Food emulsions, free radical

In contrast to solution, the higher viscosity of a lecithin liposome decreases the efficiency of free radical initiation, and retards their autoxidation. Artificial azo initiators have a very low efficiency (about 9%) when solubilized in the bilayer phase. For this reason, the oxidizability of lecithin dispersed in a liposome is much lower than in solution. Although the solvent cage effect may be unique to diazo initiators commonly used in kinetic studies, and is not necessarily relevant to food lipid systems, metal initiators which are relevant to foods and biological systems, may also be affected by solvent cage effects because of the hydrated layer in emulsions (Figure 10.4). 

Stabilizers inhibit the chemical reaction between two or more other chemicals, and inhibit the separation of suspensions, emulsions, or foams. Stabilizers include (1) antioxidants that prevent unwanted oxidation of food materials. (2) UV stabilizers that protect food materials from harmful effects of UV radiation, being (a) UV absorbers which absorb UV radiation and prevent it from penetrating the materials, as sunscreens, (b) Quenchers which dissipate the radiation energy as heat instead of letting it break chemical bonds, (c) Scavengers that eliminate the free radicals formed by UV radiation, as hindered-amine light stabilizers. (3) Sequestrants that inactivate traces of metal ions that would otherwise act as catalysts by forming chelate complexes. (4) Emulsifiers and surfactants that stabilize emulsions. 

The book starts with an introductory overview, which is intended to refresh the reader s memory on key aspects of free radicals and reactions thereof. Subsequent sections cover free radicals and food chemistry, natural antioxidants, and nutritional biochemistry and health. In the food chemistry section, topics range from analysis of free radicals within food matrices to Maillard reactions, emulsions, dairy, and meat products. In the antioxidant section, results are presented on the efficacy of antioxidants from tea, seeds, and selected naturally occurring compounds. Finally, in the nutritional biochemistry and health section, free radical inhibition is discussed in relationship to biochemical paths and cancerous cell cultures. 

Factors Influencing Free Radical Generation in Food Emulsions... 

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