3.3. Starch molecular mass determination
The molecular weight distribution in a polymer describes the
relationship between the number of moles of each polymer species
and the molar mass of the species. The molecular weight (Mp) and
percent increase in the area with graining filling were compared
among the three rice mutants. The weight average molecular
weight (Mw), the number average molecular weight (Mn), and percent
area of MR4 were found to be the lowest, whereas the MR7
exhibited the highest values regardless of the developing stages.
However, the polydispersity (Pd) of MR4 was the highest of the
three materials (Table 2). This percent area is related to the uniformity
of the molecular polymerisation. The lowest percent area that
was found for the starch of MR4 was consistent with its highest
AAC (Table 2). To investigate the differences of molecular weight
among all of these materials during kernel development, a PCA
was conducted. The differences of all materials with different
development stages were shown in Fig. 3A; the variations among
MR7 and MR1, MR4 almost can be explained by PC1. According
to the loading plots of the first two factors, besides RS, Pd could
mainly explain the first variance and Mn, Mw could explain the