Starch Gelatinization - Wikipedia, The Free Encyclopedia

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30/3/2016 Starch gelatinization - Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Starch_gelatinization

Starch gelatinizationFrom Wikipedia, the free encyclopedia

Starch gelatinization is a process of breaking down the intermolecular bonds of starch molecules in the

presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to

engage more water . This irreversibly dissolves the starch granule in water. Water acts as a plasticizer.

Three main processes ha ppen to the starch granule: granule swelling, crystal or double helical melting, andamylose leaching.

During heating, water is first absorbed in the amorphous space of starch, which leads to a swelling

phenomenon.[1]

Water then enters via amorphous regions the tightly bound ar eas of double helical structures of amylopectin. At ambient temperatures these crystalline r egions do not allow water to enter. Heatcauses such regions to become diffuse, the amylose chains begin to dissolve, to separate into anamorphous form and the number and size of crystalline regions decreases. Under the microscope in

polarized light starch loses its birefringence and its extinction cross. [2]

Penetration of water thus incr eases the randomness in the starch granule structure, and causesswelling, eventually soluble amylose molecules leach into the surrounding water and the granulestructure disintegrates.

The gelatinization temperature of starch depends upon plant type and the amount of water present, pH,

types and concentration of salt, sugar, fat and protein in the recipe, as well as starch derivatisation

technology used. Some types of unmodified native starches start swelling at 55 °C, other types at 85 °C.[3]

The gelatinization temperature of modified starch depends on for example on the degree of cross-linking o

the amylo pectin, the degree of acid treatment, acetylation. Gel tem perature can also be modified by geneti

manipulation of starch synthase genes.[4] Gelatinization temperature also depends on the amount of

damaged starch granules. These will swell faster. Damaged starch can be produced, for example, during thwheat milling process, or when drying the starch cake in the starch plant.[5] There is an inverse correlation

between gelatinization temperature and glycemic index.[4]

Gelatinization improves the availability of starch for amylase hydrolysis. So gelatinisation of starch is used

constantly in cooking to make the starch digestable or to thicken/bind water in roux sauce, a soup.

Contents

1 Retrogradation2 Pregelatinized starch3 Determination4 See also5 References6 External links

Retrogradation

https://en.wikipedia.org/wiki/Cookinghttps://en.wikipedia.org/wiki/Rouxhttps://en.wikipedia.org/wiki/Saucehttps://en.wikipedia.org/wiki/Amylasehttps://en.wikipedia.org/wiki/Hydrolysishttps://en.wikipedia.org/wiki/Glycemic_indexhttps://en.wikipedia.org/wiki/Starch_synthasehttps://en.wikipedia.org/wiki/Modified_starchhttps://en.wikipedia.org/wiki/Polarized_lighthttps://en.wikipedia.org/wiki/Birefringencehttps://en.wikipedia.org/wiki/Extinction_crosshttps://en.wikipedia.org/wiki/Amorphoushttps://en.wikipedia.org/wiki/Crystalhttps://en.wikipedia.org/wiki/Amylopectinhttps://en.wikipedia.org/wiki/Helixhttps://en.wikipedia.org/wiki/Helixhttps://en.wikipedia.org/wiki/Saucehttps://en.wikipedia.org/wiki/Rouxhttps://en.wikipedia.org/wiki/Cookinghttps://en.wikipedia.org/wiki/Hydrolysishttps://en.wikipedia.org/wiki/Amylasehttps://en.wikipedia.org/wiki/Glycemic_indexhttps://en.wikipedia.org/wiki/Starch_synthasehttps://en.wikipedia.org/wiki/Cross-linkhttps://en.wikipedia.org/wiki/Modified_starchhttps://en.wikipedia.org/wiki/PHhttps://en.wikipedia.org/wiki/Extinction_crosshttps://en.wikipedia.org/wiki/Birefringencehttps://en.wikipedia.org/wiki/Polarized_lighthttps://en.wikipedia.org/wiki/Crystalhttps://en.wikipedia.org/wiki/Amorphoushttps://en.wikipedia.org/wiki/Amylopectinhttps://en.wikipedia.org/wiki/Helixhttps://en.wikipedia.org/wiki/Plasticizerhttps://en.wikipedia.org/wiki/Granule_(cell_biology)https://en.wikipedia.org/wiki/Dissolution_(chemistry)https://en.wikipedia.org/wiki/Hydrogen_bondhttps://en.wikipedia.org/wiki/Waterhttps://en.wikipedia.org/wiki/Starch


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Diagram illustrating the appearance of various thermal

transitions on a DSC curve

Cooked, unmodified starch, when cooled for a long enough period, will thicken (or gel) and rearrange itsel

again to a more crystalline structure; this process is called retrogradation. During cooling, starch molecules

gradually aggregate to form a gel. Molecular associations occur: Amylose-Amylose ; Amylose-

Amylopectin; Amylopectin-Amylopectin. A mild association amongst chains come together with water sti

embedded in the molecule. Due to the tightly packed organization of small granule starches, retrogradation

occurs much more slowly compared to larger starch granules. High amylose starches require more energy

break up bonds to gelatinize into starch molecules, leading to a rigid and stiff gel. A mild association

amongst chains come together with water still embedded in the molecule.

Due to strong associations of hydrogen bonding, longer amylose molecules will form a stiff gel.[6]

Amylopectin molecules with longer branched structure, increases the tendency to form strong gels. Granul

size do not directly impact starch performance, but it is one of the main factors affecting starch

gelatinization and retrogradation. High amylopectin starches will have a stable gel, but will be softer than

high amylose gels.

