T E A

Camellia sinensis, the tea plant, is the species of plant whose leaves and leaf buds are used to produce tea. White tea, green tea, oolong, pu-erh tea and black tea are all harvested from this species, but are processed differently to attain different levels of oxidation. Kukicha (twig tea) is also harvested from Camellia sinensis, but uses twigs and stems rather than leaves.

Astringency is also the dry, puckering mouth feel caused by tannins found in many fruits such as blackthorn, bird cherry and persimmon fruits, and banana skins. The tannins denature the salivary proteins, causing a rough "sandpapery" sensation in the mouth. Astringency tastes unpleasant to many mammals (including humans), which tend to avoid eating astringent fruit; conversely, birds do not taste astringency and readily eat these fruit.

Catechins are polyphenolic antioxidant plant metabolites. They belong to the family of flavonoids and, to be more specific, flavan-3-ols. These compounds are abundant in teas derived from the tea-plant Camellia sinensis as well as in some cocoas and chocolates (made from the seeds of Theobroma cacao).

Pu-erh, Pu'er tea, Puer tea or Bolay tea is a type of tea made from a "large leaf" variety of the tea plant Camellia sinensis and named after Pu'er county near Simao, Yunnan, China.

The bergamot - is a small and roughly pear-shaped fragrant citrus fruit native to Southeast Asia. Today it is also commercially grown in Calabria, Italy. Bergamot grows on small trees which blossom during the spring. The distinctive aroma of the bergamot is most commonly known for its use in Earl Grey tea, though the juice of the fruit has also been used in Calabrian indigenous medicine as an herbal remedy for malaria and its essential oil is popular in aromatherapy applications.


T E A

Tea refers to the agricultural products of the leaves, leaf buds, and internodes of the Camellia sinensis plant, prepared and cured by various methods. "Tea" also refers to the aromatic beverage prepared from the cured leaves by combination with hot or boiling water, and is the colloquial name for the Camellia sinensis plant itself.

After water, tea is the most widely-consumed beverage in the world. It has a cooling, slightly bitter, astringent flavour.

The four types of tea most commonly found on the market are black tea, oolong tea, green tea and white tea, all of which can be made from the same bushes, processed differently, and in the case of fine white tea grown differently. Pu-erh tea, a double-fermented black tea, is also often classified as amongst the most popular types of tea.

The term "herbal tea" usually refers to an infusion or tisane of fruit or herbs that contains no Camellia sinensis. The term "red tea" either refers to an infusion made from the South African rooibos plant, also containing no Camellia sinensis, or, in Chinese, Korean, Japanese and other East Asian languages, refers to black tea.

Cultivation
Camellia sinensis is an evergreen plant that grows mainly in tropical and sub-tropical climates.
Tea plants require at least 50 inches of rainfall a year and prefer acidic soils. Many high-quality tea plants are cultivated at elevations of up to 1500 meters (5,000 ft): at these heights, the plants grow more slowly and acquire a better flavor.
Only the top 1-2 inches of the mature plant are picked. These buds and leaves are called flushes. A plant will grow a new flush every seven to ten days during the growing season.
A tea plant will grow into a tree if left undisturbed, but cultivated plants are pruned to waist height for ease of plucking. Two principal varieties are used: the small-leaved China plant (C. sinensis sinensis), used for most Chinese, Formosan and Japanese teas (but not Pu-erh); and the large-leaved Assam plant (C. sinensis assamica), used in most Indian and other teas (but not Darjeeling). Within these botanical varieties, especially the small-leaved China plant, there are many traditional strains and modern clonal varieties. Leaf size is the chief criterion for the classification of tea plants: tea is classified into (1) Assam type, characterized by the largest leaves; (2) China type, characterized by the smallest leaves; and (3) Cambod, characterized by leaves of intermediate size.

Processing and classification
A tea's type is determined by the processing through which it goes. Leaves of Camellia sinensis soon begin to wilt and oxidize if not dried quickly after picking. The leaves turn progressively darker as their chlorophyll breaks down and tannins are released. This process, enzymatic oxidation, is called fermentation in the tea industry, although it is not a true fermentation: it is not caused by micro-organisms, and is not an anaerobic process. The next step in processing is to stop the oxidation process at a predetermined stage by heating, which deactivates the enzymes responsible. With black tea this is done simultaneously with drying
Tea is traditionally classified based on the techniques with which it is produced and
processed.

