If mayonnaise is mostly eggs and oil, what's in fat-free mayonnaise? If fat makes cakes light and airy, why isn't fat-free cake rubbery? If whipping cream and eggs make ice cream creamy smooth, what does the job in fat-free ice cream?
The answer: commercial thickeners.
The labels call them gums: agar, xanthan, carob bean or guar gum, carrageenan, maltodextrin. These sticky substances have all passed rigorous Food and Drug Administration safety testing. They are similar to natural polymers that are added to regular salad dressing to keep the oil and vinegar from separating. (The protein in eggs, for example, is a natural polymer that stabilizes the emulsion of fat and water in mayonnaise for longer shelf life.)
But what are they really? Gums are synthesized from starches and proteins found in corn and seaweed to make foods hold water and contribute smoothness. According to Webster's New World Dictionary, agar is "A gelatinous product made from seaweed . . . used as a laxative, in jellied and preserved foods." "Carrageenan is a purplish, edible red algae . . . used in jellies, lotions, medicines, etc." "Dextrin is any of a number of water-soluble, gummy, dextrorotatory polysaccharides obtained from the breakdown of starch and used as adhesives, as sizes and in certain foods." And, "xanthan gum is a gum produced by bacterial fermentation, used as a thickener, as in commercial foods."
The Times conducted an informal taste test of two brands of cake mixes and ready-to-spread frostings that get their familiar taste and texture from gums and thickeners.
Tasters agreed that the cake mixes were practically indistinguishable from the original high-fat varieties. Pillsbury's chocolate cake had a thicker batter than Betty Crocker's. Its surface was smoother and it had a deep, dark color. Betty Crocker's chocolate cake had a hint of red. Both had the familiar light texture of regular cake mix, inside. But the outside showed resistance when sliced and after a few hours, the edges were tough.
The yellow cakes fared better. They both tasted good. They weren't crumbly or rubbery. The edges were tender and cake-like--even 24 hours later.
The frostings were a different story. Both brands of vanilla had an unpleasant plastic after taste. The chocolate varieties were sharp tasting. Pillsbury was rated higher than Betty Crocker, which was overwhelmingly sweet. Complaints about Betty Crocker's texture ranged from "grainy" to "thin." But Betty Crocker's chocolate was rated better overall for color and taste. Pillsbury's chocolate tastes chemically acidic.