Alginates

What are alginates? How are they used in organic food processing and handling?

By Taryn Kennedy

Alginates are polysaccharides derived from marine algae and brown seaweeds, such as kelp. Similar to the structure-forming component of cellulose in terrestrial plants, alginates give brown algae both mechanical strength and flexibility. Alginates are among a suite of polysaccharides or “seaweed gums” that are extracted by the hydrocolloid industry for use in food processing and for medical, pharmaceutical, textile and cosmetic applications. Alginates are extracted from brown seaweeds; carrageenan and agar are derived from red seaweeds. Alginates are designated as a synthetic substance due to the processes used to derive the substance from seaweed, either by alkali-extraction or acid hydrolysis. 

Alginates are useful in food processing, and can serve multiple functions as a(n): emulsifier or emulsifier salt, firming agent, flavor enhancer or flavor adjuvant, formulation or processing aid, stabilizer or thickener, surface-active agent or texturizer. Temperature independent gelling is a key feature of alginates. Their ability to make gels without the use of heat distinguishes alginates from other hydrocolloids that require high-temperature processes (i.e. gelatin, agar, carrageenan, locust bean gum). Alginates form a hydrogel in the presence of a positively charged ion, either ammonium, calcium, potassium or sodium. No heat or significant temperature change is required to set an alginate gel, nor will heat melt an alginate gel. Therefore, alginates can be used in baking or cooking where temperatures are increased during the process. Alginates are used to extend product shelf-life and reduce risk of pathogen growth on food surfaces. Alginates are used as carriers of active or functional food ingredients (e.g., anti-browning agents, colorants, flavors, nutrients, spices or antimicrobial compounds). As components of edible coatings or films, alginates act as a protective barrier to retard food spoilage and extend the effectiveness of an active ingredient. As selective barriers to moisture, oxygen, lipid oxidation and loss of volatile aromas and flavors, edible films increase the shelf-life of fresh-cut fruits. 

In the National Organic Program (NOP) regulations, alginates are currently listed with the allowed synthetics in section §205.605(b) as a nonagricultural (nonorganic) substance that is allowed as an ingredient in or on processed products labeled as “organic” or “made with organic (specified ingredients or food group(s)).” There are no restrictions on the use of alginates in the organic standards. However, the Food and Drug Administration outlines the maximum level of alginate use in food per specific functional use. As an ingredient, alginates are used to provide dietary fiber or to provide thickening or a stabilizing effect in yogurts, milk shakes and fruit-smoothie type drinks, frozen yogurt, ice cream bars, puddings, white and whole wheat breads, cookies, breakfast or granola bars, noodles, whole wheat cereals, meatless lasagna and pasta dishes, fruit juices and fruit juice bars. Alginates are also used in the process of spherification. Creating a truly unique food experience, liquid is shaped into spheres with a very thin membrane that explodes in your mouth!

Revised and updated in December 2017 by OMRI Technical Director Johanna Mirenda. This article was originally published in the Winter 2015 edition of the OMRI Materials Review newsletter.