Extraction, Properties And Applications Of Active Substances In Spirulina

Spirulina belongs to prokaryotes,which is a lower plant.A large number of studies have shown that spirulina is a pure natural food rich in various nutrients.The protein content of its protein dry powder is over 60%,contains 8 kinds of human essential amino acids,and the content of nutrients such as vitamins,minerals and trace elements are also very rich.Studies have shown that polysaccharide from spirulina platensis is a natural health food,which has the functions of anti-oxidation,improving human immunity and assisting in the treatment of diseases.In addition to the efficacy of medical care,spirulina has a very important application value in many fields,such as food additives,cosmetic beauty,breeding,environmental protection and so on.In this study,spirulina powder was used as the raw material to extract polysaccharide and coumaric acid of spirulina.The inhibitory effect of two substances on tyrosinase was studied by enzyme kinetics,and the effect of the free radical scavenging on the free radical of DPPH and the application of spirulina Polysaccharide in fresh cut apple were studied systematically,and the main research was made.The contents and experimental results are as follows:（1）The polysaccharide of Spirulina was obtained in this study,and the inhibitory effect of polysaccharide inhibitor on the activity of tyrosinase and the scavenging ability to the free radical of DPPH were investigated by enzyme kinetics.The results showed that the optimum extraction process was as follows:the extraction time was 2 h,the ratio of liquid to solid was 40mL/g,the extraction temperature was 90℃,and the pH value was 8.The inhibitor could significantly inhibit the activity of tyrosinase and its IC₅₀=1.1936 mg/mL;the inhibition process of tyrosinase was reversible and inhibited.The inhibition constant was K_I=0.5442 mg/mL,and it has a good scavenging effect on DPPH free radical,its IC₅₀=0.4635 g/L.The scavenging capacity was 83.24%of L-ascorbic acid at the same concentration.（2）The coumaric acid was obtained in this study,and the inhibitory effect of coumaric acid on tyrosinase was studied by enzyme kinetics.The results showed that the optimum extraction parameters were:the liquid to solid ratio was 20 mL/g,the alcohol volume fraction was 65%,the extraction time was 3 h,the pH value of was 6.Coumaric acid has an obvious inhibitory effect on tyrosinase,and its IC₅₀=55 mmol/L;tyrosinase inhibition process was reversible mixed inhibition,the inhibition constant was K_I=0.2211 mg/mL.Coumaric acid has a good scavenging effect on DPPH free radicals,IC₅₀=0.1554 g/L.（3）The effect of Spirulina Polysaccharide on preservation of fresh-cut apple slices was studied.The results showed that Spirulina Polysaccharide could keep the content of protein,ascorbic acid and total phenol in apple slices at a high level,inhibit the activity of PPO,and enhance the activity of SOD and POD,thus controlling the peroxidation of fresh-cut fruits and vegetables,reducing the browning rate,keeping the quality of food and prolonging the shelf life.