Tea seed cake meal is the remaining product after the tea seed is extracted from oil, and China's resources are rich but underutilized.
Both camellia sinensis and camellia oleifera are plants of the camellia family, and both seeds contain oils and fats of high nutritional value.
Tea seed cake meal is the product left over from the extraction of most of the oil and fat after the tea seed has been pressed or leached, also known as tea dry, tea bran;
Among them, the remaining part after pressing the oil is called the cake, and the remaining part after the pre-pressed leaching is called the meal.
According to relevant data reports, in normal years, China's annual output of camellia oleifera seeds is about 549,800 tons, tea oil is more than 150,000 tons, and camellia oleifera cake meal is about 397,100 tons.
Tea seeds are one of the most abundant by-products of the tea production process.
It is estimated that China's annual output of tea seeds is about 125,000 tons, if it can be fully utilized, it can provide 22,500 tons of tea seed oil and 90,000 tons of tea seed cake meal every year.
It can be seen that China's tea seed cake meal resources are very rich, but the current utilization of tea seed cake meal is still very insufficient.
Tea seed cake meal is rich in tea saponins, protein fats and sugars, and we can use its unique physiological functions to turn tea seed cake meal into treasure.
The following is an introduction to the main components of tea seed cake meal and a review of the research on their application in aquaculture.
The main active ingredient in tea seed cake meal
Tea saponins
Tea saponins, also known as tea saponins, belong to the pentacyclic triterpenoid saponins, which are composed of three parts: glycosides, sugars and organic acids.
Tea saponin is distributed in the roots, stems, leaves and seeds of the tea plant, but the molecular structure is somewhat different, among which the organic acid of tea seed saponin is composed of angelica acid and acetic acid.
In terms of content, the saponin content in tea seeds is the highest (about 10%-14%).
Jiang Heyuan et al. found that the tea saponins in tea seed cake meal also contain flavonoid glycosides, mainly kaempferol-3-0-rutinoside (Kaempferol-3-0-Rutinoside) and kaempferol-3-0-β-β D-galactopyrano-side.
At present, the extraction methods of camellia oleifera saponin are mainly organic solvent method and water extraction- alcohol extraction method;
Among the purification methods, saponin recovery rates such as flocculant method, ultrafiltration membrane method and macroporous resin method are high and high purity, which is suitable for industrial production.
The molecules of tea saponin have hydrophilic glycosaccharides and hydrophobic coordination groups, so it is an excellent nonionic surfactant that can be applied to industries such as daily chemical building materials.
Studies have proved that tea saponin has a variety of biological activity functions such as hemolytic effect, fish poison effect, antibacterial insecticidal effect, antidote effect and anti-exudative and anti-inflammatory effect.
Tea seed protein with polypeptides
Tea seed cake meal contains 11% to 16% protein, and there are 18 kinds of amino acids.
The content of essential amino acids in animals in tea seed cake meal is high, especially the content of effective lysine and sulfur-containing amino acids, and the actual protein level can reach 22.89%, and its nutritional value is significantly higher than that of corn wheat, rice bran and bran.
However, due to the hemolytic tea saponin contained in tea seed cake meal, it must be detoxified before it can be used as feed.
Plant proteins are enzymatically digested to produce peptides and amino acids and other substances, which have high nutritional value and functional characteristics.
Gong Jijun's research shows that the tea seed polypeptide obtained after the use of alkaline protease enzymatic digestion has a strong activity of scavenging hydroxyl radicals and superoxide free radicals;
The scavengery of hydroxyl radicals can reach up to 82.4%, and the maximum scavenger of superoxide radicals is 52.3%.
The extracted tea seed polypeptide can be used in the production of functional foods, thereby broadening the utilization route of tea seed protein.
Residual tea oil
Tea seeds are rich in oils and fats, of which tea seeds contain 15% to 35% oil, and camellia oleifera seeds contain 25% to 33% oil.