White tea: Unwilted and unoxidized
Yellow tea: Unwilted and unoxidized but allowed to yellow
Green tea: Wilted and unoxidized
Oolong: Wilted, bruised, and partially oxidized
Black tea: Wilted, sometimes crushed, and fully oxidized
Post-fermented tea: Green Tea that has been allowed to ferment.

Without careful moisture and temperature control during manufacture and packaging, the tea will grow fungi. The fungus causes real fermentation that will contaminate the tea with toxic and sometimes carcinogenic substances (related to causing cancer), as well as off-flavors, rendering the tea unfit for consumption.

Almost all teas in bags and most other teas sold in the West are blends. Blending may occur in the tea-planting area (as in the case of Assam), or teas from many areas may be blended. The aim is to obtain better taste, higher price, or both, as a more expensive, better-tasting tea may cover the inferior taste of cheaper varieties.

Content
Tea contains catechins, a type of antioxidant. In a fresh tea leaf, catechins can compose up to 30% of the dry weight. Catechins are highest in concentration in white and green teas, while black tea has substantially fewer due to its oxidative preparation. Tea also contains theanine and the stimulant caffeine at about 3% of its dry weight, translating to between 30 mg and 90 mg per 8 oz (250 ml) cup depending on type, brand and brewing method. Tea also contains small amounts of theobromine and theophylline, as well as fluoride, with certain types of brick tea made from old leaves and stems having the highest levels.
Dry tea has more caffeine by weight than coffee; nevertheless, more dried coffee is used than dry tea in preparing the beverage.
Tea has no carbohydrates, fat, or protein.

Tea processing
Although each type of tea has different taste, smell, and visual appearance, tea processing for all tea types consists of a very similar set of methods with only minor variations:

Picking: Tea leaves and flushes, which includes a terminal bud and 2 young leaves, are plucked from Camellia sinensis bushes twice a year during early spring and early summer or late spring.
Autumn or winter pickings of tea flushes are much less common, though they occur when climate permits. Picking is done by hand when a higher quality tea is needed, or where labour costs are not prohibitive. Hand-picking is done by pulling the flush with a snap of the wrist and does not involve twisting or pinching the flush, since doing the latter reduces the quality of the leaves.
Tea flushes and leaves can also be picked by machine, though there will be more broken leaves and partial flushes. It is also more difficult to harvest by machine on mountain slopes where tea is often grown.

Wilting: The tea leaves will begin to wilt soon after picking, with a gradual onset of enzymatic oxidation. Wilting is used to remove excess water from the leaves and allows a very light amount of oxidation. The leaves can be either put under the sun or left in a cool breezy room to pull moisture out from the leaves. The leaves sometimes lose more than a quarter of their weight in water during wilting.

Bruising: In order to promote and quicken oxidation, the leaves may be bruised by tumbling in baskets or by being kneaded or rolled-over by heavy wheels. This also releases some of the leaf juices, which may aid in oxidation and change the taste profile of the tea.

Oxidation: For teas that require oxidation, the leaves are left on their own in a closed room where they turn progressively darker. In this process the chlorophyll in the leaves is enzymatically broken down, and its tannins are released or transformed. This process is referred to as fermentation in the tea industry, although no true fermentation happens since this oxidative process does not generate energy (this step is also not driven by micro organisms; in other steps of tea processing--aging for example--microorganisms might be used that actually do carry out fermentation). The tea producer may choose when the oxidation should be stopped. For light oolong teas this may be anywhere from 5-40% oxidation, in darker oolong teas 60-70%, and in black teas 100% oxidation.

Kill-green: Kill-green is done to stop the tea leaf oxidation at a desired level. This process is accomplished by moderately heating tea leaves, thus deactivating their oxidative enzymes, without destroying the flavour of the tea. Traditionally, the tea leaves are panned in a wok or steamed, but with advancements in technology, kill-green is sometimes done by baking or "panning" in a rolling drum. In CTC black teas, kill-green is done simultaneously with drying.

Yellowing: Unique to yellow teas, warm and damp tea leaves from after kill-green are allowed to be lightly heated in a closed container, which causes the previously green leaves to yellow.

