, University of Illinois

www.AnaerobicDigesters.com

 

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