Preparation,Characterization And Control-release Of Property Of Peach Gum Polysaccharide Hydrogel

Peach gum and Auricularia polytricha are natural tonics,and the polysaccharide components of peach gum and Auricularia polytricha have been well proved that have many biological functions.In China,peach gum and Auricularia polytricha resourses are abundant,which have a great commercial value.Additionly,Probiotic bacteria are widely used in functional food and beverage products.However,probiotics are sensitive in various environment during the production process and human digestive process.Polysaccharides hydrogel can effectively protect the physiological activity of probiotc bacteria,therefore they have been widely applied in the food industry.In this paper,the polysaccharide of peach gum(PGP)was extracted and purified,and the structure was analyzed.Secondly,we used an emulsification polymerization to formulate a stable structural PGP hydrogels cross-linked by Fe3+.And then,Auricularia polytricha polysaccharide(APP)was introduced to preparea of a semi-interpenetrating networks(semi-IPN)hydrogel(PGP-APP semi-IPN hydrogel),the characterization of hydrogel and the mechanism of the cross-linking was explored.Further,Lactobacillus plantarum CICC20264 and Lactobacillus salivarius CICC23174 was encapsulated by the hydrogels.In addition,the acid resistance and bile salt tolerance of encapsulated probiotics were studied.The release and survival rate of probiotics encapsulated in hydrogels at the simulated gastrointestinal tract was also studied in vitro.The main contents are as follows:1.The purificated gum polysaccharide PGP-1 has a molecular weight of 5.16 x 106 Da,PGP-1 is composed of Man,Rha,GalA,Glc,Gal,Xyl with a mole ratio of 0.7:1.6:2.4:1.3:32.9:61.1.According to the results of Fourier infrared spectrum,methylation analysis and nuclear agnetic resonance spectrum,PGP-1 was identified to have a repeated(1?4)-linked?-D-Xylp core,(1?2,4)-linked ?-D-Xylp and(1?3)-,(1?6)-linked ??D-Galp in the main chain.And side chains composed of a terminal Glcp,(1?3)-linked ?-L-Rhap and(1?4)-linked a-D-GalpA residues.In addition,the mannose residues also exist in the branch chain.2.The hydrogels were prepared by the strong affinity between Fe3+and carboxylic group of peach gum polysaccharide,PGP hydrogel and PGP-APP semi-IPN hydrogels were characterized,the size distribution of hydrogel particle is 50-100 ?m,and hydrogels are negative charged,Mossbauer spectroscopy and Infrared spectrometer analysis results show that the iron ion in formed hydrogels is trivalent,Fe3+ and COO-is connected by bridging binding.Scanning electron microscopy(SEM)show that the many holes existed on the surface of PGP hydrogel,and PGP-APP semi-IPN hydrogels showed more tight and wrinkled structure,so the swelling degree of PGP hydrogel was obviously higher than that of PGP-APP semi-IPN hydrogel.As the increase of pH and salt ion intensity,the zeta potential of the hydrogels increased,the swelling ratio of hydrogels increased and decreased,respectively.In alkaline environments hydrogels degraded gradually.3.Using PGP hydrogel and PGP-APP semi-IPN hydrogel to encapsulate the L.plantarum CICC20264 and L.salivarius CICC23174 successfully,with an encapsulation rate up to 80%.The acid and bile salt tolerance of encapsulated L.plantarum CICC20264 and L.salivarius CICC23174 was significantly improved,the survival rate was researched up to 80%and 70%,respectively.In simulated gastrointestinal digestion experiment,PGP hydrogel and PGP-APP semi-IPN hydrogels had certain pH stability and mechanical strength.The encapsulated L.plantarum CICC20264 and L.salivarius CICC23174 could withstand the simulated gastric juice,duodenum and gastrointestinal movement,which would maintain a high quantity of living bacteria.At the same time,the PGP hydrogel and PGP-APP semi-IPN hydrogel has a relatively high pH-sensetive and good intestinal soluble,and the bacteria would be released completely at the sitimulated colon condition,which reached to 7 log10 cfu/mL,the survival rate of the bacteria was significantly higher than that of the unencapsulated bacteria.Compared to PGP hydrogels,the release and survival rate of L.plantarum CICC20264 and L.salivarius CICC23174 encapsulated in PGP-APP semi-IPN hydrogel,which showed that the semi-interpenetrating networks structure provided a better protection for L.plantarum CICC20264 and L.salivarius CICC23174.