Green Tea, White Tea: Health Catechin

Darjeeling Tea Processing - The process of Darjeeling Tea manufacture

Darjeeling Tea Processing - The process of Darjeeling Tea manufacture

Darjeeling Tea Processing
(Tea Manufacture)
Tea Roller Machine in Darjeeling Tea Estate used for Darjeeling Tea manufacture PLUCKING:
During quality periods i.e. first flush or second flush, two leaves and a bud are picked - this is called fine plucking, resulting in high quality teas. At other times, even three or four leaves and a bud are plucked - this is called coarse plucking. The plucking cycle is maintained at about 7 day intervals. The plucked leaves are collected in bamboo baskets, taking care that they are not crushed by overloading the baskets. WEIGHMENT : The plucked leaves are delivered to the factory for weighment. Each plucker is paid against the quantity (weight) of green leaf that he/she brings in.

The plucked leaves are delivered to the factory for weighment. Each plucker is paid against the quantity (weight) of green leaf that he/she brings in.

The green leaf, after eradication of any foreign matter, is spread on "withering troughs", loosely, to a depth of 6 inches. Fans are installed to pass air over the green leaf while it withers. The object of the withering process is to get rid of the moisture content in the green leaf and prepare the leaf to withstand the strain of rolling without breaking up. Period of withering can vary from 18 to 24 hrs. depending on the moisture content. The leaf, when properly withered, gives off a fragrant odour.

The object of rolling is to bruise the cells of the leaves so that their sap (juice) is exposed to the action of oxygen in the air. Rolling also gives a twist to the leaf. The cell sap contains tannins, caffeine, proteins and other chemical substances, which ultimately give the characteristic colour to the tea liquor during infusion. The withered leaf is given 3 or 4 rolls (each of 30 minutes). After the first roll, the leaf is sifted (kutcha sifting) and the fine leaves (about 20%) are taken out. The rest are given a second roll and in the second kutcha sifting about 20 - 25% rolled leaf is taken out. This process is repeated on the remainder with a 3rd or 4th roll. The first roll is done at low pressure, second at medium and 3rd at harder pressure.

The rolled leaves are spread on fermenting beds and left to ferment for a period of 3 to 4 hrs. The leaves are loosely spread to a thickness of 1 or 1.5. inches. Good fermentation results in the colour of the leaf to change to reddish brown giving off the characteristic aroma after the juices in the rolled leaves react with each other and the air.

The fermented leaves are then fired (i.e. heated) in a drier machine. The object of this process is to arrest fermentation and slowly dessicate the leaf in such a way so as to extract the moisture without scorching the tea and at the same time, preserving its quality and other characters to the optimum level. The leaves are passed through the driers and remain within the driers for a period of approx. 20 mins, at a temperature of around 240 to 250° F. This results in the leaves moisture content to come down to 20 - 25% from 60 - 70% before it enters the drier. A second firing is also given shortly thereafter.

Sorting of different grades is done by sorting machines which are fitted with wire mesh trays that revolve or vibrate. The tea is passed over wire mesh of varying sizes so that the whole leaf, broken leaf, fannings and dust grades fall at different places. These sorted teas comprise the different grades.

The different grades of tea are then packed into plywood chests / paper sacks lined with aluminium foil inside. Each lot is generally packed in a minimum of 5 chests / sacks or more. The chests / sacks are sealed and the grade name, garden name, lot number (called an invoice), chest number, gross and nett weight, year of manufacture etc. are printed on the chests / sacks with stencils. Lastly, Darjeeling CTM user licence number and Darjeeling "CTM-applied for" are also stencilled onto the tea chests / sacks.

Tea: A Story of Serendipity

Tea: A Story of Serendipity

As legend has it, one day in 2737 B.C. the Chinese Emperor Shen Nung was boiling drinking water over an open fire, believing that those who drank boiled water were healthier. Some leaves from a nearby Camellia sinensis plant floated into the pot. The emperor drank the mixture and declared it gave one "vigor of body, contentment of mind, and determination of purpose."

Perhaps as testament to the emperor's assessment, tea--the potion he unwittingly brewed that day--today is second only to water in worldwide consumption. The U.S. population is drinking its fair share of the brew; in 1994, Americans drank 2.25 billion gallons of tea in one form or another--hot, iced, spiced, flavored, with or without sugar, honey, milk, cream, or lemon.

