Flavor—Aroma and Taste

Flavor has been defined (Anon, 1959) as: A mingled but unitary experience which includes sensations of taste, smell, and pressure, and often cutaneous sensations such as warmth, color, or mild pain. Flavor is typically described by aroma (odor) and taste. Aroma compounds are volatile—they are perceived primarily with the nose, while taste receptors exist in the mouth and are impacted when the food is chewed. While color and appearance may be the initial quality attributes that attract us to a fruit or vegetable product, the flavor may have the largest impact on acceptability and desire to consume it again. Taste has been divided into five primary tastes—sweet, sour, salty, bitter, and umami. Umami can be described as a taste associated with salts of amino acids and nucleotides (Yamaguchi and Ninomiya, 2000). Odors are much more diverse and difficult to classify, but an attempt by Henning (Gould, 1983) includes the following— spicy, flowery, fruity, resinous or balsamic, burnt, and foul. Stevens (1985) stated that it is possible to classify vegetables into two major groups, depending on their flavor characteristics. The first group of fruits and vegetables has a strong flavor that can be attributed to a single compound or group of related compounds. Bananas with isoamylacetate, onions with characteristic sulfide compounds, and celery, with distinctive phthalides are examples of this group. The second group of fruits and vegetables includes those whose flavor is determined by a number of volatiles, none of which conveys the specific characteristic aroma. Examples in this group include snap beans, muskmelons, and tomatoes. In the evaluation of fruit and vegetable flavor, it is important to consider “off-flavors” as well as desirable ones. These off- flavors may be produced through the action of enzymes such as lipoxygenase or peroxidase, which form reactive free radicals and hydroperoxides that may catalyze the oxidation of lipid compounds. When these reactions occur, the result may be the development of undesirable flavors described as rancid, cardboard, oxidized, or wet dog. However, there are instances of enzyme-catalyzed reactions that result in desirable flavors. For example, hydroperoxide lyase catalyzes the production of typical tomato flavors (Anthon and Barrett, 2003).