Papaya - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 298

papayas were not washed prior processing. Nevertheless,
no changes in the total microbial content and in fungi and
yeasts occurred after 4 days at 4 ◦ C, while translucency de-
velopment and loss of firmness were patent after 2 days
of storage (O'Connor-Shaw et al., 1994), limiting the shelf
life of the product. However, the use of sanitizers is essen-
tial to inactivate the micro-organisms in the wash water,
playing a critical role in the prevention of microbial cross-
contamination between products in those operations where
water is reused (Sapers, 2001). Hernandez et al. (2006)
observed a reduction in aerobic mesophiles of 2 log units
and in fungi and yeasts of 1 log units when whole papayas
where washed in chlorinated water (200 mg/liter) for 1 or
3 min. There are very few studies evaluating the effective
concentration and contact time needed to improve hygiene
quality of the cut product during storage and processing.
Hernandez et al. (2007a) suggested washing the cut fruit
with 100 mg/liter for 2 min for greater safety margin to
product hygiene although no difference in the microbial
quality of untreated fruit was found. Other sanitation com-
pounds such as hydrogen peroxide, MJ, cinnamon, and
so on, have been used in many fruits but not in papaya.
The use of chitosan (2%) reduces considerably aerobic
mesophiles and fungi and yeast loads, prolonging the shelf
life of the papaya (Gonzalez-Aguilar et al., 2009). Never-
theless, Hernandez et al. (2007a) evaluated lower chitosan
concentrations (0.1% and 0.2%) as 2% gives the product
off flavors. Chitosan 0.1% reduced 1 log unit the microbial
load over those slices sanitized with sodium hypochlorite
(100 mg/liter).
Some operations within the industrial process, such as
peeling and cutting, can decisively affect the hygiene of the
minimally processed products. Thus Rivera-Lopez et al.
(2005) found that slices presented slight advantages in
overall quality comparing to cubes when stored at 5 ◦ C.
Arganosa et al. (2008) and Morais and Arganosa (2010)
evaluated the effect of the cut type (cube, rectangular par-
allelepiped, cylinder, and sphere) on the quality and shelf
life of fresh-cut papaya and found that the sphere-shaped
showed the most favorable physicochemical and microbio-
logical results when stored 10 days at 4 ◦ Cor8at10 ◦ C, re-
spectively. Hernandez et al. (2007b) found more microbial
load in pieces cut mechanically than in those cut manually.
In general, the use of low O 2 and/or high CO 2 reduces the
activity of fungi and yeasts and, consequently, the deterio-
ration of the cut products (Gonzalez-Aguilar et al., 2004).
Lima et al. (2005) observed that the microbial growth was
higher in the fruit packed in polyethylene (PE) than in
polyvinyl chloride (PVC) packages, and consequently, the
shelf life of the product was lower.

Dipping shredded green papaya in 1% ascorbic acid or
citric acid for 3 min prior to storage in 5% O 2 or 5%
CO 2 reduced growth of Escherichia coli (Lichanporn and
Kanlayanarat, 2006).
Refrigeration temperatures control microbial growth.
Thus the microbial development was higher at 20 ◦ ,15 ◦ ,
and 10 ◦ than at 5 ◦ C (Allong et al., 2001; Hernandez, 2008).

Sensorial changes
O'Connor-Shaw et al. (1994), Rivera-L opez et al. (2005),
Ergun et al. (2006), Hernandez et al. (2007c), Hernandez
(2008), and Wall et al. (2010) pointed out translucency as
a major sign of deterioration limiting the quality and shelf
life of fresh-cut papaya. This disorder begins to develop
from the first hours after cutting the fruit. In addition, Lobo
et al. (2009) determined that when the percentage of translu-
cency in papaya slices is more than 15%, it is considered
commercially unacceptable by the consumers. From a va-
riety of factors evaluated (Table 16.4), the cultivar, the fruit
ripeness, the type of cut, the packaging, the storage temper-
ature, the light exposure, and the calcium chloride treatment
crucially influence translucency development (Hernandez,
2008; Lobo et al., 2009).
Quality and shelf life of fresh-cut papaya can be ex-
tended by treating the fruit with 1-MCP prior to processing.
The treated slices had lower ethylene production rate, more
firmness and better color, being acceptable after 6 days
storage, while those untreated had a shelf life of 2-3 days
(Ergun et al., 2006). The use of alginate (2%) or gellan-
based (0.5%) coating formulations improves water vapor
resistance (WVR) and firmness. Moreover, the incorpo-
ration of 0.025% sunflower oil into the alginate or the
gellan-based formulations resulted in a 16% and 66% in-
crease in the WVR of the coated samples, respectively
(Tapia et al., 2008). Controlled atmosphere (CA) storage
and modified atmosphere packaging (MAP) are helpful in
extending the shelf life of cut fruits (Schlimme and Rooney,
1994). Shredded green papaya stored in controlled atmo-
sphere (5% O 2 and 10% CO 2 ) remained acceptable for
consumption for a period about 2 times longer than that in
air. CA remarkably reduced weight loss, suppressed res-
piratory increases, and retarded losses in color and firm-
ness although resulted to high ethylene production rates
(Techavuthiporn et al., 2003). Active MAP with 2.5% and
5% O 2 was more effective in maintaining the visual qual-
ity of the shredded green papaya and in the reduction of
respiration and color change than passive atmosphere, but
it should be noted that this condition may generate off
flavors during long-term storage (Srilaong and Chansam-
rankul, 2007). Moreover, shredded green papaya dipped