Preparation And Performance Research Of Chito-oligosaccharides From Fly Maggot

Fly Maggot was used as raw material to prepare chitin,and deacetylated to prepare chitosan.Then,chitosan was degraded to prepare COS by the enzyme,and the antibacterial and antioxidant activities of COS was detected.The main results are as follows:（1）Preparation of Fly Maggot chitosan.Fly Maggot chitin was obtained through degreasing,deproteinization and decalcification from Fly Maggot.The deacetylation reaction was performed with an ethanol-water system to prepare chitosan with a high degree of deacetylation（D.D.=89.68%）,which greatly reduced the amount of NaOH.The structure of Fly Maggot chitosan,Shrimp Shell chitosan,and Commercial chitosan was compared by Infrared Spectroscopy.The results showed that the structures of three chitosan were almost identical.（2）Enzymatic degradation of Fly Faggot chitosan.Papain,bromelain,trypsin,pepsin,α-amylase,complex cellulase and pectinase were used to degrade chitosan.The results showed thatα-amylase and bromelain were the best,and the reducing sugars were 2.894 mg/mL and2.922 mg/mL respectively.TLC analysis showed that bromelain group contained only one non-COS component and theα-amylase group contained various COS components.The RSM of the chitosan degradation conditions was optimized,and the antibacterial activity was used as an indicator.The results showed thatα-amylase had the best degradation effect when the amount of enzyme was 7.95%,the concentration of substrate was 1.17%,and the reaction time was 2.91 h.The antibacterial activity of degradation product(?OD₆₂₅)reached0.421±0.010.（3）Preparation and analysis of Fly Maggot COS.The 60.0%ethanol precipitated COS（60.0%EP-COS）,75.0%ethanol precipitated COS（75.0%EP-COS）,87.5%ethanol precipitated COS（87.5%EP-COS）and 87.5%supernatant COS（87.5%S-COS）was obtained by the ethanol fractionation precipitation and Bio-Gel P-2.The four-kind COS were orange powder,brown powder,orange powder and light yellow powder respectively,and the molecular weights were 2794.84 Da,1736.56 Da,1093.39 Da,and 1169.51 Da,respectively.（4）Antibacterial and Antioxidant activities of Fly Maggot COS.Comparing the antibacterial and antioxidant activities of 60.0%EP-COS,75%EP-COS,87.5%EP-COS and87.5%S-COS.The results showed that 75.0%EP-COS and 87.5%EP-COS had the good antibacterial activity,and the MIC was 10.0 g/L and 5.0 g/L respectively.60.0%EP-COS and87.5%S-COS had no obvious antibacterial activity.Antixidant results showed that the DPPH and·OH radical scavenging rates were 87.5%EP-COS,75.0%EP-COS,60.0%EP-COS,and87.5%S-COS,respectively.When concentration of COS was 2000μg/mL,the DPPH radical scavenging rates were 91.09%,86.83%,67.74%,and 51.41%,respectively.And the·OH radical scavenging rates were 36.83%,35.65%,24.12%and 21.34%,respectively.