Food flavor and aroma are the most important sensory properties in addition to the color/appearance, consistency/texture, trigeminal attributes, and noise in governing consumer perceptions and buying decisions for foods. The flavor is the sum of sensations perceived through the chemical senses (olfactory, gustatory, and trigeminal) from food in the mouth, and it includes aromatics (many volatile compounds), taste components (sweet, salty, sour, bitter, and umami), and chemical feeling factors (astringent, spice heat, cooling, metallic, and sweet aromatic). Bitterness, as one main taste, is perceived from the gustatory taste buds located primarily on the tongue and mucosa of the palate and throat. Bitter, sweet, and umami tastes are sensed by initiating the interaction of taste molecules with G protein-coupled receptors. The bitter taste is believed to be evolved as a central warning signal against potentially toxic substances. 1,2 There are quite diverse chemical components (flavonoids, limonoids, some phenolic acids, cyanogenic glycosides, isothio-