Luận văn trà xanh

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Tea tree is historically the oldest cultivated. Swiss botanist Candolle (1788-1881) classified into types A tea that is already planted over 4000 years . Green tea originates from China and has become associated with many cultures in Asia from Japan and South Korea to the Middle East. Recently, it has become more widespread in the West. Botanical evidence indicates that India and China were among the first countries to cultivate tea. Many varieties of green tea have been created in countries where it is grown,these varieties can differ substantially due to variable growing conditions, processing, and harvesting time....

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 INTRODUCTION I. HISTORY: Tea tree is historically the oldest cultivated. Swiss botanist Candolle (1788-1881) classified into types A tea that is already planted over 4000 years . Green tea originates from China and has become associated with many cultures in Asia from Japan and South Korea to the Middle East. Recently, it has become more widespread in the West. Botanical evidence indicates that India and China were among the first countries to cultivate tea. Many varieties of green tea have been created in countries where it is grown,these varieties can differ substantially due to variable growing conditions, processing, and harvesting time.Today, tea is the most widely consumed beverage in the world. Hundreds of millions of people drink tea around the world, and studies suggest that green tea (Camellia sinesis) in particular has many health benefits. II. TEA CONSUMPTION SITUATION:  Green tea is widely consumed in Japan, China, and other Asian nations and is becoming more popular in Western nations. Some reports indicate green tea may have the ability to help prevent cancers of the skin, esophagus, stomach, colon, pancreas, lung, bladder, prostate, and breast.  There are three main varieties of tea green, black, and oolong. The difference between the teas is in their processing.
III. TEA MANUFACTURE: 1. Tea manufacture flow chart:       2. Explain process: a/ Raw materials: Camellia is a tree of their is a tropical plant with bright green serrated leaves. Materials must be young tea leaves, have a special aroma.
b/ Withering: The objective of withering is to reduce the moisture in the tealeaf by up to 70% (varies from region to region). Tea is laid out on a wire mesh in troughs. Air is then passed through the tea removing the moisture in a uniform way. This process takes around 12 to 17 hours. At the end of this time the leaf is limp and pliable and so will roll well . ( It is the first stage of tea manufacture. During withering harvested tea flush is evenly spread on the withering troughs which are normally 4 to 5 feet wide and 50 to 70 ft long. In the first stages people do withering availability of raw materials under the effect of high temperatures. Therefore, the concentration of tannin in green tea high, less wastage during processing .During the process hot and cold air is blown through to remove the moisture of fresh leaf to 30-40 percent which is achieved during 16 to 18 hours of period. The prime object of withering is to make the turgid leaf flaccid and prepare the leaf for next stage to facilitate rolling ) c/ Primary drying –rolling: (Rub made tea extract to facilitate product after drying will shine,when dilution of tea, the tea extract water easily permeates .It making tightlycurled tea leaves and volume reduction. To pay special attention to low rate of broken pieces ( less than 60%).) d/ Rolling: Tea is placed into a rolling machine, which rotates horizontally on the rolling table. This action creates the twisted wiry looking tealeaves. During the rolling process the leaves are also broken open, which starts the third process - oxidisation. e/Drying: To stop the oxidising process the tea is passed through hot air dryers. This reduces the total moisture content down to about 3%. The oxidisation will be stopped by this process, and now the dried tea is ready to be sorted into grades before packing. f/Sorting and Packing: Sorting, or grading, is the final stage in the tea process and one of the most crucial. Here leaves are sifted into different sizes, then classified according to appearance and type. When sufficient amount of each grade has been
