Current and Innovative Packaging Technologies for Tropical and Subtropical Fruits - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 118

Figure 7.5. On-shelf performance of antifog multilayer polyethylene-based film (right) vs. normal
polyethylene-based film without antifog additive (left) (reprinted with permission from Chinsirikul et al.,
2008b; Winotapun et al., 2010a).

packaging materials with improved mechanical, barrier,
and antimicrobial properties (Rhim et al., 2006; Ahmed
et al., 2010).

into the thin inner layer instead of being dispersed across
the whole thickness of the single-layer film. This offers
several advantages: reducing the amount of additives used
(thus increasing cost-effectiveness); an easy-open function
between the two adjacent layers; and optimum antifog ap-
pearance on the shelf. Figure 7.5 illustrates clear, antifog,
multilayer PE-based film utilized as packaging for rambu-
tan fruits stored at 13 ◦ C. The film's antifog and antiblock
additives are contained only in a skin layer of

Development of packaging materials for MAP and
active packaging
Advancements in polymer science and engineering are
largely attributable to the continuous development and in-
novation of plastics. Compared with other conventional
packaging materials (e.g., glass, metal, and paper), plas-
tics offer several essential features. They are low density,
easily processed, and shapeable into thin-complex products
at low melting temperature. These advantages make plastic
a versatile material of choice for packaging fresh produce,
with benefits including economy of weight, distribution
space, and fabrication energy.
Major packaging technologies for fresh fruits are MAP,
equilibrium modified atmosphere (EMA) packaging, and
active packaging. Plastic films and trays have been widely
used in MAP and active packaging for fresh fruits, particu-
larly in the growing market of fresh-cut fruits. The primary
choices of material, thickness, and how to fabricate/process
the desired package are the controlling factors of package
performance. Plastic films can be monolayer or multilayer
structures, where the different materials in each layer can
offer certain desired functions. For multilayer films, the aim
is to obtain synergistic performance from all components,
which cannot be achieved by each material alone or by
a single layer. Layer structure design (thickness, material,
and composition) can bring about optimal integration of
technical performance, commercial appeal, and cost. As a
simple example, based on co-extrusion of multilayer films,
antifogging and antiblocking additives can be incorporated

10 μm
thick, or one-third of the total film thickness. In contrast,
common PE film without an antifog additive appears very
foggy under similar refrigerated condition.
Apart from plastic films, trays are also a popular form
for packaging of fresh and fresh-cut fruits. Advances in
two major production technologies—thermoforming and
injection molding—have resulted in competition for in-
creased market share by addressing efficiency and energy
savings. Current research is focused on developing plas-
tics for thinner packaging without sacrificing mechanical
integrity (e.g., impact strength for tray stackability).
When selecting packaging materials for fresh and pro-
cessed fruits, the main characteristics to be considered are
(1) gas permeability (PO 2 ,PCO 2 ,andPC 2 H 4 ), (2) water
vapor permeability (WVP), (3) mechanical properties (ten-
sile strength, elongation, modulus, tear, toughness, etc.),
(4) sealability, (5) clarity (low haze), (6) antifog properties,
(7) processability, and (8) printability.
The gas permeability of most traditional packaging films
has been considered inadequate for MAP of many types of
fresh fruits. This is especially the case for high-respiring
commodities such as fresh-cut fruits (Zagory and Kader,
1988; Sandhya, 2010). Of all available films, low-density
polyethylene (LDPE) and polyvinyl chloride (PVC) have

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