Study On Extraction,Structural Characterization And Application Of Polysaccharides From White Asparagus Processing Waste

In recent years,the planting area and processing industry of asparagus have developed rapidly in China,and the utilization rate of white asparagus processing waste is not high,resulting in certain environmental pollution and waste of resources.In this paper,the best process of ultrasonic assisted extraction and steam explosion pretreatment of soluble polysaccharide from white asparagus processing waste was determined by single factor test,orthogonal test and response surface optimization.The purification and analysis were carried out,and the preliminary structural characteristics,antioxidant activity and the preparation of solid beverage were studied.The main findings are as follows:1. By using single factor test and orthogonal test,the optimal process of asparagus officinalis processing waste polysaccharides of ultrasound-assisted extraction were determined as follows:ultrasonic power 300 W,extraction temperature 60?,extraction time 30 min,ratio of material to liquid 1:30.Under this condition,the highest yield of soluble polysaccharides from white asparagus processing waste could reach 8.12%.By using single factor test and response surface optimization,the optimal process of steam explosion extraction of asparagus processing waste polysaccharides were determined as follows:particle size 30 mesh,steam explosion time 128 s,steam explosion pressure1.50 MPa.Under this condition,the yield of asparagus polysaccharide reached 8.86%.2. The polysaccharides were purified by Sevage and column chromatography,and its molecular weight,crystal characteristics,monosaccharide composition and apparent morphology were studied by gel permeation chromatography,XRD,SEM,ion chromatography and infrared spectroscopy.The results showed that the degree of esterification of soluble polysaccharides was 24.62%;the weight average molecular weight was 4.3292×10⁴Da;It has less crystalline polysaccharides and is semi-crystalline;its surface is rugged,with wrinkles,and its appearance is loose and irregular geometric structure;mainly composed of rhamnose?7.7%?,arabinose?10.0%?,galactose?27.5%?,glucose?2.0%?,xylose?17.0%?,galacturonic acid?35.9%?,etc.It is confirmed that the polysaccharides has typical infrared absorption characteristics of saccharides,which contains pyranose as the main chain and contains uronic acid.3. The polysaccharides from white asparagus processing waste have certain antioxidation activity.The scavenging ability and reducing power of DPPH free radical and OH free radical are lower than V_C.The DPPH free radical scavenging ability of ascorbic acid is about 336 times of white asparagus polysaccharides in the experiment,and the OH free radical IC₅₀of polysaccharides are lower than V_C.When the concentration was more than 3 mg/m L,the scavenging effect was close to V_C,but the reducing ability was significantly lower than V_C.The reducing power of polysaccharides per gram of asparagus was equivalent to 480.20 mg reducing power of ascorbic acid.4. The preparation of antioxidant solid beverage is a kind of technical application.By single factor test and orthogonal test,the optimal ratio of antioxidant solid beverage of asparagus processing waste polysaccharides is obtained as follows:asparagus polysaccharides 0.3 g,xylitol 2.0 g,citric acid 0.02 g,pectin 0.2%.Under this condition,the average sensory score of the three repeated experiments was 9.52,which was higher than the result of orthogonal experiments.Through sensory evaluation,physical and chemical analysis and microbial indicators,the antioxidant solid beverage of asparagus polysaccharides was comprehensively evaluated.The results showed that the product can meet the requirements of various indicators of solid beverage and has certain drinking value.