Page 150 - The Manga Guide to Biochemistry

5. Why Are Mochi Rice Cakes Springy?

Differences Between Normal Rice and Mochi Rice

The final mystery is: Why are mochi rice
cakes springy?

I love mochi, so this is my kind of
mystery.

First, let’s talk about how mochi is made.
Did you know that mochi is made from
special rice, which is springier than nor­
mal rice?

Of course I know that! I’ve got serious
mochi-making experience. I’ve even
participated in a traditional “mochi-
pounding” ceremony!

But what makes mochi rice springier
than normal rice?

It’s all because of the structural differences of the starches that make up the rice.
Rice is 75% starch, so slight variances in its starch composition can seriously

affect its physical properties.
As you can see in the figure below, “normal,” non-glutinous rice contains the

two starches amylose and amylopectin. Amylose makes up about 17 to 22% of the
starch, and the rest is amylopectin.

17–22% 100%

Non-glutinous amylose
rice Amylopectin

Mochi rice

composition of the
starch contained in rice

However, mochi rice starch only contains amylopectin.

136 Chapter 3