{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/43937"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/43937","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Determination of L- and D-methionine and L- and D-valine in soy isolate and soy flour samples","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.","abstract_html":"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.","abstract_has_math":false,"creators":["Gilbert, Laura Marcella"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Human Nutrition and Foods","degree_department":"Human Nutrition and Foods","school":null,"contributors":[],"advisors":[],"committee_chairs":["Marable, Nina L."],"committee_members":["Korslund, Mary K.","Sanzone, George"],"year":1977,"date_issued":"1977-12-15","date_published":"1977-12-15","updated_at":"2026-07-22T22:19:22Z","subjects":["alkaline treatment","toasting of soy meal","isomerization of methionine","L-methionine and D-methionine"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-07282010-020132"],"render_values":[{"text":"etd-07282010-020132","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/43937","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Marable, Nina L."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Korslund, Mary K.","Sanzone, George"]},{"key":"dc:contributor.department","label":"Department","values":["Human Nutrition and Foods"]},{"key":"dc:creator","label":"Author","values":["Gilbert, Laura Marcella"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T21:41:23Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T21:41:23Z","2010-07-28"]},{"key":"dc:date.issued","label":"Date","values":["1977-12-15"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Human Nutrition and Foods"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["alkaline treatment","toasting of soy meal","isomerization of methionine","L-methionine and D-methionine"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-07282010-020132"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/43937"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["BTD"]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Determination of L- and D-methionine and L- and D-valine in soy isolate and soy flour samples"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Marable, Nina L."],"dc:contributor.committeemember":["Korslund, Mary K.","Sanzone, George"],"dc:contributor.department":["Human Nutrition and Foods"],"dc:creator":["Gilbert, Laura Marcella"],"dc:date.accessioned":["2014-03-14T21:41:23Z"],"dc:date.available":["2014-03-14T21:41:23Z","2010-07-28"],"dc:date.issued":["1977-12-15"],"dc:description.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."],"dc:description.degree":["Master of Science"],"dc:format.medium":["BTD"],"dc:format.mimetype":["application/pdf"],"dc:identifier.other":["etd-07282010-020132"],"dc:identifier.uri":["http://hdl.handle.net/10919/43937"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["alkaline treatment","toasting of soy meal","isomerization of methionine","L-methionine and D-methionine"],"dc:title":["Determination of L- and D-methionine and L- and D-valine in soy isolate and soy flour samples"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Human Nutrition and Foods"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:22Z"}