STARCH MODIFICATION TECHNOLOGY
Starch is an important nutrient in the daily diet. According greenwold and munro (1979) about 80% of energy needs human world by carbohydrates. This
carbohydrate can be met from sources such as grains (corn, rice,
wheat), tubers (cassava, sweet potato, potato) and trunk (sago) as a
storage reserve starch is food for plants.Starch
plays an important role in the food processing industry is also widely
used in industries such as paper, glue, textile, drilling mud, candy,
glucose, dextrose, fructose syrup, and others. In trade there are two kinds of modified starches and modified starches. Unmodified starch or starch are all kinds of ordinary starch produced from plants such as tapioca starch processing base. Natural
starches such as tapioca, corn starch, sago and starch-patian others
have some problems if used as raw materials in food and non-food
industry. If cooked starch takes a long time (up to high energy needs), also formed pasta loud and clear. Besides, its too sticky and not resistant to acid treatment. these constraints led to limited use of natural starch in the industry. Though
the source and production of starch-patian in our country is very rich,
consisting of tapioca (cassava starch), sago starch, starch tubers than
cassava starch fruits (eg banana starch) and more sources of starch
that has not produced commercial.
On
the other hand, industrial users want catfish starch having a stable
viscosity at both high and low temperatures, has good resistance to
treatment mekanisdan power pengentalannya resistance in acidic and high
temperature. Important
properties desired of modified starch (which is not owned by natural
starch) include: higher brightness (more white starch), retrogradasi
low, lower viscosity, gel formed is more clear, gel texture in the form
of more soft,
low tensile strength, more starch granules easily broken, time and
higher gelatinization temperature, and the time and temperature of
starch granules to rupture lower. Modification
of the nature and development of technology in the processing of
starch, natural starch can be modified here is intended as a change of
the molecular structure that can be done chemically, physically or
enzymatically.
Modified Starch
Natural starch can be made into modified starch or modified starch, with the desired properties or as needed. In
the field of modified food starch is widely used in the manufacture of
salad cream, mayonnaise, gravy, jelly mermable, konfeksioneri products
(candy, chocolate, etc.), breaded food, lemon curd, substitute gum
arabic and others. While
in the non-food sector is widely used in the paper industry (paper
coating, surface sizing), textile industry (sizing, finishing thickening
printing, finishing laundry), building materials (wall board, wood pulp
additive acoustic, insulation) and other uses such as material solvent mixing insecticides and fungicides, material mixing detergent and bar soap.
Today
the method is widely used to modify starch modified by acid adalh,
modification with enzymes, modified by oxidation and crosslinking
modification. Each method produces modified starch modified with different properties. Modified starch with acid will produce a more dilute Sefat if dissolved, more soluble, and a lower molecular weight. Modification
of the enzyme, the enzyme normally use alfaamilase, manghasilkan
setabil viscosity starches and starch in hot temperatures with clearer
properties, tensile strength and lower viscosity. While
modification with crosslinked starch produces high viscosity when the
solution is made more resistant and mechanical treatments.
