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Chapter One

Food For Thought

Think about food often? Who doesn't? Imagine a hot fudge sundae, how it smells and looks and tastes. Are the juices flowing in your mouth yet? Thoughts of food can do that You probably think about food at least ten times a day -- whenever your stomach growls, or you read a menu, or pass a bakery, or smell a deli, or follow a recipe, or plan a party, or go to the supermarket.

When my two sons were growing up, planning meals and shopping for food were part of my job. I experimented with recipes to make the job interesting for myself. One day a friend called and suggested that we collaborate on writing a cookbook for kids. I said, "Let me think about it." I hung up the phone and walked to the window. As I looked out over the Hudson River, I thought, "I don't want to write a cookbook, for kids. I want to write science books for kids" The words "science experiments you can eat" popped into my head. Suddenly I had a whole new way to think about food. One that opened up countless possibilities for experimenting in the kitchen. The book was published in 1972 and has new readers every year.

But a lot has happened since then. Microwave ovens are now popular. New fruits and vegetables have come onto the market. A few items have disappeared from supermarket shelves. I've kept on learning. It was time for me to take another look at experimenting with food.

So here is an updated version of Science Experim ments You Can Eat. It has all of the old experiments plus lots of new ones. The purpose of this book remains the same: to use food and cooking to learn about science.

If you're nothungry to learn about science, this book will whet your appetite. It is designed to nourish your curiosity and feed your mind. The ideas in this book are as easy to digest as the food. In a way, it's like a cookbook. You can use it to prepare many different dishes, although you might change your mind about eating them when you get your results. (I've done every experiment, but I must confess that I haven't eaten every experiment) This book combines learning about science with eating -- two of life's greatest pleasures. And it gives you a legitimate reason to play with your food.

Experimenting with food

Next time you sit down to eat, try to figure out how all the things on your plate began. All foods were once alive or produced by a living thing. Sometimes the food on your table has no resemblance to the animals and plants from which it came.

Many changes in food take place before it reaches your home. Some foods are prepared from only a part of a living thing, such as wheat germ, lard, or sugar. Many foods are processed so they will keep longer without spoiling. Chemicals are often added to breads and cakes to keep them moist and to crackers and potato chips to keep them dry and crisp. Fruits, vegetables, and meats are canned, dried, or frozen to keep harmful bacteria from making them unfit to eat But in some cases, the growth of bacteria or other microorganisms is necessary, such as in the preparation of bread, cheese, yogurt, and vinegar.

Cooking changes food still further. Heat makes some food softer and some food firmer. It changes the color of many foods. Different flavors blend when heated together. Heat destroys harmful bacteria and makes certain foods easier to digest.

It's easy to produce changes in food, and producing change is part of what science is about If you can produce a change in a certain food, you can learn something about the properties of that food by studying the way it changes.

All of the experiments in this book are designed to show changes. Sometimes the changes are not obvious, and you have to look closely to see if one has even occurred. But when you know what you are looking for, even a small change can be very exciting. Every experiment has been tested, but the materials you use and the conditions in your kitchen may be slightly different from those described in this book. If you don't get the expected results, try to think of what factors might have caused the different results, and how you can redesign the procedure to produce the expected results.

How to use this book

Be sure you know what you are doing in an experiment and why you are doing it. Every chapter has a short introduction that discusses the subject you will be investigating. Every experiment also has short introduction that asks a question you can answer by doing the experiment.

The materials and equipment needed are listed at the beginning of each experiment Collect everything before you begin. This way you will not be caught without some important item at a critical time during the experiment.

The procedure section tells you how to do the experiment. Often, reasons for doing a certain step are discussed as you go along. Since timing is important, you should read and understand the whole procedure section before you start the experiment.

There are certain standard practices for safety and use of equipment in every laboratory, and your kitchen is no exception. Consult the cook in your house before you start experimenting and ask for help with any procedures you are not sure about

After the procedure section there is a brief discussion of what your results mean. Men, you are directed in your observations by questions. I don't always tell you what your results should be. This gives you the opportunity to get answers for yourself from your experiments, just as real scientists do.

As you do these experiments, questions of your own will occur to you. You may get ideas for experiments of your own design. So do them! Don't worry that you are getting sidetracked. Believe it or not, finding something interesting and getting sidetracked is the goal of every working scientist. Your own discoveries are what make science an adventure! This book is your road map. Bon voyage and bon appetit!