Environmental Engineering Reference
In-Depth Information
needed to assess their performance and potential. In the present study, the
sustainability of biopolymer-based nanocomposites for packaging applica-
tions has been discussed along with their theories and gas permeability
properties. h e main objective of the present review is to compare dif er-
ent kinds of nanoi llers suitable for various biopolymers in order to enable
the materials to be used for food packaging materials. h e oxygen perme-
ability of nanocomposites of dif erent i llers was compared with the virgin
polymer/biopolymers.
13.4
Background of Food Packaging
13.4.1 Oxygen Penetration
Oxygen (O
2
) is responsible for the deterioration of many foods either
directly or indirectly. Food deterioration by indirect action of O
2
includes
food spoilage by aerobic microorganisms [7]. h e incorporation of O
2
scavengers into food packaging can maintain very low O
2
levels, which is
useful for several applications. In particular, attention has been focused on
the photocatalytic activity of nanocrystalline titania (TiO
2
) under ultra-
violet radiation. Industries estimate the food expiration date, taking into
consideration the distribution and storage conditions to which the food
product is predicted to be exposed. However, it is known that such con-
ditions are not always the real ones, and foods are frequently exposed to
temperature abuse; this is especially worrying for products which require
a cold chain. Moreover, micropores or sealing defects in packaging sys-
tems can lead to an unexpected high exposure of oxygen in food products,
which can result in undesirable changes. When integrated into food pack-
aging, nanosensors can detect certain chemical compounds, pathogens
and toxins in food [8].
Food spoilage is also caused by microorganisms, whose metabolism
produces gases which can be detected by conducting polymer nanocom-
posites (CPC) or metal oxides. h is can be used for quantiication and/
or identiication of microorganisms based on their gas emissions. Sensors
based on CPC consist of conducting particles embedded into an insulating
polymer matrix; the resistance changes of the sensors produce a pattern
that corresponds to the gas under investigation. Oxygen allows aerobic
microorganism to grow during food storage [9]. h ere has been increasing
interest in developing nontoxic and irreversible oxygen sensors to assure
oxygen absence in oxygen-free food packaging systems, such as packaging
under vacuum or nitrogen [10].
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