The objective of this study was thus to investigate the influence
of rice storage proteins, in relation to amylose content, on the RVA
pasting characteristics of newly harvested Thai waxy and nonwaxy
rice of Indica cultivars. This was done by categorising pasting
characteristics using principal component analysis (PCA). PCA is
one of the multivariate statistical techniques that can be used to
examine associations across all variables. It can be used to underlie
the data structure through reduction into two or three uncorrelated
dimensions, and hence help in visualising the data (Dillon
& Goldstein, 1984). The physicochemical characteristics of the protein
fractions were altered by accelerated aging at a temperature
and relative humidity below those required for starch gelatinisation
to enhance protein-related interactions (e.g., Maillard reaction,
disulfide bond formation, etc.); by alkali removal; and by
the addition of the reducing agent cysteine during pasting. An
understanding of the roles of starch and protein fractions on the
pasting characteristics of Thai rice cultivars could offer more insight
into the mechanisms governing the textural characteristics
of the flour composites.