Retrogradation restricts the availability for amylase hydrolysis to occur.

Pregelatinized starchPregelatinized starch is starch cooked and then dried in the starch factory on a drum dryer or in an extruder

making the starch cold-water-soluble. Also spray dryers are used to obtain dry starch sugars and low

viscous pregelatinized starch powder.

etermination

A simple technique to study starch gelation is by

using a Brabender Viscoamylograph. It is a

common technique used by food industries todetermine the pasting temperature, swelling

capacity, shear/thermal stability and the extent of

retrogradation. Under controlled conditions,

starch and distilled water is heated at a constant

heating rate in a rotating bowl and then cooled

down. The viscosity of the mixture deflects a

measuring sensor in the bowl. This deflection is

measured as viscosity in torque over time vs.

temperature, and recorded on the computer. The

viscoamylograph provides the audience with the beginning of gelatinization, gelatinization

maximum, gelatinization temperature, viscosity

during holding, and viscosity at the end of

cooling.[7]

DSC or Differential scanning calorimetry is

another methods industries use to examine

properties of gelatinized starch. As water is heated with starch granules, gelatinization occurs, involving an

endothermic reaction.[8]

https://en.wikipedia.org/wiki/Differential_scanning_calorimetryhttps://en.wikipedia.org/wiki/Distilled_waterhttps://en.wikipedia.org/w/index.php?title=Brabender_Viscoamylograph&action=edit&redlink=1https://en.wikipedia.org/wiki/Viscoushttps://en.wikipedia.org/wiki/Spray_dryerhttps://en.wikipedia.org/wiki/Food_extrusionhttps://en.wikipedia.org/wiki/Drum_dryinghttps://en.wikipedia.org/wiki/Gelhttps://en.wikipedia.org/wiki/File:InterprettingDSCcurve.png


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The initiation of gelatinization is called the T-onset. T-peak is the position where the endothermic reaction

occurs at the maximum. T-conclusion is when all the starch granules are fully gelatinized, and the curve

remains stable.

See also

Dextrin

Modified starchStarch

References

External links

Food Resource, Starch, Oregon State University (http://food.oregonstate.edu/learn/starch.html)Corn starch gelatinization, filmed with microscope, Youtube (http://www.youtube.com/watch?v=PbbnssHHO2k)

Retrieved from "https://en.wikipedia.org/w/index.php?title=Starch_gelatinization&oldid=705141933"

Categories: Starch Food science Chemical bonding

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1. Jenkins, P J, and A M. Donald. "Gelatinisation of

Starch: a Combined Saxs/waxs/dsc and Sans

Study." Carbohydrate Research. 308 (1998): 133-

147. Print.

2. Zobel, H. F. (1988), Starch Crystal

Transformations and Their Industrial Importance.Starch - Stärke, 40: 1–7.

doi:10.1002/star.19880400102

(https://dx.doi.org/10.1002%2Fstar.19880400102)

3. Hans-Dieter Belitz, Werner Grosch, Peter

Schieberle, Food chemistry, Edition 3, Springer,

page: 318-323, year: 2004, ISBN 3-540-40818-5,

ISBN 978-3-540-40818-5

4. US application 20080201807A1

(http://worldwide.espacenet.com/textdoc?

DB=EPODOC&IDX=US20080201807A1), Robert

James Henry & Daniel Lex Ean Waters,

"Gelatinization Temperature Manipulation",

assigned to SOUTHERN CROSS UNIVERSITY,

Rural Industries Research and Development

Corporation

5. Stanley P. Cauvain, Linda S. Young, Baking

problems solved , Woodhead Publishing, page: 25-

26, year: 2001, ISBN 1-85573-564-4, ISBN 978-1

85573-564-4

6. Hegenbart. S.. Understanding starch functionality.

Food product. Web. 1996http://www.foodproductdesign.com/articles/1996/0

starch-functionality.aspx

7. http://www.brabender.com

8. http://www.siint.com/en/documents/technology/the

http://www.siint.com/en/documents/technology/thermal_analysis/application_TA_006e.pdfhttp://www.brabender.com/http://www.foodproductdesign.com/articles/1996/01/understanding-starch-functionality.aspxhttps://en.wikipedia.org/wiki/Special:BookSources/9781855735644https://en.wikipedia.org/wiki/Special:BookSources/1855735644http://worldwide.espacenet.com/textdoc?DB=EPODOC&IDX=US20080201807A1https://en.wikipedia.org/wiki/Special:BookSources/9783540408185https://en.wikipedia.org/wiki/Special:BookSources/3540408185https://dx.doi.org/10.1002%2Fstar.19880400102https://en.wikipedia.org/wiki/Digital_object_identifierhttps://www.wikimediafoundation.org/https://wikimediafoundation.org/wiki/Privacy_policyhttps://wikimediafoundation.org/wiki/Terms_of_Usehttps://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_Licensehttps://en.wikipedia.org/wiki/Category:Chemical_bondinghttps://en.wikipedia.org/wiki/Category:Food_sciencehttps://en.wikipedia.org/wiki/Category:Starchhttps://en.wikipedia.org/wiki/Help:Categoryhttps://en.wikipedia.org/w/index.php?title=Starch_gelatinization&oldid=705141933http://www.youtube.com/watch?v=PbbnssHHO2khttp://food.oregonstate.edu/learn/starch.htmlhttps://en.wikipedia.org/wiki/Starchhttps://en.wikipedia.org/wiki/Modified_starchhttps://en.wikipedia.org/wiki/Dextrinhttps://en.wikipedia.org/wiki/Endothermic


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Starch Gelatinization - Wikipedia, The Free Encyclopedia