Preparation,Characterization And Application Of Hawthorn Pectin Hydrogel

Hawthorn pectin has a unique structure,a high proportion of homogalacturonan（HG）domain,high molecular weight,excellent viscosity,safety,biocompatibility and biodegradability.These properties make it unique in the pectin,give it excellent rheological and gel properties,which has the potential to be widely used in many fields.In addition,hawthorn pectin has outstanding hydrophilicity and can be used in the synthesis of hydrogel materials.Based on this,a series of hydrogel was prepared from hawthorn pectin,the physical properties and biocompatibility of synthetic hydrogel were studied.In addition,soybean isolate protein（SPI）was introduced into the system to optimize the hydrogel performance,and whether the protein-pectin composite hydrogel could combine their respective advantages to form a more stable interpenetrating network（IPN）,so as to have efficient entrapment and delivery ability.Finally,the effects of different treatment on the gel properties and the release behavior were studied.The main contents and results of this paper were as follows:（1）Extraction of low methoxy hawthorn pectin and preparation of hydrogelIn this study,low methoxy hawthorn pectin（LMHP）with high molecular weight,low side chain content,high HG configuration,high thermal stability and sensitivity to Ca²⁺was obtained by hot water extraction and alkaline de-esterification.According to this characteristic,hawthorn pectin-based single hydrogel was designed and synthesized,and the effects of different pectin concentration,Ca²⁺concentration and p H were studied.The results showed that the hydrogel hardness was more than 20 g and the shear stress was strong under the condition of p H 3.5,2.5%pectin concentration and 2mmol/L Ca²⁺concentration.Fourier transform infrared spectroscopy（FTIR）confirmed that hydrogen bonding was the key to maintain the network structure of a single hydrogel.Swelling test showed that LMHP-based hydrogel had good swelling in simulated gastrointestinal fluid,and its microstructure pores were uniform and dense.Therefore,hawthorn pectin could be used to prepare three-dimensional nano-hydrogel with good mechanical properties,swelling degree and uniform network structure,which verified its potential as a new type of hydrogel raw material.（2）Preparation and characterization of SPI/LMHP composite hydrogelThrough interpenetrating network technology and turbidity test,SPI was introduced into the system based on hawthorn pectin,and the SPI/LMHP interpenetrating network hydrogel（SHIH）was successfully designed and constructed.The composite hydrogel had the most stable state when the mixture ratio of protein-pectin was 2:1,p H was 3.35,and the Ca²⁺concentration was 15 mmol/L.The porous morphology of SHIH was uniformly distributed by scanning electron microscope（SEM）,which was obviously smaller than that of single pectin hydrogel.In addition,mechanical properties test showed that SHIH had excellent hardness and elasticity,which provided a structural basis for curcumin packaging.The results of entrapment experiment showed that curcumin embedded in SHIH could pass through the simulated gastric environment and released slowly in simulated intestinal fluid,the released curcumin still had good activity and antioxidant capacity.（3）Effect of ultrasound-microwave technology on gel properties and bioavailability of SHIHIn this study,composite hydrogel was prepared by ultrasonic-microwave technology.The results of low frequency nuclear magnetic resonance（LF-NMR）and water holding capacity（WHC）tests showed that under the action of ultrasound and microwave,the water retention capacity of SHIH system was significantly improved,and the proportion of bound water in the gel structure increased gradually.After ultrasonic-microwave treatment,the gel strength of SHIH（UMSHIH）increased to 347 g,which had a denser network structure,showed better resistance to adverse environment,could better maintain the antioxidant activity of curcumin and improved its absorption and utilization in the intestinal tract.The release of curcumin in UMSHIH fitted well with Korsmeyer-Peppas model,which showed the drug release caused by hydrogel swelling.The SHIH system explored in this paper had a stable three-dimensional network structure,excellent mechanical properties and biocompatibility,and played a significant role in protecting functional active components.It provided a theoretical basis for drug entrapment and delivery as an edible carrier,and offered experimental data support for its further use as a high-quality drug carrier.