Shaping: The damp tea leaves are then rolled to be formed into wrinkle strips. This is typically done by placing the damp leaves in large cloth bags, which are then kneaded by hand or machine to form the strips. This rolling action also causes some of the sap and juices inside the leaves to ooze out, which further enhances the taste of the tea. The strips of tea can then be formed into other shapes, such as being rolled into spirals, kneaded and rolled into pellets, or tied into balls and other elaborate shapes.

Drying: Drying is done to "finish" the tea for sale. This can be done in a myriad of ways including panning, sunning, air drying, or baking. However, baking is usually the most common. Great care must be taken to not over-cook the leaves.

Curing: While not always required, some teas required additional aging, secondary-fermentation, or baking to reach their drinking potential. As well, flavored teas are manufactured by spraying with aromas and flavors or by storing them with their flavorants.

Type specific processing

White Tea - Young leaves (new growth buds) that have undergone no oxidation; the buds may be shielded from sunlight to prevent formation of chlorophyll. White tea is produced in lesser quantities than most other styles, and can be correspondingly more expensive than tea from the same plant processed by other methods. It is less well known in countries outside of China, though this is changing with increased western interest in organic or premium teas.

Green Tea - The oxidation process is stopped after a minimal amount of oxidation by application of heat, either with steam, or by dry cooking in hot pans, the traditional Chinese method. Tea leaves may be left to dry as separate leaves or they may be rolled into small pellets to make Gunpowder tea. This process is time consuming and is typically done with pekoes of higher quality. The tea is processed within one to two days of harvesting.

Oolong - Oxidation is stopped somewhere between the standards for green tea and black tea. The oxidation process takes two to three days. In Chinese, semi-oxidized teas are collectively grouped as blue tea, while the term "oolong" is used specifically as a name for certain semi-oxidized teas.

Black tea/Red tea - The tea leaves are allowed to completely oxidize. Black tea is the most common form of tea in southern Asia (Sri Lanka, India, Pakistan, Bangladesh, etc.) and in the last century many African countries including Kenya, Burundi, Rwanda, Malawi and Zimbabwe. The literal translation of the Chinese word is red tea, which is used by some tea lovers. The Chinese call it red tea because the actual tea liquid is red. Westerners call it black tea because the tea leaves used to brew it are usually black. However, red tea may also refer to rooibos, an increasingly popular South African tisane. The oxidation process will take between two weeks and one month. Black tea is further classified as either orthodox or as CTC (Crush, Tear, Curl, a production method developed about 1932). Unblended black teas are also identified by the estate they come from, their year and the flush (first, second or autumn). Orthodox processed black teas are further graded according to the post-production leaf quality by the Orange Pekoe system, while CTC teas use a different grading system.

Post-fermented tea - Teas that undergo a second oxidation, such as Pu-erh, Liu'an, and Liubao, are collectively referred to as secondary or post-fermentation teas in English. In Chinese they are categorized as Dark tea or black tea. This is not to be confused with the English term Black tea, known in Chinese as red tea. Pu-erh, also known as Póu léi (Polee) in Cantonese is the most common type of post-fermetation tea in the market.

Kukicha - Also called winter tea, kukicha is made from twigs and old leaves pruned from the tea plant during its dormant season and dry-roasted over a fire. It is popular as a health food in Japan and in macrobiotic diets.

Preparation
The traditional method of making a cup of tea is to place loose tea leaves, either directly, or in a tea infuser, into a tea pot or teacup and pour hot water over the leaves. After a couple of minutes the leaves are usually removed again, either by removing the infuser, or by straining the tea while serving.
Most green teas should be allowed to steep for about three minutes, although some types of tea require as much as ten. The strength of the tea should be varied by changing the amount of tea leaves used, not by changing the steeping time. The amount of tea to be used per amount of water differs from tea to tea but one basic recipe may be one slightly heaped teaspoon of tea (about 5 ml) for each teacup of water (200 ml) (8 oz) prepared as above. Stronger teas, such as Assam, to be drunk with milk are often prepared with more leaves, and more delicate high grown teas such as a Darjeeling are prepared with a little less (as the stronger mid-flavors can overwhelm the champagne notes).
The best temperature for brewing tea depends on its type. Teas that have little or no oxidation period, such as a green or white tea, are best brewed at lower temperatures between 60 °C and 85 °C (140-185 °F), while teas with longer oxidation periods should be brewed at higher temperatures around 100 °C (212 °F).[46] The higher temperatures are required to extract the large, complex, flavorful phenolic molecules found in fermented tea, although boiling the water reduces the amount of dissolved oxygen in the water.

