Effects On The Stability Of Wine By Modified Chitosan Resins

Through the preparation of5different kinds of chitosan resins, they were applied in white wine clarification and stabilization and helped in discovering the main influence factors causing the wine turbidity. The aim was to provide a new alternative clarifying agent and offer kind of support to the illumination of the mechanism of wine instability. The main research results are as follows:(1) The5different kinds of resins were made from chitosan and glacial acetic acid by opposite cross linking method in this paper. Five resins were round or irregular globular, porous structure. Size distribution was uniform.The average particle size of resins were about460-660μm.Resin has a larger specific surface area, making analysis to explore the relationship between thermal stability and structure of the resin by XRD, FTIR, UV and DSC. Chitosan molecules cross-linked with metal ions Ce4+, Cu2+and Zn2+as ligand in complexes. The results of DSC showed that the cross linking reaction may take place. Pyrolysis temperature of chitosan resin is lower than the chitosan powder as well as heat enthalpy.(2) Effects on the clarification of wine with chitosan resins:White wine can be considered stable if the turbidity change do not exceed0.5EBC.Results indicated the optimum conditions of RCM, RCMB, RCMC:resins addition of20.0g/L,and the temperature was15℃, stirring by magnetic force for48h, turbidity change was lower than0.50EBC to keep higher capability. For static adsorption, the stability effects of three kinds of resins were obviously better than bentonite, mainly displaying on the faster clarification speed, strong adsorption of the proteins and polyphenols. Effect of adsorption ratio of copper ions was more remarkable than iron ions. Effect of organic acid was not significant. Respectively, effects of dynamic adsorption were better than static adsorption. For dynamic adsorption, using the processing of RCM-Column was especially significant. In the stability test, experiments proved RCM can be a fit approach to improve the stability of white wines.(3)251simulation experiment:Application of five kinds of resins to the clarification and stability experiment, the results of that were not affecting other major wine components, increased significantly completeness of solution, turbidity difference significantly reduced to remove about34%protein,30%polyphenols. Metal ions content within the scope of the national standard could not fall off the wine. The clarification and stability of wine by RCM, RCMB, RCMC was better than other resins. And RCMC had the effect of hydrolyzed protein, a better alternative clarifying agent, could stabilize wine. Experiments proved theoretical foundation and basic technology instruction for resins in the application of white wines.(4) This part is to study white wine protein stabilization in a continuous process with5different kinds of resins packed in a column and to evaluate how the treatment affects the protein profile and the final stability of the wine. The total protein of wine all decreased and then stayed stable by resins. Wine could be considered to be stable when the total protein adsorption is higher throughout the same treatment. But the content of the total protein was not able to decide whether the wine stable or not. With the help of HPLC, the protein fractions were divided into4parts:above70KDa,50-70KDa,20-30KDa, below15KDa. Their behaviors were quite different from each other. And the correlations with wine stability are also different. Protein fraction that has a molecular weight above70KDa seems to have the greatest effect on whether the white wine is thermally stable or not. However, it cannot be assumed that the50-70KDa fraction and20-30KDa fraction plays an important role in the stabilization as the fraction above70KDa. They performed a similar adsorption behavior possibly because of the same carrier-chitosan. The concentration levels of the protein fractions of20-30KDa and50-70KDa depended on the sort of the adsorbent. The protein fraction corresponding to the fraction below15KDa seems not to affect the difference in turbidity, because in all the tests it remained practically constant, although the protein stability varied. Low concentration of wine can lead to protein-stable wine. So it was inferred that SO42-itself could not affect the stability of wine. But the instability of wine can be induced by SO42-participating in some protein degeneration. It was speculated that some protein component had close relationship with SO42-.