After the tea seed is extracted by pressing the tea oil, the cake meal still contains 3% to 5% residual tea oil, and the reconquered tea oil can be obtained after the re-pressing, but the re-pressed hair tea oil is high in acid price and the impurity content is high, and it must be refined.
Tea oil is a plant-based edible oil with high nutritional value, and its fat component is mainly unsaturated fatty acids.
The content of oleic acid and linoleic acid is as high as more than 90%, of which the content of oleic acid is more than 80%, and the content of saturated fatty acids is much lower than that of various other edible oils, which is known as "oriental olive oil".
Tea oil has antioxidant and immune regulation, reduce blood lipids, improve blood circulation, delay atherosclerosis, anti-tumor, prevention of coronary heart disease, liver protection and other health care effects, is widely used in food, medicine and cosmetics industry.
Tea polysaccharides
Since the 1990s when Shimizu Zenfu concluded that the pharmacological component of tea to treat diabetes is tea polysaccharides, research reports related to tea polysaccharides have begun to increase.
It mainly focuses on the pharmacological research of crude products of tea polysaccharides.
Sun Jiping first studied the polysaccharides of tea seeds, and found that the combined use of enzymatic method and Saveage had a good effect on the deproteinization effect of tea seed polysaccharide water extract.
The results of the analysis of the crude polysaccharide composition of tea seeds showed that it is mainly composed of six kinds of sugars.
Among them, the highest content of mannose was 30.16%, followed by galactose with 23.92%, followed by arabinose 17.07%, glucose 12.24%, rhamnose 11.39% xylose 5.22%, and the average molecular weight was 24.25.
Animal experiments show that tea seed polysaccharides have anticoagulant and thrombotic effects and hypoglycemic effects.
Applications in the field of aquatic products
1. Selective pond clearance
The tea saponin in tea seed cake meal has a hemolytic effect and a fish toxin effect.
The hemolytic mechanism of theothenic saponin is that saponins cause changes in the permeability of cell membranes containing cholesterol, destroy cell membrane activity, and then lead to cytoplasmic extravasation, and eventually inactivate erythrocyte disintegration.
Zhu Quanfen et al. found that tea saponin only has a hemolytic effect on hemoglobin (including nucleated fish blood, chicken blood, seedless human blood, etc.), but no effect on white blood cells and shrimp blood cells.
The mechanism of action of fish toxin is that tea saponin destroys the gill tissue, and the epithelial cells of the gills enter the microvascular vessels, thereby causing hemolytic effects, resulting in fish poisoning and death.
The composition structure of shrimp gills and fish gills is completely different, in addition, the oxygen carrier of shrimp is heme, and fish blood is heme, so tea saponin shrimp has no fish toxic effect.
As a natural fish toxic active substance with excellent performance, tea saponin can be used as a clearing agent to selectively remove predatory fish in fish ponds and shrimp ponds.
In terms of its application, researchers have carried out a lot of practical application research.
For example, Liang Yaquan et al. conducted toxic studies on tea saponins on goby, sea bass, spot-tailed goby, barracuda and shrimp;
It was found that the LC100 of tea saponin for 24 h was 0.5 to 1 mg/L for the above fish species, while the safe concentration for shrimp use could reach 10 mg/L;
Luo Yizhi et al. conducted a study on the toxicity of tea saponin to wild trash fish such as wheat ear fish and crucian carp commonly found in freshwater crustacean culture ponds, and found that tea saponin can be killed at a concentration of 2.5 mg/L.
On the other hand, freshwater green shrimp, Giant river prawn and river crab for crustaceans are very safe, and can survive normally even at concentrations of 18 mg/L.
In actual use, each cubic meter of water body is sprinkled with 3g tea saponin and water in the whole pond, and the wild trash fish in the pool can be removed after 16 hours, and there is no impact on shrimp and crabs;
Or use the crushed fresh tea cake 30kg/mu (water depth 30~50 cm), soaked in cold water for 2~3 d, heated to 100 degrees, evenly poured wine in the pond for clearing the pond, 10-15 d after the toxicity disappears, you can try to put shrimp and crab seeds.
