Dragon Fruit and Durian - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 571

Table 30.3. Microbiological quality of fresh-cut dragon fruit (CFU/g).

Evaluation Day Enterobacteria E. coli Yeast Molds

Fresh after 4 days transit < l100 0 < 100 1,000

After 5 days additional storage at 6 ◦ C < 100 0 < 2,000 1,000

Acceptable thresholds < 5,000 0 < 20,000 < 5,000

Source: Adapted from Goldman et al. (2005).

as was judged by eating quality and external appearance.
These researchers prepared fresh-cut dragon fruit on day
0, 2, 4, and 6 days after harvesting from fruit stored at
∼ 30 ◦ C. Fresh-cut dragon fruit were packed in foam trays
and wrapped with polyvinyl chloride (PVC) film and then
stored at 4 ◦ C. Results showed that the respiration rate and
flesh firmness of fresh-cut fruit was influenced by the day
of preparation after harvesting. Samples prepared immedi-
ately after harvesting had the highest respiration rate and
firmness while those from 6 days after harvesting had the
lowest respiration rate and firmness. Shelf life of fresh-cut
product prepared from dragon fruit at day 0, 2, and 4 after
harvesting was 10 days, while those prepared from dragon
fruit at 6 days after harvesting was limited to 8 days due to
onset of translucent flesh tissue.
Chuni et al. (2010) studied the effect of postcut ap-
plication of CaCl 2 on activity of polygalacturonase (PG)
and pectin methylesterase (PME) and quality of fresh-cut
dragon fruit. Fruit slices were prepared from fully matured
fruits and dipped into 2.5 or 7.5 g/liter of CaCl 2 for 4-12
min. The activities of PG and PME enzymes of fruits ex-
tract were lower when treated with high concentration of
CaCl 2 for a longer dipping time. The CaCl 2 treatment did
not cause any marked effects on color, pH, TA, and ascor-
bic acid content, with variable results observed for fresh-cut
fruit firmness.

Composition and health benefits
The data on composition and nutritional profile of dragon
fruit are somewhat limited; Table 30.4 shows composition
for selected components. Lim et al. (2007) reported ascor-
bic acid and total phenolic content of dragon fruit as 8 and
21 mg/100 g, respectively; the ascorbic acid equivalent an-
tioxidant capacity (AEAC) was reported to be 13 mg/100 g.
The pigment-rich peel of dragon fruit offers a potential to
extract bioactive compounds that can be used in functional
foods or nutraceuticals.
Dragon fruit is reported to possess many medicinal prop-
erties; red-fleshed varieties of the fruit are rich in antioxi-
dants. This fruit is potentially effective in preventing colon
cancer and diabetes, neutralize toxic substances (such as,
heavy metals), and reduce cholesterol and high blood pres-
sure (Gunasena et al., 2007). However, it must be noted that
many of these remedial properties are reported based on tra-
ditional uses and not based on properly designed clinical
studies.
Ariffin et al. (2009) extracted oil from two varieties of
dragon fruit seeds and analyzed it for its fatty acid profile.
Essential fatty acids, namely, linoleic acid and linolenic
acid, formed a significant percentage of the unsaturated
fatty acids of the seed oil extract (Table 30.5). Both vari-
eties contained about 50% essential fatty acids (48% C18:2,
1.5% C18:3) and had two oleic acid isomers. Essential fatty
acids are important in that they are necessary substrates
in animal metabolism and cannot be synthesized in vivo
(Ariffin et al., 2009).

Dragon fruit processing
Dragon fruit processing on a large commercial scale is
rather limited. On a small scale, the fruit is processed into
juice, jam, jelly, or preserve. Dragon fruit as an ingredient
is used in a number of food applications such as sherbet,
syrup, ice cream, yogurt, pastries, and candy (Gunasena
et al., 2007). Processed products can be produced from
fresh or frozen fruit pulp as a base. The red and pink pulp
of dragon fruit has been reported to be used as a natural
food colorant (Gao-Xi and Wan, 2004). The flower buds of
dragon fruit are used for making soups or mixed in salads.
Dried dragon fruit flowers are used for making antioxidant-
rich tea (Gunasena et al., 2007).

DURIAN

Introduction
Durian ( Durio zibethinus Murray) belongs to genus
Durio and the Malvaceae family, and the name “Durian”
is derived from the Malay word Duri, meaning “thorn,”
having the title of “king of the fruits.” The com-
mon durian is ramiflorous, that is, flowering on the
branches (Fig. 30.2). The flowers/fruits are borne along
big branches that are capable of bearing the weight of