The 3 Main Structures of Carrageenan
If you’re searching for an ingredient to assist with gelling, suspension stability or thickening, carrageenan (EU) may be the solution. From the Rhodophyceae class of red seaweed, carrageenan are polysaccharides and are often extracted as a sodium salt (EU).
There are three main structures of this ingredient based on the number of sulfate groups attached to the galactose molecule: kappa (EU), iota (EU) and lambda (EU). Each structure offers distinct functionalities for a variety of food applications.
Kappa – Carrageenan = Firm Gel
Kappa-carrageenan yields a strong gel often described as firm and brittle in the presence of potassium ions, and may have syneresis. The kappa structure is a linear polysaccharide with one sulfate group per two galactose molecules and assumes a helical network that is only strengthened with potassium (EU) present. Kappa needs to be solubilized in hot water, but the sodium salts of kappa-carrageenan can be soluble in cold water. The resulting gels are not freeze-thaw stable.
Kappa-carrageenan is used in dairy applications with success because it complexes with kappa-casein to form a pourable gel formation. This link allows particles like cocoa (EU) in chocolate milk or whey (EU) proteins in other dairy products to remain suspended. In ice cream (EU), the kappa form is used to stabilize air bubbles. In processed cheese (EU), it can be used to reduce the amount of natural cheese without changing manufacturability or finished product texture.
Kappa-carrageenan is also commonly used in meat processing. It enables higher moisture content in meat products like sausages (EU) and cooked hams (EU), which results in better yields and improved slicing. In low-fat meat products, using it will result in eating qualities which mimic full fat meat products.
With known synergies, kappa-carrageenan is often paired with locust bean gum (EU) and guar gum (EU) (a blend often seen in ice cream) to produce a softer gel with better stability. Kappa2 is a weak kappa-carrageenan from a kappa/iota hybrid.
Iota – Carrageenan = Elastic Gel
Like kappa, the Iota-carrageenan structure is also a linear polysaccharide which assumes a helical conformation but with two sulfate groups per two galactose molecules. Iota forms a soft elastic gel especially in the presence of calcium ions (EU) and the resulting gel strength is ionic strength dependent. Unlike kappa, iota-carrageenan forms gels with freeze-thaw stability and is less likely to undergo syneresis. The iota form is soluble in hot water, and only the sodium salts of iota-carrageenan are soluble in cold water.
Iota-carrageenan gels have the ability to break apart during mechanical action and reform once the mechanical action stops, which is known as thixotropy. This property is helpful in cold-filled products. Within food applications, low usage levels of iota-carrageenan are used to suspend particulates within salad dressings (EU) and other beverages like soy milk (EU). At higher usage levels, iota creates a stronger gel and is used in products like pet foods to create gravy.
Lambda – Carrageenan = Thickener
With a flat structure, lambda-carrageenan has three sulfate groups per two galactose molecules, which does not form a helical structure like kappa or iota. As a result of structure, lambda is a non-gelling polysaccharide mainly used to thicken solutions. Unlike kappa, which uses potassium ions to set, and iota, which uses calcium ions to set, lambda-carrageenan does not require ions to achieve a viscous solution. The lambda form is also the only carrageenan which is cold-soluble without being a sodium salt.
In food applications, lambda creates a viscous but pseudoplastic solution, or shear-thinning, under mechanical action. In liquids, like dairy products (EU), syrups, beverages (EU), tomato sauce and salad dressings, lambda can enable a full bodied, creamy texture.
Additional Processing Considerations:
Carrageenan ingredients are known for being soluble in hot water to produce viscosity or gels. However, this quick solubility means it can be difficult to mix into formulas. When setting processing directions, first premix powdered carrageenans with dry ingredients/fillers like sugar or maltodextrin (EU), or slurry the carrageenan with oil. Alternatively, it can be premixed with a sugar syrup or salt solution, which will increase the temperature needed for hydration. This allows for carrageenan to achieve a good mix before the product is heated to set.
While carrageenan is stable at a range of pH levels, in very acidic conditions and heat, a process called autohydrolysis will reduce its function. For acidic applications requiring heat processing, consider adding carrageenan ingredients late into the processing.
Individually, the kappa, iota and lambda forms provide unique characteristics. However, as a blend, they can offer a greater range of final product attributes. For example, pairing kappa and iota can achieve a refrigeration-free, vegetarian alternative to gelatin. There is also synergy with other gums and pairing them can offer additional properties. Work with your supplier to find the blend that contains the proportion of each structure that will allow you to achieve your end goal.
Summary of carrageenan properties
Typical applications for carrageenan
While carrageenan is accepted by the USDA, USDA National Organic Program, and FDA as safe, and is approved by the Joint FAO/WHO Expert Committee on Food Additives most recently for use in infant formula, some consumers question the safety of carrageenan in foods. The form that is considered suspect – poligeenan – is not allowed in food, but early naming of poligeenan as degraded carrageenan has led to confusion, and some consumers mention inflammatory or gastro-intestinal concerns. If you encounter objections to the use of carrageenan, your supplier can recommend alternatives, but keep in mind that your product may require broad reformulation beyond the thickening ingredients to retain similar textural qualities, due to the synergistic nature of carrageenan with other components in your product.
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there are several study that carragen is a good growth promotant, what is your idea about it?
we are using Lambda Carrageenan in our evaporated milk but cant achieve more that 30 days shelf life , can you help us
the milk concentration is achieve by R.O.