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Tea (rec.drink.tea) Discussion relating to tea, the world's second most consumed beverage (after water), made by infusing or boiling the leaves of the tea plant (C. sinensis or close relatives) in water. |
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Tea Production Variables
I'm trying to figure out, in very general terms, what the variables in
tea production are (e.g., not varieties of tea leaf or tea growing regions, and not brewing variables). For now, I am leaving Pu-er out of the picture, because that seems to add a seperate layer of complexity. From various sources, and especially Hou De's video on the manufacture of Formosa Oolong (easily found on You Tube), I have narrowed things down as follows: 1. Tea is picked -- this can be mechanical, or hand-done, and can be done at several different times of year, or in different conditions, or at different stages of tea leaf growth. This variable is huge and there are a lot of parts to it. 2. Withering -- to me, this looks like some sort of abbreviated drying process, where leaves are given lots of air and frequently "stirred". It can be done indoors or outdoors, but no heat other than sun is added. Tea still has significant moisture afterwards and the leaves remain very pliable. I really don't understand what this step does. It seems like this is almost a sub-step of the next variable. 3. Fermentation -- I'm not sure I fully understand how this differs from withering, though it may be that the leaves are left in a pile and stirred less frequently (or not at all?). This does not appear to involve any particular heat sources. I would guess this step would be skipped in green or white tea production, because my understanding is that this step is what seperates oolongs and red/black tea from the green and white tea. Afterwards, I imagine the leaves still have a lot of moisture and are still very pliable. Degree of fermentation is a huge variable, but there are no other real additives in this step so this is a pretty easy variable to identify. 4. "Kill-green" -- this can involve pan-frying or oven roasting (steaming seems unlikely given the overall goal of reducing moisture) but seems to be the first time that a heat source other than the sun is added to the mix. I would guess that the tea would have to reach a certain temperature to stop the fermentation process. From the Hou De video, it is apparent that the leaves can remain flexible after this process, though I've seen some other video on long jing production that seems to show a finished product after the kill-green step (maybe because this step combines the next steps into one for this particular tea?) 5. Shaping/Further Drying -- after the kill green, the tea may still have moisture in it and the leaves may still be pliable. So I guess this is when leaves are twisted or rolled, and I imagine that shaping process is interspersed with various drying efforts that use some sort of heat sources. The variables here that may affect flavor or aging potential would be shape and perhaps the drying source (e.g., charcoal, electric heat?). I would guess the goal of all tea production is to reduce moisture levels to similar levels, no matter the tea, so extent of drying is probably not a variable here. Maybe speed of drying process and temperature are variables. 6. Roasting? -- the Hou De video doesn't appear to show tea roasting, but tea roasting is clearly a factor in some tea production. I'm not sure what that process would do other than further reduce moisture and perhaps change the flavor somehow (I imagine you are basically cooking the tea, which would change the flavor of anything). The variables here would be similar to the drying variables above -- charcoal or electric heat, as well as temperature and time. Maybe the drying is a type of roasting. I hope this doesn't repeat too much anything that has previously been posted. Seems like I never see this information in one place. If anyone has comments on the above steps in the form of additions/ subtractions/clarifications, I would be appreciative. -Charles |
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Tea Production Variables
On Aug 11, 9:12 am, cha bing > wrote:
I'm by no means an expert and do not really understand all stages, but I'll try to add what I have heard/learned from others who are much more experienced in tea making.... > > 1. Tea is picked -- this can be mechanical, or hand-done, and can be > done at several different times of year, or in different conditions, > or at different stages of tea leaf growth. This variable is huge and > there are a lot of parts to it. I think generally speaking weather is extremely important for all stages. In picking, you're not supposed to pick if it's raining or if it just rained. Time of day when you pick is important. How you pick is important. Even how you use your hand to pick it is important (no squeezing, which bruises the tea). It's complicated... > > 2. Withering -- to me, this looks like some sort of abbreviated drying > process, where leaves are given lots of air and frequently "stirred". > It can be done indoors or outdoors, but no heat other than sun is > added. Tea still has significant moisture afterwards and the leaves > remain very pliable. I really don't understand what this step does. It > seems like this is almost a sub-step of the next variable. Withering, afaik, is a step that allows for some oxidation to happen. You don't wither the tea if you want zero oxidation. Sun is often not added, from what I understand. Most of the time this is done indoors in a somewhat airy area - and again, weather plays a factor. How you place the tea, where you place it, how long do you let it go for, how you do the "stirring" are all very important. If you screw this step up, your oolong isn't going to be very good. > > 3. Fermentation -- I'm not sure I fully understand how this differs > from withering, though it may be that the leaves are left in a pile > and stirred less frequently (or not at all?). This does not appear to > involve any particular heat sources. I would guess this step would be > skipped in green or white tea production, because my understanding is > that this step is what seperates oolongs and red/black tea from the > green and white tea. Afterwards, I imagine the leaves still have a lot > of moisture and are still very pliable. Degree of fermentation is a > huge variable, but there are no other real additives in this step so > this is a pretty easy variable to identify. I think withering is where fermentation happens, but it can also happen in other stages too, for example during picking (woman with basket of tea that's laden with leaves, somewhat hot (under the sun and perhaps body heat), leaves are pretty much withering right away -- just a matter of speed and degree, like, say, a sliced apple. There's usually some oxidation in white tea too... > > 4. "Kill-green" -- this can involve pan-frying or oven roasting > (steaming seems unlikely given the overall goal of reducing moisture) > but seems to be the first time that a heat source other than the sun > is added to the mix. I would guess that the tea would have to reach a > certain temperature to stop the fermentation process. From the Hou De > video, it is apparent that the leaves can remain flexible after this > process, though I've seen some other video on long jing production > that seems to show a finished product after the kill-green step (maybe > because this step combines the next steps into one for this particular > tea?) > Leaves actually remain quite flexible after this process from what I understand. Oftentimes rolling takes place after this. For sencha, for example, you roll them very vigorously after steaming to induce the tea juices. From what I know that is also an extremely important step in shaping the taste of the tea -- different degrees of rolling will change the way things taste. There's machine and hand rolled, but there's also how much, how heavy, and how long. I don't understand this fully myself, but a tea that is lightly or not rolled at all, from what I have heard anyway, can be quite weird -- some puerhs these days are very lightly rolled because they want to preserve the big leaf shape, to the detriment of taste. > 5. Shaping/Further Drying -- after the kill green, the tea may still > have moisture in it and the leaves may still be pliable. So I guess > this is when leaves are twisted or rolled, and I imagine that shaping > process is interspersed with various drying efforts that use some sort > of heat sources. The variables here that may affect flavor or aging > potential would be shape and perhaps the drying source (e.g., > charcoal, electric heat?). I would guess the goal of all tea > production is to reduce moisture levels to similar levels, no matter > the tea, so extent of drying is probably not a variable here. Maybe > speed of drying process and temperature are variables. The rolling would've happened by the time you take it to the dryer, which can be the oven, sun, or whatever. It's just to reduce moisture to the point where the tea is more or less dry -- one measure is whether or not when you crush the leaf it becomes powdery or not. If it doesn't, then it's not dry enough. Makes sense. > > 6. Roasting? -- the Hou De video doesn't appear to show tea roasting, > but tea roasting is clearly a factor in some tea production. I'm not > sure what that process would do other than further reduce moisture and > perhaps change the flavor somehow (I imagine you are basically cooking > the tea, which would change the flavor of anything). The variables > here would be similar to the drying variables above -- charcoal or > electric heat, as well as temperature and time. Maybe the drying is a > type of roasting. > I think cooking the tea is sort of what's going on -- and I think what happens is that by applying heat, some of the aromatics are changed or dissipated, and thus give the tea a different flavour. In some cases teas are smoked (Lapsang Souchong) where they use pine wood to smoke it and that's where it gets that distinctive flavour. > I hope this doesn't repeat too much anything that has previously been > posted. Seems like I never see this information in one place. If > anyone has comments on the above steps in the form of additions/ > subtractions/clarifications, I would be appreciative. > Again, caveat being that I am only a beginner in understanding this. Perhaps a tea grower can add to this discussion? It'll be very appreciated MarshalN http://www.xanga.com/MarshalN |
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Tea Production Variables
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Posted to rec.food.drink.tea
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Tea Production Variables
Thanks for the responses. In looking at some of the other sources out
there, including the wikipedia article (d'oh! I suppose I should have looked there first), I think the biggest factor I was missing is the "bruising" stage. This seems to be part of the oxidation process, along with withering. The oxidation process seems to be ongoing too. In fact, I think MarshalN must be right that oxidation happens from the moment a leaf is picked until the kill green stage. So maybe I can take an oversimplification and make it more simple by categorizing the process into even fewer steps as follows (with some variables sub- categorized): 1. Harvest variables a. natural characteristics surrounding tea growth and harvest (e.g., weather, soil type, climate) b. how picked c. age and type of leaves 2. Early bruising and drying variables a. degree of drying/withering b. method/degree of bruising 3. Kill Green variables (method of kill green is only real variable here) 4. Shaping variables a. method b. shape 5. Roasting variables a. time and temperature b. heat source I would imagine that all of these variables can be described for a particular tea based solely on the taste and visual inspection of leaves by an experienced tea drinker (if there are any professional tea purchasers out there who want to weigh in on that, I'd be grateful). Charles |
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Tea Production Variables
The train of diffrent processes that fresh plucked leaf undergoes is designed in the first place to prepare the leaf for fermentation; in the second to establish teh best conditions for its action and finally to aresst the process when it has gone far enough. The care and attention needed to ensure satisfactory manufacture should start in the field. The treatment of the leaf from the moment of detachment from the bush to that place where manufacturing begins is also of equal importance. The fermentation process begins immediately a leaf is bruised. If this occurs in the pluckers hand, or in the containers in which the leaf is transported to the factory, such fermentation is uncontrolled. Careful handling of plucked leaf and avoidance of tight packing in bags, baskets or other containers are of the essence of good manufacturing technique. WITHERING. In systems of traditional manufacture the first stage in the processing of tea is withering. Normally this is carried out by spreading the tea leaves, thinly on banks of trays or "tats" made of tightly stretched jute hessian or wire netting. Ten to fifteen squre feet per pound of fresh leaf is a normal density of spread. The tats are spaced five to six inches apart, to allow free access of air, with alley-ways between each bank to allow distribution and removal of leaf. Light withers (40 to 42 per cent out turn) are usual in Assam and East Africa, and medium to hard withers (45 to 50 per cent out turn) are normal in ceylon. The average lenghth of time for withering is eighteen to twenty hours where tats are used. There is much flexibility in these figures depending from factory to factory. The prime objective of withering is to prepare the leaf for rolling by making the leaf tissues flaccid and permeable to the juices which the rolling will wring out and spread evenly upon the surface. Insufficent attention to withering standards leads to many complications later. In the subsequent stage of rolling it is difficult to keep under- withered leaf from being thrown out of the machine, and in extreme instances the juices may be expressed and lost. When unduly wet the macerated leaf clogs the sieves of the sifiting machine. Most serious of all, to light a wither will overtax the drier inthe firing process. Under-withered leaf also tends to produce flaky tea of low apparent specific gravity. Long withers have a favourable on colour in the brewed tea but this is secured on the expense of quality. Where long withers are the result of too slow a removal of surface moisture , in this there is a risk of the rapid proliferation of ubiquitous and unwanted bacteria which produces dull and characterless tea. ROLLING When a satisfactory wither has been obtained the leaf is ready for rolling, which twists the leaf, breaks it up and expresses the juices. The machines used vary in size and design but their