Fabrication of composite gels based on soy protein isolate and κ‐carrageenan and delivery of riboflavin: insights into microstructure, gel properties and digestive characteristics

Abstract BACKGROUND Riboflavin, a water‐soluble vitamin, is not synthesized in the human body. Hence, developing riboflavin carriers that can be retained in the gastrointestinal system for longer periods can facilitate riboflavin supplementation. RESULTS The present study aimed to prepare a soy protein isolate (SPI)–κ‐carrageenan composite gel‐mediated riboflavin delivery model. Additionally, the effects of different concentrations of κ‐carrageenan on the micromorphology, gel strength and rheological properties of SPI gels were investigated. The results showed that incorporating high‐ concentration of κ‐carrageenan (0.4 g kg −1 ) effectively enhanced the interactions among SPI aggregates, increasing the gel frontal strength to 128.65 g and water‐holding capacity up to 81.67%. Additionally, κ‐carrageenan incorporation enhanced the gel network structure, reduced gel porosity and increased the density of the gel network structure. Compared with SPI gels, SPI–κ‐carrageenan composite gel facilitated the targeted release and in vivo degradation of riboflavin, at the same time as delaying the biodegradation of riboflavin in stored gels. CONCLUSION Altogether, the findings of the present study provide insights into SPI–κ‐carrageenan composite gels regarding gel properties and interaction mechanisms, as well as a strategy for the slow release of riboflavin in the gastrointestinal tract. © 2025 Society of Chemical Industry.