Black Tea - The water for black teas should be added at boiling point (100 °C or 212 °F). Many of the active substances in black tea do not develop at temperatures lower than 90 °C. For some more delicate teas lower temperatures are recommended. The temperature will have as large an effect on the final flavor as the type of tea used. The most common fault when making black tea is to use water at too low a temperature. Since boiling point drops with increasing altitude, this makes it difficult to brew black tea properly in mountainous areas. It is also recommended that the teapot be warmed before preparing tea, easily done by adding a small amount of boiling water to the pot, swirling briefly, before discarding. Black teas are usually brewed for about 4 minutes and should not be allowed to steep for less than 30 seconds or more than about five minutes (a process known as brewing or mashing in the UK, specifically in Yorkshire [49]). Longer steeping times make the tea bitter (at this point it is referred to as being stewed in the UK). When the tea has brewed long enough to suit the tastes of the drinker, it should be strained while serving. The popular varieties of black tea include the Assam tea, the Darjeeling tea and the black Ceylon tea.Green Tea - Water for green tea, according to most accounts, should be around 80 °C to 85 °C (176 °F to 185 °F); the higher the quality of the leaves, the lower the temperature. Hotter water will burn green-tea leaves, producing a bitter taste. Preferably, the container in which the tea is steeped, the mug, or teapot should also be warmed beforehand so that the tea does not immediately cool down. High-quality green and white teas can have new water added as many as five or more times, depending on variety, at increasingly high temperatures. Recently, green tea (as well as some black teas) have been shown to significantly increase interferon levels in tea consumers, which lends credence to the theory that some teas help boost the immune system.[50]

Oolong - Oolong teas should be brewed around 90 °C to 100 °C (194 °F to 212 °F), and again the brewing vessel should be warmed before pouring in the water. Purple clay teapots are the traditional brewing vessel for oolong tea. For best results use spring water, as the minerals in spring water tend to bring out more flavor in the tea. High quality oolong can be brewed multiple times from the same leaves, and unlike green tea it improves with reuse. It is common to brew the same leaves three to five times, the third steeping usually being the best.

Premium/delicate teas - Some teas, especially green teas and delicate Oolong teas, are steeped for shorter periods, sometimes less than 30 seconds. Using a tea strainer separates the leaves from the water at the end of the brewing time if a tea bag is not being used. However black Darjeeling tea, the premium Indian tea, needs a longer than average steeping time. Elevation and time of harvest offer varying taste profiles, proper storage and water quality also have a large impact on taste.

Pu-erh - Pu-erh teas require boiling water for infusion. Some prefer to quickly rinse Pu-erh for several seconds with boiling water to remove tea dust which accumulates from the aging process. Infuse Pu-erh at the boiling point (100 °C or 212 °F), and allow to steep for 30 seconds or up to five minutes.

Serving
In order to preserve the pre-tannin tea without requiring it all to be poured into cups, a second teapot may be employed. The steeping pot is best unglazed earthenware; Yixing pots are the best known of these, famed for the high quality clay from which they are made. The serving pot is generally porcelain, which retains the heat better. Larger teapots are a post-19th century invention, as tea before this time was very rare and very expensive. Experienced tea-drinkers often insist that the tea should not be stirred around while it is steeping (sometimes called winding in the UK). This, they say, will do little to strengthen the tea, but is likely to bring the tannins out in the same way that brewing too long will do. For the same reason one should not squeeze the last drops out of a teabag; if stronger tea is desired, more tea leaves should be used.

Adding Milk to Tea
The addition of milk to tea was first mentioned in 1680 by the epistolist Madame de Sévigné. Many teas are traditionally drunk with milk. These include Indian masala chai, and British tea blends. These teas tend to be very hearty varieties which can be tasted through the milk, such as Assams, or the East Friesian blend. Milk is thought to neutralize remaining tannins and reduce acidity. The Chinese do not usually drink milk with tea (or indeed use milk at all) but the Manchurians do, and the elite of the Manchu Dynasty continued to do so. Hong Kong-style milk tea is based on British colonial habits.
The order of steps in preparing a cup of tea is a much-debated topic. Some say that it is preferable to add the milk before the tea, as the high temperature of freshly brewed tea can denature the proteins found in fresh milk, similar to the change in taste of UHT milk, resulting in an inferior tasting beverage. Others insist that it is better to add the milk after
brewing the tea, as most teas need to be brewed as close to boiling as possible. The addition of milk chills the beverage during the crucial brewing phase, meaning that the delicate flavor of a good tea cannot be fully appreciated. By adding the milk afterwards, it is easier to dissolve sugar in the tea and also to ensure that the desired amount of milk is added, as the color of the tea can be observed.

