Question from Another: Caterpillars and Butterflies

I get some really great questions from museum visitors. A parent asked me the other week whether caterpillars are classified as a stage in the life of a butterfly, or classified as their own kind of insect.

I didn’t have the answer, but I was curious enough to look it up: Caterpillars are classified under Lepidoptera as the larval stage of butterflies.

It turns out that butterflies live on every continent except Antarctica, and the largest butterflies can be as large as 11 inches across. Most butterflies travel 5 to 10 mph, but skippers can keep pace with a car at 37 mph.

Here’s some more cool info from the San Diego Zoo website:

The caterpillar’s insides grow, but not its outside—when it gets too big for its skin, the covering  splits and is shed. A new exoskeleton lies underneath. A caterpillar sheds its skin 5 times, then becomes a pupa.

The last time the caterpillar sheds, a hard casing called a chrysalis forms around its body. Inside the chrysalis, big changes are happening. The pupa is growing six legs, a proboscis, antennae, and wings. After 10 to 15 days, the chrysalis breaks open and a butterfly emerges. At first its wings are wet and crinkled, but after about an hour, they are straight, dry, and strong enough for the butterfly to flutter away.

If you ever have a chance to go to a butterfly room – several science museums offer them, though it’s sometimes seasonal – it’s a really cool experience. Take a friend; the selfie photos of yourself with a butterfly on your shoulder tend to come out a bit awkward looking :-).

Questions From Another: Yeast

I recently started volunteering at an historic grist mill. A visitor recently came in and told me that bread dough can pull yeast from the air – that, in fact, she purposely lets her dough sit overnight so it can pull extra yeast. She says it makes the bread taste much better.

I have to be honest. Although I have a basic understanding of sourdough bread, I always assumed that yeast had a short life and you needed to bake the bread sooner than later.

This same visitor wondered aloud at what point commercial yeast became popular in baking. I promised to do some research and get back to her. Since this interested me, I thought I’d share my findings.

* Up until the 19th century, people were not really sure what made dough rise, but they understood enough to make sourdough bread. Sourdough uses naturally occurring yeast from the surrounding air. Sourdough is also known as “wild yeasted” bread. (multiple sources)

* A quote about modern baking without packaged yeast:“There’s yeast everywhere,” says Oland. “It’s wild yeast. It’s present in flour, in the air, on your skin. For bread, you create an environment where it will thrive. You create a ‘starter.’ Commercial yeast is incredibly potent and reactions happen very quickly. With wild yeast the reactions unfold more slowly over time. The bread is so much better because it slowly ferments. And that slow fermentation develops complex flavors and a variety of textures. It’s an older form of baking. It’s actually the original form of baking.” (source)

* In the late 1850s, Pasteur was commissioned by an alcohol manufacturer to learn why their beer was turning sour. As a result of this research, Pasteur proved that fermentation is caused by live yeast. He also found that mild heat after fermentation would kill the yeast (known as pasteurization). This knowledge was primarily used for beer and wine until the late 1800s, when it began to be applied to milk. (source, source and source)

* In the early 1860s, on the heels of Pasteur’s discoveries, bakers began to use leftover yeast from beer brewing to bake their bread. (source)

* Also in the 1860s, Charles and Maximillian Fleischmann, immigrants to Cincinnati, OH from Austria-Hungary, patented and sold cakes of compressed yeast. (source)

* By the early 20th century, cookbook recipes began specifying commercial yeast and limiting rising time to less than two hours. (source)

I must admit that I’m very intrigued by all of this. It’s funny to see the conflicting opinions of various sources – modern bread tastes better, modern bread tastes bland; modern bread is softer, modern bread has no texture. I may have to finally try making my own sourdough starter and bread.