|
Chitosan is usually prepared from chitin (2 acetamido-2-deoxyβ-1, 4-D-glucan) and chitin has been found in a wide range of natural sources (crustaceans, fungi, insects, mollusks etc.)Firstly, the proximate composition of squid raw materials was analyzed, and chitin was extracted. The factors those affect chitin deacetylation such as the alkaline concentration, reaction time, temperature were studied and high-molecular weight of chitosan was prepared. The yield for Chitin was about 24% -25%, and for chitosan was 74 -81%.Secondly, the physicochemical properties of squid chitosan were studied. First, the physicochemical properties such as ash content, moisture content, deacetylation, molecular weight, viscosity, fat and water binding capacity of the obtained chitosans were compared. The result showed that the chitosan from squid had low ash content and relatively large molecular weight, around 1,000 kDa. From IR spectra, the structures of squid chitosan and crab Chitosan had significant differences, and showed that the chitosan from squid wasβ-chitosan.Thirdly, the antibacterial activity of squid pen chitosan was analyzed. Antibacterial activities of two chitosans with different molecular weights (Mws) and same DD were examined against Escherichia coli (E.coli), Aspergillum niger , Saccharomyces cerevisiae, and Staphylococcus aureus, the growth was almost inhibited by chitosan treatments, in particular high molecular weight chitosan.Both molecular weight and concentration of chitosan have critical effects on the inhibition of growth of microorganisms.The minimum inhibitory concentration (MIC) of chitosan ranged from 0.02% to 0.05% depending on the microorganism.Chitosan from Squid pens and from Crab were hydrolyzed using Cellulase and Lipopan. The effect of different temperature, pH systems and enzyme concentration on the hydrolysis of chitosan reaction was studied.It was found that the optimum temperature of hydrolysis was 45℃and the optimum pH was 4.7 with optimum enzyme concentration of 15mg/ml.Different hydrolysis times resulted in chitosan with different Viscosity, Glucosamine content and molecular weights. At 40℃, the Viscosity of chitosan decreased rapidly during the first hours. It was also found that the molecular weight of chitosan decreased as the viscosity decreased. The study showed that during hydrolysis viscosity, glucosamine content and molecular weight were strongly dependent on the reaction temperature, reaction time and enzyme concentration.The enzymatic hydrolysis properties of both chitosans from Squid pen and from Crab were compared.
|