The rice noodle industry in Thailand is facing problems regarding rice flour quality. This research aims to
study the effects of hydrothermally modified rice flour on improving rice noodle quality. High-amylose
rice flour (Chai Nat 1 variety) was modified using heat–moisture treatment (HMT) and annealing (ANN).
Response surface methodology (RSM) with face-centered central composite design (FCCD) was applied
to optimize the hydrothermal treatment condition. The effects of treatment conditions – moisture
content; heating temperature and heating time on pasting; rheology; and textural properties of rice flour
gel – were observed. A contour plot showed that all responses using HMT increased when moisture
content and heating temperature increased. But heating time had no significant effect on response
variables. ANN showed a lower response than HMT for all parameters. The optimum modified conditions
were then matched with those of commercial flour for fresh, semi-dry and dry rice noodles; this showed
no significant differences in texture or cooking quality (P0.05). The storage modulus (G0) after cooling of
HMT (19,100 Pa) was much higher than that of ANN (5490 Pa). The differences in rheological properties
of both treatments supported their proper uses to achieve various rice noodle qualities.