| The pitaya stem is needed to be cut constantly during the pitaya growth process,the stem contains abundant plant polysaccharide,sterol,a variety of mineral and vitamin E,it can adjust human body function and enhance human body immunity.As a waste material abandoned in plant growth,the pitaya stems are rarely studied at home and abroad.A series of systematic studies on the extraction and purification of polysaccharides have not yet been reported,and have broad prospects for development and high potential value.In this thesis,the effect of different pretreatment methods on the polysaccharides and properties of red heart pitaya stems was studied.Study on the subcritical water extraction,ultrasonic microwave co-extraction and microwave-assisted extraction.The effect of extraction and performance of stem polysaccharides was finally determined by decoloring and deproteinizing polysaccharides extracted from subcritical water extracts of the stem stalks of polysaccharides with macroporous resin to determine the optimum decolorization and deproteinization process,and the yield and solubility of the products obtained from various treatment methods.Oil holding power,scanning electron microscopy,infrared spectroscopy,ultraviolet spectroscopy,composition of monosaccharides and in vitro antioxidant activity were measured and compared.1.Effects of the different pretreatment methods on the performance of stem polysaccharide are studied.Study on the influence of pitaya stem polysaccharide under drying in the sun,drying,vacuum drying,freeze drying four different pretreatment methods,study on the influence of the yield,state,solubility,oil holding capacity of pitaya stem polysaccharide under treating by drying methods.The results show that different drying methods have significant difference on polysaccharides.Among the four kinds of polysaccharides obtained by different pretreatment methods,the obtained polysaccharides of drying in the sun,drying,vacuum drying and freeze-drying are 10.04%,8.93%,15.90%and 19.53%respectively,solubility in water are 82.50%,86.00%,76.00%,70.50%,the oil holding capacity are 0.34,0.51,0.86,0.98 g/g.2.Extraction and optimization of polysaccharide from red pulp hylocereusundatus stem by subcritical water:The effects of liquid ratio,extraction time and extraction temperature on the yield of polysaccharide are investigated.By single factor and orthogonal experiment design,the conditions for extracting the stem polysaccharide by subcritical water are optimized.Subcritical water extraction conditions of pitaya stem polysaccharide as:extraction temperature 140 ? solid-liquid ratio 1:50,extraction time 25 min,under this condition of the process,the extraction rate of pitaya stem polysaccharide is 38.07±0.15%.3.Extraction and optimization of polysaccharide from red pulp hylocereusundatus stem by Ultrasonic-Microwave:The effects of liquid ratio,extraction time and extraction power on the extraction of polysaccharide are investigated,and the polysaccharide extraction process is optimized by single factor and orthogonal test design.The results showed that the best conditions of the ultrasonic microwave synergistic to extract polysaccharide from pitaya stem are:solid-liquid ratio 1:50,extraction time 200 s,extraction power 500 w,under this condition of the process,the extraction rate of pitaya stem polysaccharide is 19.16±0.23%.4.Extraction and optimization of polysaccharide from red pulp hylocereusundatus stem by Microwave Synergistic:The effects of liquid ratio,extraction time and extraction power on the extraction of polysaccharide are investigated,and the polysaccharide extraction process is optimized by single factor and orthogonal test design.The results showed that the best conditions of the microwave assisted extraction are:solid-liquid ratio 1:50,extraction time 240 s,extraction power 700 w,under this condition of the process,the extraction rate of pitaya stem polysaccharide is 17.29±0.14%.5.Effects of the different extraction methods on the performance of stem polysaccharide are studied.The polysaccharide yield,solubility,oil holding power,electron microscopy,infrared spectrum,uv spectrum,monosaccharide composition and antioxidant activity of three different extraction methods are compared.By comparison,the results show that the stem polysaccharide extracted by subcritical water is the best.The color of HSP-S is beige white,the solubility is 99.50±0.15%,the oil holding capacity is 1.48±0.12g/g,and the cation exchange capacity is 105.00±2.00mmol/g.Scanning electron microscopy observes its surface is porous and the structure was intact,the absorption peak of polysaccharide is determined by characteristic infrared spectrum scanning,ultraviolet spectra shows no protein and nucleic acid,and has good antioxidant activity in vitro.The composition of HSP-S monosaccharide is sugar,glucose,mannose,rat lee glucosamine,glucuronic acid,galactose,galacturonic acid,amino galactose,arabinose,and its relative mole ratio is 0.26:1.47:1.63:0.04:0.24:6.25:0.71:0.04:6.58.When HSP-S polysaccharide concentration is 5 mg/mL,the free radical clearance rate of DPPH is 58.89%,and the removal capacity of ·OH is 62.66%,the reduction force and total antioxidant capacity are good.6.Optimization of decolorization and deproteinization technology by macroporous resin:The process optimization of polysaccharide decoloration and protein removal in the pitaya stem polysaccharide and the polysaccharide property changes in the pitaya stem before and after decoloration by macroporous resin was investigated.This study uses the effect of polysaccharide decolorization and the polysaccharide retention rate as evaluation index,the best decolorizing resin is selected from 6 kinds of macroporous resin,based on single factor test,the process conditions of decolorization and protein removal of macroporous resin are optimized through orthogonal experiment,and the antioxidant activity was studied.The results showed that the effect of AB 8 resin is the best,the best process conditions is:resin dosage is 0.6 g/mL,temperature 60?,pH value of 5,time for 2 h.On this condition,the decolorization rate,protein removal rate and polysaccharide retention rate are 76.51%,88.29%and 83.47%respectively.After resin treatment,the solubility of polysaccharides increases from 99.50±0.15%to 99.82±0.18,the solubility is slightly increased,the oil holding capacity increases from 1.48±0.12g/g to 1.52±0.25g/g,the cationic exchange capacity increases from 105.00±2.00 mmol/g to 125.00±1.78mmol/g.The antioxidant activity test results show that the pitaya stem polysaccharide has a certain antioxidant capacity,and its antioxidant activity has been improved after treatment by macroporous resin. |
PDF Full Text Request