Study On The Structure Modification Of Laminaria Japonica Polysaccharides And Its Properties

Fucoidan and sodium alginate are the two kinds of Laminaria japonica polysaccharide.Fucoidan content rarely in kelp,but it has good anti-tumor,antiviral,anti-inflammatory and other biological activity.The molecular weight of natural fucoidan is very high,and it is difficult to be absorbed by human body,which restricts its biological activity.Sodium alginate content is rich,do simple additive used in the food.The structure contains a large number of carbonyl,which can occur Maillard reaction with protein and amino acid.Studies have shown that maillard reaction can get good solubility and emulsification and antioxidant product.This paper extracts these two kinds of polysaccharide from kelp,according to the structure characteristics of two kinds of polysaccharide modifying with its structure and properties respectively.This dissertation is mainly consisted of three sections described as follows:1 The study on the structure modification of fucoidan and its properties.The method of ultrasonic–assisted hydrogen peroxide degradation was used in this paper,and determine to the variation in the relative viscosity of sugar in the process of degradation.Preparation of the molecular weight by ultrafiltration membrane separation>50 kDa and<50 kDa two low molecular weight component ingredient fucoidans,analysis of fucoidan structure before and after degradation by infrared spectra in the process of experiment.Meanwhile,the degradation rate of polysaccharides and sulfate group retention were determined as well as the antibacterial activity on staphylococcus aureus.The experimental results showed that after two-hours degradation,the relative viscosity of sugar has leveled off and after four hours,the relative viscosity of sugar no longer changes.Before and after degradation,fucoidan natural structure did not change significantly.After two hours degradation,the rate of hydrolysis of polysaccharides was 30.73%,sulfate group retention rate of low molecular weight fucoidans was 24.71% and the diameter of inhabiting circle for staphylococcus aureus was 28 mm,the antibacterial effect of the equivalent of 0.05 mg/mL of chloramphenicol.2 The study on the preparation of sodium alginate/soy protein isolate copolymer which by Maillard reaction and its properties.In this paper,the sodium alginate and soy protein isolate were used as the main materials,to prepare sodium alginate-soy protein isolate copolymers by the dry-heat reaction.In single factor experiments,the effects of reaction temperature,reaction time and ratio,which based on the browning index and the degree of graft of copolymer,were studied.The solubility,emulsifying ability,emulsion stability and oxidation resistance of the copolymer prepared at the optimum conditions also were studied in this paper.The experimental results showed that the optimum conditions for the preparation of copolymer were: reaction temperature 60?,reaction time 6 d,SA:SPI=3:1(w/w)according to a stable browning index and maximum degree of graft.The solubility increased 16.4%,emulsifying ability increased 4.8 times in comparison with soy protein isolate and the ABTS·+ radical-scavenging activity of copolymer were significantly improved in comparison with sodium alginate.3 The study on the preparation of sodium alginate/amino acid copolymer which by Maillard reaction and its properties.In this paper,the sodium alginate,Glycine and lysine were used as the main materials,to prepare sodium alginate-amino acid copolymers by the dry-heat reaction.The effects of reaction temperature,reaction time and ratio,which based on the browning index and the antioxidant activity of copolymer,were studied.Meanwhile,to monitored the degree of Maillard reaction by molecular fluorescence analysis of the copolymer.The experimental results showed that: the optimum conditions for the preparation of sodium alginate-lysine copolymer were: reaction temperature 100?,reaction time 36 h,SA: lysine =1:1(w/w),the optimum conditions for sodium alginate-Glycine copolymer were: reaction temperature 100?,reaction time 96 h,SA: glycine =3:1(w/w).The antioxidant activity of copolymers with dose dependent,when the copolymer concentration reached 10 mg/mL,the ABTS·+ radical-scavenging activity of sodium alginate-lysine copolymer reached 83.6%,and the sodium alginate-Glycine reached 100%.