Longan and Carambola - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 218

to prevent increasing decay incidence (Jiang et al., 2002;
Holcroft et al., 2005). Vacuum cooling is an effective
precooling method for 'Chike' longan (Chen and Lin,
2000). The pulp temperature could be reduced from 28 ◦
to 7 ◦ C within 11 min. Wetting the fruit prior to vacuum
cooling reduced water loss and increased cooling rate (Lin,
2002). However, vacuum cooling is not commercially used
due to its cost.

postharvest decay and pericarp browning of longan fruit
cv. 'Daw' and found that ozone in combination with
5% w/v of oxalic or citric acid could be a partial alter-
native to SO 2 fumigation as a control of postharvest decay
and browning.

Surface coating
Pericarp (skin) coatings can extend the storage life of lon-
gans (Jiang et al., 2002). Jiang and Li (2001) reported that
the dipping longan in a 2% chitosan in acetic acid extended
the storage life of 'Shixia' from 30 to 40 days at 5 ◦ Cby
maintaining fruit quality and delaying pericarp browning.
Application of edible konjac glucomannan film reduced
water loss and respiration rate, inhibited pathogens, re-
tarded browning, and extended storage of 'Wulongling'
longan (Zou et al., 2001).

Current storage and shipping practices
Within a few days of storage under ambient temperature,
fruit becomes dried (weight loss) and skin color changes
to dull and dark brown. This would result in loss of lon-
gan commercial value (Ratanachinakorn and Sukwiboon,
2004). Therefore, it is necessary to keep longan at a high
relative humidity and low temperature to extend the shelf
life. Beside reducing water loss and retarding browning,
storage at low temperatures helps delay changes in nutri-
tional compositions and reduce aril breakdown incidence
(Paull and Chen, 1987; Lin et al., 2001a, 2001b).
The recommended optimum storage conditions for lon-
gan is at a relative humidity of 90-95% and a tempera-
ture of 5 ◦ ±

Shelf life extension and quality
Controlled and modified atmospheres
Controlled and modified atmospheres have been reported
to reduce browning and decay, and extend the storage life
of longan (Jiang, 1999; Liu and Ma, 2000; Tian et al.,
2002; Ratanachinakorn and Sukwiboon, 2004). O'Hare and
Prasad (1991a) reported that controlled atmospheres (CA)
storage with low oxygen (5% O 2 ) helped maintain eating
quality of longan. Jiang (1999) reported that 'Shixia' lon-
gan stored in atmospheres of 4-6% O 2 and 6-8% CO 2 at
1 ◦ C for 30 days could maintain eating quality with less de-
cay. Liu and Ma (2000) reported that modified atmosphere
storage (50% air + 50% nitrogen) of longan fruits treated
with antifungal agent resulted in a 92.3% marketable fruit
ratio and high percentage of nutrient composition in fruits
stored at 24 ◦ -26 ◦ C for 7 days. In 2002, Tian et al. found
that 'Chuliang' fruit stored at 2 ◦ C under atmospheres of
70% O 2 , with the balance being nitrogen, had less decay
and browning than fruit under 4% O 2 +

1 ◦ C. With these optimum storage conditions,
the shelf life of longan could be extended to 2-4 weeks,
depending on cultivar (Kader, 2009b). Fruits undergoing
SO 2 fumigation have a longer shelf life than those without
the treatment. In China, longan could maintain quality for
30-40 days if it was treated with fungicides and stored at
1 ◦ -5 ◦ C (Lin et al., 2001a; Jiang et al., 2002). Ice is of-
ten used during short-distance transportation of longan for
1-3 days in nonrefrigerated vehicles. Fruits are usually
packed in a polythene bag of 0.04-0.05 mm thickness and
placed in polystyrene boxes with topping of ice. The ratio
of ice to fruit is approximately 1:3 to 1:4 (Chen et al., 1998,
2001). To prevent chilling injury, direct contact of fruit and
ice should be avoid.
In Asia, bamboo baskets are commonly used as packages
for local markets, while cardboard boxes and plastic crates
are preferred for export. Storage in plastic bags was effec-
tive in reducing moisture loss over a wide temperature range
of 3 ◦ -30 ◦ C (Su and Yang, 1996; Xu et al., 1998). Longest
storage life of 'Shixia' fruit at 3 ◦ C was 48 days inside
sealed bags and 30 days inside perforated bags (Zhou et al.,
1997a). Similar results have been obtained for other culti-
vars (Lu et al., 1992; Campbell, 1994; Chen et al., 1998).

5% or 15% CO 2 .
Ratanachinakorn and Sukwiboon (2004) reported that fresh
longans stored in an atmospheric composition of 2% O 2
balanced with nitrogen gas helped extending shelf life of
SO 2 -fumigated fruits to 45 days at 5 ◦ C. Kader (2009b) sug-
gested that a CA combination of 3% O 2 + 5% CO 2 was

effective in delaying skin browning and maintaining quality
of longan fruits kept at 4 ◦ C for 35 days. Modified atmo-
sphere packaging that results in 2-3% O 2 andupto5%
CO 2 is also effective in reducing water loss and associated
darkening of the skin.
Modified atmosphere packaging is used commercially
in longan to reduce browning (Lin et al., 2001a). Zhang
and Quantick (1997) reported that 'Shixia' longan stored
in 0.03 mm PE bags with an initial atmosphere of 3% O 2

Innovative postharvest technologies
Ozone treatment
Whangchai et al. (2006) investigate the effects of ozone,
in combination with citric, ascorbic, and oxalic acid, on