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Brasil
PackTrends
2020
144
quality and new technologies
oxygen concentration to very low levels (0,01%)
and keep it during storage. They effectively prevent
oxidation damages and microbiological deterioration
in many products. In oils, fats and fatty products,
oxygen absorbers prevent the rancidity; in processed
meat, fruit and vegetable they prevent discoloration;
in food rich in aroma, like juices, they reduce the loss
of typical flavor; in bakery products and cheeses, they
control the microbial deterioration; and in food rich
in vitamins, they prevent the loss of its nutritional
value. Oxygen absorbers allow the reduction or even
the elimination of preservatives like antioxidants
and antimicrobials agents. They can also be used for
controlling of the deterioration caused by insects,
which grow in nuts, grains and dried foods; they act as
well as over grown insects and their eggs.
The technologies associated to the oxygen
absorbers use one or more of the following concepts:
iron based compounds (iron oxide, iron carbonate, iron
sulphate, iron sulphite-sulphate); organic substances
with low molecular weight (ascorbic acid, sodium
ascorbate, catechol); enzymatic systems (glucose
oxidase, alcohol oxidase); photo-reducer components;
oxidable polymers; unsaturated fatty acid (for instance,
oleic, linoleic and linolenic acids); microorganisms
immobilized in solid substrate, which means, biological
oxygen absorbers; sulphite and its analogous (bisulphite,
metabisulfite and hydrosulphite).
The incorporation of active compounds in
polymers demands a very fast absorption kinetic.
The polymer permeability, in which the active is
incorporated, might be a restriction to the reaction
rate, comparing to the one obtained with iron powder
spread in appropriate vehicles in the sachets, what
provides a large superficial area for reaction. As an
alternative to the addition of metallic compounds to
the plastics, various compounds with low molar weight
are suggested for oxygen absorbers, but most of them
face regulatory barriers. The most promising alternative
seems to be the oxidation of the polymer itself to absorb
oxygen. The control of oxidation byproducts, especially
of possible toxic migrants, is one of the most important
challenges. Another important parameter, the control
of the absorber reactivity through an “activation”
step, such as the use of radiation, seems to be a
good solution to the activity loss of the incorporated
absorbers before package use.
The oxygen absorption technologies should not
start the reactions before the package to be in contact
with the product. That is because the absorbers action
has a finite characteristic. Hence, the trend is towards
the development of mechanisms that start the absorption
on demand, allowing the package storage or handling
avoiding the absorption capacity “waste” before the
contact with the product. Therefore, the absorbers will
start acting at the desired moment, which means, when
the package is sealed.
Cryovac, a division of Sealed Air Corporation,
sells the family of active packages called Freshness
Plus, which technology aims to maximize the freshness,
aroma and appearance, minimizing the microbiological
deterioration and oxidation reactions of pigments,
aromas and nutrients. The family of films includes off
odor absorbers –
Odor Scavenging
and oxygen absorbers
– OS films – Oxygen Scavenging (Figure 6.1). The
active component is an oxidable terpolymer, activated
on demand by ultraviolet light on the processing line.
Because it is not iron-based, it does not bring any
problem to the lines with metal detectors, does not
alter the coloration and transparency of the package
and does not depend on the product humidity to act as
an absorber as for iron based absorbers.
An important driving force for the development
of oxygen absorbers active packages is the need for
keeping the current quality level (or even improve
it) when the package material is changed, especially
when a new material is introduced to a food or beverage
category. That was observed when the PET bottle was
introduced as a package alternative to the metallic or
glass bottle for beverages that, for presenting a lower
barrier to the oxygen, needs to be improved. Another
driving force for it is the reduction of the complexity
of multilayer plastic structures, though keeping the
product protection, what brings environmental benefits
as it does not put the possibility of mechanical post-
consumer recycling at risk.