Extraction Optimization Of Chlorococcum Sp. GD Polysaccharide And Preparation And Properties Of Chitosan/Chlorococcum Sp. GD Polysaccharide Composite Films

Chlorococcum sp.GD is a kind of lower prokaryote belonging to green algae.It has extremely rich nutritional value,algae cells contain proteins,polysaccharides,unsaturated fatty acids and mineral elements,it has great development prospects.According to reports in the literature,algae polysaccharides has the functions of delaying aging,anti-virus,anti-tumor and anti-thrombosis,enhancing anti-radiation ability,lowering blood sugar and regulating body immunity.Moreover,polysaccharides have unique physical and chemical properties such as safety,non-toxicity and biodegradation,and have been applied in food,medicine and other fields.In this paper,the extraction conditions of Chlorococcum sp.GD polysaccharides and the preparation and properties of c chitosan / Chlorococcum sp GD polysaccharides composite films were studied in depth.The main experimental results are as follows:The optimum extraction conditions for extracting Chlorella vulgaris polysaccharides by hot water extraction were studied.The single factor experiment was carried out with the extraction time,ratio of material to liquid and extraction temperature as the influencing factors,select the three optimal levels of each factor to design the response surface optimization experiment again,analysis of the main factors affecting the extraction rate of polysaccharides,and the optimal extraction conditions were obtained.The results show,when the extraction temperature is 80 °C,the extraction time is 3 h,and the ratio of material to liquid is 1:26 g/m L,the experimental conditions are optimal,the extraction rate of Chlorococcum sp.GD polysaccharides can reach 4.21%.In order to develop a composite active packaging film with good freshness-keeping effect,in this paper,different doses of Chlorococcum sp.GD polysaccharides were composited with chitosan to make an edible active film,then its physical properties(thickness,density,solubility,swelling ratio,opacity,water vapor permeability),mechanical properties(tensile strength,elongation at break)were measured,and its structure was characterized(X-ray diffraction analysis,fourier transform infrared analysis,atomic force microscope scanning and scanning electron microscope),the scavenging activity of the composite films on DPPH free radicals was investigated.The results showed that the addition of 0.5% to 1% of Chlorococcum sp.GD polysaccharides can increase the thickness,density,solubility,swelling ratio and DPPH scavenging ability and reduce the water vapor permeability of chitosan composite film.When 0.5% Chlorococcum sp.GD polysaccharides were added,there were no significant differences in opacity,tensile strength,and elongation at break.It can be seen that the Chlorococcum sp.GD polysaccharide as a natural active substance can form a compact structure with the chitosan film,and the prepared composite film has good moisture resistance and oxidation resistance,and is favorable for the improvement of the fresh-keeping property.