Effect of hydrothermal treatment of rice flour on various rice noodles quality

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 (P≤0.05). The storage modulus (G′) 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.