Guava - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 200

freshly harvested guava (Mattiuz and Durigan, 2007). Af-
ter cooling, the fruits are carefully selected according to
their size and color, and malformed, damaged, and defec-
tive fruits are removed. The fruits should be kept under
refrigeration until further processing.

steps of peeling and cutting. The guavas are then usually
rinsed in cold water (

5 ◦ C) containing a sanitizing agent,
since the low temperature also allows for cooling of the
fruits. Dips in water with 20 to 100 ppm of free chlorine
are commonly used in postcutting operations (Mattiuz et al.,
2003; Pereira et al., 2004; Lima et al., 2010), although other
sanitizer agents could be used for this purpose to conform
to local legislation.

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Cleaning and sanitization
Guavas are first washed in water tanks and scrubbed with
soft sponges to remove dirt and debris and to reduce mi-
crobial load. The fruits are then rinsed in tap water to re-
move the remaining residues. After washing, fruit must be
sanitized by dipping the prewashed fruits in sanitizer so-
lutions to guarantee their microbiological safety (Mattiuz
and Durigan, 2007). Chlorinated water is the most common
sanitizer, although in some European countries, the use of
chlorine in fresh foods has been banned ( Olmez and Kret-
zschmar, 2009). Thus other alternatives for fruit sanitization
have been employed, such as the use of organic acid formu-
lations, such as peroxyacetic acid alone or combined with
citric and ascorbic acids, hydrogen peroxide, calcium dips,
and ozone and UV radiation, among others (Pereira et al.,
2004; Artes et al., 2009; Olmez and Kretzschmar, 2009).

Packaging and distribution
Some requirements are essential for choosing the ideal
packaging for fresh-cut guava: the packaging must avoid
fruit dehydration as well as water vapor saturation, reduce
the respiration rate without asphyxiating the tissues, and
minimize microbiological changes.
Polystyrene trays wrapped in plastic packs, such as
polyvinyl chloride stretch film (PVC), oriented polypropy-
lene, and polyethylene film are often used to pack fresh-
cut guava. Polyethylene terephthalate (PET) containers are
also an alternative, which present advantages in relation to
other plastic packaging such as great availability and ease of
handling, better visualization of the product and lower cost
(Pereira, 2002; Mattiuz et al., 2003). However, Lima et al.
(2010) observed an accumulation of water droplets on the
lid of PET packages, compromising the general appearance
of the product.
Some studies with the MAP of fresh-cut guava may also
be found in the literature. The MAP provides a longer shelf
life than conventional packaging; in principle, it consists of
reducing the rate of metabolic processes by modifying the
composition of the internal atmosphere (gas composition)
of a package. In general, low O 2 and/or high CO 2 levels
in the storage atmosphere inhibit fruit respiration, delaying
ripening and promoting an extension of the shelf life. Kader
(2009) recommended the use of 2-5% O 2 for delaying the
ripening of mature-green and partially ripe guavas at 10 ◦ C,
but no values concerning their tolerance to high CO 2 levels
were determined.
The use of low temperatures is fundamental for the con-
servation of fresh-cut guava. According to Mattiuz and
Durigan (2007), fresh-cut guava must be refrigerated dur-
ing the entire sequence, and in markets, the products should
be stored at temperatures around 3 ◦ C. Under such stor-
age conditions, minimally processed guava packed in PET
containers achieved up to 9 days of shelf life, whereas
fruits packed in polystyrene trays wrapped in PVC film
lasted for up to 6 days (Lima et al., 2010). Despite the
use of low-temperature storage, none of these studies re-
ported the occurrence of any chilling injury in the minimally
processed guava.

Peeling and cutting
For fresh-cut products, the peeling of guavas can be manual
or mechanical (Mattiuz and Durigan, 2007). Sharp knives
or vegetable peelers are used to peel fruit manually; this
is impracticable for large-scale operations since it is quite
laborious and shows a reduced yield as well as high weight
losses during peeling. For mechanical peeling, equipment
used for peeling potatoes and oranges may be adapted for
guava (Mattiuz and Durigan, 2007). The equipment may
also present rollers or rotating bowls with surfaces made of
abrasive material (abrasion peeling). Abrasion removes the
fruit skin, which is then washed away by a continuous sup-
ply of water (Sudheer and Indira, 2007). In the latter case,
the fruits should be firm for a better result (Martin and
Kato, 1988). The mechanical techniques reduce compres-
sion injuries that may occur during the manual technique
and allow for peeling the whole guava uniformly.
After peeling, the guavas are cut into halves lengthwise
and their ends and seeds are removed. The fruit can also be
cut into slices without removal of the seeds. In both cases, it
is very important to use sharp, sanitized knives to minimize
physical injury and to avoid microbiological contamination.

Washing and cooling
Before packing, the guava should be washed once again
with a sanitizing agent to reduce or eliminate any possible
contamination from the manipulation during the previous