Studies On Drying Techniques And Quality Analyses Of Chito-oligosaccharides

In this paper, spray drying method, physico-chemistry and functional properties and quality analysis of chito-oligosaccharides(COS) were researched.Firstly, drying method suitable for industrial production was studied. Spray drying conditions of COS hydrolysis solution was determined by comparing freezing drying, vacuum drying in terms of product color and water resolvability as follows: solution concentration 20%,dryer inlet temperature 180 and outlet temperature 85 and atomization pressure 0.30MPa.By this conditions, COS had good color and excellent water resolvability. At the same time, physico-chemistry and functional properties of COS were studied. It was showed COS had high water resolvability, its solubility in ethyl alcohol decreases with alcohol concentration increasing. Its stability in process of sterilization(pasteurization, HTST and HTHP)was also investigated. COS was much stable in pasteurization process when solution pH in range of 5.0-6.0, stable in HTST when pH in 5.0-8.0 ,and destroyed more or less when pH less than 3.0; COS had good hygroscopic and water-reserving properties. It was also showed COS had properties of scavenging of superoxide anion free radical(O2-). This scavenging activities increased as concentration increasing, and activities of COS with average relative molecular weight of 1000 was higher than that of 2000.Secondly, deacetylation degree, total amino sugar and average relative molecular weight of COS were researched. Comparing veracity and accuracy between two abrupt change conductometric titration and linear conductometric titration methods, the two determinations both have high accuracy, but the former is much more veracious. On the other hand, influences of chitosan solution concentration, viscosity, degree of deacetylation and measuring temperature on the result of equivalence point of two abrupt change conductometric titration were also investigated. It was showed that at room temperature, concentration of chitosan solution controlled from 2 to 6 deacetylation degree of chitosan could be determined more voraciously by means of two abrupt change conductometric titration than linear conductometric titration.Determination of total amino sugar of COS by acid hydrolysis was discussed. The optimum acid hydrolysis conditions are followed: temperature 95, concentration of HC1 12mol/L, hydrolysis time 5h and solution ratio(V/V) of HC1 to COS 4, and hydrolysis compensation of amino-glucose was also made. At the same time, determination of average relative molecular weight of COS was investigated. It appeared that molecular weigh of COS could be determined more accurately by DNS method of reducing end-group analysis techniques rather than Imoto colorimetry and viscosity method.Thirdly, quality standard specifications of COS was made. On the basis of present commercial products, quality standard of total amino sugar and average relative molecular weight of COS were complimented, and their indexes were made to 85% and 3000 respectively. Detailed specifications indexes were made as follows, appearance: light yellow powder, viscosity 5 mPa s, pH: 5-6, D.D 85%, water 10%, ash 3%, water solubility99. 9%, average relative molecular weight 3000, amino glucose 5%, total amino sugar 85%, heavy metal and microbial residual were made according to GB16740-1997.