Seaweed, Tree Sap, and Bean-Cooking Water: The Weird World of Vegan Food Additives
The starches, proteins, and other soluble plant solids in aquafaba—the viscous liquid found in cans of chickpeas and other legumes—is all the rage in vegan circles because its emulsifying, gelling, and thickening properties make it a good replacement for egg whites in meringues, macarons, mousses, pancakes, and so on. Angel food cake? Not so much, based on a recent experiment in the test kitchen at Martha Stewart Living. The batter looked great going into the oven, but the rubbery Deflategate result was about one inch high.
Don’t get me wrong. I think aquafaba is a terrific addition to the vegan arsenal, but I wonder about the sodium content (isn’t that why you’re supposed to discard that gloppy stuff?) and whether it contains BPA from the can lining. Just sayin’.
“Well, at least it’s plant-based,” said a friend, “not like the stabilizers or thickening additives in processed foods.” I’ve avoided commercial foods with long lists of ingredients for most of my life, but I feel obligated to point out that much of what she’s talking about is plant-based too. Ingredients such as tapioca, arrowroot, and agar have been used to thicken and maintain the texture of foods for centuries. Below are eight heavy hitters.
One thing you’ll notice right away is that the first three—agars, alginates, and carrageenans—all come from seaweeds. Known as phycocolloids, they contain a number of interesting polysaccharides, and their use in food products is just the tip of the iceberg. In recent years, their antioxidant, antitumor, immunomodulatory, anti-inflammatory, anticoagulant, antiviral, antiprotozoan, antibacterial, and other broad-spectrum therapeutic properties have become an intense area of study.
These partially sulfated polysaccharides, extracted from different species of red seaweeds, were discovered by accident in Japan in the 17th century. They have very high gel strength, so they are often used in jellies, commercial baked goods, sauces, fillings, and meat products. “In coastal areas of Japan, use of a variety of agar-gel-like seaweed extracts almost undoubtedly dates back to prehistoric times,” write Amos Nussinovitch and Madoka Hirashima in Cooking Innovations: Using Hydrocolloids for Thickening, Gelling, and Emulsification. “The use of agar for the manufacture of fruit and vegetable jellies was introduced to Europe by Dutch people living in Indonesia.”
These are salts of alginic acid, a viscous gum formed by the cell walls of brown algae. Used as a gelling agent in jellies, fillings, sauces, soups, and fruit drinks, they’re also found in indigestion medicines.
Red seaweed is the source of these sulfated polysaccharides. They’re used to thicken ice creams, milk shakes, and other dairy products, as well as some processed meat products. Another interesting backstory here: “The use of such an extract from Chondrus crispus was in fact first described in Ireland around 1810, when it was recommended as a cure for respiratory ailments. The name carrageen for this species seems to have been introduced around 1829,” explains the marvelous Seaweed Site, and likely derived from Carrigan Head in Donegal County, Ireland. “The use of Irish or Carrageen Moss spread from Ireland to New England, USA, probably via the Irish migrants fleeing the potato famines of the 18th and 19th centuries. A small processing industry developed there that expanded enormously during World War II, mainly to replace agar, the supply of which from Japan and elsewhere had been cut off by the war. After the war, carrageenan gradually became a major force in the food-additives business, and is now the leading seaweed-extract on the world’s markets.”
Made from the sap of the acacia tree, this mixture of saccharides and glycoproteins (that is, proteins with attached sugar molecules) is primarily extracted from trees in African countries south of the Sahara Desert. Much of it comes from small-scale producers in the “gum belt” of Sudan. In 2010, the Near East Foundation launched a pilot program to provide farmers with training in water capture and storage techniques, more-efficient tree harvesting, and general strategies to counter the effects of drought and climate change. Gum arabic is used in everything from shoe polish and newsprint to chocolate and hard candies, and it’s indispensable to soft-drink production.
The seeds of the guar bean, a legume primarily grown in India, is the source of guar gum, a kind of water-soluble polysaccharide called a galactomannan, which forms a viscous gel in cold water. Uses for the thickener and stabilizer include sauces, dressings, baked goods, commercial fillings, yogurt, ice cream, and other dairy products. In our digestive system, it can function as a laxative by forming a bulky gel that helps move things along, so to speak. “For this reason, doctors will sometimes prescribe the stuff to alleviate symptoms of irritable bowel syndrome or Crohn’s disease,” reads a 2012 Live Science report. “Another benefit: guar gum is also one example of soluble fiber, which decreases the body’s levels of LDL, or ‘bad,’ cholesterol.”
Guar gum is also used in hydrofracking to thicken water, which enables it to move grains of sand underground more effectively than water alone would. (Water movement in soil, or soil hydrology, is much more complicated than you might imagine—and very cool.) According to the Live Science report, “each hydrofracking well uses 10 tons of guar gum, and 35,000 new hydrofracking wells were drilled last year  in the United States alone, dramatically increasing demand for guar, and causing a spike in its price. As a result, guar bean farmers in India and Pakistan are smiling all the way to the bank, while food manufacturers are asking their own bean counters for a second opinion.” No wonder ice cream got more expensive.
This gelling agent, a polysaccharide made by plant cell walls, is typically extracted from dried citrus peel or the solids left over from the pressing of apples for juice. Pectin is commonly added to jams and jellies to help them set, and it’s also used to stabilize milk drinks and fruit juices. Some fruits contain so much pectin that you don’t need to add more when making jam. Come September, I’ll be filling canning jars with the best Concord grape jam ever, thanks to Gourmet.
Starch in various forms is one of the most common thickeners in foods, and the polysaccharides are isolated from grain crops, including wheat, corn, and rice; roots and tubers, such as potatoes; cassava (also called yuca, manioc, or tapioca); and arrowroot, a starch extracted from the rhizomes of a perennial tropical plant native to South America and the Caribbean.
Made by the fermentation of glucose or sucrose with the microorganism Xanthomonas campestris, this gum acts as a stabilizer, preventing emulsified sauces and salad dressings from separating. “First discovered by USDA scientists in the 1950s, xanthan gum is fermented by plant-loving bacteria, characterized by sticky cell walls,” writes Nathan Myhrvold in a blog post for Modernist Cuisine. “It is no less natural than vinegar or yeast. We think xanthan gum is one of the best discoveries in food science since yeast.” It’s especially useful in gluten-free baked goods, he adds, because it can perform some of the same functions as gluten.