Starch gelatinization

Starch is the most common carbohydrates polymer in foods. It is known to go through transformation and gives diverse physical structures and properties.

When starch granules are heated in the presence of water, the granules eventually lose the double-helical crystalline structure and the Maltese cross. This process is known as gelatinization.

Starches of different botanical sources and genetic backgrounds display different gelatinization properties, including gelatinization temperature, enthalpy change and melting of amylose-lipid complex.

The gelatinization of starch is an irreversible process, and each starch has its own characteristic gelatinization temperature.

Water acts as a plasticizer during starch gelatinization, lowering the melting temperature of starch. This decreases the glass transition temperature of the non-crystalline regions of native starch and leads to melting of the crystalline parts as temperature is increased.

Starch gels are composites of swollen gelatinized granules embedded in a continuous amylose network.

When the gelatinized starch is continuously heated in excess water, the starch granules swell, develop viscosity and become a paste. This is known as pasting.
Starch gelatinization

The process of gelatinization

Gelatinization occurs when starch granules are heated in a liquid. It is responsible for the thickening of food systems. The process is an important physic-chemical change associated with the cooking of starchy materials.

When the liquid is heated, the hydrogen bonds holding the starch together weaken, allowing water to penetrate the starch molecules, causing them to swell until their peak thickness is reached.

During the gelatinization, water will be absorbed into the individual starch granules and held there tightly, actually becoming bound water. Bound water is no longer able to flow; the water that is bound in the granules causes granule themselves to swell significantly.

The gelatinizes starch mixtures are opaque and fragile and the ordered crystalline structure of starch is lost.

Gelatinization takes place over a temperature range that varies according to the source of starch and its amylose/amylopectin ratio.

The most important factors that affect the gelatinization temperature are:
*Type of starch
*Amount of tenderizer: sweeteners and fats
*Amount of acid

The process of gelatinization

Starch gelatinization process

Gelatinization process is characterized by the gelatinization temperature, above which the gelatinization of the starch suspension starts due to heat and moisture transfer phenomena.

It is the process that starch molecules undergo to thicken a liquid. It was defined by the expert as phase transition of granules from an ordered state to a disordered one.

When moist heat is applied to starch, the granules gelatinize, forming a mixture of thick, soft and creamy consistency.

This behavior makes starch useful for many purposes in food as an adhesive and thickening agent and industrial applications such as making paper paint and cosmetics.

There are three stages of gelatinization using starch:
*Heating the starch
*Absorbing the liquid
*Thickening the liquid

The process is essential for many industrial processes as it alters the rheology and viscosity properties of the system that the starch is in and it also makes the starch more accessible to enzymatic action.
Starch gelatinization process