Understanding oxidation processes in foods - Oxidation in Foods and Beverages and Antioxidant Applications - page 30

physical and chemical processes occurring in milk powder may serve as
inspiration for such future studies (Thomsen et al., 2005). For semi-dry systems,
both Maillard reactions and lipid oxidation progress faster at increasing water
activities, but at the same time, early stages of Maillard reactions produce water
increasing the water activity. Water, as a plasticizer, further accelerates phase
transitions resulting in less water binding and increasing water activity. Such
foods provide examples of system with positive feed-back mechanism during
their degradation.
Hydrolytic degradation of proteins also affects lipid oxidation, and certain
peptides are considered to be effective antioxidants. The potential antioxidative
mechanism of peptides in biological membrane systems involves interaction
between lipid oxidation and protein oxidation as shown in Fig. 1.15 (Jongberg et
al., 2009). Peptides active as radical scavengers protect proteins from indirect
oxidative modification, a protection which depends on a prevention of lipid
oxidation derived carbonylation through formation of reactive carbonyl species
(RCS) such as ,-unsaturated aldehydes. Peptides are scavengers of aqueous
phase radicals when present at high concentrations and may act as sacrificial
rather than chain breaking antioxidants preventing direct protein oxidation.
Future food production will have more focus on raw material from plant and
possibly algae due to the increasing world population. As for the plant lipids, the
higher unsaturation calls for better oxidative protection with a special challenge
for protection of food, where plant oils are used in combination with animal
based lipids as in dairy spreads and new types of cheeses. Food science will also
have to deal with the problems associated with radical formation from meat and
meat products in the human digestive tract (Demeyer et al., 2008). Optimizing
use of plant-based antioxidants and milk proteins in processed meats as pre-
venters of radical formation from meat pigments may lead to a new generation
of meat products.
1.8 References
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PMG method and experimental TEAC values in antiradical QSAR of flavonoids',
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ANDERSEN A B, RISBO J, ANDERSEN M L and SKIBSTED L H (2000), `Oxygen permeation
through an oil-encapsulating glassy food matrix studied by ESR line broadening
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ANDERSEN M L and SKIBSTED L H (2006), `ESR spectroscopy for the study of oxidative
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ARAGAO G M F, CORRADINI M G and PELEG M (2008), `A phenomenological model of the
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BARON C and LUND M N (2010), `Protein oxidation', in Skibsted L H, Risbo J and
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