During
rice milling, the bran an
d germ are successively remove
d from the caryopsis (kernel). Because bran an
d germ contain large quantities of lipi
d, the amount of lipi
d remaining on the kernel surface may be use
d as a metho
d for the assessment of milling quality. Bulk samples of
rice pureline varieties an
d an experimental hybri
d were mille
d for 0, 10, 20, 30, an
d 40 s. Scanning electron microscopy (SEM) reveale
d that brown
rice kernels ha
d large contours of linear protuberances an
d depressions running lengthwise along the kernel surface. The protuberances were abra
de
d successively
during milling, but varying amounts of material remaine
d in the
depressions. Light microscopy combine
d with the lipi
d-specific probes Nile Blue A or Su
dan Black B
demonstrate
d that the material in the
depressions observe
d with SEM was lipi
d. Sections of whole, mille
d rice kernels, prepare
d using a mo
difie
d sectioning technique an
d staine
d with Nile Blue A, showe
d that portions of the embryo remain after milling an
d that lipi
d is locate
d on or near the surface of the kernel. Differences in quantity an
d distribution of resi
dual lipi
d as milling
duration increase
d were
documente
d photographically to in
dicate the extent to which the bran an
d embryo components were remove
d during milling. This paper provi
des proof of concept that resi
dual lipi
d is a robust measure of the
degree of milling.
Keywords:
d="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=Microscopy&qsSearchArea=searchText">Microscopy; d="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=rice+milling&qsSearchArea=searchText">rice milling; d="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=lipid+localization&qsSearchArea=searchText">lipid localization; d="authors" href="http://pubs.acs.org/action/doSearch?action=search&searchText=lipid+staining&qsSearchArea=searchText">lipid staining