The Study Of The Preparation And Performance Of Chitosan-Sodium Alginate Microcapsule Encapsulating Alkali Protease

Chitosan/calcium alginate microcapsule is a kind of microcapsule which is widely applicated in food, medicines, and personal care products and etc. It has advantage on abundant of the raw materials, simple preparing technology, environmental friendly, low prices, and good biocompatibility, so it has fairly broad prospect of application. The usage of detergent enzyme has become a trend in the detergent industry. And detergent protease is the most important in enzyme preparation among them. It can clean stains, egg stains, plant juice stains and some biological secretion protein dirt, which are very common on the cloth. However, protease is very easy to get poisoned by the environment, and cannot show its full affection of decontamination. Therefore, how to add enzyme in detergent becomes the key factor to endure the decontamination property with detergent.Adopting chitosan/alginate as shell material to encapsulate protease can effectively solve the problem of enzyme being poisoned in the process of storage and application. In this study, enzyme microcapsule was prepared with sodium alginate chitosan as wall materials, and alkali protease as the core material, followed one step emulsification method. When sodium alginate droplet met calcium ion in the emulsion, a ball skeleton was shaped by the sol phase transfer process forms - gel calcium alginate gel. And polyelectrolytes membrane was formed with combination of large amino on the chain of chitosan molecules and carboxyl of sodium alginate molecular chain, through a negative and positive nuclear formed. In calcium alginate gel ball's skeleton, chitosan filled in layers and fixed the enzyme well, finally structure controllable, good shape and high embedding rate microcapsule was produced. Meanwhile, in the preparation of microcapsule, properties of microcapsule were studied by orthogonal experiment, laser particle size analyzer and optical microscope. Results show that the best preparation conditions of chitosan/calcium alginate microcapsule encapsulating enzyme is: Span80 is 1%( mass percentage),protease is 4%( mass percentage), CaCl₂ is 2%( mass percentage), sodium alginate is 2%( mass percentage), chitosan is 0.5%( mass percentage). Under these preparing conditions, the embedding rate reaches to 60% or more. Meanwhile the surface of these microcapsules is smooth through optical microscope. . When the content of Span80 changed among 4% , 3%, 2%, 1%, the average size of these microcapsules is 45.86±2μm, 56.57±2μm,88.13±2μm,91.16±2μm. And Span80 content, pH value and chitosan content were improved to follow the law of releasing of chitosan/calcium alginate embedding enzyme microcapsule. It shows that release rate increases when Span80 content increases. In the acidic environment in where pH value is 2.8 or 4.9, enzyme releases slower than in alkaline environment in where pH value is 10, The release behavior of alkali protease is negatively correlated to Chitosan content when it is over 1%, and it is slower when Chitosan content . The greater the resistance exist on microcapsule when enzyme is spreading to the outside world, because the higher Chitosan concentration, the higher the membrane is thicker, which result in release speed slow down.Release behavior of the alkali protease is also studied finally. It shows that the release behavior of the microcapsules, which were prepared under the best preparation conditions, fits Peppass model well. Fitting equation shows that diffusion of alkali protease is Fich diffusion behavior. The engineer of releasing is the concentration gradient of internal and external enzyme solution. The relationship between Enzyme release quantity and time fits Higuchi model well, fitting equation follows: Q = 257.23t1/2 + 953.35. Correlation coefficient is 0.9771, which shows the release quantity and the square root of time is a linear, so enzyme in release behavior is released slowly.The results show that the experiment chitosan alginate microcapsules can be used to encapsulate detergent alkali protease and can achieve better encapsulation effect and release function. It can solve the interference by other enzyme in detergent applications and reduce the environmental impact of catharsis active problem.