Synergistic modification of phycocyanin composite gel by xanthan gum and flaxseed gum and the fate during in vitro digestion

Phycocyanin (PC) belongs to the "blue food" protein, and its application exploration is of great significance in the food industry. In this study, the effects of different proportions of xanthan gum (XG) and flaxseed gum (FG) on the applicability of 3D printing, rheological properties, and the structural properties of PC were studied, and the interaction and in vitro digestion properties were also discussed. In the composite gel, PC concentration [0.1% (w/v)] and blend concentration (5 wt%) were fixed, but the ratio of XG to FG was different (5:0-0:5). With the increase of FG content, the 3D printing performance of the gel was improved, and the rheological properties and texture properties were also changed. The molecular interaction between PC and XG/FG was hydrogen bonding and hydrophobic interactions. In addition, PC-XG/FG gels after in vitro digestion had better ability to remove hydroxyl free radicals. In summary, the study offered theoretical direction for the use of two polysaccharides to synergistic modification of the functional factors to improve stability. Furthermore, it provided guidance on how to improve the nutritional value of 3D-printed samples.