Animal Fat & Plant Oil, the Tooth Fairy

Dear Matthew Alice: I cook a lot, and when I do I always wonder why fat from animals, like butter or lard, are solid, but fat from plants is liquid, like olive oil or canola oil. They’re both fat, so why would they be different? — Not Betty Crocker, La Mesa

It’s probably a good thing they’re different. Imagine a bunch of fat-laden cows, slowly sloshing around a field, their oil-filled skins waving from side to side as they walk. Given the different metabolisms of animals and plants, they’ve developed their own best fat formulas. Animal fat doesn’t transmit heat very well, so it’s a very good insulator for mammals. Here’s how the two fats differ from one another chemically:

Consider a lipid (fat) molecule as something that looks like a capital letter E, or maybe an M or a W, depending on how you want to flip it. The back “spine” of the letter is glycerol. The three arms are fatty-acid chains full of carbon atoms. In animal fat, the carbon atoms are bound to the maximum number of hydrogen atoms, making a tidy, flat lipid molecule. And when these lipid molecules get together, they fit perfectly, like a jigsaw puzzle. What you get is a solid fat that remains so at room temp.

Vegetable fat, on the other hand, is as messy as an unmade bed. There are double carbon bonds in the arms that keep most of the hydrogen from bonding, so what we end up with is an E-shaped molecule with lumps and twists and lacking hydrogen bonds. Hard to make them fit together into a solid, so vegetable fats remain liquid at room temp.

You may not be Betty Crocker, but you’ve taken the first steps toward being a food chemist, which probably will take all the fun out of cooking. Hope not, but you asked for it.

Dear Matthew Alice: How Does The Tooth Fairy know that soMeoNe has Lost a Tooth? — Isabella In O.B.

You certainly are learning to write very well, Isabella. My eyesight isn’t what it used to be, so I appreciate your using blue marker pen to make giant letters that cover all of page 1. And page 2 is wonderful! A nice stick figure with a big melon head and blue-dot eyes, with an open Twinkie-shaped mouth and big shark teeth, with one missing in front, of course. And this toothy person is surrounded by huge question marks, some of them backward, to finish out the wonderful illustration. But I guess you need an answer to your question.

In olden times, long, long ago, the Tooth Fairy had a terrible time keeping up with lost teeth. The ones nearby she could hear when they fell out. Her ears got very sharp, and she could tell the difference between a tooth falling from a mouth and, say, an acorn falling from a tree. But beyond her hearing distance, she needed elves, just like Matthew Alice and Santa Claus need elves, to help. When a tooth fell many miles away, the nearest elf would hop on his unicorn and ride to the next elf to spread the news. And he’d ride his unicorn, and so on, until the news reached the Tooth Fairy, who would give the elf a coin, and he’d ride back to make sure it made its way under the appropriate pillow. A lot of work, don’t you think, Isabella? But the Tooth Fairy is very faithful, so she made the system work.

But today we live in the digital age. And the Tooth Fairy takes every advantage. All elves have cell phones and webcams that eliminate the need for unicorns. A good thing, because they’re very hard to find these days. But best of all is the tooth scanners, electronic gadgets that can scan a house and locate each of the people in it, then scan their teeth to identify a loose tooth before it even falls out. So, the Tooth Fairy elves scan their houses and watch for the loose teeth to fall, then call the TF herself, who comes in person with her reward. Even though the Tooth Fairy uses new technology to keep up her good work, she’s still as special as she always was. So, remember that when your next tooth starts to wiggle a little bit, you’re already on the Tooth Fairy’s radar and you’re sure to get your prize. Please write again if you have another question, Isabella. I love your letters!