Ultrasound Effect On The Formation Of β-lactoglobulin And Chlorogenic Acid Complexes And Its Mechanism Of Encapsulated Curcumin

Ultrasound is an efficient,environmentally friendly,and economical physical method that can significantly affect the structure and biological activity of proteins.In recent years,many studies have attempted to use ultrasound to promote protein-polyphenol interactions,construct food-grade delivery carriers to achieve nutrient embedding,shield against damage and stimulation from extreme external environments,and improve nutrient solubility,stability,bioaccessibility or achieve controlled and targeted release of nutrients.Covalent complex carriers prepared by free radical induction are important for the development of food ingredients and nutrient fortification due to their stable structures.In this paper,ultrasound and free radical induction were combined to investigate the effects of ultrasound on the preparation and properties of β-lactoglobulin(β-LG)and chlorogenic acid(CA)complexes,and to evaluate their delivery effects on curcumin(Cur):(1)Preparation of β-LG-CA molecular complexes and their characterization:Multiple sets of β-LG-CA binary complexes were prepared before and after the addition of different reagents by the free radical induction method using β-LG and CA as raw materials by ultrasound.The results showed that ultrasound could promote the formation of β-LG-CA complexes,while its release of hydroxyl radicals facilitated the covalent binding between β-LG and CA.Both ultrasound and covalent binding significantly affected the structure of β-LG,resulting in a decrease of its α-helical content and an increase of its irregular curl content.The antioxidant properties and solubility of the complexes were best when the β-LG was pretreated with ultrasound before free radical-induced binding of CA,but the thermal stability of β-LG was damaged to some extent by ultrasound.(2)Application of β-LG-CA molecular complexes for delivery of Cur: Cur was embedded using the inverse solvent method to prepare the delivery system,and the ability of different groups of β-LG/β-LG-CA to deliver Cur was analyzed and compared.It was found that the β-LG-CA complexes had a better embedding effect than β-LG,and the embedding rate of Cur was also significantly improved byβ-LG/β-LG-CA after ultrasound.The obtained nanoparticles were all less than 200 nm in diameter,with better dispersion of the system,reduced turbidity,and improved environmental stability.(3)The effect of β-LG-CA embeded Cur on the bioaccessibility and enzyme inhibition of Cur: In vitro digestion model and enzymatic reaction kinetics were constructed to analyze the release of Cur in different systems at different stages of digestion,demonstrating that β-LG-CA embedded Cur had a controlled release effect and effectively delivered more Cur to the intestine to exert its biological activity.Cur inhibited the enzymatic activity of α-amylase and α-glucosidase,and the type of inhibition was mixed.