GELATINIZATION OF STARCH

Starch in the plant network has a form of granula (grains) that is different. Amilosa show molecular shape heliks (spiral) that can trap molecules-molecules such as in other acid-fatty acid and other forms of hydrocarbons. Granula starch is generally not soluble in cold water but cold water can absorb between 9.1% to 22.7%. Increasing the volume of starch granula going in the water at a temperature of between 55oC to 65oC is indeed the swelling, and after this starch granula can return to the original condition. If the temperature continues to be the granula starch molecules to vibrate so that the bond-bond between the starch molecules and binding of water with the hydrogen bond. If heating is continued with a higher temperature until swelling starch granula a maximum, and then broken, so that at the time of the occurrence of starch gelatinisasi. (Deshaliman.2003)


Gelatinisasi phenomenon is indicated by the typical starch-patian when starch is heated with adanyaair enough. In general, the changes that occur during the heating process Suspensi starch followed by cooling, are: 1). Granula that the development is caused by water imbibisi karma kelemahanya hydrogen bond. 2). Nature of the loss of birefringence that can be observed using the electron microscope (EM). 3). The increased clarity and 4). In a rapid increase in turbidity. To the four stages of the changes can occur simultaneously or gradually, by gelatinization temperature was usually not expressed in a temperature but a range. At the time cooled faction linier as the amylose groups, cluster hydroxy will associated of fish through hydrogen bonds that form the aggregate is not soluble. At the concentration of the liquid, sludge aggregate is formed, while at high concentration will form a gel. Aggregate formation of this phenomenon will be difficult going on amilopektin karna obstructed by the structure of the pectin fork. (Murhadi. 2005)


The formation of gel is influenced by the concentration of starch because gelatinization also depends on the thickness solution. The viscous solution, the temperature is increasing slowly until the temperature reached a certain thickness is not increased, sometimes even down. Concentration to make the best solution is a 20% gel, the higher the concentration, the gel that is less thick, and after some time viskositas akan turun. And pH optimum gel formation in the pH 4-7. When the pH is too high, the formation of the gel quickly but quickly reached down again, whereas if the pH is too low and slow terbentuknya gel when heating forwarded, viscosity will down again. In the pH 4-7 gel formation speed slower than pH 10, but if the heating be continued, viscosity not changed. (Setiadi, and Surya Fitri Nurulhuda. 1993)


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Eko Susanto.2005. Lebih dekat dengan Pati Modifikasi[modified starch]. http://www.ppsdms.org/index.php?option=com_content&task=view&id=1744&Itemid=286. Diakses tanggal 15 Maret 2008