September, 1909.] 



229 



Edible Products. 



cently been most exhaustively studied 

 by Dr. Harold H. Mann, Scientific 

 Officer to the Indian Tea Association, 

 who has embodied the results of his 

 observations and experiments in pam- 

 phlet form. Hitherto no satisfactory 

 explanation of the variation in the 

 qualities of different teas has been forth- 

 coming, and a complete answer cannot, 

 in Dr. Mann's opinion, be given, Tea 

 owes its value principally to three 

 constituents : (1) Essential oil, produc- 

 ing the flavour ; (2) caffeine or theine, 

 producing the stimulating action ; and 

 (3) tannin, giving the astringency and, 

 when fermented, the colour to the 

 liquor. The essential oil, though often 

 spoken of, is in reality a material of 

 which extremely little is known. It 

 can only be said that it is an oily body 

 which can be driven off from the tea at 

 a high temperature, especially along 

 with the steam when the leaf is wet. 

 On exposure to the atmosphere the oil 

 quickly changes into a resin with a very 

 marked tea-like smell. It is evidently 

 one of the chief factors in determining 

 flavour in tea. It is equally certain that 

 caffeine is the principal stimulating 

 material in tea, and for long its quantity 

 was supposed to bear, therefore, a close 

 relationship to the market value- This 

 supposition is now xoroved to be quite 

 unfounded, and though the medicinal 

 value of tea may vary with the quantity 

 of caffeine, the market value certainly 

 does not. It is, however, present in 

 quantities which may vary from 3 to 5 

 per cent, in good teas, and in the lowest 

 grades it may go down to 2 or 3 per 

 cent. The third constituent of tea of 

 primary importance is tannin. This has 

 generally, if not always, been con- 

 sidered by the medical profession as the 

 objectionable part of tea ; but the value 

 of tea in the market, on the other hand, 

 seems to be closely connected with the 

 quantity of tannin easily extracted from 

 the tea by boiling water. The tea, in 

 tact, containing the most tannin, 

 usually have the greater value unless 

 possessed of less flavour — a fact which 

 was proved by Dr. B.H. Paul some years 

 ago. If teas possessing marked flavour 

 be eliminated and the total soluble 

 matter and tannin be determined aud 

 considered together, it is possible to 

 form a fair idea of the market value of 

 a tea so far as it depends on the liquor 

 given on infusion. The tannin is, as a 

 matter of fact, the chief, if not the only, 

 source of pungency in teas, particularly 

 when in an unfermented condition, aud 

 when changed by fermetation it is the 

 principal factor determining the colour 

 of the liquor. Thus the market poiuts 

 which have value in a tea-liquor may be 

 said to be chiefly caused as follows :— 



(a) Flavour. — Caused principally by 

 the essential oil. 



(b) Pungency.— Caused in great mea- 

 sure by the unfermented tannin. 



(c) Colour op Liquor.— Caused chiefly 

 by the fermented tannin. 



d) Body of Liquor-.— Measured prin- 

 cipally by the total soluble matter, of 

 which a large part is tannin, fermented 

 aud unfermented. 



Apart from flavour, it is evident that 

 the constituents which it is important 

 to investigate from a commercial point 

 of view are (1) the sum total of sub- 

 stauces capable of being dissolved under 

 tea-drinking conditions, and (2) the 

 ^.annin in all its various forms. 



The principal factors leading to the 

 production of quality are stated by 

 Dr. Mann to be : 



1. Elevation and in a measure latitude. 



2. Regularity and sufficiency of rain- 

 fall. 



3. Variety of plant. 



i. Special character of soil aud manur- 

 ing. 



5. Kind of pruning. 



6. Method of plucking. 



7. System of manufacture. 



Each of these factors has its influence, 

 aud these are exhaustively considered 

 by Dr. Mann, who says it has too often 

 been the first maxim learnt by a young 

 planter that " good tea is made in the 

 garden and not in the factory," con- 

 sequently comparative neglect of im- 

 provement and of close supervision and 

 care in the factory has been the result. 

 Now it is being more and more recognised 

 that while good tea can be made by no 

 known process from inferior leaf, in a 

 vast number of cases the tea actually 

 produced is inferior to what could, by 

 closer supervision and better-regulated 

 manufacture, be made from the same 

 leaf. It is established, therefore, that 

 while no one factor has been found 

 paramount, there is ample reason to 

 believe that good tea is the result of an 

 enormous number of detailed causes, 

 some under the control of a planter, 

 some beyond his power, and some 

 beyond his knowledge. But once this 

 is realised, and it is becoming in- 

 creasingly realised in the Indian tea 

 districts, it will become obvious that 

 tea-planting merits more detailed study 

 than has been given to it in the past. 



"The Lancet," in an annotation on 

 tea, some time since said that the con- 

 troversy has long been settled in the 

 minds of scientific men, but has been 

 revived by trade partisans also the 



