As an emerging digital production technology, 3D food printing intends to meet the demand for customized food design, personalized nutrition, simplification of the food supply chain system, and greater food material diversity. Most 3D food printing studies focus on the development of materials for extrusion-based food printing. Plant-based foods are essential for a healthy diet, and they are growing in popularity as their positive effects on human health gain wider recognition. The number of original studies on plant-based printable materials has increased significantly in the past few years. Currently, there is an absence of a comprehensive systematic review on the applications of plant-based materials in extrusion-based food printing. Thus, this review aims to provide a more intuitive overview and guidance for future research on 3D printing of plant-based materials. The requirements, classifications, and binding mechanisms of extrusion-based food printing materials are first summarized. Additionally, notable recent achievements and emerging trends involving the use of plant-based materials in extrusion-based food printing are reviewed across three categories, namely, hot-melt (e.g., chocolate), hydrogel, and soft (e.g., cereal- and fruit/vegetable-based) materials. Finally, the challenges facing 3D food printing technology as well as its future prospects are discussed.

Potential roles for anthocyanins in preventing various chronic diseases have been reported. These compounds are highly sensitive to external conditions and are susceptible to degradation, which increases the complexity of their metabolism in vivo. This review discusses anthocyanin metabolism in the digestive tract, phase I and II metabolism, and enterohepatic circulation (EHC), as well as their distribution of anthocyanins in blood, urine, and several organs. In the oral cavity, anthocyanins are partly hydrolyzed by microbiota into aglycones which are then conjugated by glucuronidase. In stomach, anthocyanins are absorbed without deglycosylation via specific transporters, such as sodium-dependent glucose co-transporter 1 and facilitative glucose transporters 1, while in small intestine, they are mainly absorbed as aglycones. High polymeric anthocyanins are easily degraded into low-polymeric forms or smaller phenolic acids by colonic microbiota, which improves their absorption. Anthocyanins and their derivatives are modified by phase I and II metabolic enzymes in cells and are released into the blood via the gastrovascular cavity into EHC. Notably, interconversion can be occurred under the action of enzymes such as catechol-O-methyltransferase. Taking together, differences in anthocyanin absorption, distribution, metabolism, and excretion largely depend on their glycoside and aglycone structures.