principles are alike: they compress and turn the leaf over, keeping it in continula motion, in a manner that is similar to, and derived from, the operation of rubbing leaf between the palms of the hand in primitive chinese fashion. What the machines do in the process of rolling is another long chapter - that we shall discuss some other time - have kipped it for the moment. The green color of the leaves diminishes and the brown or coppery colour of the oxidation products begins to appear. At this stage there are a number of points related to the design of rollers and to procedure that require emphasis because they affect the whole course of manufacture and the quality of finished tea. The first is that the onset of rolling is accompanied by the evolution of heat. Pressure, by consolidating the leaf, confines the accumulated heat and that is why, in traditional rolling programmes, periods with and without pressure are generally alternated. Excessive pressure in the early stages of rolling affects the physical appearance of the tea. The number of times a batch of leaf is rolled varies according to the type of tea to be produced, the degree of wither of the leaf and the kind of roller used. In general the lightly withered leaf common to Assam or African procedures receives a smaller number of rolls than medium or hard withered leaf in Ceylon. The usual range is from three to five rolling periods. The aim is first to twist the leaf and then progressively to break it up into small particles by increased pressure till the major portion has been sifted through the green leaf sifters. ROLL BREAKING AND GREEN LEAF SIFTING On discharge from the roller the leaf mass is more or less compressed into lumps. These are broken up in the sifting process by the machine which usually combines the operation of roll breaker and sifter. In essence this is a rectangular sieve, set at a moderate angle, mechanically agitated. The roller discharge is fed into a hopper in which beaters revolve to break up the mass, after which the tea falls onto the sieve and slowly travels to the other end for discharge. In the course of this passage the smaller particles fall through. The roll breaker and green leaf sifter performs three essential functions. In the first instance it cools the leaf and thus prevents the retention of excessive heat: secondly, it aerates the mass, and thirdly, by sieving out particles of small size, it seperates leaf into portions that will be reasonably uniform in their rate of fermentation. To achieve this uniformity careful operation is needed. The leaf should be fed continuously at an even rate and be well spread across the width of the sieve. FERMENTATION Fermentation starts in the rollers but is continued in the dhool stage. The sifted dhools (smaller particles) are spread out in thin layers, in order to continue the oxidative processes. There is great variety in the materials that are used to accomodate this spread - out leaf. Tiles, cement and aluminium are most commonly used, the essential point being that they should be easily cleaned. The thickness of spread controls three important factors, the temperature of the leaf, the rate of moisture loss and the access of oxygen. With layers two inches thick temperature losses sufficient to retard fermentation are not likely. Some factories install air - conditioning plant to ensure controlled conditions. Good air circulation without draughts is needed to attain good fermentation conditions. In hot climates the air is kept humid with less than 4 degree F. hygrometric difference. In colder regions the circulating atmosphere is artifically heated. In either event moist air, to prevent surface drying, is advisable. For economical working it is better to ferment in a special fermentation room whose atmospheric conditions can be easily controlled. During fermentation the leaf changes colour and becomes a dark copper colour. The typical aroma develops and by the subjective judgement of its intensity the period necessary for completion is judged. Time of fermentation is reckoned from the time at which rolling begins and it should be as short as practicable. After four and a half hours there is appreciable loss of quality. FIRING The general principle adopted in firing is that of subjecting the fermented tea to a forced blast of hot air in such a manner that the hottest air comes first into contact with the driest tea. To bring this about the older driers, some of which are still in use, were provided with a banked series of perforated trays carrying the dhools, which were systematically altered in position as the drying operation proceeded; a fresh tray being inserted at the exhaust end as the trays were moved and the final one removed. A similar pattern of movement was also provided for in machines which had fixed trays built in narrow strips which could be mechanically tilted so as to discharge their leaf onto the tray below, leaving the upper one ready to load with the next portion of unfired dhool. Modern machines employ the principle of perforated sections mounted on an endless chain. The sections are arranged in a tier of six units which alternate in their direction of motion. The tea is fed onto the top section, and moves in conveyor - belt fashion till it discharges onto the tray immediately below, which is moving in the opposite direction; and so on till the dried tea is discharged at the bottom. Hot air is provided by means of a furnance or steam boiler through which pass tubes connecting with the outer atmosphere. Thickness of spread, speed of trays and volume or air blown can all be regulated at will. Inlet temperatures usually range from 180 degree F to 200 degree F., according to the degree of wither, and outlet temperatures are in the range of 120 degree F. to 130 degree F. During the drying process the enzyme responsibly for fermentation is inactivated. After the tea is dry maturation processes occur but these are not due to enzyme activity. The manner of firing plays an important role in determining the quality. Teas fired at high temperature are deficient in pungency, quality and flavour, but their keeping properties are satisfactory. Contrariwise teas can be satisfactorily fired at temperatures as low as 160 degree F. provided that the final moisture content is correct. These teas retain their quality and flavour but deteriorate on storage. GRADING AND SORTING Grading is carried out for the most part on mechanically oscillated sieves, similar in genral principle to those used in the green stage, and fitted with meshes of appropriate size. The grades in general production are named as follows: Broken Orange Pekoe; Broken Pekoe; Orange Pekoe; Pekoe; Souchong; Broken Orange Pekoe Fannings; Fannings and Dust. Before tea is packed the accumulated series of daily batches of each grade are bulked and mixed in order to ensure as high a degree of uniformity as possible. The tea is then packed into chests holding approximately 100 lb. or 50 lb. (half chests). These chests are usually of plywood lined with almunium foil and paper and sealed with similar material. Hope i have been able to make things simpler - please feel free to ask any questions that you may have. Regards Ankit www.xanga.com/lochantea |
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Tea Production Variables
Ankit
Thanks for the great post It is really informative. Could you quote the source of the article? This article is very comprehensive, I mention it just in case somebody decided to quote it elsewhere and not quite sure who to attribute it to. Also can I clarify that if the process refers to the making of ctc black tea? Many thanks. Julian http://www.amazing-green-tea.com |
