The Food Lab: Better Home Cooking Through Science

that the grated potatoes released far more starch than either
of the other types. Let’s see how it translates down the line.
Turns out that another weird phenomenon occurs when
you try to cook grated and rinsed potatoes: they simply
don’t soften. I boiled the grated potatoes for a full 45
minutes to no avail. Even after forcing them through a ricer,
pebbly, hard bits remained. What the heck was going on?
It’s got to do with that pesky pectin. When exposed to
calcium ions, pectin cross-links, forming stronger bonds that
are resistant even to prolonged cooking. As it happens,
potato cells are full of calcium ions just waiting to burst out.
By grating the taters, I ended up releasing so much calcium
that the pectin got strengthened to a point where it never
softened. The other two batches—the large chunks and the
smaller dice—both formed a moderately fluffy mash, but to
get the potatoes even fluffier, I found that rinsing the
potatoes of excess starch both before and after cooking was
the key. A quick pass through the ricer, and a little bit of
lubrication provided by some butter and whole milk gently
stirred in with a rubber spatula, and my sister’s potatoes
were ready for sculpting.
With both potato cooking methods in order, my sister and
I can finally get back to fighting over really important
things, like who gets to play the guitar part on Beatles Rock
Band.