254 P. BISWAS ET AL.
is a direct effect of chilling or simply an indirect effect of delayed
ripening.
Tomato flavor results from a combination of taste components, aroma
compounds, and a complex interaction between them (Petro-Turza
1987). The five tastes—sweet, sour, salty, bitter, and umami—are per-
ceived by certain regions of the tongue, while volatiles are perceived
by the olfactory nerve endings of the nose (Acree 1993). With more
than 400 volatile compounds identified in tomato, only 30 are present
in concentrations over 1 ppb (Petro-Turza 1987). Buttery et al. (1971)
determined odor thresholds (the level at which a compound can be
detected by smell) for these 30 compounds. Of these, only 16 have “posi-
tive” log odor units and are likely to contribute to characteristic “tomato
flavor” (Baldwin et al. 2000). Hexanal,cis-3-hexenal,trans-2-hexenal,
1-hexanal,cis-3-hexan-1-ol, hexanol, 2-isobutylthiazole, 6-methyl-5-
hepten-2-one, and methyl salicylate are considered the most important
flavor-contributing factors (Buttery et al. 1987). These flavor compounds
are synthesized from a diverse set of precursors, including lipid deriva-
tives (hexanal, hexanol,cis-3-hexenal,trans-2-hexenal, 1-hexanal,cis-
3-hexanol, and 2-isobutylthiazole), amino acids (3-methylbutanol and
3-methylbutanal), lignins (guaiacol), and carotenoids (훽-ionone and ger-
anylacetone) through different biochemical pathways (Tieman et al.
2006).
Evidence of the adverse effects of low temperature storage on tomato
flavor has been documented elsewhere (Kader et al. 1978; McDonald
et al. 1996; Maul et al. 2000; Boukobza and Taylor 2002; D ́ıaz de Leon- ́
Sanchez et al. 2009; Bai et al. 2011; Farneti et al. 2015). Loss of flavor ́
occurs before other symptoms of chilling become apparent (Kader et al.
1978). The modification of aroma compounds in cool-stored tomatoes
could be related to alterations in the availability of precursor contents or
reduction of enzyme activity in the biosynthesis of aroma compounds
(Boukobza and Taylor 2002).
Low temperature storage often alters or inhibits red color develop-
ment of mature-green tomatoes (Hobson 1987) and subsequently lowers
flavor intensity particularly by reducing concentrations of carotenoid-
derived compounds (Baldwin et al. 2000). Tomatoes with a “high
lycopene” content are believed to have a high aroma. Kader (1986)
reported that high훽-carotene cultivars (“Caro Red”) and high delta-
carotene cultivars (“Gold Jubilee”) had a distinct volatile composition
and flavor. When tomato fruit were culturedin vitroand treated with
2-(4-chlorophenylthio)trimethylamine (a lycopene훽-cyclase inhibitor),
lycopene content increased and so did carotenoid-derived aroma