"It's so primal to baking and our food system, so to remove it requires a lot of work behind the scenes that no one sees," says Rees.
The easy part, she says, is replacing the yolk. You need an emulsifier — something that helps oils mix with other ingredients. Glanbia uses a gum-like substance extracted from flax seed. "It can behave like guar gum, or xanthan gum. Or some of the emulsifiers that you see out on the market: sodium stearoyl lactylate; GMS-90," Rees says.
But food companies would much rather put "flax" on their list of ingredient, instead of sodium stearoyl lactylate. Shoppers want what the industry calls "clean labels" these days.
The hard part of egg replacement, Rees says, is coming up with a substitute for the protein in egg whites, especially in foods like angel food cake, where it's really important.
For this, some companies use protein from the whey that's a byproduct of making cheese. Others use bean protein; others, protein from algae.
Rees says that these products can get close to egg white, but it's never a perfect match. "Can we replace 100 percent of eggs in an angel food cake, the egg white? And make an angel food cake? Is it identical? No. Is it a cake? Yes," she says.
Then there's the final piece: the flavor.
For that, companies turn to flavor chemists like Michael Walsh, who works for Glanbia's flavor group, called Flavor Artistry.
According to Walsh, flavor chemistry is, in fact, art. "If you look at it like a painter, a painter has a palette of colors, and he's going to blend them together. Or a musician has a bunch of different notes. Flavor is very much the same. Each flavor component is a note," he says.
There's a symphony of flavor notes in each food. Some come from the egg itself; others are created in the cooking process. Walsh's job is to use the notes at his disposal — hundreds of flavor extracts, mostly distilled from products of nature — to recreate the smell and flavor of the original.
He comes up with an egg flavor formula, usually including anywhere from 10 to 20 different flavor extracts. The formula may be a bit different, depending if it's for a sponge cake or a custard.
Glanbia will add this flavor combination to the rest of the egg replacement product, which contains the flax and the whey protein.
Together, they're ready for their starring role in some commercial bakery, appearing as a collective understudy for the simple egg.
Copyright 2015 NPR.