The news that the food maker Hostess filed for bankruptcy protection has triggered a national discussion of its products, including Wonder bread, Ho Hos and that nostalgic lunchbox favorite, the Twinkie.

I recently spoke with the food writer Steve Ettlinger, author of the book “Twinkie, Deconstructed,” about the ingredients that go into a Twinkie, why it matters and what happens when you try to make one at home. Here’s our conversation:

In deciding to write a book about processed foods, why did you settle on the Twinkie to tell your story?

I realized that the label of a food product would be a great organizing vehicle for a book. I looked at Yoo-hoo chocolate soda and Wonder bread and Entenmann’s coffee cakes. One day I noticed Twinkies and thought, “My gosh, look at that incredibly long ingredient list.” Not only are they well known, but they are the archetype of processed foods. It worked out perfectly.

What ingredients used in Twinkies most surprised you?

Vitamins. I didn’t have a clue where they came from, but I suspect that, like me, many people think that they are squeezed from seeds or extracted from bark or something like that. I found they were, by and large, made from petroleum and fermented in enormous industrial plants mostly in China. To find out that a lot of my vitamins, and in particular the B vitamins in enriched flour that are in a Twinkie, were made from Chinese petroleum just blew my mind.

How do you get a vitamin from petroleum?

Like so many basic chemical processes, it’s about breaking down a source material into its essential molecular structure. If you want a lot of carbon or hydrogen or oxygen from an organic compound, petroleum is not a bad place to start. They manipulate it in various ways to get what they want. For a chemical engineer, the source of the carbon or hydrogen or oxygen is not that important. It’s about the availability and the ease of working with it.

For instance, with something like sorbic acid, which is a common preservative, at one point in the process they need a carbon source, so they hit it with carbon monoxide. I found that dismaying, for what is eventually a food product. But the chemists kept telling me: “It’s just a chemical reaction. On your table you have two very dangerous chemicals, sodium and chlorine, but they’ve combined into table salt, which is benign.” I had to work to shed my chemical-phobia.

It’s an entirely new way of looking at food, though, isn’t it?

It’s a humbling reminder of how much there is to know about everyday things around us.

So what does the story of the Twinkie tell us about processed foods in the United States?

It tells us that processed foods are part of a very serious industrial complex. I call it the Twinkie Industrial Complex.

Processed food ingredients are made in large parts from the most common industrial chemicals, like phosphoric acid and sulfuric acid and ethylene, which comes from natural gas. That, for me, is sobering. I’m not saying,, “Oh, shocker, we rely on petroleum for our food.” Petroleum is needed to transport locally produced organic food too. Petroleum is used for transportation, for pesticides and herbicides, for processing.

One thing I noticed in my travels is there are certain food processing hubs in the Midwest where these large plants that process beans and seeds are located. The power needed to run these things is extraordinary. That was very unfoodlike, in my mind, and really surprised me.

In the book, you write about visiting a plant that mines phosphorus, an ingredient used in explosives, matches and artillery shells. Why is it used in a Twinkie?

Phosphoric acid is a fairly common food processing ingredient. It’s also used in cheese processing. It is used in a dry form, ultimately, to make the acidic part of baking powder, which is why I was looking at it. The elementary phosphorus I saw being made was destined to be turned into phosphoric acid. It was being mined in Idaho and sent to a plant in the Midwest, where’s it’s stored in a giant spherical tank because it’s dangerous. It’s odd to see this kind of scale and chemistry and think, ”˜Wow, that would be a really great ingredient in a little yellow snack cake.”

How many different types of rocks are used to make a Twinkie?

Five, if you count salt. Gypsum, trona, limestone and phosphorus ore, but a geologist might take issue with calling phosphorus ore a rock. You can argue that over beers.

What’s in the white filling of a Twinkie?

I asked a Twinkie employee I cornered at the exit of the plant. He smiled and said, “If I told you, I’d have to kill you.” It seems that the “cream” is probably partially hydrogenated vegetable oil. I think the key ingredient is polysorbate 60, and possibly cellulose gum. The filling has to be of a consistency that works well in the pumps and tubes that make these things. On the label they call it a “creamy filling.” They don’t actually say what it is.

Given all the processing involved, how long does a Twinkie last? Does it ever degrade?

They get hard, but they don’t spoil. I’ve got a bunch of them scattered around my office. I’ve got one from 2005 in my hand. It’s a little hard. I don’t think I’d want to eat it. It’s solid, but it hasn’t spoiled. As part of my research, I made Twinkies at home. We made cake from scratch with whole-food ingredients. It was yellow cake and cream filling from whipped cream with sugar and vanilla. It was absolutely delicious, and we devoured most of them right away. I wrapped one in plastic wrap and put it aside, and it was solid green in a week.