Derivation of x=0.779


In the equation


where


Mo=Initial mass of ungelatinized starch
Mt=Mass of ungelatinized starch at time t
Mf=Mass of ungelatinized starch at final time

If we divide the top and bottom of the above fraction by the total mass of starch present, M, we get:


Initially, when the potato is raw, 23% of the starch in it is amorphous. That means


From the literature search, it was found that the highest percentage of starch that was gelatinized was 96.2%. That means


So now we have


The potato is said to be cooked when 80% of the starch in the center has been gelatinized. That means:



So the potato is cooked when: