3) Bitter – examples: coffee, teas, stout beer, tonic water, unsweetened chocolate or cocoa, green vegetables such as broccoli, spinach, green beans, field greens, arugula, dandelion greens, collards, frisee, radicchio, Brussels sprouts, asparagus; some nuts such as walnuts, black walnuts, pecans, filberts, almonds, Brazil nuts, olives; certain zests, if too much of the white pith is included, such as lemon zest, orange zest, grapefruit zest, lime zest