A serving of tea generally contains about 40 milligrams of caffeine (less than half as much caffeine as in coffee), but the actual levels vary depending on the specific blend and the strength of the brew. Decaffeinated tea is also available.

Many tea drinkers find the beverage soothing, and folk medicine has long valued it as a remedy for sore throats and unsettled stomachs. Recent studies have shown that certain chemicals in tea called polyphenols may help reduce the risk of far more serious illnesses, including atherosclerosis and some cancers, although the data are not conclusive. (See "Tonic in a Teapot?")

Black, Green and Oolong

Two leaves and a bud at a time--This is the secret of fine tea picking. The work is done chiefly by women, who carry light bamboo baskets strapped to their backs.

Tea comes in black, green and oolong varieties, all produced from the leaves of Camellia sinensis, a white-flowered evergreen. The method of processing the leaf distinguishes the three types. (Herbal teas are made from leaves of other plants. FDA requires that herbal tea labels carry the name of the plant the product derives from, such as chamomile. For more on herbal teas, see "Herbal Teas and Toxicity" in the May 1991 FDA Consumer.)

The traditional method of producing black tea begins with withering. The plucked leaves are placed on shelves called withering racks, where excess moisture is removed. They are then rolled in special machines that release the leaves' enzymes and juices, which give tea its aroma and taste. Next, the leaves ferment in a room with controlled temperature and humidity; finally they are dried in ovens. More recently some processors have forsaken the traditional method to speed production by using machines that finely chop the leaves, thereby cutting the time for withering and fermenting.

Green tea is made by steaming or otherwise heating the leaves immediately after plucking to prevent the fermentation that makes black tea. Then the leaves are rolled and dried.

Oolong tea is fermented only partially--to a point between black and green. While the leaves wilt naturally, enzymes begin to ferment them. Processors interrupt the fermentation by stirring the leaves in heated pans, then rolling and drying them.

Different varieties of Camellia sinensis grow in different geographic areas and produce leaves that vary from a very small China leaf, perhaps one-half to three-quarters of an inch long, to the Assam leaf, which may be 3 or 4 inches long. Certain varieties are better suited than others for a particular processing method. For example, the China leaf from China and Formosa produces the best oolongs.

Scented and spiced teas are made from black tea. "Scented teas look just like any other tea," says FDA chemist and tea expert Robert Dick, "because the scent is more or less sprayed on. They're flavored with just about anything--peach, vanilla, cherry. The spiced teas, on the other hand, usually contain pieces of spices--cinnamon or nutmeg or orange or lemon peel--so you can see there's something in there."

What about orange pekoe? Orange pekoe refers to the size of the tea leaf. Processed tea leaves are sorted into sizes by passing them over screens with different size holes. The largest leaves are orange pekoe, pekoe, and pekoe souchong. The smaller or broken leaves are classified as broken orange pekoe, broken pekoe souchong, broken orange pekoe fannings, and fines (also called "dust").

In brewing, flavor and color come out of the larger leaves more slowly than out of the broken and fine grades. The broken grades, which make up about 80 percent of the total black tea crop, produce a stronger, darker tea. The grades have nothing to do with the quality or flavor of tea; they simply refer to leaf size.

"Technically, except for fannings and fines, the terms should apply only to black, or fermented, tea," Dick says, "but nowadays I often see oolongs labeled "orange pekoe," and even some green teas are labeled pekoe or flowery pekoe."

Tea tastes vary, and one aficionado who squirts lemon in his cup may cringe at the sight of another pouring milk or honey. But no matter how the tea may be doctored, in the United States the odds are overwhelming that it starts out black. Nearly 95 percent of all tea consumed here is black, according to the New York City-based Tea Council of the U.S.A.; 4 percent is green, 1 percent oolong, and 1 percent flavored.

That wasn't always the case, and our proclivity for drinking black tea over green or oolong may have been influenced by events in history. Sixty years ago and more, the amount of black and green tea Americans drank was split fairly evenly--each accounting for about 40 percent of the market--with oolong constituting the rest. During World War II, however, the major sources of green tea--China and Japan--were cut off from the United States, leaving us with tea almost exclusively from British-controlled India, which produces black tea. Americans came out of the war drinking nearly 99 percent black tea.

With the Korean War in the 1950s, uncertainties about tea supplies resurfaced, and the United States began to look for other suppliers.

