Preparation,Kinetic Analysis And Application Of Microencapsulated Lipase TTI

At present,food quality and safety is still an important issue related to people’s livelihood.Inorder to accurately obtain the food shelflife information,the time-temperature indicator displays the food quality change and remaining shelflife information by monitoring and recording the temperature accumulation effect of the product.The time length from activation to termination is reflected by color change,which corresponds to the quality change process of the packaged food.Based on the principle of lipase hydrolysis of glycerol triacetate to change the color of p H indicator,combined with microencapsulated enzyme immobilization technology,a solid-state enzyme time-temperature indicator was developped,and its kinetic properties and food application were studied.The main research contents and results of this thesis are as follows:(1)Lipase microcapsules were prepared by ionic gel method.The factors influencing the activity of lipase microcapsules were determined by single factor experiments.The best theoretical process for the preparation of lipase microcapsules was determined by orthogonal analysis and variance analysis.The optimum process was alginate concentration of 3 %w/v,chitosan concentration of 0.6 % w/v,and calcium chloride concentration of 0.3 mol/L.Then the thermal stability,optimum temperature and p H value of lipase microcapsules were studied,and the microcapsules prepared with this ratio were applied to the subsequent TTI research.(2)A solid-state enzyme type time-temperature indicator was developed.The lipase microcapsule and the discolored bottom layer were immobilized with agar respectively.The initial reaction time is controlled by contact activation,and the indication process of TTI is reflected according to the change of its color difference value.Through single factor analysis and orthogonal test on six factors of agar content,substrate content,indicator type and content,microcapsule content and color changing substrate thickness in the color changing layer,five groups of indicator formulations with reaction time of 5~6 days at 4 ℃ were finally determined.(3)The temperature control experiments were carried out for the five groups of time-temperature indicators obtained above,and kinetic analysis were carried out using ΔE00 in the color difference formula of CIEDE2000 as the response parameter.Goodness of fit of color difference value was evaluated and activation energy was obtained.The application of TTI in food quality change is also discussed.(4)The variation process of TVB-N value and p H value in the process of quality change of chilled meat was measured and analyzed.The TVB-N value was selected as the response parameter of quality change of chilled meat,and its relationship with storage time and temperature was analyzed dynamically,and it was matched with solid enzyme TTI.