Construction and application of Spirulina carotenoid hydrogel sustained-release system

The fat solubility, sensitivity to light and heat, and special molecular structure of carotenoids limit their application in solid recreational foods. In this study, a carotenoid hydrogel slow-release system was constructed using Spirulina as raw material to regulate the effects of carotenoid fat solubility and heat sensitivity on its processed products, and liposomal encapsulation of Spirulina carotenoids was utilized to explore the mechanism of lecithin molecules-mediated formation of carotenoid/sodium alginate molecular gels and to study the molecular structure of the gels, so as to regulate the effects of carotenoid fat solubility and heat sensitivity on its processed products and apply them to solid leisure foods such as soft candies. The results showed that the optimal conditions for gel preparation were 2% sodium alginate dosage and 5% calcium ion concentration, and the gel water holding capacity was maintained between 63% and 68% depending on the amount of liposomes added, and the hardness and elasticity of the hydrogel beads showed a tendency to increase with the increase in the amount of liposomes added. Egg yolk lecithin existed in the system as a bridge with regular and orderly arrangement, and was well connected with carotenoids and sodium alginate molecules. The interaction between the three molecules was mainly hydrogen bond and van der Waals interaction. Compared with free carotenoids, the sustained-release effect of carotenoid liposome (Car-Lip) and carotenoid liposome hydrogel (Car-Lip-hy) was enhanced. However, the free radical scavenging rate of Car-Lip was 11.87% higher than that of free carotenoids. This study will have great reference significance for the food application of Spirulina carotenoid and other fat-soluble nutrients.