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
Keywords	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
Abstract 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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