Properties and Application of Kappa-Carrageenan

Properties and Application of Kappa-Carrageenan

Carrageenan is a natural vegetable gelatin extracted from some red algae and widely used in such fields as food, daily chemical industry and medical research. Its properties such as the formation of hydrocolloid, gelling, thickening, emulsifying, film formation and stable dispersion has been booming the development of carrageenan industry.

Carrageenan products appear as white or yellowish powders, odorless and tasteless. The gel formed by carrageenan has reversibility, that is, the gel will melt into solution with heat and return back when cooling off. Carrageenan has very good water solubility and begins to dissolve at 70℃ and totally soluble at 80℃. Carrageenan in dry powder has strong stability and won’t get hydrolyzed for long time exposure. It is also very stable in neutral or alkaline solution, and won’t get hydrolyzed even with heat. In acid solution (especially pH≤4.0), however, can easily get acid hydrolysis. Due to its many physical and chemical properties, carrageenan can act as the gelling, emulsifying, thickening and suspending agents in order to stabilize the emulsion and control the shrinking, shaping, gelling and dispersion of lost fluids. The safe properties has been recognized by the FAO (United Nations Food and Agriculture Organization) and JECFA (Joint FAO/WHO Expert Committee on Food Additives).

 

A. Definition of Carrageenan

 Kappa Carrageenan

Carrageenan is the algal polysaccharide extracted from such alga varieties of red algae as Chondrus, Eucheuma, Gigartina, and Hypnea. Carrageenan with different sources has different fine structures and different properties. The named types of carrageenan include kappa, iota, lambda, mu, nu, theta, xi, but commercial production mainly applies to the first three.

 

Even with the same variety source, the product properties will also be different because different technological conditions lead to the difference in degradation of molecular weight. Therefore, the term carrageenan is only used in a broad sense but when it comes to the specific application, different products require different specifications, alga varieties and plants because various alga varieties contain different carrageenan in type and quantity. For example, the Eucheuma cottonii variety, mainly produced in Philippine waters, mainly contains the kappa carrageenan while the E. spinosum variety mainly contains the iota carrageenan. Gigartina acicularis, produced in Morocco waters, mainly contains the lambda carrageenan while many other varieties such as Chondrus crispus, Gigartina stellata, Iridaea sp. contain, however, several types of carrageenan and become the mixed type so the special process is needed to break them up. At present, the most widely used carrageenan is theκ-carrageenan. According to the technological processes, carrageenan can be divided into Refined Carrageenan and Semi-refined Carrageenan. The differences between the two lie in the gel strength, the solution transparency and certainly the price. Therefore, different types and grades of carrageenan should be selected for different uses and the most economical and effective choice can be obtained.

B. Main Properties and Application of Carrageenan

In the food industry, carrageenan mainly acts as the gelling, stabilizing and water carrying agents. The gel strength, viscosity and other properties, to a great extent, depend on its types, molecular weight, the pH value, and the contents of salt, alcohol, oxidant and other food colloids. In the practical application, we need take into consideration the gel strength, gelatinizing temperature, the viscosity, fluid characteristics, reaction activity with protein and freezing syneresis.

Under different conditions, carrageenan has different functions. First, it can react with protein and form either the gel or non-gel suspension and sediment. Second, it can form the gel, transparent or turbid, elastic or brittle, of high strength or weak strength, and of the thermal reversible type or thermal irreversible type. Third, it can form various kinds of gel with different melting temperature (including the repeated melting type and the frozen type).

Generally speaking, kappa carrageenan can be totally soluble in hot water over 70℃. After cooling, it can form strong but brittle reversible gel with poor transparency and cause syneresis once frozen. The existence of kalium ions causes the gel to reach the maximum strength while the addition of calcium ions makes the gel shrink and close to be brittle. The ion concentration can be adjusted to change the gel strength and the gelling temperature. Therefore, the organization structure can become more elastic and brittle by adding locust bean gum while the addition of cane sugar helps to improve transparency. The iota carrageenan is similarly only soluble in hot water and with the existence of kalium ions, it can produce softer, more elastic and transparent gel than kappa carrageenan does. This kind of gel also belongs to the thermal reversible type and has favorable resistance to syneresis. Besides, it has thixotropic fluid properties in milk or water system and is resistant to high salt. The lambda carrageenan can be soluble in cold water but doesn’t gelate and has high-viscosity thickening effect. All the types of Carrageenan have strong stability in neutral or alkaline solution, but in acid solution (pH=3.5), however, can easily get degraded and the heat helps to accelerate the degradation velocity.

Only the kappa carrageenan and locust bean gum can produce synergistic effect to improve the gel strength. The proportion 2:1 helps to attain the maximum while the 1:4 proportion will lead to the minimum. In order to fully hydrate the locust bean gum, the solution should be heated over 82℃ and the formed gel is still thermal reversible and reaches the similar gel strength. The dosage of the complex gun of the kappa carrageenan and locust bean gum is only 1/3 that of the kappa carrageenan alone. The kappa carrageenan can gelate in the water system of concentration over 0.5% while in the milk system the gelling concentration can be as low as 0.1-0.2%. In the food industry, carrageenan is used to serve as the gelling, thickening, stabilizing and water-carrying agents. For example, in dairy drinks, it act as the suspending agent; in pudding, yoghourt, ice cream and cheese, it acts as the thickening and stabilizing agent; in the production of sausage and western-style ham, it can be used as the water carrying agent while in jelly as the gelling agent. Carrageenan’s application in food is shown in the following table.

 

Table: Application Examples of Carrageenan in the Food Industry

 

Food Name

Function

Types of Carrageenan

Dosage (%)

Water System:
Jelly gelling Kappa + iota + locust bean gum 0.5-1.0
Sauce thickening, weak gelling Kappa type 0.2-0.5
Tomato Sauce thickening, weak gelling Iota type+ starch 0.1-0.25
Western-style Ham gelling Kappa type + STPP 1-2

Milk System:
Ice Cream Stable Kappa + locust bean gum +CMC+guar gum 0.1-0.3
Yoghourt Stable Kappa + locust bean gum 0.2-0.5
Cheese Improve coating ability Kappa type+ locust bean gum 0.01-0.05

 

Social Share Counters

On January 30th, 2013, posted in: carrageenan, Products and Techniques by Tags:

Comments are closed.