[Ed note: This story has been extended with online bonuscontent.]

Photo: Roxana Marroquin

THE WATER

Wiener soup A downtown street-cart vendor sold our food scientist—chef Dave Arnold, of the French Culinary Institute—a cup of his hot-dog water for $1, no questions asked (already, we were scared). Arnold first took a temperature reading: 177 degrees Fahrenheit, well above the Health Department’s safety minimum mandate of 140 degrees. That was reassuring. Then he took a whiff. “It smells distinctly of hot dog,” he said. “Almost overpoweringly so. Even the thermometer I used to take the temperature now smells like hot dog.”

Globs “It has little balls of fat floating in it, like in a soup,” says Arnold. “There are also wispy chunklets of something floating around.” That something: “onion bits,” says Arnold with relief. “And I’m surprised the water had so much yellow color. It’s almost like a hot-dog bouillon.”

“Something else” “I don’t see anything that looks like a nonfood product in there, so that’s good. But I could see why people refer to them as dirty dogs.”

THE HOT DOG

Beef: This one, like the majority around the city, is a Sabrett, and believe it or not, 100 percent beef.

Salt: 410 milligrams—one fifth of your daily allowance (oh, and there are 110 calories from fat).

Sorbitol: A sweetener that also functions as a moisture-retaining agent. And Arnold points out that it constitutes less than 2 percent of this hot dog, to give it sweetness.

Sodium nitrite: This is what gives smoked meats their distinctive flavor and character, says Arnold. It is also extremely effective at preventing botulism. Some studies suggest that sodium nitrites encourage cancer growth as they break down into nitrosamines, possibly carcinogenic agents.

Sodium erythorbate: Similar to vitamin C, it helps prevent the nitrite from breaking down into nitrosamines. (This does not mean vitamin C cures cancer.)

Nisin: It’s a naturally occurring protein that is used in hundreds of food products to guard against bacteria and prevent spoilage.

MR. SOFTEE

Ingredients in vanilla flavor: Milk, Cream, Cane Sugar Syrup, Corn Syrup, Whey, Mono and Diglycerides, Cellulose Gum, Natural and Artificial Vanilla Flavor, Tetrasodium Pyrophosphate, and Carrageenan.

Mono and Diglycerides: Modified fats used to hold the ice cream together. Says Arnold, “Ice cream is a foam with air bubbles stabilized by fat globules which migrate to the surface of the bubbles and agglomerate. Emulsifiers aid in this fat agglomeration process and can help increase mix stiffness.” Hungry yet?

Cellulose gum: The easier name for carboxymethylcellulose, which is used to thicken, stabilize and improve the ice cream’s mouth-feel.” Other, possibly related uses for cellulose gum is as an ingredient in both toothpaste and personal lubricants.

Natural and Artificial Vanilla Flavor: The real vanilla is extracted from the fruit of the vanilla orchid, while the artificial stuff (which is much cheaper) is synthesized, traditionally from lignin, a waste product of paper manufacturing.

Tetrasodium Pyrophosphate: Often added to ice cream to prevent grittiness and over churning, according to Arnold’s research.

Carrageenan: An all natural seaweed derivative. It prevents ice crystals from developing in stored ice cream and improves texture, says Arnold. It is used in dairy products because it has a synergistic reaction with milk and only a small amount is needed.

Air: Arnold says some ice cream truck operators may use a very high overrun, meaning there is more air in the air cream. As he explains, “Overrun is the amount of air, by volume, added to an ice cream mix during manufacture. An overrun of 100 percent means that, for every liter of ice cream base used, a liter of air has been added.” Air is free, so high overrun means high profit. But oh Mr. Softee, how could we hate you?

M&T PRETZEL

Ingredients: Flour, Water, Yeast, Salt, Bicarbonate of soda

What you didn’t know: Among the most common street cart pretzels, M&T are made in Brooklyn with a traditional cooking process that includes boiling in a solution of lye—the same chemical used to dissolve hair clogs in drains, and to polish silver. Granted, it’s less than a 2 percent solution of the highly caustic agent, which browns the outside of the pretzel and gives it a character distinct from a bagel, but still. Lye is very dangerous in its crystalline form, says Arnold. It’s much worse than most of the chemicals in your house, and can eat right though body. Yet it’s completely harmless when used in pretzels.