Bitters are defined as a "liquor that is flavored with the sharp pungent taste of plant extracts and is used as an additive in cocktails or as a medicinal substance to promote appetite or digestion." (Bitters are also employed in cocktails via drinkable bitter liqueurs called Amari or Amaro, but for today we'll stick with those tiny little bottles of boozy flavor bombs, most often dispensed via an eye dropper.) The plant extracts can be from spices, herbs, barks, nuts and seeds, fruits and berries and/or roots which are used in various combinations to create specific flavor profiles to accent a cocktail.
One of the first mentions of the use of bitters simply for taste comes from The Balance, and Columbian Repository which defined a cocktail as a "stimulating liquor, composed of spirits of any kind, sugar, water, and bitters.” The practice itself was much older, dating back to around 7,000 B.C. when a drink of grapes, rice, honey, and (very bitter) hawthorn berry was discovered in China, though this may well have been a medicinal application.
Thanks to the Temperance movement in the 1800s, bitters became mainstream because, as a medicinal cure, they were not subject to spirit taxation. Being touted as medicine they were also a vehicle of profit for flim-flam men who brewed up and sold all nature of nasty bitter concoctions (most often high proof) as cure-alls for nearly every disease known to man. In 1908 the Pure Food and Drug act put an end to the flim-flam trade and only reputable brands remained, at least until Prohibition when alcohol based bitters were deemed illegal. At the end of Prohibition, Peychaud's and Angostura were the only two brands to survive the Volstead Act.
TYPES OF BITTERS
The basic bitters necessary to every well stocked bar are Angostura Bitters, orange bitters and Peychaud's bitters. There are too many classic cocktails that cannot be made without one of these three, but you can personalize the classics or any drink (check out my Chocolate version of a Rob Roy) by substituting any one of the wonderful new bitters flavors available in today's craft cocktail loving world. The standard aromatic bitters of the medicinal days are things of the past as bitters rapidly expand into new territory like chocolate, coffee, lemon, lime, grapefruit, cherry, peach, rhubarb, mint, cardamom, cinnamon, ginger, lavender, arugula, celery, chocolate mole, fig and sriracha. Combos are gaining ground and even specialties like barbecue, Mexican mole and Prickly Pear are showing up to play. If that's not enough for you to play with, try making your own bitters.
WAYS TO USE COCKTAIL BITTERS IN FOOD
CAKES, COOKIE, MUFFINS: Wherever it calls for an extract? Use some bitters instead, just be careful as bitters are generally much more powerful than extracts. Start with a few drops, not teaspoons.
DRINKING WATER: Add a few drops to carbonated soda water for a refreshing cooler. Sweeten this with honey and you have a great way to kick the cola habit. Tap a bit of a citrus bitters into your tap water to cover the taste of the purifying chemicals.
SALAD DRESSING: Add a few drops of an aromatic or herbal bitters to your oil & vinegar. I love using arugula bitters and celery bitters for this application. I've also been know to tap in some orange, pomegranate or fig bitters.
ICE CREAM: Add a few drops of bitters to the custard for homemade ice cream (add after cooking the custard because heat can disrupt the balance and flavor of the bitters depending on its ingredients) or tap a drop right on top of that pint of Ben & Jerry's® or Häagen-Dazs®. My favorite combinations are a drop of floral bitters on fruit ice creams and a drop or two of coffee bitters on chocolate ice creams.
ADD THEM TO WHIPPED CREAM for a punch of extra flavor. My favorites here are coffee, chocolate and cardamom.
If you want to experiment you can buy travel or tester sets of many brands which include several different flavors of bitters. This is a great way to add to your home bar bitters collection as well. Amazon has several sampler sets including The Bitter Truth and Scrappy's Bitters, which gives two flavor group options.
Here's a short list of some of the other popular bitters available:
AZ Bitters Lab
Hella Cocktail Company
Frape & Sons
Cecil & Merl
The Bitter Truth