Title page for ETD etd-07282010-020132

Type of Document Master's Thesis
Author Gilbert, Laura Marcella
URN etd-07282010-020132
Title Determination of L- and D-methionine and L- and D-valine in soy isolate and soy flour samples.
Degree Master of Science
Department Human Nutrition and Foods
Advisory Committee
Advisor Name Title
Marable, Nina L. Committee Chair
Korslund, Mary K. Committee Member
Sanzone, George Committee Member
  • and alkaline treatment are all conditions which ma
  • toasting of soy meal
  • isomerization of methionine appeared to occur at a
  • L-methionine and D-methionine in both soy flour an
  • chemicals in soy productsL to D isomerization of a
Date of Defense 1977-12-15
Availability restricted

L to D isomerization of amino acids in a commercially prepared alkali-treated food-grade soy isolate was investigated. A soy flour product was also investigated as a control which had not been alkali treated. Methionine and valine collected from two soy flour and two soy isolate samples were coupled with L-leucine-N-carboxyanhydride.

If both D- and L-forms were present this would produce diastereomeric dipeptide derivatives. The derivatives were separated by ion-exchange chromatography using a TSM Amino Acid Analyzer. Comparison of the sample methionine and valine dipeptide peaks to standard dipeptide peaks revealed the presence of L-valine, L-methionine and D-methionine in both soy flour and soy isolate samples. Methionine was substantially isomerized in both products. D-valine was not observed in either soy flour or soy isolate samples. Thus, isomerization of methionine appeared to occur at a faster rate than valine. Acid hydrolysis, toasting of soy meal, and alkaline treatment are all conditions which may be responsible for the isomerization of methionine.

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