Modification of the amino acid carried out using klotida. First
starch is mixed with a solution of chloride at a temperature of 37 º C
and heated, and then added with 80 percent ethanol and centrifuging to
separate performed modified starches from the liquid. The precipitate starch is then washed with water until free of chloride ions and dried to 10 percent moisture content. Enzymatic modifications done using the enzyme alpha-amylase. At
first the starch solution at 37 º C heat then add phosphate buffer pH
6.9, and then added a solution of the enzyme alpha-amylase, and let it
react. Subsequently the mixture was heated and added 80% ethanol. The mixture was then disentrifusi and sediment derived starch is separated, washed and dried to a moisture content of 10%
Crosslinking modifications made by reacting starch with compounds that can form crosslinks at temperatures specific pH. The compounds used were efiklorohidrin, trimeta phosphate, diepoksida and so on. Starch produced in the form of the solution generally thicker than natural starch. In
sedrhana crosslinking modifications carried out as follows: Starch in
mixed water forming viscous suspension, then the pH is set to 9.0 using
sodium hydroxide. Then the addition of crosslinking compound formation, such as POCI, followed by neutralization using hydrochloric acid. Starch is then separated from the liquid by centrifugation or centrifugation. Sediment starch washed with water until free of chloride ions, and dried (50 º C oven-or sun-dried) and after dry milled again.Characteristics Starcha. Structure of StarchStarch
is a carbohydrate that is a polymer of glucose that consists of amylose
and amylopectin and amylose ratio in which the magnitude of this
amiloektin vary depending on the type of starch. Various kinds of starch is not the same character, depending on the length of the carbon chain, and straight or branched. In its original form natural starch granules small merupakana called granules. Merupkan
granule shape and size characteristics of each type of starch, because
it was used for identification (Hill and Kelly, 1942).The shape and size of starch ganula varies from plant sources. Rice starch granules have a size small (3-8 μm), polygonal-shaped and tend to occur aggregation or lumpy. Corn starch granules slightly larger (about 15 μm), round to polygonal direction. Tapioca granules are larger (about 20 μm), slightly rounded shape and on one side of the cone-shaped ujunnya. Wheat starch granules tend to be in groups of various sizes. Normal size is 18 μm, the larger granule size average is 24 μm and the smaller-sized granules 7-8 μm. Forms of wheat starch granules are rounded to oval. Potato starch and very large oval shaped, measuring an average of 30-50 μm.
starch granulesa. AmyloseAmylose is a polymer composed of glucose as a monomer. Each monomer is connected to the 1.6-glycosidic bond. Amylose is an unbranched polymer. Despite
the fact amylosa hydrolyzed by β-amylase on some kind of starch
obtained results didrolisis not perfect (Bank, 1973), β-amilasi
hydrolyze amylose into units of glucose residues to break the α-(1,4) of
the non-reducing end of the chain amylose produce maltose.
b. AmylopectinAmylopectin is tersusundari polysaccharide α-glucose monomers. Although composed of the same monomer, unlike amylopectin klarakteristik physical. Structurally,
amylopectin chains formed from glucose that is bound with
1.6-glycosidic bond with amylose, however, the amylopectin branches
formed by 1,4-glycosidic bond.Amylopectin and amylose have different physical properties. amylose more soluble in water than amylopectin. When treated with a solution of iodine; amylose will result in dark blue, while amylopectin will produce a red color.Amylopectin
in food products is stimulating the process of blooming (Puffing) where
the food products that contain high amilopektinnya will be light,
porous, crisp and crunchy. Kebalikanya, containing high amylose starch, tend to produce a hard, solid, because the blooms are limited.
7.5. Kinds of Modified StarchModified
starch is starch hydroxyl groups have been modified by a chemical
reaction (esterification, sterifikasi and oxidation) or by using the
native structure (flenche, 1985). Meanwhile, according to Glicksman (1969), certain starches treated in order to produce better properties. To improve the properties of the previous or to change some other properties.Treatment
may include the use of heat, acid, alkali, oxidizing agents or other
chemicals that will menghasilkangugus new chemical and or changes in
shape, size and structure of the starch molecules. Beberpa
method to modify starch include modifications to the plant breeding,
conversion by hydrolysis, cross-linking, derivatization chemically
change into syrup and sugar as well as changes in the physical
properties (furia 1968)Modification
of the conversion is intended to reduce the viscosity of the starch to
be cooked and used at a higher concentration, the starch will be more
soluble in cold water and improve the properties of starch tendency to
form a gel or paste (furia 1968)Starch
hydroxyl groups have changed the chemical reactions that may include
esterification, and oxidation sterifikasi (flenche, 1985). Modified starch that will change the properties that can be tailored for specific purposes. Desirable
