Understanding oxidation processes in foods - Oxidation in Foods and Beverages and Antioxidant Applications - page 2

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Understanding oxidation processes in
foods
L. H. Skibsted, University of Copenhagen, Denmark
Abstract: Oxidative deterioration in foods involves oxidation in both the
aqueous phase (e.g., proteins) and the lipid phase (e.g., polyunsaturated
lipids). Formation of free radicals is an early event that occurs prior to the
progression of oxidation and is most often associated with the aqueous
phase. Linear free energy relationships are found valuable for classification
of such early events as electron transfer and hydrogen atom transfer.
Inspiration for protection of processed foods against oxidative deterioration
of their vulnerable constituents has been found in the antioxidant
mechanisms appearing during evolution of aerobic life forms in an
increasingly oxidizing atmosphere. A two-dimensional classification of
antioxidants opens up for an understanding of the special role of carotenoids,
and optimal protection seems to depend on a proper balance between
antioxidants and antireductants.
Key words: food protection, protein oxidation, lipid oxidation, free radical
kinetics, antioxidants, antireductants.
1.1 Introduction
Other forms of life than the aerobic forms dominating now were previously
characteristic of our planet. When, almost three billion years ago, blue-green
algae (Cyanobacteria) developed photosynthesis, oxygen accumulated in
terrestrial atmosphere concomitant with oxygenation of the shallower surface
ocean (Frei et al., 2009). The oxygenation of the Earth's atmosphere seems to
have fluctuated and lagged behind the development of oxygenic photosynthetic
organisms in the upper ocean because bacteria became deprived of nitrogen