Abstract
Commercial isolated soy proteins (ISP) contain 22 and 31 ppm sulfite as measured by the optimized Monier-Williams method (Sulfites in Foods, Official Methods of Analysis, 16th edn., AOAC, Washington, DC, 1995, Official Method 990.28). A method was developed to cryogenically trap and quantify the sulfur dioxide produced by this method using GC-MS. The same commercial ISP samples were found to contain 17 and 26 ppm sulfite, respectively, with GC-MS. ISP prepared in the laboratory contained 33 ppm sulfur dioxide, and defatted soybean flakes contained only a trace. Adding dithiothreitol after beginning the boiling step of the Monier-Williams assay had no significant effect on the sulfite content of a commercial ISP, whereas adding dithiothreitol prior to bringing the sample to a boil reduced the sulfite content from 17 to about 1 ppm.
Original language | English |
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Pages (from-to) | 829-833 |
Number of pages | 5 |
Journal | JAOCS, Journal of the American Oil Chemists' Society |
Volume | 81 |
Issue number | 9 |
DOIs | |
State | Published - Sep 2004 |
Bibliographical note
Funding Information:This research was funded in part by USDA NRICGP grant #KY0-05018, by the Archer Daniels Midland Company, and by Kentucky Agricultural Experiment Station Project #KY 007029. It is published with the approval of the Director of the Kentucky Agricultural Experiment Station as Journal Article #04-07-058.
Funding
This research was funded in part by USDA NRICGP grant #KY0-05018, by the Archer Daniels Midland Company, and by Kentucky Agricultural Experiment Station Project #KY 007029. It is published with the approval of the Director of the Kentucky Agricultural Experiment Station as Journal Article #04-07-058.
Funders | Funder number |
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NRICGP/USDA | 0-05018 |
Kentucky Agricultural Experiment Station | 007029 |
Keywords
- GC-MS
- Methanethiol
- Monier-williams assay
- Soy protein
- Sulfites
ASJC Scopus subject areas
- General Chemical Engineering
- Organic Chemistry