Gelling Property of Carrageenan powder

Gelling Property of Carrageenan

 

1. Influencing factors of gel strength

 

One important property of κ-Carrageenan powder is that it can form various kinds of gels in water and cream-based food system at low temperatures. Gelation is the basic function of κ-Carrageenan powder. The influencing factors of the gelling property include the concentration of Carrageenan powder, temperature, gel time, the pH value, type and concentration of electrolyte.

1.1 Influence ofκ-Carrageenan powder concentration on gel strength

 

The gel strength will linearly enhance as the concentration of κ-Carrageenan powder increases. This is because the number of molecules will increase and the intermolecular cross-link will be strengthened with the increase of concentration. The gel strength ofκ-Carrageenan powder added with KCl is greater than that without KCl at low concentration but gradually become similar at high concentration. When the concentration of κ-Carrageenan powder is relatively high, it becomes the main factor that influences the gel strength.

 

 

1.2 Influence of temperature on gel strength

 

The rise of temperature can lead to reduction in gel strength of κ-Carrageenan powder solution but the variation is different with the change of temperature. With the decrease of temperature,κ-Carrageenan powder molecules in the gel can further develop a double helix, then form a 3D net structure, and release heat in the process of gelation. On the contrary, it will absorb heat with the increase of temperature. Both the release and absorption of heat can produce the hysteresis on the gel strength and the rates of curve of heating and cooling are different.

 

 

1.3 Influence of gel time on gel strength

 

Experimental results have confirmed that the gel strength ofκ-Carrageenan powder added with 0.2% KCl is 4.6 times greater than that without KCl. In the very short time of the formation of gel, the gel strength increases proportionally to the time, then will be relatively stable, and about 10 hours later will begin to decrease. During the early stage of gelation, theκ-Carrageenan powder net structure can be formed and the gel strength will rapidly increase and reach to a stable state. Later on, free water will be released, so it will decrease by syneresis. During the later stage, the gel strength ofκ-Carrageenan powder added with KCl rapidly decreases because electrolytes help to promote dewatering and shrinking process.

 

1.4 Influence of pH value on gel strength

When pH<5.0, the gel strength of Carrageenan powder will be improved with the pH value; while pH value is 5.0~8.5, it will decrease; But when pH>9.5, it will go up back again.

 

 

1.5 Influence of electrolytes on gel strength

According to the researches by A.S.Micheel and others, the gel strength will increase as the electrolyte concentration becomes high. Furthermore, the cation types also play an important role. For example, such cations as Ca2+, K+, NH4+, Rb+, Cs+ can form hard gels while other cations like Na+,Li+ will form weak gels, so these two cations cannot gel effectively.

 

For the reasons above, the requirements for the test ofκ-Carrageenan powder gel strength is generally laid out as the following. Prepare 1.5% colloid and 0.2%KCl, then heat to dissolve (90-100℃), cool for about 10 hours and test the colloid at the temperature of 20℃.

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On February 28th, 2013, posted in: carrageenan, Products and Techniques by Tags:

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