Sciency Super Bowl Snacks: Modernist Seven-Layer Dip

Fire up the pressure cooker and emulsify the cheese: it's almost game time!

Johnny Zhu from the Modernist Cuisine kitchen shares a seasonal recipe. The layers are: pressure-cooked pork carnitas; pressure-cooked refried beans; cheese emulsified with sodium citrate; and startlingly traditional top strata of salsa, avocado, sour cream, and scallions. See the recipe here.

The question remains, though: why seven layers? What is the numerological significance?