Guava - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 199

mass loss and decreased pectin methylesterase activity dur-
ing storage. Refrigerated guava immersed in 0.5% and 1%
calcium solutions maintained up to 16 days of postharvest
shelf life (Gonzaga-Neto et al., 1999).
The use of heat treatment can increase the shelf life of
fresh fruits due to inhibition of some postharvest diseases,
although excessive time/temperatures may scald and soften
the fruits. Guava scald is observed by the presence of brown
discolored regions and/or pits and sunken areas on the fruit
surface (Gould, 1994). Some studies have been carried out
to evaluate the effect of heat treatment on guava, showing
the possibility of completely reducing the occurrence of
anthracnose with a warm water bath (10 min at 50 ◦ C), with
no influence on the soluble solids content, pH, titratable
acidity, or firmness (Ponzo, 2009).
The use of edible coatings has been also employed in
hurdle technology to reduce gas exchange and moisture
transfer between the fruit and its environment. Formulations
of edible emulsions containing starch, waxes, gelatin, or
acids have proven to be an efficient method of enhancing the
shelf life of guava. As compared to nontreated guava, coated
fruits exhibited lower weight loss during storage, which was
associated with the increase in shelf life and, consequently,
a decrease in postharvest losses (Oliveira and Cereda, 1999;
Fakhouri and Grosso, 2003; Ribeiro et al., 2005).
Several researchers evaluated the effect of 1-
methylcyclopropene (1-MCP) on delaying the ripening of
different varieties of guava by blocking the action of ethy-
lene (Basseto et al., 2005; Singh and Pal, 2008; Phebe and
Ong, 2010). It was generally observed that 1-MCP treat-
ment extended the shelf life of guava and maintained its
quality during both cold and ambient storage conditions.
However, very high concentrations of 1-MCP (900 nl/l, 6
or 12 hours) may inhibit fruit ripening and limit its subse-
quent flavor development (Basseto et al., 2005).

Harvest

Rapid cooling

Selection/Grading

Storage

Cleaning/Sanitization

Peeling

Cut in halves Cut in slices

Seed removal

Washing

Cooling

Packaging

Distribution

Figure 11.1. Flow diagram of minimal processing of
guavas.

is low, decreasing water loss and the cooling time in the
following steps (Mattiuz and Durigan, 2007).
The stage of maturity at harvest is one of the most im-
portant factors for the minimal processing of guava. As
observed before, the skin color generally determines the
ripening degree. According to Pinto et al. (2010), white
guava of the 'Kumagai' variety harvested at the light green
color are the most suitable, while red guava of the variety
'Pedro Sato' should be harvested at the yellowish green
maturity stage for minimal processing.

MINIMALLY PROCESSED OR
FRESH-CUT PRODUCTS
The main unit operations involved in the preparation of
fresh-cut guava are shown in Fig. 11.1 and described in this
section. The use of sanitary equipments and the adoption
of good manufacturing practices (GMP) as well as hazard
analysis and critical control points (HACCP) during the
whole processing are essential to maintain the high quality
of minimally processed guava (Garcia and Barrett, 2005).

Harvesting
The harvesting of guava should be carried out in the early
hours of the morning when the temperature of the fruits

Fast cooling, selection, and storage
Cooling is applied by immersing the fruits in cold water
tanks in order to decrease the metabolic activity of the