properties is starch that has a stable viscosity at high and low
temperatures, resistance to "sharing" good mechanical and power
thickeners that are resistant to acidic conditions and temperature
sterilization (wirakartakusuma, et al, 1989)Modification
techniques can be divided into three types, namely modification of
rheological properties, modification of the stabilization, and specific
modifications. Included in the rheological modification is depolymerization and crosslinking. Depolymerization process will reduce the viscosity and can therefore be used at higher total solids. How do include dekstrinisasi, acid conversion, and the conversion of wet and oxidation.Murwani study (1989) showed that the modification of the acid and oxidant can reduce the viscosity of corn starch. The
resulting modified starch properties affected by pH, incubation
temperature and concentration of starch used submarine modification
process. While the technique will form jebatan crosslinking between molecular chains to obtain a rigid network of macro molecules. This method will change the rheological properties of the starch and the nature of resistance to acids.Modifications to the stability through esterification and etherification reactions. As a result we will get starch briefly retrogradasi more rendahdan increased stability. Commercial modified starch is produced from a combination of stabilization and crosslinking method. Specific
modifications derived from such typical reaction reaksiyang
kationisasi, karboksimetilasi, grafting and periodic acid oksdasi
7.6. Modified Starch Applications In IndustryUse of modified starch products in the industry are as follows:- Thin Boilling starch is mainly used in the manufacture of gypsum wallboard and also used gumdrop candies and textile sizing.- Starch teroksidai, greatest usage is on high quality paper mill-
Starch crosslinked starch which has a multitude of uses, the starch in
the paper industry is mixed in the resulting paper pulp so much
stronger. Some starch is used in the manufacture of instant foods, such as pudding and control the viscosity of drilling mud-
Starch crosslinking, used in food canning partially filling soup, gravy
sauce uses in food preparation, such as for making baby food and salad
dressings. The use of outside food is very diverse including the giving nature of water-resistant cardboard box, textile and paper sizing-
Starch derivatives, such as cationic starch used in paper mills to
additive and as an emulsifier starch hydroxy alkyl much useful for all
surface sizing of the paper and for paper coating and beberpa other
uses.Basic Principles For Getting Modified Starch Products1. Thin
Boiling Starch obtained by acidify starch suspension at a particular pH
and heated at a certain temperature to obtain the degree of conversion
or modification is desired. Then do the neutralization, screening, washing, and drying. The influence of pH and sushu resulting in part hydrolysed starch into dextrin is produced starch with low viscosity.2. Oxidized
starch, obtained by oxidizing the starch with oxidizing compounds
(oxidants) with the aid of a catalyst, usually heavy metals or salts of
heavy metals were carried out at a certain pH, temperature and reaction
time accordingly.3. Pregelatinized
Starch, starch is obtained by cooking the starch in the cooking
temperature, then dry using rollers (drum drying) that is heated by
passing it. Pregelatinisasi starch has a common trait that is dispersible in cold water. Drying
parameters like gap between the rollers and the rollers can affect the
properties and characteristics of starch obtained as, smooth and creamy
product that providing a high viscosity of the dispersion but tend to
absorb water too quickly causing the product to be soft, this can be
prevented by administration of a hydrophobic agent in particles. The
shape and density characteristics influence due to the formation of
thick and dense layer as well as having a low level of water absorption,
high thermal paste viscosity and cold paste viscosity is low.4. Crosslinked
starch (cross-lingking), where starch is obtained by chemical treatment
is to increase cross-lingking agent that can cause the formation of
bonds (bridges) between molecules in the new starch itself or between
the starch molecules with one molecule other starches.5. Dextrin, made from starch through enzymatic or acid process accompanied by heat treatment. Important properties of dextrin viscosity is decreased, increased cold water solubility and decreased sugar content.6. Derivatives
of starch, modified starch is made by reacting starch with a
monofunctional reagent to include groups substitute the hydroxyl group. The
usefulness of this process is separately stabilize amylose and
amylopectin, to acquire the properties of a specific functional. By entering group (acetate, hydroxypropyl, etc.) to the molecule, the starch properties will change.7. Cyclodextrin (CD), a modified starch products in the form of a cyclic (ring) containing 6-12 glucose units. CD alpha, beta, and gamma each containing 6, 7, and 8 glucose units. CD made from starch with the help of enzymes cyclomaltodextrin glucanotransferase (CGTase). CDs can also be chemically modified so as to increase their solubility in water or depolimerasi be copolimer insoluble. CD
