Postharvest Biology and Technology of Fruits, Vegetables, and Flowers

POSTHARVEST TREATMENTS AFFECTING SENSORY QUALITY 307
due to its antifungal and film-forming properties (Han et al., 2005). Three 1% chitosan-based
solutions were developed for coating strawberries: chitosan in 0.6% acetic acid solution,
in 0.6% lactic acid solution, and in 0.6% lactic acid solution plus 0.2% vitamin E. Trained
panel showed that chitosan-coated strawberries have similar sensory descriptors as those of
fresh berries, whereas coatings containing vitamin E developed the waxy-and-white surface
of the samples. The trained panel did not detect astringency difference among all samples,
indicating that 1% chitosan coating did not change astringency of strawberries. A novel
edible coating based on aloe vera gel has been used as a means of preservation to maintain
the quality of cv. “Crimson” seedless table grapes during cold storage and subsequent shelf
life (Valverde et al., 2005). After 7 days at 1 ◦ C plus 4 days at 20 ◦ C, the sensory analyses
of clusters treated with aloe vera gel revealed beneficial effects such as slow weight loss
and color changes, without any detrimental effect on taste, aroma, or flavors. Similar results
with beneficial effects regarding the sensory quality were reported for sweet cherry treated
with aloe vera gel (Martinez-Romero et al., 2006). The sensory traits of “Galia”-type melon
fruit coated with three polyethylene-based waxes with different solid matter and shellac
contents (“Zivdar,” “Tag,” and “Tag-A”) or with natural beeswax (“Beeswax”) was evaluated
after prolonged storage. “Tag”-treated melons had better sensory quality, as evaluated
by organoleptic tests and aroma volatiles. Treatment with the waxes “Zivdar” and “Tag-A,”
which contain high amounts of shellac in proportion to “Tag” and “Beeswax,” significantly
increased off-flavor in the melon fruit due to high internal levels of CO 2 , ethanol, acetaldehyde,
and ethyl acetate. Untreated fruit, or fruits that were coated with “Beeswax,” had the
best taste (Fallik et al., 2005b). “Mor” is a new mandarin variety, which has a rich aromatic
taste. The variety suffers from the development of off-flavors, which are often enhanced
by coating the fruit with waxes, which restrict gas exchange and lead to the development
of anaerobic conditions in the internal atmosphere of the fruit. Porat et al. (2005) found
that, in order to maintain the best sensory quality of the fruit, it was necessary to include at
least 13% of total solids and half the regular amount of shellac to improve fruit taste and
reduce the formation of off-flavors, compared with fruit coated with the commercial wax
formulation.
14.4.3 Heat treatments
Heat treatments appear to be one of the most promising means for postharvest control of
decay (Lurie, 1998). Heat treatments against decay-causing agents may be applied to fruits
and vegetables in several ways: by hot water dips, by vapor heat, or by hot dry air (Lurie,
1998), or by a short hot water rinsing and brushing (Fallik, 2004). Heat treatments can also
be used to inhibit ripening processes, or enhance resistance to chilling injury during storage,
thus extending storability and marketing (Lurie, 1998).
Heat treatment of apple fruits (4 days at 38 ◦ C) markedly inhibited emission of total
volatile esters, compounds commonly associated with apple aroma of apple within 1 day
of treatment. However, after an extended refrigerated storage at 1 ◦ C, the heat-treated fruit
recovered and produced more total volatiles, compared to non-heat-treated fruit (Fallik
et al., 1998). Abbott et al. (2000) found that calcium infiltration significantly increased
sensory and overall acceptability scores of “Golden Delicious” apples held at 38 ◦ C for 4
days. Apples exposed to heat before storage were sweeter than those not heated. Only the
untreated (unheated) fruits were scored in the unacceptable range for crispness and overall