Other Additives
Much flavouring is added to varieties of tea during processing. Among the best known are Chinese Jasmine tea, with jasmine oil or flowers, the spices in Indian Masala chai and Earl Grey tea, which contains oil of bergamot. A great range of modern flavours have been added to these traditional ones.
Other popular additives to tea by the tea-brewer or drinker include sugar, honey, lemon
(traditional in Russia and Italy), fruit jams, and mint. In China sweetening tea was
traditionally regarded as a feminine practice. In colder regions such as Mongolia, Tibet and Nepal, butter is added to provide necessary calories. Tibetan butter tea contains rock salt and dre (yak) butter, which is then churned vigorously in a cylindrical vessel closely resembling a butter churn. The same may be said for salt tea, which is consumed in some cultures in the Hindu Kush region of northern Pakistan.
Tea can also be fortified by the addition of alcohol, such as whisky or brandy.

Wine Chemistry

Wine Chemistry
The Importance of Chemical Understanding in Wine Manufacture
An explanation of the chemical processes involved in the production of wine and in those that determine the appearance, flavour and aroma of different wines.
Wine-making is essentially a chemical process. It involves a chemical reaction in which sugars are turned to alcohol and carbon dioxide in the presence of yeast. There are also many other chemical processes going on which affect the strength, appearance, colour and taste of the wine.

Grape Ingredients
Wine is made from grapes. In addition to water, grapes contain two different sugars: glucose and fructose, tartaric acid, malic acid, amino acids and a few other chemicals. The chemical processes of wine-making involve several of these components and the amount of each is important in determining the character of the wine produced.

Glucose to Ethanol
The most important chemical reaction in the wine making process is the breaking down of glucose by yeast, forming ethanol and carbon dioxide as gas. There are various important factors at this stage which affect the wine. First, sulphur dioxide gas is passed through the crushed grapes to kill off wild yeasts. If this was not done the yeasts would compete with one another and fermentation would stop prematurely.

Controlling pH
Next the pH (acidity) of the grape pulp needs to be controlled. If grapes are too sweet, then their pH is too high (acidity too low) then less flavours are produced in the wine. The pH can be lowered by adding tartaric acid at the start of the fermentation process.

Temperature
Finally the temperature must be controlled throughout the process. Fermentation is an exothermic process (heat is produced by the reaction), but there are various reasons for keeping the temperature as low as possible. Yeast stops growing as temperatures increase and will die at higher temperatures. Also at lower temperatures colours and flavours are extracted from the skins and by-products such as esters and aromatic compounds are produced which add to the flavour and also the clarity of the wine.

Advances in Wine Chemistry
As more and more research is done into the constituents of the wine and the way they are formed, two areas in particular stand out. First is the idea that regular consumption of wine in moderation is good for you. Statistical studies have shown that wine drinkers are less prone to heart disease, cancer and other diseases. This may be explained by the fact that wine drinkers tend to have a healthier lifestyle and are in groups which are less at risk to these diseases. It may be that there are certain chemicals that combat certain conditions, for example the antioxidant resveratrol which may reduce cholesterol and the risk of Alzheimer’s disease. These chemicals can, of course, be found in other food and drink without the damaging presence of alcohol.

Improving Wine Making
Then there is the development of the scientific study of the process of wine making, and the technology to improve it. There are many who would desire to depend on the natural processes of grapes and fermentation. Others have studied the chemicals which make up wine, seeking to determine those that cause the flavour, aroma and appearance of wine so that these can be manipulated in the production process. This tension will continue as the desire to make money affects the love of natural processes.

Wine chemistry explains the flavor, balance, color, stability that was once only possible through subjective description. Understanding the principles of wine chemistry will open your eyes to a new level of wine appreciation.