1. Types of carotene:

There are many kinds of carotenoids in nature, which can be divided into two categories according to their different structures: carotenoids and carotenoid oxygen derivatives. β -carotene is a typical representative of carotenoid family, which can be split into two molecules of vitamin A and is an animal.

Carotene essential for human body. The important isomorphic structure of carotenoids is that they all contain an isoprene chain with 9 double bonds, and there are two B- ionone rings at both ends of the chain, which may exist in isomeric, substituted and ring-opening forms.

The number of double bonds in the double bond yoke and chain can indicate its antioxidant capacity.

Generally speaking, β -carotene has the highest content in carotenoids deposited in livestock, and lutein has the highest content in carotenoids deposited in poultry. Studies have found that carotenoids mainly exist in human adipose tissue.

In animals, it mainly exists in the liver, and a small amount exists in adipose tissue, kidney and skin. Different kinds of animals have different kinds of carotenoids. Yang et al. (1992) believed that carotenoids existed in adipose tissue and serum of sheep and goats.

Lutein is the main substance of tonic, but there is no lutein in the liver, but the content of β -carotene is high. The content of β -carotene in bovine serum and adipose tissue is the highest, and the content of lutein in adipose tissue is also high, but β -carotene in its liver.

Busu content is low. Carotenoids are distributed in different parts of animals at different growth stages. Carotenoids mainly exist in liver, adipose tissue, blood, skin and feathers in the early stage of growth, and gradually mature.

Transferred to reproductive organs such as ovaries. Kathallna( 1985) reported that 50% of lutein consumed by chickens during laying is in the ovary and 25% in the yolk. Carotenoids are mainly distributed in the muscles and skin of salmon in the middle and juvenile stages.

After sexual maturity, it is mainly deposited in the ovary.

Absorption of 1 Carotenoids in Animals

Carotenoids can only be synthesized by plants, not animals, and can only be obtained from feed. Carotenoids in feed are separated from their protein conjugates by digestive enzymes in the gastrointestinal tract of animals, and separated from other lipids in the duodenum.

Similar substances are emulsified by bile to form chylomicrons, which are absorbed by intestinal mucosal epithelial cells. Carotenoids are mainly converted into vitamin A in intestinal mucosa, and the conversion efficiency of different kinds of animals is different. In addition, some scholars believe that lymphatic circulation is β-Hu.

The main absorption route of carotene is that only a small amount of polar metabolites such as retinoic acid rotate through portal vein. However, Wang et al. (1994) found that most of β -carotene in ferrets was absorbed through the hepatic portal vein, including polar generations.

Thanks to the products, including the existing yellow esters, etc. As for the absorption mechanism of carotenoids, many scholars have proved that the absorption of carotenoids is passive diffusion through experiments. Scitur et al. (1992) used isolated rat small intestine cells and human lung fibroblasts.

In vitro experiments show that the absorption of carotene is passive. Zhou (1996) found that the absorption of β -carotene and lutein by bovine intestinal mucosal cells was concentration-dependent, and the change of temperature did not affect the absorption of β -carotene and lutein by cattle.

The absorption of carotenoids showed that the absorption of carotenoids by bovine intestinal mucosal cells was passive diffusion.

2 factors affecting the absorption of carotenoids

2. The absorption and transport of1β-carotene in animal species vary from animal to animal, such as rats, pigs, sheep and rabbits. Buffalo metabolizes almost all beta-carotene in the intestine, and little beta-carotene is stored in other parts of the body.

Horses, cattle and carp can transport the undecomposed β -carotene to liver, fat and other tissues for storage.

2.2 The content of fat in fat and fatty acid diet will affect the absorption of carotenoids. This is mainly because carotenoids are fat-soluble, fat can transport carotenoids, and fat in food can form colloidal particles through pancreatin and bile salts.

Carotenoids are dissolved in it and absorbed together. It is reported that when fat accounts for 7% of the total dietary calories, the absorption rate of carotenoids is only 5%, and the absorption rate can be increased to 50% by adding oil. Many studies have shown that fatty acids promote the body's response to carotenoids.

Absorption, because fat can accelerate the decomposition of carotenoids into vitamin A in cells, thus accelerating the diffusion of carotenoids and promoting absorption.

2.3 The change of intestinal pH will affect the diffusion and absorption of carotenoids, and the change of pH is mainly to induce the potential change of fine cells, thus promoting the absorption of carotenoids. Holland-der reported that the intestinal pH was adjusted from 7.4 to 5.3.

