The extraction of collagen peptides is divided into three key steps. The first step is to pretreat the raw materials to purify the raw materials: removing lipids, impurities, pigments, dirt, and fishy odors. The second step is to apply physical, chemical, and biological enzymatic methods to destroy collagen fiber tissue. It can weaken the ability of hydrophobic force and hydrogen bond force to adhere to the collagen structure so that peptide bonds are hydrolyzed and finally extract the collagen. The third is to hydrolyze/enzymatically hydrolyze collagen based on collagen. Standard extraction methods are divided into chemical processes according to their properties as follows: acid way, subtractive extraction, enzymatic extraction, physical extraction: hydrothermal extraction and hot-pressure extraction, neutral salt extraction, microbial fermentation, and the new method is to The above techniques are combined to extract collagen peptides, and enzymatic extraction is now commonly used.
1. Acid extraction
Concentration, hydrolysis temperature, and time are the three factors that need to be strictly controlled for acid extraction to prevent collagen from being completely hydrolyzed and destroying amino acid components. The extraction rate of collagen by a single acid method is relatively low, and the extraction rate is generally improved by combining it with an enzymatic process. Commonly used acids are low-concentration acetic acid, hydrochloric acid, and dilute sulfuric acid, which increases the cost to a certain extent, so this method is not commonly used now
2. Alkaline extraction
Alkaline extraction is also a relatively simple extraction method. Alkaline extraction can both extract and modify proteins. Alkaline substances can decompose the protein matrix to increase the yield of protein and peptides. It Will produce harmful substances to the human body, and the reaction process is challenging to control. Nowadays, it is rarely used in laboratories and industries.
3. Enzymatic extraction
Enzymatic extraction adds a specific enzyme to the dissolved bone, skin, shell, etc., to promote the degradation of the peptide bond of the non-helical segment of collagen. This method can improve the quality of bone-derived protein and its functional characteristics. The enzymatic method is an essential method for the production of collagen peptides and is widely used in industrial production and laboratories
4. Hydrothermal extraction and hot pressure extraction
Protein in the range of 150~190℃, as long as the temperature rises, the degree of protein hydrolysis will increase, free amino acids increase, and the yield of collagen peptides will increase. In contrast, In the range of 190~240℃, protein is hydrolyzed into small peptides and free amino acids. This method is an environmentally friendly and effective method for extracting collagen. Its significant advantage is that it is non-toxic and safe.
5. Neutral salt extraction method
The neutral salt extraction method principle is that collagen will dissolve when the salt concentration reaches a certain level to obtain salt-soluble collagen. The collagen prepared by this method is salt-soluble. The structural stability of collagen peptides is inconsistent with different salts; some increase, and some decrease, so this method is hardly used to extract collagen peptides alone.
6. Microbial fermentation method
This method uses enzymes produced by microorganisms in the growth process to act on the peptide chain for enzymatic hydrolysis to prepare biologically active peptides with different functions. Compared with the enzymatic method, the microbial fermentation method has complex operations and high requirements for conditions. Cell metabolism may also produce products contaminated by secondary cell metabolites, so this method has not been promoted and applied.
7. Compound extraction
The compound method, as the name suggests, is a method that combines different extraction methods. It is proposed to overcome the too low extraction rate of the acid method. The standard techniques include the acid enzyme compound method, acid hot water method, ultrasonic-assisted method, acid-alkali enzyme compound method, etc.