Abstract:The effects of ball milling and ultrafine grinding on the microstructure, physicochemical properties, and application characteristics of mung bean starch used in 3D printing of food were investigated. Commercial mung bean starch was used as the raw material, and ultrafine powder was prepared by planetary ball milling. The particle size and distribution, microscopic morphology, crystal structure, short-range ordered structure, gelatinization and rheological properties, and 3D printing characteristics of mung bean starch before and after ultrafine grinding were studied using laser particle size analyzer, scanning electron microscope, X-ray diffraction, Fourier transform infrared spectrometer, viscometer, rheometer, and 3D printer. The results showed that the particle size of mung bean starch first decreased, and then increased, after ball milling. The particle size was small at 6 h, and the median diameter (D50) was 15.68 μm. The sample surface was rough and flat. The crystal structure of the starch granules was destroyed, and the crystallinity and R1047/1022 value of short-range ordered structure of the starch granules decreased from 33.43% to 13.93% at 9 h and from 0.82 to 0.76, respectively. After ball milling, the gelatinization and rheological properties of the mung bean starch were modified, and the viscosity and retrogradation value decreased from 2 377.5 cp to 1 481.5 cp and from 1,008.5 cp to 549 cp, respectively. The loss factors G′ and G″ first decreased and then increased. After ball milling, mung bean starch powder can be effectively used in 3D printing. At 3 h, the model deviation rate was 0.66%, and mung bean starch samples with low deviation rate and high printing accuracy were obtained. The study provides a theoretical basis for processing mung bean starch and its application in 3D printed food products.