sorted, it is then packed. This is either packed into foil lined paper sacks, which provide a moisture barrier, keeping the tea dry. Tea chests, however, are used for larger leaf teas as they provide an extra degree of protection against the leaves being damaged in transit. h /Product: IV. TEA AND APPLICATION OF TEA : A. Chemical Composition: 1/ The ingredients in green tea: Green tea is tea in general and in particular, is not only something to drink soft drinks, but also a remedy very helpful to protect human health. This has been research scientists. Its main chemical theanine, polyphenols and flavonoids have added Quercetin, kaempferol and myrecetin, there are also other substances such as aluminum, fluoride, manganese and carotene, with many other vitamins such as vitamin B2 (riboflavin), vitamin C and vitamin A...  The chemical components in green tea Ingredients (mg/cup) Amino acids 40-60 Carbohydrates 75 Electrolytes 50 Caffeine 50 Flavanoids - Catechines 150-210 Theaflavines - Thearubigines - Theanine
It is a powerful amino acid to affect the relaxation of the brain, and also a unique amino acid found in tea leaves. Competition with other theanine and catechin polyphenols in green tea polyphenols and catechins will be used against oxidation, anti anxiety and relax the most effective. Theanine is stimulated relaxation, brought to the attention, concentration and creativity. Unlike coffee, coffee causes irritability, confusion, panic, nervous as can anything else, from the nerve (nervousness) (J. Zittlau, 1999) about three to four cups of green tea, it would have been about 100- 200mg theanine. According to Prof Helen Charley (1982) is the ethyl amide theanine, an amino acid may be in the green tea leaves and tea leaves are dried, it weighs about 1-2% of dry tea. When rendered obsolete by the reaction of oxidation of fatty acids and theaflavins, and theanine losing aldehyde and volatile substances coming out. So, if the moisture content in the tea from 6.5 -7.5%, the tea will be damaged. Therefore, the tea should be kept in a box covered with a lid, and leave at room temperature is 30 ° C. Polyphenols Polyphenols are antioxidant protection, inhibiting the formation of free radicals, and oxygen for the patterns of activity. Prevent the kind of tumor (benign or evil) and cancer ... in the formation and growth.  What are free radicals ? Free radicals have been in our bodies is produced by the body during the natural oxidation by cells to generate power operations, is seen as a residue in the manufacturing process, make a preliminary arteriosclerosis (atherosclerosis), damaging biochemical structure of DNA, and damaging the membranes of cells, etc. .. This substance in the blood flow, exists everywhere in the body, with a large number, but modern science is discovering that the main cause devastating human body. Free radicals are found from the surrounding environment as it brings sunlight, X- rays, radioactive substances and chemicals such as antiseptic, petroleum products such as aromatic hydrocarbons, it is also due to food source , offer beverages such as frying, the volatile (solvents), alcohol, coffee... The human body has available the enzymes to convert free radicals into non-toxic substance and is discharged, but the number of enzymes in the body is not enough to neutralize it, as the number of excessive free radical in the body should be thanks to the anti-oxidation (antioxidants) from outside. The anti-oxidation is present in vegetables, yellow-orange tubers are ... And the great thing is that there are many antioxidants in green tea. Caffeine An odourless, slightly bitter-tasting alkaloid found in tea. When used in moderation,caffeine acts as a mild stimulant to the nervous system, blocking the neurotransmitter adenosine and resulting in a feeling of well-being and alertness. It increases the heart rate, blood pressure, and urination and stimulates secretion of stomach acids.
-Amount of caffeine per 180ml cup (approximate): Black Tea: 23 - 110 mg Oolong Tea: 12 - 55 mg Green Tea: 8 - 36 mg White Tea: 6 – 25 mg. Flavanoids: Flavonoids have an important role in the inhibition of all forms of cancer in our body. Catechines: Catechines belong to the flavan-3-ol class of flavonoids. They are all tannins which are polyphenolic substances. The four main catechins found in tea are: Gallocatechin (GC), Epigallocatechin (EGC), Epicatechin (EC), and Epigallocatechin -3-Gallate (ECGC). Epigallocatechin-3-gallate (EGCG) is the most important components of tea leaves, but retains a lot of green tea to be dried.They have an antioxidant activity and have also been associated with tea’s anticarcinogenic, anti-inflammatory, anti-atherogenic, Thermogenic and antimicrobial properties. Classification Special nature of the types of tea Total Tea Polyphenols >98% Green Tea ExtractsTotal Tea Catechins >90% 98% EGCG >60%-70% Caffeine 98% Green Tea ExtractsTotal Tea Catechins >80%-85 % 98% EGCG >50%-60% Caffeine 95% Green Tea ExtractsTotal Tea Catechins >70%-80% 95% EGCG >45%-50% Caffeine 90%
