Application of alkaline protease

1. Use alkaline protease to catalyze the hydrolysis of protein to prepare foaming agent mother liquor
Foaming agent is an essential raw material for preparing lightweight materials for civil engineering such as bubble mixed lightweight soil and foam concrete. The performance of the foaming agent is the decisive factor affecting the performance of bubble mixed lightweight soil and foam concrete, and the preparation performance is excellent. The composite foaming agent needs to prepare the foaming agent mother liquor first.

CN201811148311.7 provides a method for preparing a foaming agent mother liquor by using alkaline protease to catalyze the hydrolysis of protein. This method can catalyze the hydrolysis of raw protein, significantly reduce the hydrolysis time, and solve the hydrolysis efficiency of existing alkali hydrolysis, acid hydrolysis, salt hydrolysis and other methods. low question. The method includes the following steps: 1) Place raw protein, alkaline protease and water in a container, stir evenly to obtain a mixed liquid, and adjust the pH value to 9 to 13; 2) Heat the mixed liquid obtained in step 1) for a heat preservation reaction, After the reaction for a certain period of time, readjust the pH value to 9-13 and repeat several times to prepare the foaming agent mother liquor.

2. Extraction of shrimp shell protein
The extraction of protein from shrimp shells mainly uses acid to remove calcium from shrimp shells, and then uses alkali to extract the protein from shrimp shells, adjust the pH of the extraction solution, precipitate the protein, or recover the protein by salting out. Another method is to use protease to hydrolyze the protein in shrimp shells. The resulting hydrolyzate can be further formulated into shrimp oil, or spray-dried into protein powder.

The process of extracting protein by alkaline method will cause serious environmental pollution, and simply using enzymatic method to hydrolyze protein also involves serious waste because the enzyme cannot be recycled. CN201710186400.X provides a method for extracting shrimp shell protein using magnetically immobilized alkaline protease. The method is simple and easy to operate, has good stability, good protein hydrolysis effect, and low extraction cost. Includes the following steps:

1. Preparation of magnetically immobilized alkaline protease:

1.1. Add magnetic chitosan microspheres to borax buffer with pH=9-12, and then add alkaline protease. The ratio of magnetic chitosan microspheres, alkaline protease and borax buffer is 1mg:100-400U: 0.1-1ml, react at 0-10°C for 2-5h to obtain a mixed product;

1.2. Add glutaraldehyde to the mixed product so that the final concentration of glutaraldehyde is 0.005-0.01g/ml, react at 0-10°C for 2-5 hours, filter, and wash the filter residue with borax buffer and dry to obtain Magnetic immobilized alkaline protease;

2. Extract protein from shrimp shells:

2.1. Add shrimp shell powder to an acetic acid solution with a concentration of 50-90g/L. The mass-volume ratio of shrimp shell powder to acetic acid solution is 1g:6-14ml. React at 55-75°C for 1-5h to obtain a mixed solution. ;

2.2. Filter the mixture, add alkaline solution to the filter residue until the system becomes neutral, filter, then wash the filter residue with distilled water and dry to obtain modified shrimp shell powder;

2.3. Determine the content of shrimp shell protein in modified shrimp shell powder;

2.4. Add the modified shrimp shell powder to the borax buffer with a pH of 9-12, then add the magnetically immobilized alkaline protease (the activity of the magnetically immobilized alkaline protease can be measured by the Folin-phenol method), and magnetically fix it. The ratio of alkaline protease to shrimp shell protein is 10-20U:1mg. Stir for enzymatic hydrolysis at a temperature of 45-60°C for 1-5 hours. After the enzymatic hydrolysis is completed, use a magnet to separate the magnetically immobilized alkaline protease. The separated magnetically immobilized alkaline protease is washed and stored for later use. The resulting enzymatic hydrolyzate is filtered and the filtrate is freeze-dried to obtain shrimp shell protein polypeptide, which is shrimp shell protein powder.