3. Flavouring agents, such as vanilla, lemon peel, and fruit essences, are used to give a pleasant flavour to various dishes.
4. Acidulous substances are taken chiefly because of their sharp and agreeable taste. Vinegar is the chief acid employed. It is produced by the action of a fungus (Mycoderma aceti) on alcoholic liquids, as wine, or beer, C₂H₅OH (alcohol) becoming C₂H₄O₂ (acetic acid). It is also produced by the destructive distillation of wood. In small quantities it does not stop digestion, but, by exciting the nerves of taste, may be of actual service. It helps to soften the vegetable fibres in a salad; and is also useful for the same purpose with hard meats, as lobster, etc. In large quantities it diminishes the power to assimilate food.
Good vinegar ought not to contain less than 3 per cent. of acetic acid; and sulphuric acid beyond 1 in 1000 in vinegar is to be regarded as an adulteration. A specific gravity below 1015 indicates the addition of water.
Citric acid and lemon-juice are useful for their refreshing properties, and the latter also because of its alkaline salts.
Oils, such as olive oil, have been sometimes classed under condiments, but as they have great nutritive properties, this is hardly accurate. For the same reason, salt is not classed under this head.
BEVERAGES.
Water is the universal beverage, and for healthy persons is preferable to any other. All other beverages necessarily contain it as their basis.
It will be convenient to consider first aërated and other natural waters; then tea, coffee, and cocoa; and finally, alcohol.
1. Aerated Waters contain carbonic acid (carbon dioxide) in solution, which gives to them their characteristic sharp taste and sparkling character. Thus distilled water charged with gas is sold as Salutaris or Puralis water. Soda water contains three to five grains, and medicinal soda water fifteen grains of bicarbonate of soda to the bottle. Potash water contains fifteen grains of bicarbonate of potash to the pint, in each case carbonic acid being dissolved under pressure. In lemonade, ginger-beer, etc., the basis is sweetened water, rendered tart by the addition of an acid, and finally charged with carbonic acid. Lemonade frequently contains acetic or phosphoric acid instead of citric or tartaric, and ginger-beer the same constituents with some added tincture of ginger. Home-made lemonade prepared from fresh lemons is a much more wholesome drink. Ginger-beer (stone ginger) is produced by the fermentative action of yeast on a solution containing sugar, bruised ginger, tartaric acid, and oil of lemon. It usually contains at least two per cent. of alcohol.
Natural Mineral Waters usually contain common salt (chloride of sodium) and alkaline salts of soda or lime, and are impregnated with carbonic acid gas. Apollinaris, Rosbach, and Johannis possess these characteristics. The carbonic acid in natural waters is partially combined, and is given off more gradually than that in artificial mineral waters.