Passion Fruit - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 313

conditions, geographic location, cultural practices, and
other factors. In the tropics, as in northern and northeastern
Brazil, production occurs throughout the year (Salomao,
2002). In subtropical regions, vegetation ceases in winter
and in the spring months; thus, in these regions, the pro-
ductive period is reduced to 6 or 7 months. In southeastern
Brazil, harvest extends from November to August of the
following year, the peak being in January to March.
Harvesting usually consists of allowing the ripe passion
fruits to fall from the vine, after which they are picked from
the ground, graded, and marketed. In contact with the soil,
the fruits lose their quality in a few days, thus collecting the
fruits at least twice a week is necessary. This harvesting
method causes mechanical damage, reduces the storage
life of the fruit, and results in poor quality for marketing
the fresh fruit locally or for export. Ideally, the fruits should
be picked from the plant, keeping 3 cm of the peduncle.
In practice, a major difficulty is determining the time
when the fruit has reached the physiological age adequate
for harvest. Rojas and Medina (1997) found that develop-
ment of the yellow passion fruit was characterized by three
distinct phases: fast fruit growth up to 25 days after anthe-
sis, when the fruit reached its maximum fresh weight and
volume; accumulation of fruit assimilates, between 25 and
50 days from ovule fecundation; and physiological matu-
rity of the fruit, at about 50 days after anthesis. It was
concluded that the yellow passion fruit's age was a good
index of the developmental stage for all variables evaluated
and could be used to choose the most suitable harvest stage
for ensuring long conservation of the product.
Investigating the characteristics of purple passion fruit,
detached at intervals from the vine and ripened, compared
with fruit left attached until just before analysis, Shiomi
et al. (1996b) observed that soluble solid content steadily
increased and reached maximum level at 70 days after flow-
ering (DAF), whereas titratable acidity increased rapidly up
to 60 DAF and then decreased up to 80 DAF. Change in
fruit color from green to purple occurred between 70 and
80 DAF, which corresponded to the commencement of au-
tocatalytic ethylene production. As indicated by the results,
the purple passion fruit appeared to reach physiological ma-
turity at about 60 DAF and can be harvested with acceptable
quality at about 70 DAF for commercial use.
Yellow passion fruit reached maximum size in 21 DAF
(Enamorado et al., 1995). Soluble solids and acids accu-
mulated and peaked at 63 DAF, followed by a decline of
the soluble solids, coinciding with the initiation of the cli-
macteric rise of respiration and ethylene production. It was
concluded that physiological maturity of yellow passion
fruit was reached 40 DAF.

According to Salomao (2002), the yellow passion fruit
reaches harvesting time in 50 to 60 DAF, that is, 30 to
20 days before it falls to the ground. At this point the
fruit has attained its maximum weight, maximum yield in
terms of the juice, and maximum content of soluble solids.
Fruits harvested at 50 (green skin), 60 (skin 75% yellow
and 25% green), and 70 (yellow skin) DAF ripen naturally.
Fruits collected at 40 DAF do not ripen, indicating incom-
plete morphological formation, and those collected 80 DAF
are already in the postclimacteric stage (Enamorado et al.,
1995). For export, the fruit can be harvested when 50% of
the skin is pigmented yellow or purple, although this per-
centage may vary, depending on the geographic location
of production, the market of destination, and the means of
transport (Salomao, 2002).

POSTHARVEST PHYSIOLOGY AND HANDLING
Passion fruit is one of the tropical fruits most difficult
to conserve (Salomao, 2002). The respiration rates (mg
CO 2 /kg/hr) of passion fruit at different temperatures, as
reported by Paull and Chen (2004), are 29-58 (5 ◦ C), 39-
78 (10 ◦ C), 87-194 (20 ◦ C), and 175-349 (25 ◦ C). Ethy-
lene production rate of passion fruit is high (160-400 μ l/
kg/hr at 20 ◦ C at their climacteric peak (Shiomi et al.,
1996a). Arjona and Matta (1991) reported that exposure to
100 μ l/kg/hr ethylene accelerated the rate of ripening.
Both purple and yellow passion fruit cannot be stored
for more than 7-10 days at ambient temperature because
wilting, fungal decay, and fermentation of the pulp set in
(Pruthi, 1963). The appearance, fruit weight, flavor, and
food value of the pulp are negatively affected, rendering the
fruit unfit for marketing and processing. Thus refrigerated
storage is necessary.
The postharvest life of the fruit is affected by a number of
factors (Pruthi, 1963; Sigrist, 2002): (1) cultivar —purple
passion fruit maintains its quality for a longer period than
the yellow fruit; (2) region of cultivation —regional variabil-
ity significantly affects the physicochemical characteris-
tics and storage life of the fruits; (3) climate/season —wide
seasonal and yearly variations have been observed among
fruits of the same variety in various physical and chemical
attributes; considerable variations in physiological losses
in weight and respiration were observed; (4) stage of ma-
turity at harvest —fruits harvested too early (color of the
skin totally green) or too late (skin three-fourths or to-
tally yellow) shrivel rapidly and the storage life is short;
(5) fruit size —bigger fruits generally undergo less weight
loss and yield more juice; the bigger the fruit, the greater
the storage period; (6) harvesting method —fruits harvested