At 8.3, the absorption of carotenoids was significantly promoted. In addition, the increase of intestinal chyme velocity will reduce the thickness of water layer, which is beneficial to the absorption of carotenoids.

2.4 Cholic acid and cholate Moori( 1954) found that bile can accelerate the absorption of carotenoids, which is attributed to the emulsification of fat by bile. Bile promotes fat emulsification to form tiny colloidal particles, which are easily absorbed in the liquid environment of small intestine.

And promote the dissolution of carotenoids in colloidal particles. There is no interspecific specificity in promoting carotenoid absorption by bile, and all kinds of animal bile can promote carotenoid absorption. Bile acts on cholic acid and bile salts. The optimum concentration to promote absorption is

0.004-0.008 mol/L, too high concentration will have inhibitory effect.

2.5 Other factors The increase of protein level in the diet is beneficial to the decomposition of carotenoids to form retinaldehyde and to maintain the gradient of carotenoid diffusion; The increase of vitamin E content in diet is beneficial to the absorption of carotenoids.

Physiological Functions of Carotenoids

3. L β -carotene is the precursor of vitamin A, which was reported by Tony (1985). When β -carotene is deficient, it will cause vitamin A deficiency, make corneal epithelium fall off, thicken and keratinize, make the original transparent membrane opaque, and cause corneal ulcer.

Selection, lens loss and blindness, light can cause night blindness; It can also destroy the growth and differentiation of epithelial cells and make the skin thicker, dry, stupid or wrinkled, so vitamin A can treat keratosis. Beta-carotene is vitamin a.

It turns out that the body can be decomposed into two molecules of vitamin A after taking pictures, thus supplementing the deficiency of vitamin A in the body. Moreover, human β -carotene can be stored in the liver and gradually converted into vitamin A as needed, without causing excessive vitamin.

Biological A. The poison produced by exogenous β -carotene is called nontoxic vitamin A, which is used in most fields of vitamin A application.

3.2 Carotenoids can enhance the reproductive capacity of animals. Carotenoids are physiological antioxidants, which can prevent lipid peroxidation, thus protecting follicles and steroid-producing cells in uterus from oxidative damage; On the other hand, like carrots.

Busu may regulate the activity of nucleus in rake tissue. Tian Yunbo (199 1) found that β -carotene affects the quality of bull semen, and the level of β -carotene in blood is closely related to the reproductive performance of cattle. The higher the beta-carotene in the blood, the more reproduction.

Strong reproductive function and low content will lead to early embryonic death, estrus, decreased pregnancy rate and placenta retention. Xiang Xiao et al. (2000) thought that carotenoids can promote gonad development during the growth of female fish.

The deposition in the nest promotes the maturation of egg yolk. Zhan Yong et al. (1997) reported that adding 50, 100 and150mg/kg β-carotene to the breeder's diet increased the laying rate of breeder by 2. 15%, 5.07% and 2.73% respectively compared with the control group.

Both the hatching rate and the hatching rate have been improved. Adding 30-60 mg/kg β -carotene to the diet has a good effect on improving the laying rate of laying hens.

3.3 Carotenoids can enhance immune function. The immune system in organisms has two main functions: one is to protect the body from diseases caused by pathogens such as bacteria and viruses, and the other is to inhibit cancer cells and prevent their growth.

Very long. Bendiab( 199 1) points out: l) Carotenoids can enhance the activity of B cells in the immune system, and B cells can circulate in the body, so that the body can eliminate pathogens invaded by foreigners; 2) Carotenoids can improve the ability of CD4 cells and help B cells to refine.

Cells produce antibodies to improve the activity of other immune components; 3) Carotenoids can increase the number of neutrophils, which can surround bacteria and secrete various enzymes that degrade bacteria; 4) Carotenoids can also increase the number of natural killer cells (NK)

Objective: to eliminate infect cells or canc cells in vivo. The results of in vitro experiments by TjoeLKer et al. showed that 10-6 moi/L carotene could stimulate the phagocytosis and sterilization of peritoneal macrophages (PMN) of dairy cows before and after dry lactation. While retinol and retinoic acid

It has no effect on the bactericidal ability of PMN and reduces its phagocytosis. SChwartz et al. added canthaxanthin, β -carotene and α -carotene to mouse PMN medium, which could improve the activities of cytochrome oxidase and peroxidase. Even at very low concentrations.

Carotenoids can also stimulate phagocytosis of phagocytes.

