Known as "processing aids," these hidden additives are not labeled because technically they are not part of the food product itself, but are rather residues left over from the food production process.

Common processing aids include additives that "soak and wash" certain ingredients, "filter" beverages like wine and juice to make them appear clearer, and improve the texture of bread products to make them softer and more elastic, among other uses.

"During the production process, these aids are consumed, transformed, or removed, rendering them virtually undetectable in the final product," warns Flora Zhao from The Epoch Times about the hidden presence of processing aids in processed foods.

In fruit juice, for example, some manufacturers will add enzymes to the juice extraction to produce yields upwards of 90 percent of the fruit's weight. When heated for a few hours in juice, enzymes like pectinase and amylase liquefy the final product by breaking down cellulase and polysaccharides such as pectin, and more juice and sugars.

"These enzymes improve the flow of the juice in processing containers and enhance its sweetness," Zhao explains. "They are consumed and transformed during processing, ultimately not appearing on the ingredient label."

Another processed food containing hidden processing aids is "lactose-free" milk, which contains added lactase to counter the damage caused by pasteurization. Raw milk contains natural enzymes that break down lactose but pasteurized milk does not, which is why many people cannot drink it due to "lactose intolerance."

"Additionally, applying palm wax to baking molds aids in easy cake release," Zhao says. "Bottled sauces often have nitrogen added during bottling to displace oxygen, preventing oxidation and product spoilage."