Chemistry Reference
In-Depth Information
the product before they buy. Furthermore, in some cases natural photosensitizers
can not be removed, or sometimes photosensitizers are added to fortify the
product.
Therefore, an alternative approach to maintain product quality is to use anti-
oxidants that specifically interact with singlet oxygen. Conventional anti-
oxidants such as BHA and BHT are typical radical quenchers and therefore will
only interfere with radical compounds which mainly appear in the process of
triplet oxidation. In order to prevent singlet oxidation a molecule is required that
is able to absorb the energy that is stored in the `excited' singlet oxygen
molecule. Such compounds are generally referred to as singlet oxygen
quenchers. Typical singlet oxygen quenchers are ascorbic acid, carotenoids
and tocopherols. These molecules are able to transform excited singlet oxygen
into ground-state triplet oxygen while the antioxidant itself will shift from the
triplet state into the singlet state.
3.7 Future trends
Singlet oxygen can have a dramatic impact on the quality and the shelf life of
food products. Because of its very different chemical nature compared to triplet
oxygen distinctive oxidation breakdown products will be formed. Simul-
taneously a different set of antioxidant molecules will be required in all attempts
to reduce the level of singlet oxidation.
The results from the quantification of volatile breakdown products obtained
with GC-MS analyses helps to understand the influence of oxygen quenching
antioxidants on the formation of rancid flavors. As a result, the information
obtained from these analyses will be valuable to optimize antioxidant formula-
tions for specific food and feed applications (Van Dyck, 2007). Owing to the
complexity and interaction between all stages of the oxidation process it is often
very difficult to develop an antioxidant formulation that is suitable for all food
and feed matrices and for all storage conditions. Some antioxidants may become
pro-oxidant when the main oxygen species responsible for the oxidation changes
due to a change in storage conditions or packaging. Therefore it is of extreme
importance to carefully balance antioxidant formulations for specific applica-
tions and to assess the efficacy of products under a variety of different relevant
storage conditions.
Also the study of the effects of singlet oxidation will need to be developed
further. Many studies make use of models to identify the parameters that play a
role in the oxidation. Unfortunately the insights from the simpler model systems
are not always verified against real food systems. However, this is a crucial step
that is required to give the food and feed industry the required information on
the complete food matrix in order to develop suitable formulations or strategies
to inhibit singlet oxidation.
Although formulation of products with a focus on oxidative stability is still an
area that needs further research, further exploration of new packaging strategies
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