Today, I went out to lunch with some friends from the laboratory where I got my PhD. Being biochemists, naturally our lunch topic meandered to that of the amount of synthetic stuff in various foods. This turned into trying to name some of the most processed or chemical-laden foods that are incredibly popular here in the United States.
This is the preliminary list of things we came up with:
Twinkies: Perhaps most well known for the discussions of their shelf life, jokingly estimated to be sometime after the apocalypse and capable of withstanding nuclear holocaust. Recently, a photographer did a nice set of images of the 37 ingredients in twinkies
http://www.fooducate.com/blog/2010/06/11/a-visual-of-twinkies-37-ingredients/
Ingredients: Enriched Bleached Wheat Flour [Flour, Reduced Iron, B Vitamins (Niacin, Thiamine Mononitrate (B1), Riboflavin (B2), Folic Acid)], Corn Syrup, Sugar, High Fructose Corn Syrup, Water, Partially Hydrogenated Vegetable and/or Animal Shortening (Soybean, Cottonseed and/or Canola Oil, Beef Fat), Whole Eggs, Dextrose. Contains 2% or Less of: Modified Corn Starch, Glucose, Leavenings (Sodium Acid Pyrophosphate, Baking Soda, Monocalcium Phosphate), Sweet Dairy Whey, Soy Protein Isolate, Calcium and Sodium Caseinate, Salt, Mono and Diglycerides, Polysorbate 60, Soy Lecithin, Soy Flour, Cornstarch, Cellulose Gum, Sodium Stearoyl Lactylate, Natural and Artificial Flavors, Sorbic Acid (to Retain Freshness), Yellow 5, Red 40.

Spam: This tasty meat product was originally invented in 1937 by Hormel Foods. It was reportedly going to be called 'spiced ham,' hence the name. It was a popular commodity purchased by the US military during WWII, some 20 thousands tons of it were given to our troops.
Ingredients: from this website... http://www.madehow.com/Volume-6/Spam.html
"The primary ingredient in Spam is chopped pork shoulder meat mixed with ham. About 90% of Spam is pork from a pig's shoulders. The remaining 10% (or so) comes from the pig's buttock and thigh, better known as ham. This ratio varies according to ham and pork prices. The U.S. Department of Agriculture does not permit any nonmeat fillers in lunchmeat, nor does it allow pig snouts, lips, or ears. The second ingredient is salt, added for flavor and for use as a preservative. Also, a small amount of water is used to bind all ingredients together. Sugar is also included for flavor. Finally, sodium nitrate is added to prevent botulism and acts as a preservative as well. It is the sodium nitrite that gives Spam its bright pink color—without it, Spam would discolor and become brown."

Starburst: Who doesn't like all the flavors in Starburst? I remember getting tons of them on halloween, and boy are the newer Starburst jelly beans really excellent. However, we tend to think that there's not much natural or unprocessed ingredients in a Starburst. In fact, we weren't really sure what, besides sugar, is in one.
Ingredients: According to Answers.com, this is the list. Corn syrup, sugar, hydrogenated palm kernel oil, fruit juice from concentrate (apple, strawberry, lemon, orange, cherry), citric acid, dextrin, gelatin, food starch-modified, natural and artificial flavors, ascorbic acid (vitamin c), coloring (red 40, yellow 5, yellow 6, blue 1).
Mountain Dew (and many other sodas): Our favorite for a soda to list was Mountain Dew. We were fairly certain that many sodas could substitute, but none are more popular for being full of chemicals than the Dew. Also, there was that whole myth about the properties of Yellow 5 that made this a winner for our list of processed foods.
Ingredients: Again, answers.com was useful here listing the ingredients as...
- Carbonated water, High fructose corn syrup (HFCS), Concentrated orange juice and other natural flavors, Citric acid, Sodium benzoate (preserves freshness), Caffeine (55.2 mg per 12 oz.), Sodium citrate, Gum arabic, Erythorbic acid (preserves freshness), Calcium disodium, EDTA (to protect flavor), Brominated vegetable oil, Yellow 5
Cheese Whiz: Anytime something is called a "processed cheese food," rather than cheese, it must be processed heavily. Especially telling is that it comes in a can that sprays it. Lovely.
This gem of processed food is pretty old, originally released in 1953 by Kraft foods. What you'll notice in the ingredients list below is that cheese culture is surprising late in the list.
Ingredients: Whey, canola oil, milk protein concentrate, maltodextrin, sodium phosphate, contains less than 2% of whey protein concentrate, salt, lactic acid, sodium alginate, mustard flour, worchestershire sauce, (vinegar, molasses, corn syrup, water, salt, caramel color, garlic powder, sugar, spices, tamarind, natural flavor), sorbic acid as a preservative, milkfat, cheese
culture, oleoresin paprika (color), annatto (color), natural flavor, enzymes.
Movie Theater Popcorn butter: One of the most common ones is made by Paragon and is actually called 'Movie Theater Popcorn Butter Topping.' We've all seen this goo in what looks like a saline bag at the theatre. It's warmed and then oozed out of a very noisy squirting device all over your $5 bag of popcorn. We all were convinced that there had to be very little real butter in there.
Ingredients: Partially hydrogenated soybean oil, Beta carotene, Buttery flavoring, TBHQ, Polydimethylsiloxane.
Jello: Almost everyone has had Jello. It's gelatin, sure we know that. But, what else is in there that makes this oddly textured and vibrantly colored food stuff?
Ingredients: Yet again, answers.com was useful here...
- Gelatin, Maltodextrin, Adipic Acid / Fumaric Acid, Disodium Phosphate, Butylated Hydroxyanisole (BHA), Sugar, Artificial flavors,, Food Colors.
Sunny Delight: Yes, that wonderful fruit inspired drink. I like to think of it as a citrusy version of terpentine.
Ingredients: Water, High Fructose, Corn Syrup and 2% or Less of Each of the Following: Concentrated Juices (Orange, Tangerine, Apple, Lime, Grapefruit). Citric Acid, Ascorbic Acid (Vitamin C), Beta-Carotene, Thiamin Hydrochloride (Vitamin B1), Natural Flavors, Food Starch-Modified, Canola Oil, Cellulose Gum, Xanthan Gum, Sodium Hexametaphosphate, Sodium Benzoate To Protect Flavor, Yellow #5, Yellow #6