This was evidenced by microscopy work
in which high concentration of proteins were distributed in the
brown kernel sample. Thus kernels with high protein content are
more susceptible to browning. Regardless of sucrose concentration,
the amount of glucose and fructose hydrolysed during drying are
the key determinants in the degree of browning. The third possible
mechanism, enzymatic browning is related to phenol content as
the brown sections of the kernels had higher bound phenolic concentrations
than the white sections of the same kernel. The brown
sections result from esterification of the phenolic compounds with
associated protein substrates. The ‘Daddow’ variety had the highest
activity of polyphenol oxidase compared to other varieties studied
but it contains lowest phenolic content. Thus, that phenolic content
as well as polyphenol oxidase activity play a role in kernel
discoloration.