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Tea Production Variables
Thank you so much, Ankit. That is a lot of great information, even if
it doesn't really make my project simpler per se. In fact, I think your post has made me doubt even more my attempts to simplify the tea making process into simple discreet categories and limited variables. There is a lot of really vital information behind the most outer layer of the onion that I am trying to grasp. But posts like yours are invaluable to people like me, who are trying to understand how everything works without the benefit of being able to visit a tea plantation. I doubt I will ever be able to taste a tea and be able to tell whether there was a hard or soft wither in the process, but it all contributes to my appreciation of the beverage and I hope to continue understanding how tea is made. I think I will save your post and put it in a file somewhere. Also, thanks to Julian Tai, whose web page has a good primer on the production of oolong tea, which is what I really had in mind when I made my initial post (because that is what I have been drinking lately). (see http://www.amazing-green-tea.com/ool...ocessing.html). |
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Tea Production Variables
On Aug 12, 6:04 pm, juliantai > wrote:
> Ankit > > Thanks for the great post It is really informative. > > > > Could you quote the source of the article? This article is very > comprehensive, I mention it just in case somebody decided to quote it > elsewhere and not quite sure who to attribute it to. > > Also can I clarify that if the process refers to the making of ctc > black tea? > > Many thanks. > > Julianhttp://www.amazing-green-tea.com hi julian i am happy that you liked the post - glad to be of help to people. this process is generally for orthodox black (leaf) and ctc tea. regarding the source - it is from many places - a couple of books and some info from my own brain. if you want the names of all the books i would be really happy to give it to you. regards ankit www.xanga.com/lochantea |
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Tea Production Variables
On Aug 13, 6:52 am, cha bing > wrote:
> Thank you so much, Ankit. That is a lot of great information, even if > it doesn't really make my project simpler per se. In fact, I think > your post has made me doubt even more my attempts to simplify the tea > making process into simple discreet categories and limited variables. > There is a lot of really vital information behind the most outer layer > of the onion that I am trying to grasp. But posts like yours are > invaluable to people like me, who are trying to understand how > everything works without the benefit of being able to visit a tea > plantation. I doubt I will ever be able to taste a tea and be able to > tell whether there was a hard or soft wither in the process, but it > all contributes to my appreciation of the beverage and I hope to > continue understanding how tea is made. I think I will save your post > and put it in a file somewhere. > > Also, thanks to Julian Tai, whose web page has a good primer on the > production of oolong tea, which is what I really had in mind when I > made my initial post (because that is what I have been drinking > lately). (seehttp://www.amazing-green-tea.com/oolong-tea-processing.html). Glad that you found the article informative - i will try and write something more simpler for you soon. Thanks |
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Tea Production Variables
On Aug 12, 1:39 am, Ankit Lochan > wrote:
> The train of diffrent processes that fresh plucked leaf undergoes is > designed in the first place to prepare the leaf for fermentation; in > the second to establish teh best conditions for its action and finally > to aresst the process when it has gone far enough. > > The care and attention needed to ensure satisfactory manufacture > should start in the field. The treatment of the leaf from the moment > of detachment from the bush to that place where manufacturing begins > is also of equal importance. The fermentation process begins > immediately a leaf is bruised. If this occurs in the pluckers hand, or > in the containers in which the leaf is transported to the factory, > such fermentation is uncontrolled. Careful handling of plucked leaf > and avoidance of tight packing in bags, baskets or other containers > are of the essence of good manufacturing technique. > > WITHERING. > > In systems of traditional manufacture the first stage in the > processing of tea is withering. Normally this is carried out by > spreading the tea leaves, thinly on banks of trays or "tats" made of > tightly stretched jute hessian or wire netting. Ten to fifteen squre > feet per pound of fresh leaf is a normal density of spread. The tats > are spaced five to six inches apart, to allow free access of air, with > alley-ways between each bank to allow distribution and removal of > leaf. > > Light withers (40 to 42 per cent out turn) are usual in Assam and East > Africa, and medium to hard withers (45 to 50 per cent out turn) are > normal in ceylon. The average lenghth of time for withering is > eighteen to twenty hours where tats are used. There is much > flexibility in these figures depending from factory to factory. > > The prime objective of withering is to prepare the leaf for rolling by > making the leaf tissues flaccid and permeable to the juices which the > rolling will wring out and spread evenly upon the surface. > > Insufficent attention to withering standards leads to many > complications later. > > In the subsequent stage of rolling it is difficult to keep under- > withered leaf from being thrown out of the machine, and in extreme > instances the juices may be expressed and lost. When unduly wet the > macerated leaf clogs the sieves of the sifiting machine. Most serious > of all, to light a wither will overtax the drier inthe firing process. > Under-withered leaf also tends to produce flaky tea of low apparent > specific gravity. > > Long withers have a favourable on colour in the brewed tea but this is > secured on the expense of quality. Where long withers are the result > of too slow a removal of surface moisture , in this there is a risk of > the rapid proliferation of ubiquitous and unwanted bacteria which > produces dull and characterless tea. > > ROLLING > > When a satisfactory wither has been obtained the leaf is ready for > rolling, which twists the leaf, breaks it up and expresses the juices. > The machines used vary in size and design but their principles are > alike: they compress and turn the leaf over, keeping it in continula > motion, in a manner that is similar to, and derived from, the > operation of rubbing leaf between the palms of the hand in primitive > chinese fashion. > > What the machines do in the process of rolling is another long chapter > - that we shall discuss some other time - have kipped it for the > moment. > > The green color of the leaves diminishes and the brown or coppery > colour of the oxidation products begins to appear. > > At this stage there are a number of points related to the design of > rollers and to procedure that require emphasis because they affect the > whole course of manufacture and the quality of finished tea. The first > is that the onset of rolling is accompanied by the evolution of heat. > > Pressure, by consolidating the leaf, confines the accumulated heat and > that is why, in traditional rolling programmes, periods with and > without pressure are generally alternated. > > Excessive pressure in the early stages of rolling affects the physical > appearance of the tea. > > The number of times a batch of leaf is rolled varies according to the > type of tea to be produced, the degree of wither of the leaf and the > kind of roller used. In general the lightly withered leaf common to > Assam or African procedures receives a smaller number of rolls than > medium or hard withered leaf in Ceylon. The usual range is from three > to five rolling periods. The aim is first to twist the leaf and then > progressively to break it up into small particles by increased > pressure till the major portion has been sifted through the green leaf > sifters. > > ROLL BREAKING AND GREEN LEAF SIFTING > > On discharge from the roller the leaf mass is more or less compressed > into lumps. These are broken up in the sifting process by the machine > which usually combines the operation of roll breaker and sifter. In > essence this is a rectangular sieve, set at a moderate angle, > mechanically agitated. The roller discharge is fed into a hopper in > which beaters revolve to break up the mass, after which the tea falls > onto the sieve and slowly travels to the other end for discharge. In > the course of this passage the smaller particles fall through. > > The roll breaker and green leaf sifter performs three essential > functions. In the first instance it cools the leaf and thus prevents > the retention of excessive heat: secondly, it aerates the mass, and > thirdly, by sieving out particles of small size, it seperates leaf > into portions that will be reasonably uniform in their rate of > fermentation. To achieve this uniformity careful operation is needed. > The leaf should be fed continuously at an even rate and be well spread > across the width of the sieve. > > FERMENTATION > > Fermentation starts in the rollers but is continued in the dhool > stage. The sifted dhools (smaller particles) are spread out in thin > layers, in order to continue the oxidative processes. There is great > variety in the materials that are used to accomodate this spread - out > leaf. Tiles, cement and aluminium are most commonly used, the > essential point being that they should be easily cleaned. The > thickness of spread controls three important factors, the temperature > of the leaf, the rate of moisture loss and the access of oxygen. With > layers two inches thick temperature losses sufficient to retard > fermentation are not likely. Some factories install air - conditioning > plant to ensure controlled conditions. Good air circulation without > draughts is needed to attain good fermentation conditions. In hot > climates the air is kept humid with less than 4 degree F. hygrometric > difference. In colder regions the circulating atmosphere is > artifically heated. In either event moist air, to prevent surface > drying, is advisable. For economical working it is better to ferment > in a special fermentation room whose atmospheric conditions can be > easily controlled. > > During fermentation the leaf changes colour and becomes a dark copper > colour. The typical aroma develops and by the subjective judgement of > its intensity the period necessary for completion is judged. Time of > fermentation is reckoned from the time at which rolling begins and it > should be as short as practicable. After four and a half hours there > is appreciable loss of quality. > > FIRING > > The general principle adopted in firing is that of subjecting the > fermented tea to a forced blast of hot air in such a manner that the > hottest air comes first into contact with the driest tea. To bring > this about the older driers, some of which are still in use, were > provided with a banked series of perforated trays carrying the dhools, > which were systematically altered in position as the drying operation > proceeded; a fresh tray being inserted at the exhaust end as the trays > were moved and the final one removed. > A similar pattern of movement was also provided for in machines which > had fixed trays built in narrow strips which could be mechanically > tilted so as to discharge their leaf onto the tray below, leaving the > upper one ready to load with the next portion of unfired dhool. > > Modern machines employ the principle of perforated sections mounted on > an endless chain. The sections are arranged in a tier of six units > which alternate in their direction of motion. The tea is fed onto the > top section, and moves in conveyor - belt fashion till it discharges > onto the tray immediately below, which is moving in the opposite > direction; and so on till the dried tea is discharged at the bottom. > Hot air is provided by means of a furnance or steam boiler through > which pass tubes connecting with the outer atmosphere. > > Thickness of spread, speed of trays and volume or air blown can all be > regulated at will. > > Inlet temperatures usually range from 180 degree F to 200 degree F., > according to the degree of wither, and outlet temperatures are in the > range of 120 degree F. to 130 degree F. > > During the drying process the enzyme responsibly for fermentation is > inactivated. After the tea is dry maturation processes occur but these > are not due to enzyme activity. The manner of firing plays an > important role in determining the quality. Teas fired at high > temperature are deficient in pungency, quality and flavour, but their > keeping properties are satisfactory. Contrariwise teas can be > satisfactorily fired at temperatures as low as 160 degree F. provided > that the final moisture content is correct. These teas retain their > quality and flavour but deteriorate on storage. > > GRADING AND SORTING > > Grading is carried out for the most part on mechanically oscillated > sieves, similar in genral principle to those used in the green stage, > and fitted with meshes of appropriate size. > > The grades in general production are named as follows: Broken Orange > Pekoe; Broken Pekoe; Orange Pekoe; Pekoe; Souchong; Broken Orange > Pekoe Fannings; Fannings and Dust. > > Before tea is packed the accumulated series of daily batches of each > grade are bulked and mixed in order to ensure as high a degree of > uniformity as possible. The tea is then packed into chests holding > approximately 100 lb. or 50 lb. (half chests). These chests are > usually of plywood lined with ... > > read more » Thank you, again, Ankit. Your posts are so informative and very appreciated. I personally wish you'd start a blog (hint, hint!). Shen |
Posted to rec.food.drink.tea
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Tea Production Variables
On Aug 12, 11:55 pm, Shen > wrote:
