293: Generation of pH-Responsive Starch and Alginate-Pectin Hydrogels Using Coaxial 3D Food Printing: The Release of Methylene Blue

Introduction

pH-responsive alginate-pectin hydrogels have received great attention due to their ability to protect and deliver bioactive compounds/microorganisms/cells to specific targets. However, the conventional encapsulation methods suffer from inefficiencies, poor control over size and shape, and inconsistent results. The emergence of 3DFOODP offers an advanced solution to overcome these challenges since it can provide high flexibility and precision in manufacturing. Therefore, this study aimed to develop an innovative, coaxial 3DFOODP approach to create an alginate-pectin and starch hydrogel system.

Methods

A spiral cube (30x30x5mm) was designed digitally and printed using a coaxial nozzle to produce a core (starch)-shell (alginate-pectin) structure. The printing parameters (i.e., ink concentrations, printing pressure, and printing temperature) were optimized. The rheological properties (including viscosity, recovery, and storage-loss moduli) of the gel solutions were assessed before printing. The 3D-printed hydrogels were characterized using FTIR, XRD, and SEM. The release profiles of a model bioactive compound, methylene blue (MB), from 3D-printed samples were determined in simulated gastric and intestinal fluids (SGF and SIF). The statistical analysis was conducted using Tukey's test with a significance level of p < 0.05.

Results

Optimal conditions for 3DFOODP were determined as 11 wt.% starch for the core and 2 wt.% alginate-pectin with 0.02M CaCl2 for the shell, printed at 95°C and 23°C, respectively. The printing process achieved 98% printability, closely replicating the digital design. Both hydrogels exhibited shear-thinning behavior, supporting flowability and printability. Freeze-dried hydrogels displayed porous, interconnected fibrillar structures, ideal for loading bioactive compounds or probiotics. The MB release from the 3D-printed matrix in SGF (25%) was significantly lower compared to crude MB under the same conditions (89%), protecting the loaded compounds in acidic environments (i.e., stomach).

Significance

This study highlights the potential of coaxial 3DFOODP to create innovative hydrogel systems for targeted delivery of pH-sensitive nutrients. The technology offers enhanced precision and flexibility for incorporating and delivering micronutrients, including probiotics and bioactive compounds, for the first time. The proposed approach provides a blueprint for developing highly customized functional foods for personalized nutrition.

Author: Le Que Anh Truong