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EPR Studies of Thermally Treated Oxidized Corn Starch
Author(s) -
Bidzińska Ewa,
Dyrek Krystyna,
Fortuna Teresa,
Łabanowska Maria,
Pietrzyk Sławomir
Publication year - 2004
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.200400278
Subject(s) - electron paramagnetic resonance , radical , starch , chemistry , copper , catalysis , corn starch , photochemistry , polymer chemistry , organic chemistry , nuclear magnetic resonance , physics
The formation of radicals in oxidized corn starch at 20–250°C in air was investigated by quantitative EPR spectroscopy. It was found that the presence of carboxyl groups in the oxidized starch increases the starch's ability to generate radical species. Introducing Cu 2+ ions into the starch, as a catalyst or as an EPR probe, leads to the formation of copper‐carboxyl complexes containing two carboxyl ligands. Drastic increase in the number of radical species at about 250°C is accompanied by a decrease in the intensity of EPR signal of Cu 2+ ‐carboxyl complexes, indicating that the thermal degradation of oxidized corn starch occurs with the formation of radicals, probably via breaking the chemical bonds in the carboxyl groups.