Development of 3D Food Printing Ink Based on Germinated Brown Rice Modified by Dry Heat and High-Pressure Steam.

Abstract

High-performance whole-grain ingredients that integrate superior nutritional properties and favorable printability are essential for the advancement of 3D food printing technology. Germinated brown rice (GBR) is rich in γ-aminobutyric acid (GABA), a key bioactive compound, rendering it a viable whole-grain material for 3D food printing applications. Nevertheless, native GBR-based gels suffer from poor dimensional accuracy during 3D printing, which severely restricts their practical application. To tackle this issue, this study adopted a green heat treatment method to improve both the nutritional benefits and 3D printing performance of GBR. Brown rice was first germinated to obtain GBR, followed by modification via dry heat treatment (90-150 °C) or high-pressure steam treatment (5-25 min). The effects of the two treatments on GABA retention, starch recrosslinking, gel rheology, texture, microstructure, and printing accuracy were systematically characterized. Results indicated that germination significantly elevated GABA content from 47.66 mg/kg in brown rice to 104.85 mg/kg in GBR, but unmodified GBR gels exhibited relative dimensional deviations of 9.01% and 18.70% for the "letter W" and "Android robot" models, respectively. Moderate thermal modification retained and further improved GABA bioactivity, while promoting starch recrosslinking to form a uniform porous gel network. The optimal groups (GD-135 and GS-15) yielded significantly reduced printing deviations (p < 0.05), with a maximum deviation reduction exceeding 93%. Collectively, dry heat and high-pressure steam modification enabled concurrent improvement of GABA retention and 3D printing precision of GBR. This work provides a non-chemical, energy-efficient green modification approach for whole-grain raw materials applied in personalized 3D-printed foods.