| Pumpkin has high edible and medicinal value.Pumpkin polysaccharide has hypoglycemic,hypolipidemic and antihypertensive activities.Flaxseed oil was rich in unsaturated fatty acids and has hypoglycemic and hypolipidemic activities,but it was easily oxidized and damages flavor and nutrients.In order to strengthen the synergistic effect of pumpkin polysaccharide in reducing blood sugar and blood lipid and protect the active nature of linseed oil,microcapsules were prepared with pumpkin polysaccharide and soybean protein isolate as composite wall materials and linseed oil as core materials,and the morphology,physical and chemical properties and stability of the prepared microcapsules were tested.The main research contents and results were as follows:Pumpkin polysaccharide was extracted by enzymatic method combined with water.Based on the investigaion of the influence of three factors,enzymolysis time,enzymolysis temperature and enzymolysis p H on pumpkin polysaccharide yield,response surface methodology was used to determine the optimal extraction conditions of pumpkin polysaccharide:enzymolysis temperature 45℃,enzymolysis time 170 min,enzymolysis p H5.5,at which time pumpkin polysaccharide yield was 26.29±0.31%.Qualitative and quantitative analysis was carried out on the extracted substances by HPLC method.The results showed that the composition of the extracted material contained nine monosaccharides composed of Mannose,Ribose,Rhamnose,Glucuronic Acid,Galacturonic Acid,Glucose,Galactose,Xylose and Arabinose.The monosaccharide contents were 0.31,0.29,0.13,1.22,0.34,129.51,0.76,1.75,1.84 mg/g,respectively.In the experiment,pumpkin polysaccharide microcapsules was prepared by emulsion polymerization method.A single factor test was used to investigate the effects of compound wall materials（soybean protein isolate and pumpkin polysaccharide）ratio,core wall material ratio,and solid content on the embedding rate.The response surface method was used to optimize and determine the optimal process parameters:the core-wall ratio of 1:1.97,the ratio of core wall materials 1:2.09,and the amount of solid added 25.47%.The microcapsule embedding rate was 74.32±0.81%after optimizing the prediction model results and carrying out three repeated verification tests,which was in good agreement with the predicted value.The physical and chemical properties of Pumpkin polysaccharide composite wall material linseed oil microcapsules can be determined as follows:the water content of the microcapsules was 3.80%,the solubility was 76.30%,and the particle size was concentrated between10.82-179.9μm,showing a normal distribution;scanning electron microscopy showed that it was round and no crack was found on its surface;the results of FT-IR showed that the composite wall material composed of soybean protein isolate and pumpkin polysaccharide had better embedding effect on linseed oil.Taking the retention rate as an index,investigate the storage stability of linseed oil and its microcapsules under different environmental conditions（temperature,light,O2）.The results showed that the retention time of flaxseed oil could be prolonged by microencapsulation,the retention rate of microencapsulation was higher at 4℃than 25℃,higher under oxygen-free condition than under aerobic condition,and higher under non-light condition than under light condition.Therefore,pumpkin polysaccharide microcapsules should be stored under low temperature,oxygen-free and light-proof conditions.The results of in-vitro simulation experiment of flaxseed oil microcapsule showed that the release rate of core material in stomach was 34.98%,and the cumulative release rate in intestine was 80.83%,which indicated that flaxseed oil microcapsule had good slow-release characteristics and released most of oil effectively in the intestine. |
