Preparation and characterization of casein-carrageenan conjugates and self-assembled microcapsules for encapsulation of red pigment from paprika

This study aimed to investigate the optimum preparation condition of casein- carrageenan conjugate by ultrasonic Maillard dry treatment. The stable microcapsule was self-assembly prepared by the conjugates applied to protect red pigment from paprika. The optimum substrate ratio of Cas-Ca is 1:2, the reaction time and temperature were 24 h and 60 °C. Finally, the optimal degree of grafting reached 78.05%. Conjugation with carrageenan could further enhance solubility and emulsifying properties of casein. Glycosylation self-assembly nanoparticles were prepared with ultrasonic treatment, and the stability of the nanoparticles were excellent. Cas-Ca was effectively used to encapsulate PRP, and the PRP and PRP-microcapsule were stored for six days under the condition of high temperature, lighting, and food additives to observe the PRP retention rate. These results indicated the outstanding protective effect of microcapsule on PRP. Cas-Ca could be used as an effective carrier of PRP. They could effectively control release behavior in simulated gastrointestinal fluid. Cas-Ca microcapsule was disintegrated and released slowly within 3 h in simulated gastric fluid, but released rapidly within 1 h in intestinal environments, and the total release rate reached 76.6%.