Carrageenans: Stabilizers from the Sea

The seaweed polysaccharide, carrageenan, or Irish moss, was named after Carragheen, a small town near Waterford, in southern Ireland. Records show it has been used in food for several centuries.

USDA and FDA describe carrageenan as derived from a purified seaweed, with a molecular weight higher than 100,000, and exhibiting thickening and gelling properties. In Europe, carrageenans (E 407) are considered safe for use in food applications, and the Joint FAO/WHO Expert Committee on Food Additives does not specify acceptable daily intake (ADI). Red seaweeds from the class Rhodophyceae include agar, furcelleran and carrageenan. Three general types of carrageenan are commercially available to the industry: the idealized structures are designated as kappa, iota and lambda.

What carrageenan can do

Carrageenans are highly protein-reactive due to their high ester-sulfate ionic moieties, and are soluble in hot water or milk. The isoelectric point of the protein being stabilized and the mediums pH are important factors to attain the desired end-product functionality. Kappa carrageenan forms a helix in the presence of potassium ions and yields a strong, rigid and heat-reversible gel that shows some syneresis. Iota carrageenan forms a helix with calcium ions and yields an elastic, freeze/thaw-stable gel. Lambda carrageenan is nongelling, mainly due to its higher ester-sulfate content, but contributes viscosity. Carrageenan solutions exhibit non-Newtonian, thixotropic properties, as shown by decreasing viscosity with increasing shear rate. Several steps, including seaweed selection, sorting, processing conditions and blending operations will minimize variations in gel strength, solubility and functionality.

Food Chemicals Codex includes a monograph of microbial, physical and chemical specifications for carrageenans. Industry typically employs standardizing agents, such as dextrin, dextrose, potassium chloride and other foodgrade diluents, to reduce variation in physical, chemical and functional properties. It is recommended that suppliers include the identity of the standardizing agents in the label declaration as a guideline for the food formulator.

Putting carrageenan to work

Carrageenans are typically mixed with other synergistic gums like locust bean gum, konjac flour and other thickeners, e.g., guar gum and xanthan gum. The industry uses a wide variety of applications for carrageenan combined with other gums.

In cottage cheese, kappa carrageenan improves cling and texture, and in chocolate milk, it acts as a suspending agent and protein stabilizer. Lambda carrageenan, with tetrasodium pyrophosphate, stabilizes overrun in whipped cream, and kappa and iota types are used at 0.20% to 0.30% as gelling agents in cooked flans or custards. Janelle Wilt, marketing manager, Gum Technology Corporation, Tucson, AZ, recommends a blend of carrageenans to provide suspension and mouthfeel in cocoa beverages. She suggests a blend of tara gum and carrageenan that creates smooth gels, for cream pie fillings and puddings.

Dessert gels and low-calorie jellies use kappa and iota carrageenans, along with locust bean gum, to obtain a gel with minimum syneresis. According to Steve Andon, CEO, TIC Gums, Belcamp, MD, canned pet foods use TICAgel with guar gum, locust bean gum and kappa carrageenan as gelling, suspending and thickening agents at 0.5% to 1.0%. Pizza and barbecue sauces may use a synergistic system with xanthan gum, guar and carrageenan as bodying agents at 0.2% to 0.5%. For firm, heat-reversible gels with high clarity, he recommends a low-ash kappa carrageenan with no added diluents.

A blend of gum arabic, xanthan, and carrageenan works well in salad dressings and sauces, notes Aida Prenzno, laboratory director, Gum Technology Corporation.

The meat industry uses kappa carrageenan to help minimize cooking losses. Tom Laaman, Ph.D., president, Guaranteed Gums, Madbury, NH, recommends a semi-refined kappa carrageenan with high gel strength, for processed meats as a highly functional and economical ingredient added to the brine in meat and poultry injection systems.

The current demand for functional foods with low caloric value has expanded the use of carrageenans in food products with low solids content. New applications in bread, noodles, extruded foods and minced fish products have been reported. Due to its unique properties, carrageenan, a natural, renewable resource from the sea, is now marketed widely for industrial applications.

Florian M. Ward earned her Ph.D. in food science from the University of Washington, Seattle, as well as an M.S. in pharmaceutical chemistry, a B.S. in processing technology and a B.S. Pharmacy from the University of the Philippines. Her company, FMWard Consulting LLC, Chadds Ford, PA, offers technical assistance on the use of hydrocolloid systems. She can be reached at [email protected].