Degree Type

Dissertation

Date of Award

1981

Degree Name

Doctor of Philosophy

Department

Food Technology

Abstract

A rapid, reliable determination of the carbonyl flavor compounds in oxidized fats and oils has proved elusive, especially because of the ease with which hydroperoxides can generate additional carbonyl compounds during isolation procedures. Carbonyl compounds can be converted to trichlorophenylhydrazones (TCPH's) and isolated from fat in a simple two-column procedure. A solution of fat in cyclohexane:ether (99:1) is passed through a Florisil column and nonvolatile hydrocarbons, which interfere with later stages of the analysis, are eluted. The remaining lipid constituents including carbonyls are eluted with 100% ether, reacted with TCPH using a Florisil catalyst, and packed on a second Florisil column. The resulting TCPH-carbonyl derivatives are isolated by elution with cyclohexane:ether (99:1). The TCPH's are quantified by gas chromatography on a 10-m capillary column coated with SE-30;To study formation of carbonyl artifacts from hydroperoxides during the isolation procedure, methods were devised to reduce the peroxides in fats to alcohols by passing the fat through reaction columns of stannous chloride or hydroiodic acid. Some carbonyl artifact production did occur because of the TCPH procedure. However, these artifacts could be identified and, thus, eliminated from the total carbonyl profile. These reduction methods, which do not require solvent dilution of the fat, may prove useful in other methods for the determination of carbonyls and volatiles in fats and oils. The usefulness of the TCPH method was illustrated by application to stability tests on soybean oils and was compared with other methods of determining oxidation, such as peroxide value, sensory tests and total volatiles.

DOI

https://doi.org/10.31274/rtd-180813-5706

Publisher

Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/

Copyright Owner

Pamela June White

Language

en

Proquest ID

AAI8128868

File Format

application/pdf

File Size

74 pages

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