18-8 |
Analysis and properties of natural antioxidants |
F. SHAHIDI, Dept. of Biochemistry, Memorial Univ. of Newfoundland, 300 Prince Philip Dr., St. John's, NF A1B 3X9, Canada Natural antioxidants are generally derived from plant sources and these are primarily phenolic and polyphenolic compounds, but also include phytates and peptides, among others. Phenolic compounds in plant sources occur in the free, esterified/esterified and insoluble-bound forms. In most cases, free phenolics are monitored, but following digestion, all forms of phenolics may become available. In general, the compounds involved may be extracted into an appropriate solvent/solvent mixture. Amongst solvents most frequently used are water, methanol/ethanol, acetone or combinations thereof. Following fractionation and further separation the activity of isolated compounds is determined using different in-vitro or in-vivo tests. Effect of processing on phenolics constituents in foods is also important in that they may lead to their release to the free form, oxidation and possible removal. Application of natural antioxidants in foods in the form of source material has particularly been successful.
Session 18, Chemistry and analysis of phytochemicals or plant bioactive materials
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