> On Aug 12, 1:39 am, Ankit Lochan > wrote: > > > > > The train of diffrent processes that fresh plucked leaf undergoes is > > designed in the first place to prepare the leaf for fermentation; in > > the second to establish teh best conditions for its action and finally > > to aresst the process when it has gone far enough. > > > The care and attention needed to ensure satisfactory manufacture > > should start in the field. The treatment of the leaf from the moment > > of detachment from the bush to that place where manufacturing begins > > is also of equal importance. The fermentation process begins > > immediately a leaf is bruised. If this occurs in the pluckers hand, or > > in the containers in which the leaf is transported to the factory, > > such fermentation is uncontrolled. Careful handling of plucked leaf > > and avoidance of tight packing in bags, baskets or other containers > > are of the essence of good manufacturing technique. > > > WITHERING. > > > In systems of traditional manufacture the first stage in the > > processing of tea is withering. Normally this is carried out by > > spreading the tea leaves, thinly on banks of trays or "tats" made of > > tightly stretched jute hessian or wire netting. Ten to fifteen squre > > feet per pound of fresh leaf is a normal density of spread. The tats > > are spaced five to six inches apart, to allow free access of air, with > > alley-ways between each bank to allow distribution and removal of > > leaf. > > > Light withers (40 to 42 per cent out turn) are usual in Assam and East > > Africa, and medium to hard withers (45 to 50 per cent out turn) are > > normal in ceylon. The average lenghth of time for withering is > > eighteen to twenty hours where tats are used. There is much > > flexibility in these figures depending from factory to factory. > > > The prime objective of withering is to prepare the leaf for rolling by > > making the leaf tissues flaccid and permeable to the juices which the > > rolling will wring out and spread evenly upon the surface. > > > Insufficent attention to withering standards leads to many > > complications later. > > > In the subsequent stage of rolling it is difficult to keep under- > > withered leaf from being thrown out of the machine, and in extreme > > instances the juices may be expressed and lost. When unduly wet the > > macerated leaf clogs the sieves of the sifiting machine. Most serious > > of all, to light a wither will overtax the drier inthe firing process. > > Under-withered leaf also tends to produce flaky tea of low apparent > > specific gravity. > > > Long withers have a favourable on colour in the brewed tea but this is > > secured on the expense of quality. Where long withers are the result > > of too slow a removal of surface moisture , in this there is a risk of > > the rapid proliferation of ubiquitous and unwanted bacteria which > > produces dull and characterless tea. > > > ROLLING > > > When a satisfactory wither has been obtained the leaf is ready for > > rolling, which twists the leaf, breaks it up and expresses the juices. > > The machines used vary in size and design but their principles are > > alike: they compress and turn the leaf over, keeping it in continula > > motion, in a manner that is similar to, and derived from, the > > operation of rubbing leaf between the palms of the hand in primitive > > chinese fashion. > > > What the machines do in the process of rolling is another long chapter > > - that we shall discuss some other time - have kipped it for the > > moment. > > > The green color of the leaves diminishes and the brown or coppery > > colour of the oxidation products begins to appear. > > > At this stage there are a number of points related to the design of > > rollers and to procedure that require emphasis because they affect the > > whole course of manufacture and the quality of finished tea. The first > > is that the onset of rolling is accompanied by the evolution of heat. > > > Pressure, by consolidating the leaf, confines the accumulated heat and > > that is why, in traditional rolling programmes, periods with and > > without pressure are generally alternated. > > > Excessive pressure in the early stages of rolling affects the physical > > appearance of the tea. > > > The number of times a batch of leaf is rolled varies according to the > > type of tea to be produced, the degree of wither of the leaf and the > > kind of roller used. In general the lightly withered leaf common to > > Assam or African procedures receives a smaller number of rolls than > > medium or hard withered leaf in Ceylon. The usual range is from three > > to five rolling periods. The aim is first to twist the leaf and then > > progressively to break it up into small particles by increased > > pressure till the major portion has been sifted through the green leaf > > sifters. > > > ROLL BREAKING AND GREEN LEAF SIFTING > > > On discharge from the roller the leaf mass is more or less compressed > > into lumps. These are broken up in the sifting process by the machine > > which usually combines the operation of roll breaker and sifter. In > > essence this is a rectangular sieve, set at a moderate angle, > > mechanically agitated. The roller discharge is fed into a hopper in > > which beaters revolve to break up the mass, after which the tea falls > > onto the sieve and slowly travels to the other end for discharge. In > > the course of this passage the smaller particles fall through. > > > The roll breaker and green leaf sifter performs three essential > > functions. In the first instance it cools the leaf and thus prevents > > the retention of excessive heat: secondly, it aerates the mass, and > > thirdly, by sieving out particles of small size, it seperates leaf > > into portions that will be reasonably uniform in their rate of > > fermentation. To achieve this uniformity careful operation is needed. > > The leaf should be fed continuously at an even rate and be well spread > > across the width of the sieve. > > > FERMENTATION > > > Fermentation starts in the rollers but is continued in the dhool > > stage. The sifted dhools (smaller particles) are spread out in thin > > layers, in order to continue the oxidative processes. There is great > > variety in the materials that are used to accomodate this spread - out > > leaf. Tiles, cement and aluminium are most commonly used, the > > essential point being that they should be easily cleaned. The > > thickness of spread controls three important factors, the temperature > > of the leaf, the rate of moisture loss and the access of oxygen. With > > layers two inches thick temperature losses sufficient to retard > > fermentation are not likely. Some factories install air - conditioning > > plant to ensure controlled conditions. Good air circulation without > > draughts is needed to attain good fermentation conditions. In hot > > climates the air is kept humid with less than 4 degree F. hygrometric > > difference. In colder regions the circulating atmosphere is > > artifically heated. In either event moist air, to prevent surface > > drying, is advisable. For economical working it is better to ferment > > in a special fermentation room whose atmospheric conditions can be > > easily controlled. > > > During fermentation the leaf changes colour and becomes a dark copper > > colour. The typical aroma develops and by the subjective judgement of > > its intensity the period necessary for completion is judged. Time of > > fermentation is reckoned from the time at which rolling begins and it > > should be as short as practicable. After four and a half hours there > > is appreciable loss of quality. > > > FIRING > > > The general principle adopted in firing is that of subjecting the > > fermented tea to a forced blast of hot air in such a manner that the > > hottest air comes first into contact with the driest tea. To bring > > this about the older driers, some of which are still in use, were > > provided with a banked series of perforated trays carrying the dhools, > > which were systematically altered in position as the drying operation > > proceeded; a fresh tray being inserted at the exhaust end as the trays > > were moved and the final one removed. > > A similar pattern of movement was also provided for in machines which > > had fixed trays built in narrow strips which could be mechanically > > tilted so as to discharge their