HMT influenced the crystalline properties, pasting properties,
thermal properties, and enzyme digestibility of both waxy- and
normal-type starches in different degrees. Although the effect of
the presence/absence of amylose on starch changes by HMT was
not consistent for the three starches, there was a tendency that
the amylose in the normal type starch would facilitate the destruction
and rearrangement of amylopectin branch chains, as indicated
by crystallinity data. The different effects of HMT on pasting/gelatinization
parameters of waxy and normal starches also supported
the role of amylose. Partial gelatinization had been occurred in
waxy rice starch by HMT as evidenced by obvious changes in granule
morphology, and significant reductions in crystallinity and enthalpy
of gelatinization. The increase in enzyme digestibility of
HMT normal starches was somewhat higher than of the waxy type
starches; therefore it was believed that amylose would be one factor
influencing the change in digestibility of the HMT starches. We
also speculated that there was a new layer formed on the surface of
starch granules during HMT, and this layer restricted water penetration
into the granules and retarded the granule swelling. Thus,
the detailed structure of starch granules on the surface region
should be investigated.