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.
|Number of pages||5|
|Journal||Journal of the American Oil Chemists' Society|
|State||Published - Sep 2004|
Bibliographical noteFunding 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.
- Monier-williams assay
- Soy protein
ASJC Scopus subject areas
- Chemical Engineering (all)
- Organic Chemistry