leaf onto the tray below, leaving the > > upper one ready to load with the next portion of unfired dhool. > > > Modern machines employ the principle of perforated sections mounted on > > an endless chain. The sections are arranged in a tier of six units > > which alternate in their direction of motion. The tea is fed onto the > > top section, and moves in conveyor - belt fashion till it discharges > > onto the tray immediately below, which is moving in the opposite > > direction; and so on till the dried tea is discharged at the bottom. > > Hot air is provided by means of a furnance or steam boiler through > > which pass tubes connecting with the outer atmosphere. > > > Thickness of spread, speed of trays and volume or air blown can all be > > regulated at will. > > > Inlet temperatures usually range from 180 degree F to 200 degree F., > > according to the degree of wither, and outlet temperatures are in the > > range of 120 degree F. to 130 degree F. > > > During the drying process the enzyme responsibly for fermentation is > > inactivated. After the tea is dry maturation processes occur but these > > are not due to enzyme activity. The manner of firing plays an > > important role in determining the quality. Teas fired at high > > temperature are deficient in pungency, quality and flavour, but their > > keeping properties are satisfactory. Contrariwise teas can be > > satisfactorily fired at temperatures as low as 160 degree F. provided > > that the final moisture content is correct. These teas retain their > > quality and flavour but deteriorate on storage. > > > GRADING AND SORTING > > > Grading is carried out for the most part on mechanically oscillated > > sieves, similar in genral principle to those used in the green stage, > > and fitted with meshes of appropriate size. > > > The grades in general production are named as follows: Broken > > ... > > read more »- Hide quoted text - > > - Show quoted text - Oops, I see you have one................ Shen |
Posted to rec.food.drink.tea
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Tea Production Variables
On Aug 13, 11:55 am, Shen > wrote:
> On Aug 12, 1:39 am, Ankit Lochan > wrote: > > > The train of diffrent processes that fresh plucked leaf undergoes is > > designed in the first place to prepare the leaf for fermentation; in > > the second to establish teh best conditions for its action and finally > > to aresst the process when it has gone far enough. > > > The care and attention needed to ensure satisfactory manufacture > > should start in the field. The treatment of the leaf from the moment > > of detachment from the bush to that place where manufacturing begins > > is also of equal importance. The fermentation process begins > > immediately a leaf is bruised. If this occurs in the pluckers hand, or > > in the containers in which the leaf is transported to the factory, > > such fermentation is uncontrolled. Careful handling of plucked leaf > > and avoidance of tight packing in bags, baskets or other containers > > are of the essence of good manufacturing technique. > > > WITHERING. > > > In systems of traditional manufacture the first stage in the > > processing of tea is withering. Normally this is carried out by > > spreading the tea leaves, thinly on banks of trays or "tats" made of > > tightly stretched jute hessian or wire netting. Ten to fifteen squre > > feet per pound of fresh leaf is a normal density of spread. The tats > > are spaced five to six inches apart, to allow free access of air, with > > alley-ways between each bank to allow distribution and removal of > > leaf. > > > Light withers (40 to 42 per cent out turn) are usual in Assam and East > > Africa, and medium to hard withers (45 to 50 per cent out turn) are > > normal in ceylon. The average lenghth of time for withering is > > eighteen to twenty hours where tats are used. There is much > > flexibility in these figures depending from factory to factory. > > > The prime objective of withering is to prepare the leaf for rolling by > > making the leaf tissues flaccid and permeable to the juices which the > > rolling will wring out and spread evenly upon the surface. > > > Insufficent attention to withering standards leads to many > > complications later. > > > In the subsequent stage of rolling it is difficult to keep under- > > withered leaf from being thrown out of the machine, and in extreme > > instances the juices may be expressed and lost. When unduly wet the > > macerated leaf clogs the sieves of the sifiting machine. Most serious > > of all, to light a wither will overtax the drier inthe firing process. > > Under-withered leaf also tends to produce flaky tea of low apparent > > specific gravity. > > > Long withers have a favourable on colour in the brewed tea but this is > > secured on the expense of quality. Where long withers are the result > > of too slow a removal of surface moisture , in this there is a risk of > > the rapid proliferation of ubiquitous and unwanted bacteria which > > produces dull and characterless tea. > > > ROLLING > > > When a satisfactory wither has been obtained the leaf is ready for > > rolling, which twists the leaf, breaks it up and expresses the juices. > > The machines used vary in size and design but their principles are > > alike: they compress and turn the leaf over, keeping it in continula > > motion, in a manner that is similar to, and derived from, the > > operation of rubbing leaf between the palms of the hand in primitive > > chinese fashion. > > > What the machines do in the process of rolling is another long chapter > > - that we shall discuss some other time - have kipped it for the > > moment. > > > The green color of the leaves diminishes and the brown or coppery > > colour of the oxidation products begins to appear. > > > At this stage there are a number of points related to the design of > > rollers and to procedure that require emphasis because they affect the > > whole course of manufacture and the quality of finished tea. The first > > is that the onset of rolling is accompanied by the evolution of heat. > > > Pressure, by consolidating the leaf, confines the accumulated heat and > > that is why, in traditional rolling programmes, periods with and > > without pressure are generally alternated. > > > Excessive pressure in the early stages of rolling affects the physical > > appearance of the tea. > > > The number of times a batch of leaf is rolled varies according to the > > type of tea to be produced, the degree of wither of the leaf and the > > kind of roller used. In general the lightly withered leaf common to > > Assam or African procedures receives a smaller number of rolls than > > medium or hard withered leaf in Ceylon. The usual range is from three > > to five rolling periods. The aim is first to twist the leaf and then > > progressively to break it up into small particles by increased > > pressure till the major portion has been sifted through the green leaf > > sifters. > > > ROLL BREAKING AND GREEN LEAF SIFTING > > > On discharge from the roller the leaf mass is more or less compressed > > into lumps. These are broken up in the sifting process by the machine > > which usually combines the operation of roll breaker and sifter. In > > essence this is a rectangular sieve, set at a moderate angle, > > mechanically agitated. The roller discharge is fed into a hopper in > > which beaters revolve to break up the mass, after which the tea falls > > onto the sieve and slowly travels to the other end for discharge. In > > the course of this passage the smaller particles