bitterness

arugula

baking powder

baking soda

beans, lima

beer, esp. hoppy (e.g., bitter ales)

bell peppers, green

bitters

broccoli rabe

Brussels sprouts

cabbage, green

caffeine (e.g., as in coffee, tea)

chard (e.g., Swiss chard)

chicory

chocolate, dark

cocoa

coffee

cranberries

eggplant

endive

escarole

fenugreek

frisée

grapefruit (bitter-sour)

greens: bitter, dark leafy (e.g., beet, dandelion, mustard, turnip)

herbs, many

horseradish

kale

lettuce, romaine

liver, calf’s

melon, bitter

olives (bitter-salty)

radicchio

rhubarb

spices, many

spinach

tea

tonic water

turmeric

walnuts, esp. black

watercress

wine, red, esp. tannic

zest: lemon, orange, etc.

zucchini