- CHILLING INJURY IN TOMATO FRUIT 243
many fruits and vegetables and can be a misleading indicator of quality,
for example, refrigerated supermarket red tomatoes with a lack of flavor
(Shewfelt 2002). Tomatoes harvested for fresh consumption are often
picked at mature-green or early ripe stages and transported to retailers
at a low temperature (Chomchalow et al. 2002). Depending on storage
temperature, uneven blotchy red coloration or complete failure of red
color development in tomatoes can be induced (Cheng and Shewfelt
1988; Lurie et al. 1996). For instance, at 2◦C, one of the most obvious
responses of mature-green tomatoes is complete failure to ripen (Hobson
1987). Fruit locules remain green and seeds turn brown even when fruit
are returned to warm temperatures (Moline 1976). Storage at 2◦Cor6◦C
can inhibit full red color development in tomatoes harvested even at
advanced maturity stages (i.e., breaker or pink) (Ilic and Fallik 2005;
Gomez et al. 2009). ́
Tomato color changes from green to red during normal ripening as
chloroplasts transform into chromoplasts, chlorophyll degrades, and
lycopene, a major carotenoid responsible for red coloration, accumu-
lates (Shewfelt 2002). During low temperature conditions, modifica-
tion of red color development may be because chloroplasts are the first
organelles that undergo structural changes (Marangoni et al. 1989; Yang
et al. 2009). Ultrastructural observations indicated that failure to ripen
was due, in part, to interruption in conversion of chloroplasts to chro-
moplasts while non-chilled fruit showed lycopene crystals in healthy
plastids (Moline 1976). Rugkong et al. (2011) suggested that loss of
chlorophyll in tomato during cool storage was manifested as yellowing.
Decreased levels of chlorophyll in chilled tomatoes probably unveil훽-
carotene, causing the appearance of a yellow blush color (Dodds et al.
1991). Chilling may also cause accumulation of chalconaringenin, a yel-
low compound found in tomato pericarp (Baker et al. 1982 as cited in
Dodds et al. 1991).
The physiological abnormalities associated with blotchy red col-
oration could be a result of abnormal functioning of random patches
of tissue. It is believed that CI does not produce translocatable signals
(Saltveit and Morris 1990). Eaks and Morris (1957) found that CI symp-
toms in cucumber were localized to the half of an intact fruit that was
exposed to chilling. Equally, failure of uniform heating may induce dif-
ferences in CI and color development between heated and non-heated
halves of a tomato (Lu et al. 2010) or an avocado (Woolf 1997), indicating
a localized rather than systemic effect of heat treatment on postharvest
quality attributes of tomatoes (Lu et al. 2010). It is possible that uneven
red coloration in tomatoes is due to localized failure of patches of tis-
sues to develop red color. Alternatively, it may be possible that blotchy