fall through. > > > The roll breaker and green leaf sifter performs three essential > > functions. In the first instance it cools the leaf and thus prevents > > the retention of excessive heat: secondly, it aerates the mass, and > > thirdly, by sieving out particles of small size, it seperates leaf > > into portions that will be reasonably uniform in their rate of > > fermentation. To achieve this uniformity careful operation is needed. > > The leaf should be fed continuously at an even rate and be well spread > > across the width of the sieve. > > > FERMENTATION > > > Fermentation starts in the rollers but is continued in the dhool > > stage. The sifted dhools (smaller particles) are spread out in thin > > layers, in order to continue the oxidative processes. There is great > > variety in the materials that are used to accomodate this spread - out > > leaf. Tiles, cement and aluminium are most commonly used, the > > essential point being that they should be easily cleaned. The > > thickness of spread controls three important factors, the temperature > > of the leaf, the rate of moisture loss and the access of oxygen. With > > layers two inches thick temperature losses sufficient to retard > > fermentation are not likely. Some factories install air - conditioning > > plant to ensure controlled conditions. Good air circulation without > > draughts is needed to attain good fermentation conditions. In hot > > climates the air is kept humid with less than 4 degree F. hygrometric > > difference. In colder regions the circulating atmosphere is > > artifically heated. In either event moist air, to prevent surface > > drying, is advisable. For economical working it is better to ferment > > in a special fermentation room whose atmospheric conditions can be > > easily controlled. > > > During fermentation the leaf changes colour and becomes a dark copper > > colour. The typical aroma develops and by the subjective judgement of > > its intensity the period necessary for completion is judged. Time of > > fermentation is reckoned from the time at which rolling begins and it > > should be as short as practicable. After four and a half hours there > > is appreciable loss of quality. > > > FIRING > > > The general principle adopted in firing is that of subjecting the > > fermented tea to a forced blast of hot air in such a manner that the > > hottest air comes first into contact with the driest tea. To bring > > this about the older driers, some of which are still in use, were > > provided with a banked series of perforated trays carrying the dhools, > > which were systematically altered in position as the drying operation > > proceeded; a fresh tray being inserted at the exhaust end as the trays > > were moved and the final one removed. > > A similar pattern of movement was also provided for in machines which > > had fixed trays built in narrow strips which could be mechanically > > tilted so as to discharge their leaf onto the tray below, leaving the > > upper one ready to load with the next portion of unfired dhool. > > > Modern machines employ the principle of perforated sections mounted on > > an endless chain. The sections are arranged in a tier of six units > > which alternate in their direction of motion. The tea is fed onto the > > top section, and moves in conveyor - belt fashion till it discharges > > onto the tray immediately below, which is moving in the opposite > > direction; and so on till the dried tea is discharged at the bottom. > > Hot air is provided by means of a furnance or steam boiler through > > which pass tubes connecting with the outer atmosphere. > > > Thickness of spread, speed of trays and volume or air blown can all be > > regulated at will. > > > Inlet temperatures usually range from 180 degree F to 200 degree F., > > according to the degree of wither, and outlet temperatures are in the > > range of 120 degree F. to 130 degree F. > > > During the drying process the enzyme responsibly for fermentation is > > inactivated. After the tea is dry maturation processes occur but these > > are not due to enzyme activity. The manner of firing plays an > > important role in determining the quality. Teas fired at high > > temperature are deficient in pungency, quality and flavour, but their > > keeping properties are satisfactory. Contrariwise teas can be > > satisfactorily fired at temperatures as low as 160 degree F. provided > > that the final moisture content is correct. These teas retain their > > quality and flavour but deteriorate on storage. > > > GRADING AND SORTING > > > Grading is carried out for the most part on mechanically oscillated > > sieves, similar in genral principle to those used in the green stage, > > and fitted with meshes of appropriate size. > > > The grades in general production are named as follows: Broken Orange > > Pekoe; Broken Pekoe; Orange Pekoe; Pekoe; Souchong; Broken Orange > > Pekoe Fannings; Fannings and Dust. > > > Before tea is packed the accumulated series of daily batches of each > > grade are bulked and mixed in order to ensure as high a degree of > > uniformity as possible. The tea is then packed into chests holding > > approximately 100 lb. or 50 lb. (half chests). These chests are > > usually of plywood lined with ... > > > read more » > > Thank you, again, Ankit. Your posts are so informative and very > appreciated. I personally wish you'd start a blog (hint, hint!). > Shen hi shen, www.xanga.com/lochantea please join in. regards ankit |
Posted to rec.food.drink.tea
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Tea Production Variables
Ankit
Thanks for being so helpful As a side line, it will actually be useful if you can share with us your favourite tea references, either here or in your blog. There have been several threads on this subject before, but it will be great to know what a tea grower would read Julian http://www.amazing-green-tea.com |
Posted to rec.food.drink.tea
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Tea Production Variables
On Aug 14, 9:55 pm, juliantai > wrote:
> Ankit > > Thanks for being so helpful > > As a side line, it will actually be useful if you can share with us > your favourite tea references, either here or in your blog. > > There have been several threads on this subject before, but it will be > great to know what a tea grower would read > > Julianhttp://www.amazing-green-tea.com hi ! some of them are profiles of tea by prafulla goradia, tea by t.eden, tea culture, processing and marketing by m.jmulky and v.s.sharma, tea production and processing by barundeb bannerjee, the story of tea by e.jaiwant paul, tea the universal health drink by r.s.jhawar, the tea book by serena hardy, the heritage of indian tea by d.k.taknet, tea legend, life and livelihood of india by g.p.baroowah. there are many more - these are the ones i find more orignal and informative. regards ankit www.xanga.com/lochantea |
Posted to rec.food.drink.tea
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Tea Production Variables
On Aug 14, 9:55 pm, juliantai > wrote:
> Ankit > > Thanks for being so helpful > > As a side line, it will actually be useful if you can share with us > your favourite tea references, either here or in your blog. > > There have been several threads on this subject before, but it will be > great to know what a tea grower would read > > Julianhttp://www.amazing-green-tea.com hi again, i missed out this one - really an intresting one the culture and marketing of tea by c.r.hurler. regards www.xanga.com/lochantea |
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