The Study Of Naringinase Immobilization By Porous Silica Material

Citrus fruits such as orange,pomelo and orange and their products are tasted bitter,and the bitterness is mainly from naringin.Naringinase is a complex enzyme consisting of?-L-rhamnosidase and?-D-glucosidase,which can hydrolyze naringin into non-bitter substance.As a result,it is commonly used in citrus juice industry for improving the taste and quality of the products.Meanwhile,in order to reducing cost,the free enzyme is industrially prepared as immobilized enzyme to enhance the recyclability and stability.Mesoporous material had the characteristics of large specific surface area and uniform pore size,and it was suitable to be the carrier for enzyme immobilization.In this work,porous silica materials were used for naringinase immobilization process,and the characteristics and hydrolysis properties of immobilized nariginase were further explored.In addition,the porous silica materials were subjected to osmosis treatment and make them have fast magnetic responsiveness and facilitate the application of solid-liquid separation while external magnetic fields were added.Naringinase was immobilized using mesoporous silica material SBA-15 as the carrier and glutaraldehyde as the crosslinking agent.The optimum immobilization parameters were:immobilization pH of 3.5,immobilization temperature of 40?,immobilization time of 4 h,initial nariginase activity of 89.04 U·mL^-1,and the enzymatic activity,enzyme activity recovery and maximum enzyme specific activity of immobilized naringinase were 63.66%,87.64%and 517.63 U·g^-1,respectively.It was indicated that the immobilized enzyme had high thermal stability and perfect operation stability.After eight cycles of recycling,the relative enzyme activity was61.81%;and 80.95%of the enzyme activity was retained after storage of 30 days at4?.Then magnetic SBA-15 was prepared by magnetic osmosis method,and the optimal naringinase immobilization conditions were as follows:immobilization pH of4.0,immobilization temperature of 35?,immobilization time of 3 h,initial nariginase activity of 72.67 U·mL^-1.The enzymatic activity,enzyme activity recovery and maximum enzyme specific activity of magnetic SBA-15 immobilized naringinase were 87.84%,60.91%and 463.64 U·g^-1,respectively,and it had high thermal stability and good operation stability.After seven cycles of recycling,the relative enzyme activity was 50.21%,and retained 62.36%of enzyme activity after storage of 30 days at 4?.