Total Tea Catechins >60%-70% 90% EGCG >45%-40% Caffeine 80% Green Tea ExtractTotal Tea Catechins >55% 80% EGCG >35% Caffeine 70% Green Tea ExtractTotal Tea Catechins >50% 70% EGCG >25%-30% Caffeine 60% Green Tea ExtractTotal Tea Catechins >40%-50% 60% EGCG >20%-25% Caffeine 50-30% Green Tea Extract Total Tea Catechins >40%-10% 50%-30% EGCG >8%-20% Caffeine
- Antioxidants - Cancer prevention - Cholesterol reduction - Blood pressure reduction - Blood sugar reduction. Preventing two types of diabetes - Relieve fatigue and stress - Reducing the risk of stroke - Preventing osteoporosis - Reducing DNA damage - Delaying the signs of aging - Preventing dangerous blood clotting -Preventing cardiovascular disease - Preventing bad breath - Prevent cavities 2_Uses of tea There are three main varieties of tea -- green, black, and oolong. The difference between the teas is in their processing. Green tea is made from unfermented leaves and reportedly contains the highest concentration of powerful antioxidants called
polyphenols. Antioxidants are substances that scavenge free radicals -- damaging compounds in the body that alter cells, tamper with DNA (genetic material), and even cause cell death. Free radicals occur naturally in the body, but environmental toxins (including ultraviolet rays from the sun, radiation, cigarette smoke, and air pollution) also give rise to these damaging particles. Many scientists believe that free radicals contribute to the aging process as well as the development of a number of health problems, including cancer and heart disease. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause. The secret of green tea lies in the fact it is rich in catechin polyphenols, particularly epigallocatechin gallate (EGCG). EGCG is a powerful anti-oxidant: besides inhibiting the growth of cancer cells, it kills cancer cells without harming healthy tissue. It has also been effective in lowering LDL cholesterol levels, and inhibiting the abnormal formation of blood clots. The latter takes on added importance when you consider that thrombosis (the formation of abnormal blood clots) is the leading cause of heart attacks and stroke. Bí mật của trà xanh nằm trong thực tế nó rất giàu polyphenol catechin, đặc biệt là epigallocatechin gallate (EGCG). EGCG là một chống oxy hóa mạnh: bên cạnh việc tăng trưởng các ức chế tế bào ung thư, nó giết chết tế bào ung thư mà không làm tổn hại đến các mô khỏe mạnh. Nó cũng đã được hiệu quả trong việc giảm mức cholesterol LDL, và ức chế sự hình thành cục máu đông bất thường. thứ hai có tầm quan trọng nhất khi bạn xem xét rằng huyết khối (sự hình thành các cục máu đông bất thường) là nguyên nhân hàng đầu của cơn đau tim và đột quỵ .. Polyphenols contained in teas are classified as catechins. Green tea contains six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (also known as EGCG). EGCG is the most studied polyphenol component in green tea and the most active. Polyphenol có trong trà được phân loại là catechins. Trà xanh có chứa các hợp chất catechin sáu tiểu học: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, và gallate apigallocatechin (còn gọi là EGCG). EGCG là thành phần nghiên cứu nhiều nhất polyphenol trong trà xanh và các hoạt động nhất. Green tea also contains alkaloids including caffeine, theobromine, and theophylline. These alkaloids provide green tea's stimulant effects. L-theanine, an amino acid compound found in green tea, has been studied for its calming effects on the nervous system Trà xanh cũng chứa các ancaloit như theobromine, caffeine, và theophylline. Các ancaloit cung cấp các hiệu kích thích của trà xanh. L-theanine, m ột h ợp ch ất amino acid có trong trà xanh, đã được nghiên cứu cho các hiệu ứng làm d ịu c ủa nó trên h ệ thần kinh Green tea has been extensively studied in people, animals, and laboratory experiments. Results from these studies suggest that green tea may be useful for the following health conditions:
trà xanh đã được nghiên cứu ở người, động vật, và thí nghiệm phòng thí nghi ệm. Kết quả từ các nghiên cứu này cho thấy rằng trà xanh có thể hữu ích cho các điều kiện sức khỏe sau