Structural, physicochemical properties and noodle-making potential of quinoa starch and type 3, type 4, and type 5 quinoa resistant starch

This study prepared type 3, type 4, and type 5 quinoa resistant starch (QRS3, QRS4, and QRS5) from quinoa starch (QS), compared their structural and physicochemical properties and evaluated their noodle-making potential. The results showed that the molecular weight of QRS3 decreased, the number of short-chain molecules increased, and its crystal type changed to B-type after gelatinization, enzymatic hydrolysis, and retrogradation. QRS4 is a phosphorylated cross-linked starch, with a surface morphology, particle size range, and crystal type similar to QS, but displaying modified thermodynamic properties. QRS5 is a complex of amylose and palmitic acid. It displays typical V-type crystals, mainly composed of long chain molecules and primarily exhibits a block morphology. The noodles prepared by replacing 20 % wheat flour with QS, QRS3 and QRS5 have higher hardness and are suitable for people who like elasticity and chewiness. QRS4 noodles are softer and suitable for people like elderly and infants who prefer soft foods. In conclusion, significant differences were evident between the fine structures, crystal types, physicochemical properties and potential applications of QS and the three QRSs. The results may expand the application of QS and QRS in the food and pharmaceutical industries. •Type 3, type 4 and type 5 quinoa resistant starch (QRS) were prepared from starch.•The type 3 QRS formed new carboxyl groups and changed to B-type crystals.•The type 4 QRS displayed a smaller Mw and consisted of more short-chain molecules.•The type 5 QRS had more long-chains molecules and showed a blocky morphology.•The QS, QRS3 and QRS5 noodles have higher hardness, and QRS4 noodles are softer.