Guava - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 197

are also numerous other ways of consuming and process-
ing guava, which depend on the local customs: guava may
be eaten with salt, pepper, vinegar, or soy sauce or may
be canned or preserved into jam, butter, marmalades, rel-
ishes, and chutneys. The red guava may also be a substitute
for some tomato products, such as sauces and ketchup, the
latter being known as guatchup.

(Castro and Sigrist, 1988; Tucker, 1993; Mercado-Silva
et al., 1998; Azzolini et al., 2004). The pectin content of
guava increases during fruit development but declines in
overripe fruits, while the activities of the softening enzymes
such as polygalacturonase, pectinesterase, β -galactosidase,
and cellulase increase during ripening (El-Buluk et al.,
1995). The SS/TA ratio usually increases during fruit ripen-
ing due to the biosynthesis of sugars (directly related to sol-
uble solids) (Chitarra and Chitarra, 2005) and/or decrease
in titratable acidity, which is a consequence of the oxidation
of acids during fruit respiration (Brody, 1996).

POSTHARVEST PHYSIOLOGY
AND STORAGE TECHNOLOGIES
Guava is a highly perishable fruit that, at room tempera-
ture, completes its ripening process in just a few days af-
ter harvest at room temperature. Inadequate handling dur-
ing harvesting and postharvest processes accelerate fruit
senescence, significantly affecting its quality. Moreover, its
delicate skin offers very little protection against injury, ag-
gravating the incidence of bruising, which may lead to the
development of diseases and other disorders during storage.
Thus the extent of the postharvest losses of guava depends
not only on handling care but also on the storage conditions.

Postharvest losses
The main factors that depreciate the postharvest quality of
guava are excessive softening, mechanical injuries, high
incidence of rottenness caused by fungi, shriveling of the
fruit, malformation, and loss of brightness, which may
be grouped as morphological, physical, physiological, or
pathological defects (Kader, 2002). Of these, mechanical
injuries and postharvest diseases are the main factors re-
sponsible for reducing guava quality, leading to significant
postharvest losses. Harvesting and postharvesting losses
are estimated to reach up to 40% in some countries, such
as Brazil and Pakistan (Vieira and Santos, 2003; Khushk
et al., 2009).
Besides compromising the visual aspect, mechanical in-
juries can increase ethylene production, accelerating ripen-
ing and, consequently, reducing the shelf life. Moreover,
scratches, incisions, wounds, and any other mechanical in-
jury are points of entry for pathogens to penetrate the fruit
(Barkai-Golan, 2001). Thus, owing to its delicate skin, han-
dling guava demands additional care, from growth in the
fields through storage, shipment, and distribution channels.
Covering the developing fruit with paper bags when it
reaches about 2.5 cm in diameter reduces some types of
insect infestation, such as the Caribbean fruit fly and the
guava moth (Pereira, 1990; Crane and Balerdi, 2009), be-
sides reducing injuries caused by birds, leading to an over-
all improvement in fruit quality (Amarante et al., 2002).
During guava harvesting, manual operations also lead to a
reduced extent of fruit injury as compared to mechanical
ones and are thus preferred for fruits destined for the fresh
market. Moreover, shipment and transportation of guava
fruits is usually in small boxes, and the fruits are individ-
ually protected since they are easily crushed or bruised,
accelerating their deterioration (Vieira and Santos, 2003).

Postharvest physiology
There is no consensus concerning the classification of guava
according to its respiratory activity (whether climacteric
or nonclimacteric), despite the fact that the flesh softens
and the skin color develops after harvesting, characteristic
of climacteric fruits. Thus a number of authors consider
it a climacteric fruit (Mercado-Silva et al., 1998; Bashir
and Abu-Goukh, 2003; Sidhu, 2006), whereas some oth-
ers consider it nonclimacteric (Medina, 1988; Chitarra and
Chitarra, 2005). For some guava cultivars, such as 'Pe-
dro Sato,' it was observed that postharvest ripening and
senescence occur independently of the CO 2 and ethylene
climacteric behavior (Azzolini et al., 2005).
The stage of ripening at harvest determines the quality of
the fruit offered to the consumers. Immature fruits do not
usually develop good flavor during the postharvest period.
Moreover, they tend to show high rates of water loss and to
be more susceptible to physiological disorders. On the other
hand fully ripe guava fruit is often damaged by birds and
insects and are difficult to handle and transport due to its
softness (Manica et al., 2000; Sidhu, 2006). The maturity of
the guava is usually indicated by its skin color (Mercado-
Silva et al., 1998). It turns from dark green to yellowish
green due to degradation of the chlorophyll and the syn-
thesis of carotenoids and anthocyanins (Tucker, 1993), al-
though some cultivars maintain the green color during mat-
uration (Sidhu, 2006). Firmness and the soluble solids/total
acidity ratio (SS/TA) are other indicators of fruit maturity

Postharvest diseases
Generally, postharvest diseases may be classified as
quiescent infections or those which are a consequence of