"Argentina filled the bill," Dick says, "because tea could grow very fast there. Although the country didn't produce an outstanding tea, it produced a good average tea."

Today, most of our tea comes from Argentina, China (which got back into the U.S. market in 1978), and Java. Thirty years ago most of it came from India and Ceylon (now Sri Lanka). Argentine black tea is the kind most used for iced tea, and that's another reason black tea dominates the U.S. market.

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A Science Odyssey: People and Discoveries: Worldwide flu pandemic strikes

A Science Odyssey: People and Discoveries: Worldwide flu pandemic strikes

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A Science Odyssey
People and Discoveries

Worldwide flu pandemic strikes
1918 - 1919

Late in the spring of 1918 the Spanish wire service Agencia Fabra sent cables of an unusual nature to Reuter's news service headquarters in London. "A strange form of disease of epidemic character has appeared in Madrid," it said. "The epidemic is of a mild nature, no deaths having been reported." The illness began with a cough, then headache and backache, fatigue, high fever, racing heart, loss of appetite and labored breathing. It usually lasted about three days. Cases had cropped up over the spring and summer in other countries, too, from Norway to India, China to Costa Rica. But in Spain, suddenly 8 million people were down with the bug. And as the summer of 1918 turned to fall, the epidemic lost its mildness: people started to die.

The influenza commonly called "Spanish flu" killed more people than the guns of World War I. Estimates put the worldwide death toll at 21,642,274. Some one billion people were affected by the disease -- half of the total human population. It came at a time when 19 nations were at war and the disruption, stress, and privation of war certainly aided the flu's transmission. It killed people on every continent except Antarctica, with the most lives lost in Asia and the highest percentage of population killed in India. From August 1918, when cases of the flu started looking abnormally high, until the following July when they returned to about normal, 20 million Americans became sick and more than 500,000 died. In October, 1918, the flu reached its peak, killing about 195,000 Americans. About 57,000 American soldiers died from influenza while the U.S. was at war; about 53,500 died in battle.

There wasn't much doctors could do. In the course of the epidemic nearly every known therapy was tried -- quinine tablets, bleeding, castor oil, digitalis, morphine, enemas, aspirin, tobacco, hot baths, cold baths, iron tonics, and expectorants of pine tar. Little was known about the virus, except that it was contagious. After deaths from the disease began in earnest, many local governing bodies closed down theaters, churches, and other public gatherings. Ordinances made it illegal to spit, cough, or sneeze in public -- with threat of $500 fines in New York City. When people went out they wore gauze masks over their nose and mouth, often soaked in camphor or other medicinal substances.

After months of terrorizing people around the world, the "Spanish lady" (called "The Naples Soldier" in Spain, and a variety of other names around the world) seemed to withdraw. It had been the most dire epidemic since the Middle Ages, the third worst in recorded history. For all its destruction, it did not get much press at the time. War and then peace monopolized the front pages. And still little is known about the origin or nature of the killer virus. Many believe the modern "swine flu" virus is a descendant of the deadly 1918 flu. Some theorize that its stronger ancestor ganged up with a bacteria to wreak havoc on the human population. In recent years, vaccinations against various strains of influenza have been introduced.

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The 1918 Influenza Pandemic

The 1918 Influenza Pandemic: "North America, Europe, Asia, Africa, Brazil and the South Pacific"

The Influenza Pandemic of 1918

The influenza pandemic of 1918-1919 killed more people than the Great War, known today as World War I (WWI), at somewhere between 20 and 40 million people. It has been cited as the most devastating epidemic in recorded world history. More people died of influenza in a single year than in four-years of the Black Death Bubonic Plague from 1347 to 1351. Known as "Spanish Flu" or "La Grippe" the influenza of 1918-1919 was a global disaster.

