Preparation And Microencapsulation Of Hydrilla Verticillata Royle Polypeptide-ferrous Chelate And In Vitro Digestion And Uptake

Hydrilla verticillata Royle is a large freshwater submerged plant of Hydrilla verticillata Royle genus,hydrocharitaceae and it is often used for feed and water restoration,but the comprehensive utilization degree is low.Therefore,it is of great significance to develop and utilize Hydrilla verticillata Royle with high added value.Ferrous is an essential trace element in human,the existing inorganic and organic ferrous supplements have side effects on gastrointestinal,and the production cost of amino acid ferrous supplements is high,while polypeptide-ferrous chelate has been proved to have good functional characteristics.With Hydrilla verticillata Royle crude protein content was higher and the high value utilization degree was low,in this paper,Hydrilla verticillata Royle polypeptide-ferrous chelate was prepared by chelating Hydrilla verticillata Royle polypeptide with Fe²⁺,and then microencapsulated,finally,its digestion characteristics in simulated gastrointestinal tract and ferrous uptake characteristics in Caco-2 cells were explored,which laid the foundation for the high-value resource utiliztion technology of Hydrilla verticillata Royle.The main condusions were as follows:（1）Preparation and characteristic of Hydrilla verticillata Royle polypeptide-ferrous chelate:the optimal preparation conditions were as follows:30℃,p H 7.0,30 minutes,mass ratio of polypeptide to ferrous chloride 8:1,addition of ascorbic acid 4.5 mg/m L,and chelating rate of 64.53%.The results of UV-vis and FT-IR spectra showed that the Hydrilla verticillata Royle polypeptide-ferrous chelate was successfully prepared,and the amino,carboxyl,hydroxyl and amide bonds in the Hydrilla verticillata Royle polypeptide may bind to Fe²⁺in ionic and covalent ways.SEM analysis showed that the Hydrilla verticillata Royle polypeptide-ferrous chelate was spherical,XRD analysis showed that it had good solubility,TG analysis showed that it had good thermal stability,acid and base stability analysis showed that it was not acid resistant.（2）Microencapsulation and characteristic of Hydrilla verticillata Royle polypeptide-ferrous chelate:the optimal preparation conditions of sodium alginate（SA）-chelate microcapsules were as follows:SA concentration 1%,Ca Cl₂concentration 2%,core-wall ratio（chelate:SA）1:2,curing time 30 minutes,embedding rate 64.01%.The optimal conditions for preparing CS-SA-chelate microcapsules by embedding SA-chelate microcapsules in chitosan（CS）were as follows:CS concentration 1.5%,CS solution p H 4.0,embedding rate 47.07%.FT-IR analysis showed that CS firmly embedded the SA-chelate microcapsules through electrostatic interaction,and CS-SA-chelate microcapsules were obtained,SEM analysis showed that CS-SA-chelate microcapsules had no cracks on the surface,XRD analysis showed that CS-SA-chelate microcapsules had good solubility,TG analysis showed that the thermal stability of CS-SA-chelate microcapsules was improved.（3）Comparative analysis of CS-SA-chelate microcapsules,SA-chelate microcapsules,Hydrilla verticillata Royle polypeptide-ferrous chelate,commercial ferrous sulfate and ferrous lactate in vitro simulated fgastrointesinal digestion,the digestive stability was CS-SA-chelate microcapsules>SA-chelate microcapsules>ferrous sulfate>ferrous lactate>Hydrilla verticillata Royle polypeptide-ferrous chelate.The Caco-2 cells uptake experiment of CS-SA-chelate microcapsules,ferrous sulfate and ferrous lactate simulated gastrointestinal digestion showed that the Hydrilla verticillata Royle polypeptide-ferrous chelate could promote the absorption of Fe²⁺.