Monoglycerides and diglycerides, which replace eggs in the Twinkie recipe, are compounds that act as emulsifiers. They stabilize the cake batter, enhance flavor and extend shelf life [source: Ettlinger]. A very small amount of egg is used to leaven the cake. Polysorbate 60 serves a similar function to the glycerides, keeping the cream filling creamy without the use of real fat. Hydrogenated shortening replaces butter, giving the cake some of its texture and flavor and prolonging shelf life.
Taste tests by flavor experts have revealed that artificial butter flavoring is used in the cake and artificial vanilla flavoring goes into the cream filling [source: Ettlinger]. Both flavorings are chemicals derived from petroleum.
Despite the Twinkie's reputation, only one ingredient is an actual preservative: sorbic acid. Other ingredients have preservative functions, but sorbic acid has one primary purpose -- it stops the formation of mold [source: Ettlinger].
Finally, cellulose gum replaces fat in the filling. This ingredient can absorb 15 to 20 times its own weight in water. It keeps the filling smooth and creamy.
Once all these ingredients have been mixed, they are poured into metal pans with Twinkie-shaped molds. The batter is baked at 350 degrees F for nine to 12 minutes [source: Ettlinger]. The bottom of the mold is rounded, and the batter at the top of the mold is browned by the baking process. After cooling, the cakes are released from the trays and turned upside down. The familiar round top of a Twinkie is actually the bottom when it's made.
Automated machines carry the Twinkies to a series of cream-filling injectors. Three injectors simultaneously pierce the bottom of the cake, filling it with three "globs" of filling. If you look at the bottom of a Twinkie, you can usually see where the filling was injected.
From there, machines wrap the Twinkies in airtight plastic packaging. They might be wrapped individually or in pairs, depending on how they will ultimately be sold. Then the wrapped Twinkies are packed into boxes, which are packed into larger boxes, which are loaded onto trucks for delivery to stores across the United States.
A single Twinkie has 150 calories (160, according to some sources), which by itself isn't that bad as far as snacks go. However, it contains 4.5 grams of fat, including 2.5 grams of saturated fat, 19 grams of sugars and no dietary fiber [source: Calorie King]. So while a Twinkie now and then isn't going to kill anyone, your doctor probably wouldn't recommend an all-Twinkie diet.