Here is the ingredient that makes burgers impossible

When you bite into a meatless burger, you may notice that it "bleeds".

It's a feature film that companies like Impossible Foods have been working for years. The distinct red color is part of the appeal of the mash, allowing it to look like real meat.

In a report published by Associated Press, biochemist Smita Shankar explained that the key ingredient used to give hamburgers this bleeding effect is actually designed rather than extracted from a plant.

To replicate the taste of the meat, the company analyzed the plants for molecules that mimic a meat protein containing iron, which makes the blood red. They finally opted for soy leghemoglobin, which is found in the root of the soybean plants.

The company's website boasts of its plant-based foods, but "no plant is touched" in the process of making its famous "burger". Instead of using these plants directly, they insert synthetic versions of sections of soy DNA into the yeast so that it produces soy leghemoglobin during fermentation.

The ingredient is supposed to be less than 1% of the cake.

Many ingredients do not need the approval of the Food and Drug Administration. Companies often hire scientific experts to state that ingredients are "generally recognized as safe". Impossible Foods says soybean leghemoglobin met this requirement in 2014.

Nevertheless, critics such as the Center for Science in the Public Interest and the Environmental Defense Fund have challenged the fact that companies make their own decisions about consumer safety.

A lawsuit brought by lobbies against this system is under way.

Impossible Foods does not just use soy leghemoglobin for its cakes. The company recently announced its use in a fish-free fish recipe.

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