Why does grape candy taste so fake? What on earth is blue raspberry, anyway? And what is the difference between natural and artificial, at least when it comes to flavor?
Join us as we taste the rainbow on this episode of Gastropod, from artificial flavoring's public debut at the 1851 Crystal Palace exhibition, to the vanilla-burping yeasts of the future. We'll experiment with Skittles, discover how invented flavors first appeared in our daily diets, and visit a synthetic biology lab, all in our quest to understand what artificial flavor is, was, and might be. Along the way, we'll learn what exactly goes into designing the perfect pineapple from one of America's top flavorists, investigate beaver butts, and discover the taste of an extinct banana. Listen now!

The Great Exhibition of 1851 was housed in Joseph Paxton's extraordinary Crystal Palaces, and contained "the wonders of industry and manufacturing from around the modern world," including folding pianos for yachtsmen, a couple of velocipedes (the early version of a bicycle), and, of course, some lozenges flavored with artificial fruit ethers.

Throughout human history, if you wanted to make a dish taste like strawberry, you had no choice but to add a strawberry. But in the 19th century, scientists began to understand how to synthesize flavor chemicals, whether from plants or from byproducts of coal processing, to evoke familiar flavors. While the technology to evaluate the flavor molecules of a particular food have become increasingly sophisticated in the past century, the basic concept of synthetic flavor has remained unchanged. Until now. In this episode of Gastropod, molecular biologists explain how they're designing yeasts to ferment the tastes of the future.
Natural vs. Artificial
Let's start with a graham cracker. Just like Sylvester Graham back in 1829, if you're baking at home, you'd probably use coarse-ground whole-wheat flour, wheat bran, and wheat germ. These, along with some honey for sweetness, would give your graham crackers their distinctive toasty, malty, and slightly nutty flavor. If you're making them by the billion, however, at a Nabisco or Keebler factory, the ingredients list looks a little different. That extra wheat germ and bran contain natural oils with a tendency to go rancid—but, when you cut them out to gain shelf-life, you lose the flavor.

Fortunately, there's an easy solution: you can add all that flavor back with just a touch of a light yellow, crystalline powder called 2-acetylpyrazine. This is an aromatic, carbon-based chemical, known by flavorists as the "graham-cracker" flavor. It occurs naturally in nuts and toasted grains; as the vital ingredient giving factory-made graham crackers their signature flavor, it can either be extracted from a plant or synthesized using petrochemical derivatives.

The major difference is that 2-acetylpyrazine produced by performing chemical reactions on plant matter costs about $25 per lb—compared to the $5 or $6 per lb it costs to produce the kind whose raw ingredients come in a drum.

However, using the cheap version comes with another, increasingly significant cost: it means you have to include the words "artificial flavor" on your graham cracker ingredients list. Under FDA rules, if the raw material to make your flavor chemical comes from a plant, animal, or edible yeast, it's "natural," for the purposes of labeling. If it comes from anything else, it's artificial. And consumers increasingly don't want to buy things that are "artificial." In fact, Michelle Hagen, a senior flavorist at Givaudan, the world's largest fragrance and flavor company, told Gastropod that, despite the cost savings, she hasn't used a single artificial chemical in her flavorings for the past four years—because the companies she mostly works with know that customers are turned off when they see that word on a label.

Enter the (Genetically Engineered) Yeast
Until recently,