Revealing the reasons for the pasting property changes of rice during aging from the perspective of starch granule disaggregation.

BACKGROUND: The pasting properties of rice change markedly after aging, although the mechanism for this still remains unknown. Aged and fresh rice grains were ground and the flours were fractionated by particle size, and then the pasting properties, particle size distribution and microscopic morphology of the heated flour fractions were evaluated. RESULTS: Compared to the corresponding fresh flour fractions with the same particle size, a lower peak viscosity for those aged flour fractions from 80 µm to 450 µm and a higher peak viscosity for those aged flour fractions from 20 µm to 60 µm were observed. The amounts of smaller particles disaggregated from the aged flour fractions were significantly less and the separated entities were always larger than the corresponding fresh rice fractions. CONCLUSION: Disaggregation difficulty of starch granules was the reason for the changes in the pasting properties of rice after aging. This finding is helpful for understanding rice aging mechanisms and regulating eating quality of rice flour as an ingredient. © 2022 Society of Chemical Industry.