Agriculture Reference
In-Depth Information
Table 30.1.
Common varieties of dragon fruits.
Fruit Type
Scientific Name
Varietal Characteristics
White flesh/pink
skin
Hylocereus
undatus
The most common of the three varieties of dragon fruit; fruits are slightly to
significantly less sweeter than the pink- or red-fleshed pitaya fruit
White flesh/yellow
skin
Selenicereus
megalanthus
Typically the sweetest of the three varieties of dragon fruit, with relatively
smaller sized fruits
Colored flesh/pink
skin
Hylocereus
polyrhizus
This is sweeter of the two pink-skinned varieties; fruits are larger than those of
the yellow-skinned dragon fruits
Source: Anon (2010); DFB (2011).
that fruit splitting is a problem at
35 days from flowering,
where rainfall or excessive irrigation during ripening may
have been received (Le et al., 2000a).
Bacterial (
Xanthomonas campestris
)and
Dothiorella
spp. diseases have been reported in dragon fruit by Barbeau
(1990); postharvest disease has been associated with
Fusar-
ium lateritium, Aspergillus riger,
and
Aspergillus flavus
(Le
et al., 2000a).
>
Controlled atmosphere (CA) storage of dragon fruit has
not been reported in the literature (Paull, 2004). Le et al.
(2000b) reported that fruit harvested 28-30 days after
flowering and stored under modified atmosphere (MA) in
polyethylene bag (O
2
transmission rate 4000 ml/m
2
/day)
can be held for 35 days at 10
◦
C as compared to 14 days
for air controls. Fruit with higher maturity (40 days from
flowering) were shown to exhibit 50% lower shelf life.
The use of X-ray irradiation at 150 grays (Gy) for
disinfection of dragon fruit at a commercial facility in
Hawaii has been reported by Yao (2011). The treatment was
found suitable for controlling the three species of
tephritid
fruit flies found in Hawaii. Such phytosanitary treatments
are helpful in expanding the export markets for dragon
fruit. The USDA's Animal Plant Health Inspection Ser-
vice (APHIS) allows export of dragon fruit from Hawaii
after irradiation with a 400 Gy dose or after irradiation
with a 50 Gy dose and inspection for mealybugs (Wall and
Khan, 2008).
Postharvest storage and shelf life
The optimum storage temperature recommended for dragon
fruit is 10
◦
C; a temperature lower than this can induce chill-
ing injury (Nerd and Mizrahi, 1999). Nerd and Mizrahi
(1999) recommended a lower temperature of 6
◦
Cforthe
yellow dragon fruit (
Selenicereus megalanthus
). The stor-
age life of dragon fruit is about 14 days at 10
◦
C; however,
at 5
◦
C and 90% relative humidity (RH), a 17-day shelf life
can be achieved (Le et al., 2000a). The latter storage con-
ditions are not recommended because the fruit can develop
chilling injury symptoms upon transfer to 20
◦
C; moreover,
it can result in the deterioration of peel and flesh and thus
imparting an inferior taste (Nerd and Mizrahi, 1999).
Fresh-cut or minimally processed products
Fresh-cut dragon fruit, except for culinary applications, is
marketed on a limited scale only for ethnic niche markets.
However, there is a potential to significantly expand its
consumption, provided that the quality, safety, and shelf
life are preserved. Goldman et al. (2005) reported that
peeled and/or sliced dragon fruit maintained its quality
in microperforated packages during a 10-day storage at
6
◦
C (Table 30.3). Cutting or slicing did not aggravate fruit
deterioration; however, during storage, the cut slices ad-
hered together and were hardly separable (Goldman et al.,
2005). The use of appropriate edible coatings on fresh-cut
dragon fruit can further improve the quality and extend
shelf life.
Chansamrankul et al. (2008) reported that the suitable
storage duration prior to preparation of fresh-cut dragon
fruit was 2-4 days after harvesting at ambient temperature,
Table 30.2.
Physical and chemical properties of
two varieties of dragon fruit.
Fruit Characteristic
White Flesh
Red Flesh
Avg. fruit length (cm)
13.4
12.7
Avg. fruit diameter (cm)
9.4
6.6
Avg. fruit flesh weight (g)
305
215
Avg. fruit skin weight (g)
100
75
Sweetness (
◦
Brix)
12.5
14.8
Glucose (g/100 g)
35.3
40.1
Fructose (g/100 g)
23.8
15.8
Oligosaccharides (g/100 g)
8.6
8.9
Source: Adapted from Wichienchot et al. (2010).
Search WWH ::
Custom Search