Walk down the aisles of any grocery store and grab a product off the shelf. Chances are, the label of whatever you grabbed will contain at least a few ingredients whose names don’t exactly roll off the tongue. There’s everything from xanthan gum in salad dressing to tripotassium phosphate in Cheerios, not to mention calcium disodium ethylenediaminetetraacetic acid in mayonnaise. But what if the label also included the citric acid wash that cleaned your apple, or the ammonium hydroxide used to control the pH of your ground beef? These are two examples of processing aids, substances used in the production of food but don’t have to be included in the ingredient list. What parts of food production get labeled and which don’t, and why not? There’s an entire category of substances used in food production that don’t ever make their way onto the label for a number of reasons. These substances are known as “incidental additives,” and they encompass everything from oil for fish filets to anti-caking agents for seasonings. Processing aids are a subcategory of incidental additives. All processing aids are incidental additives, though not all incidental additives are processing aids. Any substance is considered a processing aid and can be legally excluded from labels if it meets one of three criteria:

1. It’s added to the food but later removed. Think of something like activated charcoal, which filters out impurities.
2. It’s added to the food, but gets converted into a substance already present in the food. This could be something like a pH adjuster that converts to salt and doesn’t significantly add to the level of salt in the food.
3. It’s added for a technical effect during processing but isn’t present at “significant” levels in the food. This could be a preservative added to an ingredient, like anti-caking agent sodium silicoaluminate in the seasoning of some sausages.

One critical note is that any incidental ingredient that might affect the stability of the finished food (i.e. improve its shelf life), must be labeled, said Mark Itzkoff, food compliance lawyer for Washington, D.C.-based OFW Law. Any such substance, however insignificant, would be considered a preservative that would need to be labeled. Processing aids are allowed in food production as long as each one falls within the guidelines of being “Generally Recognized as Safe,” a classification for ingredients often abbreviated as “GRAS.” The FDA and USDA rely on a consensus of qualified experts, via published peer-reviewed literature, to assess the safety of GRAS substances. The agencies lack the resources to perform the vetting process themselves. “It’s a fairly intensive process,” Itzkoff said.

To get GRAS approval for a substance from the FDA, a food company needs to undertake a number of steps. They first need to determine what the consumer exposure would be to their product, which is usually done by an independent toxicology panel that reviews peer-reviewed literature on the substance. “You can’t come up with a component and run your own tests and say, ‘OK, this is GRAS now,'” Itzkoff said. “That can only happen if there’s literature in peer-reviewed journals so that food safety experts and toxicologists can review and run confirmation studies.” Once a company classifies a substance as GRAS, its subsequent food industry customers may further vet its safety and accept or reject that GRAS determination. If companies wish to use a new processing aid on a USDA-regulated product such as meat or poultry, they must submit a GRAS notification. A GRAS notification is optional for substances only meant for FDA-regulated products, but the majority of companies still submit them for transparency purposes, Itzkoff said. Ultimately, the FDA and USDA don’t consider processing aids necessary to label because mentioning each nonfunctional component of the food production chain would be impractical and unhelpful information for consumers. Don’t be surprised to not find ‘dimethylamine epichlorohydrin copolymer’ listed on your bag of sugar anytime soon. By all legal definitions, it’s just as sweet without that on the label.