Study On Extraction Of Castanea Henryi Polysaccharide And Its Physicochemical Properties

Castanea henryi is a kind of natural green food,which rich in nutritional value and health effects.This paper intends to extract polysaccharide from Castanea henryi,remove protein from the Castanea henryi polysaccharide solution and determine some physicochemical properties.In order to provide a theoretical basis for the development of new varieties of polysaccharide beverage industry in the future,the study was carried out.(1)Polysaccharide was extracted from the raw material--Castanea henryi by ultrasonic assisting hot water extraction method and it’s extraction rate was the main index.The O2-· scavenging rate was used as the auxiliary index.In this paper,the response surface was used to analyze the impact of liquid-solid ratio,ultrasonic time and the water bath time to the extraction rate of Castanea henryi polysaccharide.The results showed that these three single factors had significant influence on the extraction rate of Castanea henryi polysaccharides.The optimum extraction conditions were:the solid-liquid ratio 47:1,ultrasonic power 130 W,ultrasonic time 34 min,water bath temperature 70℃,water bath time 1.3 h.Under these conditions,the extraction rate of Castanea henryi polysaccharides was 12.40%.(2)Taking the protein clearance rate and the polysaccharide retention rate after treatment as indexes,this paper discussed the protein clearance effects of four methods.The results showed that:Trichloroacetic acid method>hydrochloric acid method>enzymatic method>Sevag method.Trichloroacetic acid method could effectively remove the protein and make the loss of polysaccharide less.When the amount of added trichloroacetic acid was 3%,the removal rate of protein was about 92.56%,and the retention rate of polysaccharide was about 85.31%.But in the subsequent operation process,it was difficult to complete separate the trichloroacetic acid with polysaccharide.Therefore,in this study,hydrochloric acid method was chosen as the best method of removing protein.In the condition of pH 3.0,the protein clearance rate was 87.29%,the retention rate of polysaccharide was 75.00%.(3)The antioxidant and rheological characteristics of the Castanea henryi polysaccharide were studied.The results showed that with the increase of the concentration of polysaccharide,the scavenging ability of Castanea henryi polysaccharides on DPPH·and ABTS+ also increased,showing a good dose effect relationship.The rheological type of Castanea henryi polysaccharides,the effect of polysaccharides,concentration,the adding amount of sucrose,Na+and Ca2+and the change of pH on the rheological property of Castanea henryi polysaccharides were also studied.The experimental results showed that the polysaccharide solution of Castanea henryi had shear thinning phenomenon,showing a characteristic of non-Newtonian fluid(or pseudoplastic fluid).The impact of the changes of pH on apparent viscosity was very obvious.Especially in alkaline,the apparent viscosity was greatly reduced.The adding of sucrose,Na+and Ca2+into Castanea henryi polysaccharide had different degrees of impact on the solution viscosity.And the effects were dependent on the addition of sucrose,Na+and Ca2+,but they could not change the type of the fluid.