3.4 Carotenoids have antioxidant effects. The molecular structure of carotenoids contains multiple yoke double bonds, which can reduce the damage of free radicals to cellular genetic materials (DNA, RNA) and cell membranes (such as protein, lipids and carbohydrates). thing

Once the highly active and destructive free radicals are formed in the system, they will get close to the important components of fine cells, such as protein, lipids, nucleic acids, etc., and destroy them strongly. For example, hydroxyl radicals can destroy 90%

DNA, singlet oxygen and hydroxyl radicals can destroy DNA chains. If the damage of genetic material is not repaired for a long time, it will lead to the formation of cancer cells. Autologous free radicals are produced under normal aerobic conditions. Many studies show that in the process of aging, disease and inflammation, the body

Free radicals increase, carotenoids can inhibit the production of free radicals, delay aging and prevent cancer.

3.5 Carotenoids have coloring function. Carotenoids are natural yellow or orange, and they are effective colorants. In poultry, carotenoids are deposited in claws, elephants and subcutaneous fat to color them, which improves the quality of poultry carcasses. exist

Carotenoids in egg birds are deposited in egg yolk, which makes it yellow and improves the quality of eggs. Fish can't synthesize carotenoids in their own bodies, and all the carotenoids needed in the growth process come from feed. The skin color of fish and shrimp depends on the species.

Carotene intake. Storebadden and others have proved that carotene can be deposited in animal muscles to improve the color of fish. Okaguchi and others studied the relationship between body color and carotenoids in cultured Penaeus monodon, and found that the carotenoid content in shrimp was 2.3-2.5%.

Between 33.33. Indkg, generally, the higher the carotenoid content, the stronger the shrimp body color.

3.6 Carotenoids can increase the communication between cells, Bert. And others 199 1) have proved that carotenoids such as carotene can strengthen the communication ability between cells, thus inhibiting or reducing cancer.

The appearance of symptoms. Yalnasaki et al. (1990) pointed out that suture connection refers to a pearl-like connecting channel between adjacent cells, which is formed by connective protein chains, through which intercellular communication can be generated. Cancer cells in the transformation stage will be made up of

Because the channel is destroyed, it interferes with the exchange, which is a factor to control the growth. In vitro, cancer-promoting substances can inhibit the exchange by connecting the gene of egg white, and the expression of connexin gene is greatly reduced during the accelerated period of cancer. Wolf (1992) certificate

Ming: β -carotene and retinoic acid can exchange information through the activation or reactivation of connexin, thus inhibiting cancer-induced cells from upgrading to the deterioration stage.

4 production methods of natural carotenoids: there are three main production methods of natural β -carotene abroad: l) extraction from natural plants; 2) obtaining large-scale culture of Dunaliella salina; 3) Production by microbial fermentation. Recently, Liu Jiayong et al. (1999) targeted

The extraction of natural β -carotene from Dunaliella salina is limited. Natural carotenoids were extracted from corn gluten meal, a by-product of corn starch production, by one-step chromatography, and a high yield was obtained. The extraction principle is as follows

According to the molecular structure characteristics of carotene, that is, the substituted cyclohexene is connected by a straight-chain yoke composed of two carbon atoms in the middle, and different organic solvents are selected for extraction according to the principle of "similarity and compatibility".

Synthetic β -carotene has chromosome aberration effect, while natural β -carotene has good anti-chromosome aberration effect. In particular, natural carotenoids have recently been proved to have anti-cancer and anti-aging effects. Radiation protection, cardiovascular disease prevention and other new effects.

It is found that the market demand is increasing, and the application has also shifted from colorants to various feed microecological preparations such as nutritious food, health care products, medicines and additives.

Second, a scientific diet.

The scientific and reasonable way to eat carrots is to cook them before eating them. There are two best cooking methods to keep its nutrition. One is to cut carrots into blocks, add seasonings and fry them with enough oil. The second is to cut carrots into blocks, add seasonings, and stew them with pork, beef and mutton in a pressure cooker 15 ~ 20 minutes.

Experiments show that if cooked in pressure cooker, the preservation rate of β -carotene can be as high as 97% because of reducing the contact between carrots and air. The experiment also shows that the digestion and absorption rate of β -carotene in the body is closely related to the amount of cooking oil. The digestion and absorption rate of β -carotene in cooked food cooked with enough edible oil can reach 90%. Because β -carotene is a fat-soluble substance, it is only soluble in oil and insoluble in water.

A recent study by the University of Arkansas pointed out that cooked mushy carrot soup does not lose any nutrients and contains more antioxidants than fresh carrots.

Thank you!