Shao Guoer's research showed that the tea seed cake leaching solution in the range of 15 to 60mg/L concentration can effectively kill the budding branch tube jellyfish that are largely propagated in the pond breeding pond, and has no effect on the pond shrimp and crab breeding species.
Su Shiping's research found that in the production of river crab seedlings, the tea seed cake solution with a mass concentration of 10mg/L can effectively control the larvae of The Richter female insect, and the remaining very small number of larvae can become the natural bait of the river crab with the growth of crab seedlings, thereby saving the cost of bait.
Zhu Yanfang et al. made a mother liquor (concentration of 10g/L) by soaking 10g of camellia oleifera cake with a 20 mesh sieve and soaking it in 1L of water for 12 hours, and conducted toxicity experiments on yellow eels and eels;
The results showed that the oleifera seed cake water immersion solution was a micro-toxic drug for both calves and adult eels, and its 96-hour LC50 (the concentration of poison that killed half of the animals in the subject animals) for calamus and adult eels was 25 mg/L and 30 mg/L, respectively.
Studies have also shown that the appropriate concentration of camellia oleifera seed cake water immersion has the effect of disinfection and sterilization to improve the survival rate of juvenile fish.
Zhang Xiufeng et al. on the acute toxicity of tea seed cake to ginseng showed that in the process of ginseng pond culture, tea seed cake can be applied as a fish medicine with ginseng:
Its safe concentration for ginseng is 10.056mg/L, and the residue of tea seed cake used in this concentration range can be ingested by ginseng.
Control of diseases of aquatic animals
Tea saponin can stimulate the endocrine hormones of crustaceans such as shrimp to promote molting, such as 10 to 15 mg/L of tea saponin can promote shrimp molting, which is conducive to the growth and development of shrimp.
The shrimp farming protection agent developed according to the biological activity of tea saponin not only exerts the fish toxic effect of tea saponin, but also plays the role of tea saponin in promoting the growth of shrimp, and forms a comprehensive effect in shrimp farming.
In addition, tea saponin can also prevent the occurrence of shrimp black gill disease and control parasites.
Biological snail control
Tea saponin has a good killing effect on the intermediate host snail of schistosomiasis, and is rich in resources and low price.
Chen Yongjun studied the tea saponin killing nail snail, using different concentrations of tea saponin acetate solution in the range of 4 to 15 mg/L to submerge the nail snail, and the mortality rate of each group after 48 h was 61%-96%.
It is proved that tea saponin has a certain killing effect on snails.
Zhang Chushuang, Zhou Lihong, Zhu Jinhua, etc. observed the effect of tea saponin on-site snail killing, and found that the on-site spraying of wine to kill snails was poor, and in the ditch in the epidemic area, the water-blocking shoveling grass soaking method was used to kill snails, and tea saponin could achieve better snail killing.
Song Gengming et al. applied electron microscopy to observe the liver and germ cells after the snail was soaked in tea saponin 5mg/L for 24 hours, and found that the drug could cause serious damage to its liver cells and germ cells, and killed the snail.
Although the snails that have undergone small doses of tea seed action do not die, the mating of the snails is affected by the damage of mature cells, which reduces the chance of fertilization of the snails and the density of the snails.
Due to the rapid reproduction of Fushou snail, in order to harm vegetable crops such as rice russet, rhombus, lotus root, and mustard, Wang Xiaoyizhou and others conducted a test on the medicinal efficacy of tea saponin on Fushou snail:
The virulence measurement results showed that tea saponin had a high inhibitory effect on the hatching of Fushou snail eggs, and at the same time had a very high toxic killing effect on young snails, with a mortality rate of 100% at 2.5 mg/L3 days, but the control effect on snails was poor.
The indoor poisoning test of tea bran on Fushou snail conducted by Chen Jianping showed that under the condition of relatively high temperature (more than 30 C), soaking tea bran with boiling water and soaking fushou snail with 2000 times the tea bran leaching liquid had a good toxic killing effect.
