Effects of particle size on the structure, cooking quality and anthocyanin diffusion of purple sweet potato noodles

The effects of different particle sizes of purple sweet potato flour (PSPF) on the structure and quality of noodles and the diffusion kinetics of anthocyanins during cooking were studied. As the particle size of the PSPF decreased (from 269 to 66 μm), the adverse effects of the addition of PSPF on the quality of noodles were reduced. The smaller particle size of PSPF was beneficial for the secondary structure orderliness and the tighter microstructure of PSP noodles. The diffusion of anthocyanins in noodles to the soup during cooking could be fitted well with Fick's second law, and diffusion coefficients were in the range of 8.3248–14.0893 × 10-9 m2/s. The noodles with 15% 66 μm PSPF showed the best cooking properties, the highest sensory score, the highest anthocyanin retention ability and a compact and orderly microstructure. Thus, they could be considered as noodles rich in anthocyanins for commercial application.