Papaya - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 295

parts of the fruit had higher concentrations of organic acids
(lactic, acetic, and pyruvic) and ethanol, pointing out a fer-
mentative process that might be caused by a local lack of
oxygen. Campostrini et al. (2010) related the magnesium
and calcium deficiencies in the pulp of the gelled tissue
with the disruption of proton pump functioning.

zole (Sepiah, 1994), or Mancozeb/Dithane (do Nascimento
et al., 2008). Sometimes inorganic salts are also used: am-
monium carbonate (Sivakumar et al., 2002). Nevertheless,
consumers are increasingly in agreement on the prohibi-
tion in the use of chemicals for the control of decay in
fruits and vegetables, due to the hazards of them in the
human health, the ecosystem, and the environment. Conse-
quently, alternative control strategies, such as natural com-
pounds, antagonists, and physical treatments, have drawn
attention. Thus thyme and Mexican lime essential oils
demonstrated inhibitory effects against anthracnose disease
(a major postharvest disease on papaya during storage) and
Rhizopus rot of papaya. Incorporation of these two oils in
mesquite gum-based coating gave excellent control of these
two postharvest diseases (Bosquez-Molina et al., 2010).
Resistant inducers such as Bion, Ecolife, and Agro-mos
have been also assayed on papayas artificially inoculated
with fungus. Bion was efficient for papaya stem-end rot
(do Nascimento et al., 2008). Aqueous seed extract ex-
hibited remarkable mycelial inhibition of Rhizopus spp.,
Aspergillus spp., and Mucor spp. (Nwinyi and Anthonia,
2010). Chitosan coatings on papaya not only controlled the
fruit decay but also delayed the onset of disease symp-
toms of anthracnose disease and Rhizopus rot (Bautista-
Ba nos et al., 2003; Hewajulige et al., 2009; Ali et al., 2010;
Hernandez-Lauzardo et al., 2010). Sivakumar et al. (2005)
observed that the effect of chitosan with ammonium carbon-
ate on the incidence and severity of anthracnose was greater
than chitosan alone or chitosan with sodium bicarbonate.
Likewise, Gonzalez-Aguilar et al. (2003) treated the fruit
with MJ and obtained an important fungal decay inhibition,
CI development reduction, and less firmness loss during
storage (14-32 days at 10 ◦ C and 4 days shelf life at 20 ◦ C).
The combination of this treatment with modified atmo-
sphere was beneficial to maintain postharvest quality of pa-
paya during low-temperature storage and shelf life period.
Another promising alternative to chemicals to control an-
thracnose is the biocontrol. Thus the combination of sodium
bicarbonate with the antagonist yeast Candida oleophila
(Gamagae et al., 2003); the yeast Cryptococcus magnus (de
Capdeville et al., 2007); or the bacteria Burkholderia cepa-
cia B23 enhanced by the presence of chitosan and CaCl 2
(Rahman et al., 2009), represent a promising alternative
to synthetic fungicides. The use of physical treatments is
promising but more studies should be done. Chitarra and
Chitarra (1990) indicated that low doses irradiation exhibit
insecticidal effects on fruit flies and that the storage pe-
riod of the fruit could be extended when associated with
thermal treatments for disease control. Cia et al. (2007)
observed that gamma irradiation (0.75 or 1 kGy) reduced

Pathological disorders
Anthracnose caused by Colletotrichum gloeosporioides is
a major cause of postharvest losses. Latent infections of
unripe papayas develop as the fruits ripen. The disease
symptoms begin as small water-soaked spots on ripening
fruit. As the spots develop, they become sunken, turn brown
or black, and may enlarge to 5 cm in diameter. These le-
sions are referred to as “chocolate spots.” The fungus may
produce a pink mass of spores in the middle of these older
spots. The pathogen can grow into the fruit, resulting in
softening of the tissue and an off flavor of the pulp.
Black stem-end rot caused by Phoma caricae-papayae
attacks the pedicel of the fruit. After harvest, the disease
lesion on fruits appears in the stem area which becomes
dark-brown to black. Another stem-end rot is caused by
Lasiodiplodia theobromae.
Phomopsis rot caused by Phomopsis caricae-papayae
begins in the stem-end or a fruit skin wound and can develop
rapidly in ripe fruits; invaded tissue softens and darkens
slightly.
Phytophthora stem-end rot caused by Phytophthora
nicotianae var. Parasitica is characterized by circular
translucent lesions, which develop with gray surface
mycelium, and is particularly apparent around the peduncle.
Rhizopus soft rot is characterized by a soft and watery
rot that quickly collapses the entire fruit but leaves the
cuticle intact. The fungus can grow out through any break
in the cuticle and spread rapidly to adjacent fruits, often
destroying the entire contents of a box within a few days.
The infected fruit is often covered by coarse, gray, hairy
mycelia that form a mass of black sporangia at their tips.
The affected fruit becomes quickly colonized by yeasts and
bacteria and emanates a sour odor.
Alternaria rot caused by Alternaria alternata follows CI
of papayas kept at temperatures below 12 ◦ C. It is character-
ized by black circular to oval injuries covered with a mass
of black spores. Old leaves and petioles are the fundamen-
tal source of inoculums. This disease is restricted to dry
ambient. This opportunistic fungus can manifest itself in
the field and during postharvest handling.
To control these postharvest diseases, papayas are treated
with synthetic fungicides as thiabendazole (Sommer and
Arpaia, 1992; Perez-Carrillo and Yahia, 2004), propicona-