Functional Changes in 5D Printed Starch-Based Gel Systems Caused by Spontaneous Growth of Probiotics

Following the development trend of intelligentialize and vitalization in the additive manufacturing field, five-dimensional (5D) printing has emerged. 5D printing is a life-active material that changes in the life dimension in the three-dimensional (3D) printed model over time, thus showing favorable changes in structure, performance, or function. In this study, probiotics were used as life materials to explore the feasibility of starch-based gel systems for 5D printing. With the evolution of time, probiotics spontaneously grew and multiplied in the 5D printed model. The number of probiotics in the 100% filled printed model increased from 5.57 x 107 to 3.11 x 1011 CFU/g within 8 h, realizing the dynamic change of the nutritional function. With the decrease of pH and the increase of titratable acidity, casein gelation improved the texture properties of printed samples. The redness of the printed model increased in the spontaneous change process of probiotics, and the flavor function and antioxidant ability were raised. Due to the micro-oxygen requirement of probiotic growth, the probiotic proliferation capacity of 50% and 75% filled printed samples was weaker than that of 100% filled printed samples. In addition, the microbiological differences between printed samples and mold-made samples were discussed. This study aimed to provide some data support and theoretical basis for the application of 5D printing technology.