The Grim Reaper by Louis Raemaekers

In the fall of 1918 the Great War in Europe was winding down and peace was on the horizon. The Americans had joined in the fight, bringing the Allies closer to victory against the Germans. Deep within the trenches these men lived through some of the most brutal conditions of life, which it seemed could not be any worse. Then, in pockets across the globe, something erupted that seemed as benign as the common cold. The influenza of that season, however, was far more than a cold. In the two years that this scourge ravaged the earth, a fifth of the world's population was infected. The flu was most deadly for people ages 20 to 40. This pattern of morbidity was unusual for influenza which is usually a killer of the elderly and young children. It infected 28% of all Americans (Tice). An estimated 675,000 Americans died of influenza during the pandemic, ten times as many as in the world war. Of the U.S. soldiers who died in Europe, half of them fell to the influenza virus and not to the enemy (Deseret News). An estimated 43,000 servicemen mobilized for WWI died of influenza (Crosby). 1918 would go down as unforgettable year of suffering and death and yet of peace. As noted in the Journal of the American Medical Association final edition of 1918:

"The 1918 has gone: a year momentous as the termination of the most cruel war in the annals of the human race; a year which marked, the end at least for a time, of man's destruction of man; unfortunately a year in which developed a most fatal infectious disease causing the death of hundreds of thousands of human beings. Medical science for four and one-half years devoted itself to putting men on the firing line and keeping them there. Now it must turn with its whole might to combating the greatest enemy of all--infectious disease," (12/28/1918).

An Emergency Hospital for Influenza Patients

The effect of the influenza epidemic was so severe that the average life span in the US was depressed by 10 years. The influenza virus had a profound virulence, with a mortality rate at 2.5% compared to the previous influenza epidemics, which were less than 0.1%. The death rate for 15 to 34-year-olds of influenza and pneumonia were 20 times higher in 1918 than in previous years (Taubenberger). People were struck with illness on the street and died rapid deaths. One anectode shared of 1918 was of four women playing bridge together late into the night. Overnight, three of the women died from influenza (Hoagg). Others told stories of people on their way to work suddenly developing the flu and dying within hours (Henig). One physician writes that patients with seemingly ordinary influenza would rapidly "develop the most viscous type of pneumonia that has ever been seen" and later when cyanosis appeared in the patients, "it is simply a struggle for air until they suffocate," (Grist, 1979). Another physician recalls that the influenza patients "died struggling to clear their airways of a blood-tinged froth that sometimes gushed from their nose and mouth," (Starr, 1976). The physicians of the time were helpless against this powerful agent of influenza. In 1918 children would skip rope to the rhyme (Crawford):

I had a little bird,
Its name was Enza.
I opened the window,
And in-flu-enza.

The influenza pandemic circled the globe. Most of humanity felt the effects of this strain of the influenza virus. It spread following the path of its human carriers, along trade routes and shipping lines. Outbreaks swept through North America, Europe, Asia, Africa, Brazil and the South Pacific (Taubenberger). In India the mortality rate was extremely high at around 50 deaths from influenza per 1,000 people (Brown). The Great War, with its mass movements of men in armies and aboard ships, probably aided in its rapid diffusion and attack. The origins of the deadly flu disease were unknown but widely speculated upon. Some of the allies thought of the epidemic as a biological warfare tool of the Germans. Many thought it was a result of the trench warfare, the use of mustard gases and the generated "smoke and fumes" of the war. A national campaign began using the ready rhetoric of war to fight the new enemy of microscopic proportions. A study attempted to reason why the disease had been so devastating in certain localized regions, looking at the climate, the weather and the racial composition of cities. They found humidity to be linked with more severe epidemics as it "fosters the dissemination of the bacteria," (Committee on Atmosphere and Man, 1923). Meanwhile the new sciences of the infectious agents and immunology were racing to come up with a vaccine or therapy to stop the epidemics.

The experiences of people in military camps encountering the influenza pandemic:

An excerpt for the memoirs of a survivor at Camp Funston of the pandemic Survivor

A letter to a fellow physician describing conditions during the influenza epidemic at Camp Devens

A collection of letters of a soldier stationed in Camp Funston Soldier

The origins of this influenza variant is not precisely known. It is thought to have originated in China in a rare genetic shift of the influenza virus. The recombination of its surface proteins created a virus novel to almost everyone and a loss of herd immunity. Recently the virus has been reconstructed from the tissue of a dead soldier and is now being genetically characterized. The name of Spanish Flu came from the early affliction and large mortalities in Spain (BMJ,10/19/1918) where it allegedly killed 8 million in May (BMJ, 7/13/1918). However, a first wave of influenza appeared early in the spring of 1918 in Kansas and in military camps throughout the US. Few noticed the epidemic in the midst of the war. Wilson had just given his 14 point address. There was virtually no response or acknowledgment to the epidemics in March and April in the military camps. It was unfortunate that no steps were taken to prepare for the usual recrudescence of the virulent influenza strain in the winter. The lack of action was later criticized when the epidemic could not be ignored in the winter of 1918 (BMJ, 1918). These first epidemics at training camps were a sign of what was coming in greater magnitude in the fall and winter of 1918 to the entire world.

