| Protein is a sort of organic compound that widely exists in organisms, it is formed by dehydration with different kinds of amino acids. Protein has been widely used in food industry, its primary hydrolysate boasts a desirable biological activity and the amino acids produced by completely hydrolysis not only provide the necessary nutrition for human body, but also play an important role in promoting food flavor. Conventionally, protein has been hydrolyzed by enzyme.Although the efficiency of enzyme is high, it is easy to be inactivated with the slightly change of condition and the active sites are much fewer. And in industrial area, separating enzyme from hydrolysate is not easy and recovery process is quite intricate when it comes to enzymatic hydrolysis. Immobilized enzyme can solve the problem of subsequent recovery, but the cost is high-priced dues to the enzyme source and long-term, complicated purificatioin. Even more, immobilized enzyme is not able to overcome the unstability of enzymetic catalysis which leaves the problem stand still.Protein has a great influence on the quality of the alcohol during the brewing process of wine and beer. Sensitive protein is prone to complex with polyphenols which will not only impair the nutritional value of alcohol beverage but also lower the shelf life and flavor quality. Traditionally, the combination of PVPP and bentonite can easily absorb the protein which evidently contributes to the stability of alcoholic beverage. However, since the amount of adsorption reagents used in protein deprivation is vast and adsorption capacity of the fluid is considerable, it is not accessible to cut down the cost and energy consumption. It has been not common to use chemical modified chitosan resin to deal with the porblem caused by protein-polyphenols precipitation.In this study, by reverse suspension cross-linking method with epichlorohydrin as the cross-linking agent ,we use chitosan,heterocyclic compound and metal ions as primary materials to prepare chemical modified chitosan resin complexed with metal ions(MCCR) which has the ability to hydrolyse proteins at mild conditions.MCCR takes on as dark blue beads,which has appropriate particle diameter distribution and mechanical strength contributing a good stability toward acid and alkali. It also possesses a porous structure inside that is liable to protein hydrolysis. The hydrolying ability of MCCR was investigated through methods like HPLC , SDS-PAGE , etc. The results demonstrated that BSA and OVA can be hydrolysed more than 95% during 48h and 32h respectively.The optimum pH for degrading BSA was around 6.0 and 8.0 for OVA.The catalytic efficiency can be accelerated along with the additional amount of substrate, the Vmax for decomposing BSA was 7.01×10-2h-1 and 12.22×10-2h-1 for OVA. Althought the rate constant can be accelerated by temperature rise, the higher temperature aggravates the degradation of control protein as well. The reusable experiments showed that MCCR can be used repeatedly more than 4 times while the catalytic capability maintains 85% of the original. Copper ions chelated on the resin hold a desirable stability, there are more than 98.17% copper ions still complexed with the resin after the first application.It is safe to conclude that MCCR is capable of lowering the content of protein and polyphenols by the degree of 19.07% and 21.46% which can further improve the clarity of the original wine more than 75%. Proteins in brewing wine could be decomposed which subsequently increase the content of amino acids. As well as reduced the sediment formed by protein and polyphenols, it also ehanced the trophic value of the processed wine. This process technology is suitable for industrialized production, which may reduce the costs and raw materials. With the great social benefits and economic results, it deserves further promtion with effort. |
PDF Full Text Request