Type II. Uncooked potato starch, green banana starch,
gingko starch, and high-amylose maize starch, which display
the B- or C-type polymorph, are highly resistant to enzymatic hydrolysis (17) and are examples of type II resistant
starch (RSII) However, after cooking, most of the starch,
such as that in baked potato and cooked banana, becomes
highly digestible as a result of starch gelatinization and loss
of the B- and C-type crystallites. An exception is high-amylose
starch produced by mutation of the amylose-extender (ae)
gene and the gene encoding starch branching-enzyme I,
which has substantially longer branch chains of intermediate
components and a larger proportion of amylose (18–20).
Thus, this starch displays a high gelatinization temperature,
above the boiling point of water. After boiling or cooking at
a temperature below its gelatinization temperature, this type
of starch retains its crystalline structure and remains resistant
to enzymatic hydrolysis.