Abstract:
The expanding of the market of plant-based meat brings numerous challenges of traditional 3D printing technologies, which are used to produce plant protein-based meat (PPM), such as loose texture and reduced chewiness due to insufficient protein cross-linking. This study aims to optimize the rheological and forming properties of plant protein ink through high-moisture extrusion (HME) technology, and investigate the impact of HME processing parameters on product quality, thereby overcoming the texture limitations of 3D-printed PPM, and providing theoretical support for the development of highly realistic PPM. This study selected soy protein isolate, wheat gluten, and potato starch as raw materials, and used a twin-screw extruder for HME pretreatment (moisture content of 60%) to prepare plant-based protein ink. The study investigated the effects of HME pretreatment on the rheological properties and moisture distribution of the ink. In the experimental design, ink not subjected to HME pretreatment was set as the control group (CG), while ink subjected to HME pretreatment at different cooking temperatures (160~200 ℃, with a temperature gradient of 10℃, totaling five groups) was set as the experimental group. A rotational rheometer was used to measure the yield stress, shear viscosity storage and loss modulus, and thixotropic recovery rate of each ink group; a halogen moisture analyzer was used to determine the moisture content of the ink; and a food 3D printer was used to print PPM samples. The rheometer's texture profile analysis (TPA) function was used to measure the texture parameters of the samples, including hardness, elasticity, and chewiness, and the degree of organization of the samples was assessed through a single-blade shear test. A scanning electron microscope (SEM) was used to analyze the microstructure, porosity, and fiber orientation of the samples. Additionally, this study systematically investigated the 3D printing formability of the ink. The results showed that HME altered the rheological properties of the ink, with the viscosity, storage modulus, and loss modulus of the experimental group enhanced compared to the CG, indicating improved solid sample behavior and structural integrity. The thixotropic recovery rate decreased from 83.0% in the CG to 41.6%~70.7% in the experimental group, making the 3D printing extrusion process smoother and confirming the regulatory effect of HME self-healing ability after extrusion. Moisture content tests indicated that HME treatment at 170~200 ℃ significantly affects the moisture state of the ink. Texture parameters exhibited obvious temperature dependence, with samples treated at 180 ℃ showing increases in hardness, elasticity, and chewiness of 182.38%, 206.02%, and 1 542.65%, respectively. Microscopic structural analysis indicated that HME promoted the dissolution of raw materials and increased the porosity of printed PPM. HME technology effectively improves the rheological properties and printing accuracy of the ink by regulating intermolecular disulfide bonds and hydrogen bonds, with a cooking temperature of 180℃ maximizing texture enhancement effects. Additionally, 3D printing forming performance experiments of PPM further validated that HME treatment at specific temperatures enhances the 3D printing accuracy of PPM. This study reveals the synergistic mechanism between HME and 3D printing, providing an innovative technical solution to address issues such as low fiber content and monotonous texture in PPM products, and laying a solid technical foundation for the development of customized plant-based meat products.