Museum of Science and Industry

Ingredients:

Unbleached Enriched Flour

Is there bleach in some types of flour?  No. Bleaching, as it pertains to flour, simply means letting freshly milled grain sit for a few months while the oxygen in the air goes to work on the wheat's naturally occurring pigments (called xanthophylls), oxidizing them from yellowish to white.  The bleaching process was very popular in America immediately after World War II, leading to what detractors call the “white bread” homogeneity of the 1950s.  Because the flour also has niacin, iron and various B vitamins added to it, it is also  described as “enriched”.

Pepperoni

Technically, pepperoni is a variety of salami, a dry sausage that can be stored at room temperature (“shelf-stable”, as they say in the food industry).  It is loaded with salt, which draws the water out of the meat, making the internal environment too dry for bacterial growth.  Pepperoni can be made of almost any meat: Hot Pockets uses a mixture of pork and beef.

Imitation Mozzarella Cheese

It's not what you think: imitation mozzarella actually contains mozzarella cheese, just not enough of it.  Most of the imitation cheese by weight is made of things like milk, cheese culture, food starch, lactic acid, and gum made from the fronds of red seaweed.

Tomato Paste

Tomato juice, tomato sauce, and tomato paste are all more or less macerated tomatoes without the seeds and skin: the difference between the three lies in their water content.  In Italy, really old fashioned tomato paste is made by letting pureed tomatoes dry in the summer sun.  Here, tomato paste is much wetter, but still dryer than  tomato juice or sauce.

Partially Hydrogenated Soybean Oil

Hydrogenation, as applied here, refers to the art of bubbling pressurized hydrogen gas through a liquid; in this case, soybean oil.  Some of the hydrogen will attach itself to the carbon chains in the soybean oil molecules, making the oil more saturated (with hydrogen), and thus raising its melting point so that it remains solid at room temperature.  The problem is that in the hydrogenation process, some of the soybean oil may be converted from healthy cis-fats, which your body needs, into unhealthy trans-fats, which your body most emphatically doesn't need.

Methylcellulose

Made from the absorbant cell walls of nearly any green plant from algae to cotton to oak trees.  Humans can't digest it, so the food industry uses methylcellulose as a water-absorbent, non-toxic, and non-caloric thickener. 

Autolyzed Yeast Extract

Autolyze means “self-digest”.  Yep, dead yeast cells are left to stew in their own juices so that the yeast's digestive enzymes go to work breaking down the bodies of dead yeast cells.  The result is an incredibly high protein edible paste that is safe for vegans and vegetarians to eat.

Disodium Inosinate

This is a nucleotide, very similar to the building blocks of DNA.  It is used as a flavor enhancer, often in conjunction with monosodium glutamate.

Calcium Sulfate

Plaster of paris.  No, really.  This white powder is commonly used in baked goods that might be frozen before they are eaten.  It serves as a drying agent to keep the Hot Pocket's outer shell from getting too soggy as it defrosts.