Infrared and Raman Spectroscopic
Characterization
of Structural Changes in Albumin, Globulin, Glutelin, and Prolamin
during Rice Aging
- Publication date
- Publisher
Abstract
Structural changes in albumin, globulin, glutelin, and
prolamin
from fresh and aged rice were characterized in this study. Infrared
and Raman spectroscopies revealed changes in interactions between
protein and starch, and the occurrence of structural changes involving
secondary and tertiary structures of protein induced by rice aging.
The α-helical structure was reduced, and aliphatic amino-acid
side chains became more buried in albumin after rice aging. Oxidation
of the sulfhydryl group in globulin was evident. The unordered coil
in glutelin decreased, and a characteristic frequency of the free
sulfhydryl group appeared. The antiparallel β-sheet in prolamin
increased, the conformation of disulfide bonds changed, and tyrosine
residues became exposed to a polar environment. The association between
globulin and starch strengthened, whereas that between glutelin and
starch diminished. These differences in structure and interactions
with starch might be responsible for the dissimilar pasting properties
between fresh and aged rice