Key Concepts
Chemistry
Materials
Fiber
Starch
Food science
Introduction
Have you ever encountered "paper" on your plate—perhaps in the form of thin paper for spring rolls, sushi or cake decorating? Did it make you wonder how this paper relates to the paper you write on? You will find out in this activity! In addition, you can discover the recipe to make the edible paper you like best.
Background
Paper is made up of plant fibers pressed together into a thin, flexible-but-strong mat. The fibers are from a material called cellulose, which gives plants their structural support. Cellulose is the threadlike component in grains, greens and other vegetables or fruits. It is also found in other plants as well. Wood also has a lot of cellulose; in fact, approximately 50 percent of the matter in wood is cellulose. Brown rice flour by comparison contains about 2 percent cellulose.
Cellulose has many qualities that make it an excellent material for creating paper. If it is soaked and then dried, it becomes a flexible, strong material. Evaluate an unwrinkled sheet of paper—which is essentially a mat of cellulose. How smooth is it? Can it be stretched? To test its flexibility, try rolling it into a tube. To evaluate its strength, try gently tearing a corner. Observe how much resistance the paper provides.
To make commercial paper strong, manufacturers also add starches. Starches are sugars found in plants. When heated with a liquid, starches absorb the liquid, expand, and form a network of starch particles. This makes starches handy as a gluing and stiffening agent for paper.
Cellulose and starch are both edible, so homemade paper can be, too. (Of course, you wouldn't want to eat notebook or other store-bought paper because it is made with other chemicals.) Is it possible to make paper that works as paper but is also tasty? Try the activity to find out!
Materials
- Brown rice flour
- Potato starch
- Water
- Small bowl
- Tablespoon
- Spoon
- Microwavable plate
- Three plates
- Three sticky notes
- Plastic wrap
- Microwave
- Sheet of paper
- Pencil or pen
- Salt (optional)
- Adult helper (optional)
- Zip-top bag to store the edible paper (optional)
- Food-color (edible ink) pen (optional)
- Cornstarch (optional)
- Wheat flour (optional)
Preparation
- Write "Recipe 1" on one of the three sticky notes and stick it to a plate. Repeat for "Recipe 2" and "Recipe 3."
- Divide your sheet of paper into four columns. Leave the first blank, write "Recipe 1" at the top of the second, "Recipe 2" in the next and "Recipe 3" in the last column.
- Stretch plastic wrap tightly over the microwavable plate so it does not touch the bottom of the plate.
- To the small bowl, add 2 tablespoons of rice flour and about 1.5 Tbs. of water, as well as, optionally, a pinch of salt—this will be Recipe 1. Mix the ingredients until you have a smooth paste. The paste should have the consistency of white school glue. Add a little additional water if the paste is too stiff.
- Pour the paste onto the plastic wrap. Help the paste spread out evenly with a spoon and/or by tilting the plate.
- Put the plate in the microwave, and heat the paste on high for about 45 seconds to dry the paste. (Note that the exact duration depends on your microwave.) The sheet of paper will look dry when it is done.
- Let the sheet of paper cool. The edges might curl up a bit while cooling.
- Remove the sheet of paper from the plastic wrap. This can be tricky so take your time! (Removing the plastic wrap from the plate first might help. Turning over the plate with plastic wrap and paper is another strategy.) You could also ask an adult to help with this step.
- Lay your finished sheet on the plate with the correct recipe number.
- Now it's time to make Recipe 2. Follow the same procedure but this time mixing: 1 Tbs. of rice flour, 1 Tbs. potato starch and about 1.5 Tbs. of water, as well as the optional pinch of salt if you used it in the first recipe.
- Finally, make Recipe 3 using the same procedure but mixing: no rice flour, 2 Tbs. potato starch and about 1.5 Tbs. of water (as well as the pinch of salt if you have used it previously).
- If any of your sheets did not turn out well, try that recipe one more time. Note that some recipes are harder to make paper from than others, but even a small sheet will work for this activity.
