Effects of flaxseed gum/egg white protein-based edible curcumin nanoemulsion coatings on starch retrogradation and quality of fried rice in freeze-thaw treatment

Hydrophilic colloid -based edible curcumin nanoemulsion coatings was exploited to keep fried rice stabilization in the freeze -thaw cycles (FTCs), including texture, moisture loss, color and other aspects of the quality characteristics. Fried rice were coated with nanoemulsion what was obtained by flaxseed gum (FG), egg white protein (EWP), Olive oil (O), and Curcumin (Cur), namely as CFEO. The scanning electron microscopy (SEM) results showed that the CFEO nanoemulsion coating had a more homogeneous and dense surface structure. In the fried rice quality determination, the hardness of the CFEO nanoemulsion coating was significantly less than the CONTROL group in each cycle. Alternatively, for moisture loss, CONTROL group significantly accelerating the rate of loss. For the color index, the CFEO group had outstanding performance in delaying the increase of the total color difference ( Delta E) and brown index (BI), additionally, significantly delayed the decline in whiteness index (WI). Retrogradation enthalpy, crystallinity and short range order analysis demonstrated the contribution of the CFEO group in the delayed starch retrogradation, and further assisted in explaining the changes in texture properties. In addition, the CFEO also played a stabilizing role in preventing the fluctuation of the T 2 water distribution. Therefore, curcumin nanoemulsion as the coating of fried rice is appropriate and can delay the decline of quality in freeze -thaw cycle.