Extraction Process Optimization And Structure Analysis Of Water-soluble Polysaccharides From Tillering Onion

In this paper,three methods,namely traditional water extraction,ultrasonic extraction,ultrasonic-microwave synergistic extraction of water-soluble polysaccharides from tillering onion,and optimization of the extraction process parameters,the nature of water-soluble polysaccharides extracted from the three methods were analyzed.Structural characterization and analysis of the antioxidant activity of water-soluble polysaccharides obtained from three methods were analyzed.By comparison,the water-soluble polysaccharides obtained from the ultrasonic-microwave synergistic method had the highest yield and the best antioxidant activity.Therefore,the water-soluble polysaccharides obtained from the tillering onion was extracted by ultrasonic-microwave synergistic method,and the monosaccharide composition was determined.The structure of the purified components was analyzed by NMR.The main findings are as follows: 1.Traditional water extraction process optimization of water soluble polysaccharides from tillering onionThrough single-factor tests and response surface tests,the optimum process for traditional water extraction of water-soluble polysaccharides from tillering onion was determined.When the ratio of liquid to material was 33:1(m L/g),the temperature was 76°C,and the time was 4hours,The highest yield of water-soluble polysaccharides from onion was(6.93±0.71)%.2.Ultrasound-assisted process optimization of water-soluble polysaccharides from tillering onionThrough single-factor tests and response surface tests,the optimum process for extraction of water-soluble polysaccharides from tillering onion was determined by ultrasonic assisted method: When the ratio of liquid to material was 26:1(m L/g),ultrasonic power was 400 W,and the time was 31 min,The highest yield of water-soluble polysaccharides from tillering onion was(9.88±0.59)%.3.Optimization of ultrasonic-microwave synergistic method for water-soluble polysaccharides from tillering onionThrough single-factor experiments and response surface tests,the optimal ultrasonic-microwave synergistic method for water-soluble polysaccharides from tillering onion was determined: when the ratio of liquid to material was 17:1(m L/g),ultrasonic power was 360 W,microwave power was 200 W,and the coordination time was 16 min,The highest yield of water-soluble polysaccharides from tillering onion was(11.92±0.13)%.4.Characterization and structural characterization of water-soluble polysaccharides from tillering onionThe results of solubility test showed that the water-soluble polysaccharides of the tillering onion were soluble in water;they were insoluble in organic solvents such as ethanol and anhydrous ether;and the results of the chromogenic reaction showed that the water-soluble polysaccharides of the tillering onion contained uronic acid and did not contain starch and phenols.Structural characterization results: Ultraviolet spectroscopy analysis showed that there were no interferences between nucleic acid and protein in water-soluble polysaccharides extracted from three kinds of methods;Fourier transform infrared spectroscopy showed that the water-soluble polysaccharides on the tillering onion have the characteristic absorption peaks of polysaccharides.High-performance gel permeation chromatography analysis showed that the compositional structure of water-soluble polysaccharides from tillering onion was not uniform.5.Determination of free radical scavenging capabilities of water-soluble polysaccharides from tillering onionThe water-soluble polysaccharides extracted from traditional onion by traditional water extraction method,ultrasonic assisted method and ultrasonic-microwave synergistic method has scavenging ability for DPPH radical,hydroxyl radical and superoxide anion radical,and is cleared in a certain concentration range.The effect presents a good dose-effect relationship.The antioxidant activity of the water-soluble polysaccharides extracted from the tillering onion by ultrasonic-microwave synergistic method was higher than that by the ultrasonic-assisted method and the traditional water extraction method.6.Extraction and purification of monosaccharides from water-soluble polysaccharides extracted from tillering onion by ultrasonic-microwave synergistic methodThe water-soluble polysaccharides extracted from the tillering onion by ultrasonic-microwave synergistic method was purified by DEAE-52 cellulose column and Sephadex G-100 to obtain the purified polysaccharides component.GC-MS analysis showed that the monosaccharide composition of the purified polysaccharides was mainly glucose and galacturonic acid,followed by arabinose,rhamnose,xylose,mannose,fructose,galactose and glucuronic acid.The structure of the purified polysaccharide was analyzed by H-NMR and C-spectrum.It was judged that the purified polysaccharides was glucopyranose linked by ?-(1?4)glycosidic bond and ?-(1?6)glycosidic bond.