Beverages.
TEA.
Tannin is an astringent of vegetable origin which exists in tea, is also found in coffee and wines, and is very injurious. Tea is a preparation made from the leaves of a shrub called Thea. The difference between black and green tea is due to the mode of preparation, and not to separate species of plant. Green tea contains more tannin than black. The following table will show the difference:—
| Green Tea. | Black Tea. | |
| Crude protein | 37.43 | 38.90 |
| Fibre | 10.06 | 10.07 |
| Ash (mineral matter) | 4.92 | 4.93 |
| Theine | 3.20 | 3.30 |
| Tannin | 10.64 | 4.89 |
| Total nitrogen | 5.99 | 6.22 |
The stimulating properties which tea possesses, as well as its color and flavor, depend upon the season of the year at which the leaves are gathered, the variety of the plant, the age of the leaves, which become tough as they grow older, and the care exercised in their preparation. Much depends upon the manner in which tea is infused. (1) Use freshly boiled water; (2) allow it to infuse only three or four minutes, in order to avoid extracting the tannin. When carefully prepared as above, tea is not considered unwholesome for people in good health.
COFFEE.
Coffee is made from the berries of coffee-arabica, which are dried, roasted and browned. The following table gives an approximate idea of the composition of coffee beans (Konig):—
| Water | 1.15 |
| Fat | 14.48 |
| Crude fibre | 19.89 |
| Ash (mineral matter) | 4.75 |
| Caffeine | 1.24 |
| Albuminoids | 13.98 |
| Other nitrogenous matter | 45.09 |
| Sugar, gum and dextrin | 1.66 |
Coffee is frequently adulterated with chicory, which is harmless. Coffee should not be allowed to boil long or stand in the coffee pot over a fire, as the tannin is extracted, which renders it more indigestible. Much controversy has been indulged in over the effect of coffee upon the system, but like many other similar questions it has not reached a practical solution. The general opinion seems to be that when properly made and used in moderation it is a valuable stimulant and not harmful to adults.
COCOA.
Cocoa and chocolate contain more food substances than tea or coffee, although their use in this respect is not of much value. The following table gives the analysis of cocoa (Stutzer):—
| Theobromine | 1.73 |
| Total nitrogenous substance | 19.28 |
| Fat | 30.51 |
| Water | 3.83 |
| Ash (mineral matter) | 8.30 |
| Fibre and non-nitrogenous extract | 37.48 |
ALCOHOL.
The use of alcohol is wholly unnecessary for the health of the human organism. (See Public School Physiology and Temperance.)