- Repeat the paper making procedure for each recipe one more time so, if all goes well, you have two sheets of paper for each recipe. This time aim to produce sheets that are as thin as you can make them. It is ok if some break in the process. A small piece to test is enough for the activity, and you will get better with practice. (If you need to take a break, store the sheets of paper in a zip-top bag so they do not dry out.)
- Create at least eight rows in your table. In the first column of the table, label the first one "easy to make," the second one "appearance," the third one "smoothness," the fourth one "flexibility," the fifth one "strength," the sixth one "stretchiness," the seventh one "taste" and the eighth one "total."
Procedure
- Now it is time to test the sheets of edible paper! As you observe differences, see if you can explain why this difference occurs. Remember that Recipe 1 has only rice flour, which contains cellulose fiber, the thread-like part you find in plant material. Recipe 2 has some rice flour, and Recipe 3 contains no rice flour. The potato starch contains no fiber but does contain starch, which can act to provide strength and resiliency.
- Evaluate how easy it was to make each of the sheets. Was one recipe easier to make paper from than the others? Why do you think that was the case? Mark an "X" in the box that corresponds to the recipe that was easiest to make (or, if it was a tie, write an "X" in the columns of all of the winners).
- Observe the sheets' appearance. Do sheets made of one recipe look more appealing than those made from another recipe? If so, why do you think this happens? Place an "X" in the corresponding box(es).
- Compare the smoothness of the surface of the sheets. Is there a considerable difference? If so, why would this happen? Place an "X" in the corresponding box(es).
- Bend your papers as if you were going to roll them. Which recipe gives the most flexible sheets? Place an "X" in the corresponding box(es).
- Try to create a small rip in the sheets. Are some sheets more prone to ripping than others? Place an "X" in the box(es) for the strongest one(s). Why do you think this happens?
- Try to stretch the sheets. Are some stiffer than others? Would you like your paper to be stretchy or stiff? Place an "X" in the corresponding box(es) for the paper that has the optimal stiffness for you.
- Have a taste. Do sheets of one recipe taste better than sheets of the other recipes? Which one creates paper that has the most pleasant feeling in your mouth? Place an "X" in the corresponding box(es).
- Tally the Xs for each recipe, and write the totals in the eighth row. Is one recipe a clear winner for the most criteria?
- Extra: Are there other criteria you would like to test? If so, write them out in your table, and test them. Do the results change the overall winner?
- Extra: Can you create your own recipe that is better than the best results you obtained with recipes 1, 2 or 3?
- Extra: Think of different uses for paper—from writing to origami to food uses. What sorts of qualities are most important for each of those uses? Can you create a recipe that perform best for a specialized use?
- Extra: Use a food-color pen to write on the papers or color the paper with food coloring. Does the "ink" bleed? Which recipe is best to write on or to make colored edible paper?
- Extra: Switch ingredients to others that have similar fiber content. For example, switch the potato starch for cornstarch or tapioca and/or the rice flour for wheat flour. How does a change of one ingredient change the characteristics of the paper? Can you explain why this might happen?
Observations and Results
Was Recipe 2 the overall winner? Rice flour contains insoluble fibers called cellulose. These fibers make the sheets made of pure rice flour flexible, non-stretchy and strong, characteristics we associate with sheets of paper. It also makes for a rougher surface and feeling in the mouth.
Potato starch contains no fiber. Sheets made from pure starches are flexible and smooth but stretchy. It is also difficult to make a thin sheet with this paste. These sheets do not show the characteristics we associate with paper because they do not contain insoluble fiber.
The combination of the insoluble fibers from rice and the starches from potato starch can create the desired outcome: a smooth surface on a strong, flexible, non-stretchy sheet. The reduced amount of fibers also provides a smoother feel in the mouth.
More to Explore
Alternative Sources for Paper Fiber, from Science Buddies
How Is Paper Made?, from California State University, Northridge
Recycle! Make Old Paper New, from Scientific American
Make Marbled Cards Using Science!, from Scientific American
STEM Activities for Kids, from Science Buddies
This activity brought to you in partnership with Science Buddies
