An Optimization Study of 3D Printing Technology Utilizing a Hybrid Gel System Based on Astragalus Polysaccharide and Wheat Starch

Abstract

This study utilizes a lab-developed pneumatic-extrusion condensing 3D food printer to prepare astragalus–starch mixed gels by blending different ratios of astragalus polysaccharide and wheat starch and applies these gels to 3D printing experiments. The aim of this paper is to investigate the impacts of mixed-gel concentrations on printing outcomes in order to identify the optimal blending ratio. Under this rationale, the effects of printing layer height and nozzle diameter on print quality were studied. Single-factor analysis and response surface methodology were employed to optimize the experiments and determine the optimal printing process parameters for the astragalus–starch mixed gels. The results indicate that an increase in astragalus polysaccharide content leads to a decrease in the sedimentation rate of the mixed gels and a tendency towards a more fluid consistency. After storage of samples in a sealed space for equal durations, it was found that an increase in astragalus polysaccharide content enhances the textural properties of the mixed gels, with optimal printing effects achieved at a 2% polysaccharide content. The optimal print quality is achieved when the ratio of nozzle diameter to layer height is between 0.5 and 0.55. The influence order of printing process parameters on the overall completion rate of the samples is nozzle diameter > printing speed > fill rate. The predicted optimal printing parameters are a nozzle diameter of 0.6 mm, a printing speed of 767 mm/min, and a fill rate of 83%, with a predicted overall completion rate of the printed samples at 99.45%. Experimental validation revealed an actual overall completion rate of the printed samples at 99.52%, slightly higher than the predicted value. This discrepancy was attributed to the precision of the measurement methods and the variability in the printing process. The study demonstrates that the addition of astragalus polysaccharide significantly improves the 3D printing molding effect of wheat starch, and the printing parameter settings obtained by response surface optimization effectively enhance printing accuracy. This research provides experimental evidence and parameter optimization references for the application of non-starch polysaccharides in starch-based 3D food printing.