Detoxified tea seed cake meal is used as fish feed
Tea seed cake meal generally contains 0.5% to 7% crude fat and 10% to 20% protein;
15% to 25% crude fiber, 30% to 60% carbohydrates, 20% to 50% nitrogen-free extracts;
Digestion energy of 8 to 10 MJ/kg (digestion energy = total feed energy - manure energy - methane and other gas energy that cannot be used by animals. i.e. the energy contained in the digested and absorbed feed).
In addition, minerals and trace elements Ca, K, Mg, Fe, Mn and other content is also relatively rich, is an excellent feed raw materials.
However, tea seed cake meal also contains a certain amount of tea saponins, 2% to 7% tannins, 1.5% to 3% alkaloids, about 0.2% flavonoids and a small amount of phytic acid and other anti-nutritional factors.
If it is not removed, it will affect the use of cake meal and the growth of fish and shrimp.
The extraction process of tea saponin, that is, the detoxification of tea meal, can remove most of the tannin alkaloids and flavonoids.
After organic solvent extraction, the content of tea saponin in cake meal can be controlled below 1%, and the tannin content can be controlled below 2%, which can be directly used in aquatic production.
Li Hongquan et al. studies on the application of camellia oleifera meal feed in heterogeneous silver crucian carp culture have shown that the addition of appropriate detoxified camellia oleifera meal to feed has obvious effect on the growth of fish.
The 10% addition amount worked best, and the alien silver crucian carp was fed normal and slightly better meat quality than the control group.
Studies have also shown that low-dose tea saponins have a certain activating effect on intestinal digestive enzymes in fish bodies, and may play a certain role in increasing the permeability of the intestinal mucosa.
Promotes the absorption of nutrients, thereby promoting animal growth and improving feed utilization.
Studies by Zhou Jiangjiang et al. also show that feeding with 10% to 15% detoxified oil tea meal in tilapia fry and fish fingerling stage has a better feeding effect.
In order to further improve the protein content and utilization rate of tea meal and reduce the crude fiber content, domestic scholars have been studying the solid fermentation process of tea seed cake meal since the early 1990s.
Fermentation of tea seed cake meal using microbial strains such as mucorb, purple fungus, candida 117 or a combination of them can greatly increase the protein content.
For example, after Deng Guilan used the selected composite strains to ferment Camellia oleifera meal, its crude protein content increased from 17.2% before fermentation to 32.7%, and the crude fiber content decreased from 19.2% before fermentation to 9.7%, and the amino acid composition and ratio of its protein became more reasonable, and the nutritional value was greatly improved.
prospect
China's tea seed cake meal is rich in resources, but it has not been fully developed and utilized, and detoxification technology is the bottleneck of its utilization.
In the early 1980s, China successively established a number of tea saponin processing plants, but most of the enterprises stopped production due to low product purity, high production costs and low efficiency.
Due to the stagnation of tea saponin extraction production, the industrial production of tea seed cake meal as feed cannot be carried out.
At present, tea seed cake meal is still directly used as a pond clearing agent.
The types and contents of tea saponins in tea seed cake meal are different, and the effect of direct use of cake meal is quite different, and the pond clearing agent and snail extinguisher with purified tea saponin as raw material can play an accurate and effective role.
Due to the high toxicity and easy residue of chemical agents, with the continuous deepening of the concept of sustainable development.
People's demand for natural biological agents is increasing, and the use of tea saponin in tea seed cake meal to develop pollution-free selective pond clearing agents, snail extinguishers, protective agents, etc. has broad market prospects.
At the same time, the detoxified tea seed cake meal can be used as a high-quality aquatic feed raw material.
With the continuous improvement of tea saponin extraction and purification technology and the continuous improvement of the comprehensive utilization of tea seed cake meal, tea seed cake meal will eventually play a greater role in the development of aquaculture.