Effects of mung bean starch on quality of rice noodles made by direct dry flour extrusion

- Physicochemical properties of rice flour changed significantly after addition mung bean starch.
- Adding 5 g/100 g mung bean starch to rice flour significantly improves the rice noodle quality.
- Mechanisms and reasons for the changes observed in our study have been discussed.

The effects of mung bean starch (MS) on physicochemical properties of rice flour (RF) and the quality of extruded rice noodles were investigated. Results showed that the amylose content, retrogradation degree, storage modulus (G′) and loss modulus (G″) increased gradually as addition levels of MS increased, while the solubility, swelling power and pasting viscosities decreased with increasing MS content. Acceptable cooking quality and textural properties in the extruded rice noodles were obtained when MS content was up to 5 g/100 g. Sensory evaluation results showed that the scores of firmness, elasticity, slipperiness and chewiness increased gradually as addition levels of MS increased. Scanning electron micrographs of raw extruded rice noodles showed that the surface was smoother and the network of cross-section was more compacted for noodles made from blends of 95 g/100 g RF and 5 g/100 g MS than those from pure RF. This study provides a crucial basis for understanding the interaction between MS and RF and the quality improvement in the extruded rice noodles.