Bitters can have angostura bark, cascarilla, cassia, gentian, orange peel, and quinine from Cinchona bark. The flavor of Angostura bitters, Suze Bitters and Peychaud's Bitters derives primarily from gentian, a bitter herb. Bitters are prepared by infusion or distillation, using aromatic herbs, bark, roots, and/or fruit for their flavor and medicinal properties.
Christopher Hobbs LAc, AHG author of Foundations of Health lists angelica root (A. archangelica), artichoke leaf (Cynara scolymus), bitter orange peel (Citrus aurantium), blessed thistle leaves (Cnicus bendicutus), gentian root (Gentiana lutea), goldenseal rhizome (Hydrastis canadensis), wormwood leaves (Artemisia absinthium) and yarrow flowers (Achillea millefolium) as typical contents of bitters formulas
Angostura bitters was first compounded in Venezuela in 1824 by a German physician, Dr. Johann Gottlieb Benjamin Siegert, as a cure for sea sickness and stomach maladies (though their other medicinal uses had been discovered long before this). Dr. Siegert subsequently formed the House of Angostura, a company selling the bitters to sailors.
It was exported to England and to Trinidad, where it came to be used in a number of cocktails, following its medicinal use by the Royal Navy in Pink Gin. Angostura and similar gentian bitters can be of some value for settling a mild case of nausea. It is used to stimulate the appetite, either for food or for cocktails. Used in both apéritifs and digestifs, it settles the stomach before a meal or before a night of drinking.
It is used as the "starter" ingredient in a Pink Gin, where a splash (or two) of Angostura Bitters is swirled around the inner surface of a tumbler before adding a generous measure of gin. The resulting drink is so named from the colour imparted by the Bitters. In addition to the options of drinking a Pink straight, it may also be consumed with a little water, still or sparkling. Some Pink Gin drinkers even have preference for drinking it "in" or "out", i.e., leaving in or pouring out the remaining dribble of bitters (after the glass has been "pinked"), before the gin is added.
Peychaud's Bitters is associated with New Orleans, Louisiana, and the Sazerac cocktail. It is also aromatic, showing subtle cloves and other spices on the nose.
Orange bitters are made from the rinds of Seville oranges, plus spices of varying recipes to enhance the orange flavour. Orange bitters are often called for in older cocktail recipes and range from aromatic to fruity.
Medicinal quantities of quinine were occasionally used in old cocktail recipes. Quinine is still found in much lower concentrations in tonic water, used today mostly in drinks with gin.