Effect of different hydrocolloids on the physicochemical, printing, and digestion properties of 3D printed purple sweet potato

This study investigated the influence of different hydrocolloids, namely hydroxypropyl methylcellulose, xanthan gum, guar gum, flaxseed gum, and κ-carrageenan gum on the physicochemical, printing, and digestion properties of 3D printed purple sweet potato (PSP). Aside from κ-carrageenan gum, addition of these hydrocolloids could improve the 3D printing performance of PSP. Addition of hydrocolloids significantly altered the water mobility and rheological characteristics of PSP. The tanδ (G"/G') values of PSP-hydrocolloid mixtures were strongly related to their 3D printability. The hydrogen bonds in PSP-hydrocolloid samples were weakened compared to PSP-H2O. In comparison to other hydrocolloids, the addition of guar gum significantly decreased the level of starch digestion in PSP during in vitro digestion. The release of phenolics and anthocyanins was highly correlated with the extent of starch digestion. The variations in interactions between hydrocolloids and phenolics affected the release of individual phenolics from PSP during gastrointestinal digestion and colonic fermentation. PSP-guar gum exhibited a significantly higher content of phenolics released after colonic fermentation than the other PSP-hydrocolloid samples. Overall, this study provided theoretical guidance for addition of hydrocolloids into plant-based food materials to enhance their 3D printing performance and modulate their release of intrinsic bioactives as well as digestion of starch during gastrointestinal digestion and colonic fermentation.