The war brought the virus back into the US for the second wave of the epidemic. It first arrived in Boston in September of 1918 through the port busy with war shipments of machinery and supplies. The war also enabled the virus to spread and diffuse. Men across the nation were mobilizing to join the military and the cause. As they came together, they brought the virus with them and to those they contacted. The virus killed almost 200,00 in October of 1918 alone. In November 11 of 1918 the end of the war enabled a resurgence. As people celebrated Armistice Day with parades and large partiess, a complete disaster from the public health standpoint, a rebirth of the epidemic occurred in some cities. The flu that winter was beyond imagination as millions were infected and thousands died. Just as the war had effected the course of influenza, influenza affected the war. Entire fleets were ill with the disease and men on the front were too sick to fight. The flu was devastating to both sides, killing more men than their own weapons could.


With the military patients coming home from the war with battle wounds and mustard gas burns, hospital facilities and staff were taxed to the limit. This created a shortage of physicians, especially in the civilian sector as many had been lost for service with the military. Since the medical practitioners were away with the troops, only the medical students were left to care for the sick. Third and forth year classes were closed and the students assigned jobs as interns or nurses (Starr,1976). One article noted that "depletion has been carried to such an extent that the practitioners are brought very near the breaking point," (BMJ, 11/2/1918). The shortage was further confounded by the added loss of physicians to the epidemic. In the U.S., the Red Cross had to recruit more volunteers to contribute to the new cause at home of fighting the influenza epidemic. To respond with the fullest utilization of nurses, volunteers and medical supplies, the Red Cross created a National Committee on Influenza. It was involved in both military and civilian sectors to mobilize all forces to fight Spanish influenza (Crosby, 1989). In some areas of the US, the nursing shortage was so acute that the Red Cross had to ask local businesses to allow workers to have the day off if they volunteer in the hospitals at night (Deseret News). Emergency hospitals were created to take in the patients from the US and those arriving sick from overseas.

The pandemic affected everyone. With one-quarter of the US and one-fifth of the world infected with the influenza, it was impossible to escape from the illness. Even President Woodrow Wilson suffered from the flu in early 1919 while negotiating the crucial treaty of Versailles to end the World War (Tice). Those who were lucky enough to avoid infection had to deal with the public health ordinances to restrain the spread of the disease. The public health departments distributed gauze masks to be worn in public. Stores could not hold sales, funerals were limited to 15 minutes. Some towns required a signed certificate to enter and railroads would not accept passengers without them. Those who ignored the flu ordinances had to pay steep fines enforced by extra officers (Deseret News). Bodies pilled up as the massive deaths of the epidemic ensued. Besides the lack of health care workers and medical supplies, there was a shortage of coffins, morticians and gravediggers (Knox). The conditions in 1918 were not so far removed from the Black Death in the era of the bubonic plague of the Middle Ages.

In 1918-19 this deadly influenza pandemic erupted during the final stages of World War I. Nations were already attempting to deal with the effects and costs of the war. Propaganda campaigns and war restrictions and rations had been implemented by governments. Nationalism pervaded as people accepted government authority. This allowed the public health departments to easily step in and implement their restrictive measures. The war also gave science greater importance as governments relied on scientists, now armed with the new germ theory and the development of antiseptic surgery, to design vaccines and reduce mortalities of disease and battle wounds. Their new technologies could preserve the men on the front and ultimately save the world. These conditions created by World War I, together with the current social attitudes and ideas, led to the relatively calm response of the public and application of scientific ideas. People allowed for strict measures and loss of freedom during the war as they submitted to the needs of the nation ahead of their personal needs. They had accepted the limitations placed with rationing and drafting. The responses of the public health officials reflected the new allegiance to science and the wartime society. The medical and scientific communities had developed new theories and applied them to prevention, diagnostics and treatment of the influenza patients.

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Graphs of the Influenza Epidemic Impact

The Public Health Response
Authoritative Measures
Preventative Measures

The Scientific and Medical Response
Clinical Descriptions
Treatment and Therapy
The Etiology of Influenza


by Molly Billings, June, 1997 modified RDS February, 2005

Teaching Units: Epidemiology