has interesting properties that can protect other molecules in ringnya,
therefore CD can protect emulsions and materials are sensitive to
light, oxygen, and heat. CD applications in the food, protecting Flavouring ingredients and flavor. So
that the spices do not evaporate, closes a bitter taste in fruit
juices, increase oil emulsion stability (protect the oil from
oxidation), increase the foaming ability of egg white, control, and
cover the color of the product, preventing precipitation in soft drinks
and fruit in cans and many more use of the otherMethod of Modified StarchAcid HydrolysisBy
administering acid modified starch will be generated with several
properties that make these products acceptable to consumers. If a product is less favored by the pre-treatment is often performed to obtain starch with desired physical properties. Treatment
of starch below the gel formation in an acidic solution will produce
products with low thermal paste viscosity ratios have cold and hot paste
viscosity is high and the number of alkali (alkali number) higher than
natural starches.Compared with the original starch, modified starch exhibit acid properties of different starches, such as(1) Decrease in viscosity, thus allowing the use of large amounts of starch.(2) Decrease in iodine binding ability.(3) Reduction of granule swelling during gelatinization.(4) Decrease in intrinsic viscosity.(5) The increase in solubility in hot water below the gelatinization temperature.(6) lower gelatinization temperature.(7) Decrease in osmotic pressure (molecular weight).(8) Increasing the viscosity ratio of hot to cold viscosity.(9) Increased uptake of NaOH (alkali number higher).Modified starch is not soluble in cold water and birefringence properties of the equation. Acid concentration, temperature, starch concentration, and reaction time can vary depending on the desired properties of starch.From research conducted by Bechtel (1950) shows that:1. Increased acid modification lowers the viscosity of the hot pasta and lowers hardness and gel strength.2. Acid treatment will cause a decrease in viscosity of the hot pasta is faster than the decrease in gel strength.3. Hot
paste viscosity ratio with violence and destruction of gel strength was
higher in starch modification of acid modified starch is not where the
comparison would both increase with increasing acid treatment.4. When
the strength of gel formation is defined as the ratio between the
viscosity of the hot pasta and cold paste viscosity at standard
conditions of acid-modified starch have the same fluidity.7.8.1 Modification Association Cross (cross-linking)
As
generally used in industrial starch is determined by the rheological
properties of starch pastes produced from starches such as viscosity,
gel strength, clarity and rheological stability. In
the heating of starch suspensions that make up the primary bonding
molecules in a compact structure that will break due to the hydration
and granule sucking water expands, some granules will expand at very
limited, development occurs on two levels named after gelatinization and
cooling.
Maxwell
and Radley (1976) tried to develop a cross-linking reaction to inhibit
the development of starch for the purpose of starch paste viscosity
stability. "Cross-linking"
is used where necessary with high viscosity starch or starch with good
shear resistance as in the manufacture of cooking pasta with continuous
and rapid cooking in steam injection.
Crosslinked starch is made by adding a cross-linking agent in starch suspension at a specific temperature and pH accordingly. Type
of cross-linking agent has been widely used as hepikhlorohidrin,
tri-meta phosphate which are both commonly used for the manufacture of
food and industrial starches. Other
cross-linking agent used in the industry are aldehydes, di-aldehyde,
vinyl sulfone, di-epoxide, 1,3,5 tri-khloro, 1,3,5 tri-acryl-5-triazine,
n-methyl ethylene bis- acrylamide, bis-hydroxy methyl etiln urea, and others.
Alkaline Hypochlorite Oxidation
Dissolved
starch powder bleach (alkaline hypochlorite) will increase the
temperature during the reaction temperature increases are controlled
during manufacture of oxidized starch are alkaline. Starch, drier will increase the speed of this reaction is caused probably due to hydration or heating. The
procedure for making oxidized starch can be done with a 10% solution of
sodium hypochlorite and then do the heating in a suitable water
conditions will produce dry product. Starch by hypochlorite oxidation speed increases when there is kana cobalt, bromine, or nickel sulfate. For
heating corn starch can be done at a temperature of 95 ° C, microscopic
image shows that some of the starch granules to rupture and sized
variety with specific rotation 198oC. Staining
with iodine will blue-violet with a lower molecular weight than natural
starch and very high viscosity at 25 ° C despite a decline in the
conductivity of the solution. The resulting gels after purification was increased 8-fold productivity. Reducing the rotational strength increases and is lower than the natural starch. Increased
viscosity due to particle size reduction caused by the hydrophilic
group is formed which causes an increase in hydration.
