Appropriate microwave improved the texture properties of quinoa due to starch gelatinization from the destructed cyptomere structure

Graphical abstract

Highlights

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  Microwave dispersed quinoa starch aggregates into independent granules.

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  Dispersed starch granules were hydrated and gelatinized to form network structure.

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  Microwave maintained the crystal form while changed the crystallinity.

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  Excessive microwave makes the starch partially gelatinize and formed blocks.

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  Moderate microwave treatment can improve the hardness and stickiness of quinoa.

Abstract

Texture characteristics of quinoa under microwave (MW) irradiation were studied from the perspective of starch gelatinization. MW reduced the light transmittance and increased the hardness and stickiness of quinoa. Microstructure showed that MW dispersed the vesicular structure of starch aggregates into separate starch particles, resulting in the full hydration of starch and water molecules to form denser network structures. The value of peak viscosity and setback decreased in RVA after MW treatment, but the gelatinization temperature remained stable. DSC further proved that moderate MW treatment could reduce the gelatinization enthalpy of starch and made quinoa accessible to gelatinize. However, XRD showed that the crystal structure of starch was preserved, but the crystallinity increased. Finally, low field NMR showed that moderate MW stimulated the full hydration of starch to form denser network structures, while excessive MW treatment made starch partially gelatinize and form rigid structure, resulting in negative texture properties.