With the deepening of research on enzyme modulators and inhibitors, they play an increasingly important role in the health of organisms.

Antibacterial peptides: also known as antibacterial functional peptides, it is usually associated with antibiotic peptides and antiviral peptides, including cyclic peptides, glycopeptidesand lipopeptides, such as gramicidin, bacitracin, polymyxin, lactic acid bacteria, Subtilisin and nisin, etc. Antimicrobial peptides have good thermal stability and strong antibacterial effect.
In addition to microorganisms, animals and plants that can produce endogenous antibacterial peptides, effective antibacterial peptides can also be obtained by enzymatic hydrolysis of food proteins, such as antibacterial peptides obtained from lactoferrin. Lactoferrin is a glycoprotein that binds iron. As a prototype protein, it is considered to be a very important defense mechanism for the host against bacterial infections. Research biologists used pepsin to split lactoferrin and purified three antimicrobial peptides, which can act on E. coli, all in cationic form. These biological functional peptides are effective 30 minutes after contact with pathogenic bacteria and are good alternatives to antibiotics.

Neuropeptides: After enzymatic hydrolysis of a variety of food proteins, neurological functional peptides will be produced, such as the opioid functional peptide derived from wheat gluten, which is the product of in vitro pepsin and thermolysin hydrolysis. Neurofunctional peptides include opioid functional peptides, endorphins, enkephalins and other regulatory peptides. Neurofunctional peptides play an important role in organisms. They can regulate emotions, breathing, pulse, body temperature, etc. Unlike ordinary analgesics, they have no side effects.
Immune peptides. Immune functional peptides can stimulate the phagocytic ability of macrophages and inhibit the growth of tumor cells. We call this peptide an immune functional peptide. It is divided into endogenous immune functional peptides and exogenous immune functional peptides. Endogenous immune function peptides include interferons, interleukins and β-endorphins, which are the center of activating and regulating the body's immune response. Exogenous immune functional peptides mainly come from casein in biological milk and cow milk. Immune functional peptides have a variety of physiological functions. They can not only enhance the body’s immune ability and play an important immunomodulatory role in animals; but also stimulate the proliferation of lymphocytes in the body and enhance the phagocytic ability of macrophages to improve the body’s ability to external pathogenic substances.
Flavoring peptides. Certain functional peptides can improve the palatability of food and improve the flavor of food. We call this peptide flavoring peptide. Contains the following: 1): Sour peptide: Sour peptide is usually related to sour taste and Umami taste. Umami has the taste of sodium glutamate, and it is usually composed of dipeptides or tripeptides containing sodium glutamate and sodium aspartate. The octapeptide isolated from papain-treated beef extract for the first time is called "delicious peptide" and is the best example of Umami's flavor. It is reported that the delicious peptide has a typical beef soup taste, which is mainly attributed to the synergistic effect of the N-terminal dipeptide Lys-Gly, the central acidic tripeptide Asp-Glu-Glu and the C-terminal tripeptide Ser-Leu-Ala. 2): Sweet peptides: The typical representatives of sweet peptides are dipeptide sweetener and alitame, which have the characteristics of good taste, high safety, and low calories. Among them, dipeptide sweeteners have been approved by more than 70 countries to be used in more than 500 kinds of foods and medicines, and can be used to enhance the sweetness of foods and adjust the flavor. In addition, lysine dipeptide has been proven to be an effective substitute for dipeptide sweeteners. It does not contain esters and is more stable during food processing and storage. 3): Bitter peptide: Bitterness is an important taste component of some foods such as beer, coffee, cheese and so on. Basic dipeptides such as ornithine-β-alanine exhibit a strong bitter taste, and glutamic acid oligomers are often used as bitter components in many foods. At present, research biologists have separated bitter peptides from fermented foods and enzymatic hydrolysis products of casein; 4): salty peptides: certain basic dipeptides, such as ornithyl taurine-hydrochloride, ornithyl Beta-alanine-hydrochloride exhibits a strong salty taste, sometimes accompanied by Umami flavor. However, studies have found that peptides are not salty in the absence of hydrogen chloride. It canbe developed as a substitute for high-sodium condiments.
Flavor-enhancing peptides: Although certain food additives have better antibacterial effects, they will not produce residues in animals. They are safe and non-residual antibiotics. However, the taste is too bad, and the palatability of the food is significantly reduced after adding food. Certain dipeptides such as Gly-Leu, Pro-Glu and Val-Glu can use their buffering effect to improve the palatability of food. Short-chain glutamate peptides can effectively mask the bitter taste. Curculin and Miraculin can mask the sourness and turn the sourness into sweetness. In short, certain biological functional peptides can improve the palatability of food by mimicking, masking, and enhancing flavor.
Hormone peptides: Hormone peptides include growth hormone releasing peptide, oxytocin, etc., which produce a variety of physiological effects by acting as hormones or regulating hormone responses. Hormone peptides, as a newly synthesized bioactive peptide developed in the 1990s, have the biological activity of releasing growth hormone in animals.
Antioxidant peptides: Certain food-derived peptides have antioxidative effects. Among them, the most familiar organism is carnosine, a natural dipeptide found in animal muscles. According to reports, antioxidant peptides can inhibit the failure of fatty acids catalyzed by hemoglobin, lipoxygenase in vivo and singlet oxygen in vitro. In addition, several low molecular weight antioxidant peptides have been identified from mushrooms, potatoes and honey. They can inhibit the activity of polyphenol oxidase and can directly react with the quinoid product catalyzed by polyphenol oxidase to prevent polymerization of oxides, thereby preventing the brown reaction of food. By scavenging heavy metal ions and promoting the decomposition of peroxides that may become free radicals, some antioxidant peptides and proteolytic enzymes can reduce the rate of auto-oxidation and the peroxide content of fats.
Nutritional peptides: peptides that have nutritional effects on the growth and development of organisms or animals are called nutritional peptides. For example, the enzymatic digestion of protein in the intestine can release free amino acids and peptides. A large number of studies have shown that in addition to directly supplying the amino acid needs of animals, proteins and peptides also have some special additional effects on animal growth. The number of free amino acids to replace intact protein is limited, and low-protein diets cannot achieve the production level of high-protein diets no matter how balanced the amino acids are. Part of the importance of protein in animal diets is that the small intestine can produce peptides with biological activity. The nutritional value of peptides is higher than that of free amino acids and complete proteins. The reasons are as follows:
1). Generally speaking, the antigenicity of small peptides is lower than that of large peptides or prototype proteins.

2). Compared with the transport of free amino acids, the body transports small peptides through the wall of the small intestine faster.

3). The osmotic pressure of peptides is lower than that of free amino acids, so it can improve the absorption efficiency of small peptides and reduce penetration problems.

4). Small peptides also have good sensory/taste effects.