title: Influence of high-pressure processing on the profile of polyglutamyl 5-methyltetrahydrofolate in selected vegetables.
abstract: In plants, folate occurs predominantly as 5-methyltetrahydrofolate (5MTHF) polyglutamyl forms. Differences in stability and bioavailability of food folate compared to synthetic folic acid have been attributed to the presence of the polyglutamyl chain. High-pressure processing (HPP) was tested for whether it might shorten polyglutamyl chains of 5MTHF species in fresh vegetables by enabling action of native γ-glutamylhydrolase (GGH). A validated ultrahigh-performance reversed-phase liquid chromatography-tandem mass spectrometry method using stable isotope as internal standard was applied for characterizing 5MTHF polyglutamyl profiles. HPP conditions included 300, 450, and 600 MPa at 30 °C for 0 or 5 min, and vegetables were vacuum-packed before treatment. Investigated vegetables included cauliflower (Brassica oleracea), baby carrots (Daucus carota), and carrot greens (D. carota). HPP treatment caused conversion of polyglutamyl 5MTHF species to short-chain and monoglutamyl forms. Maximal conversion of polyglutamyl folate to monoglutamyl folate occurred at the highest pressure/time combination investigated, 600 MPa/30 °C/5 min. Under this condition, cauliflower monoglutamyl folate increased nearly 4-fold, diglutamyl folate 32-fold, and triglutamyl folate 8-fold; carrot monoglutamyl increased 23-fold and diglutamyl 32-fold; and carrot greens monoglutamyl increased 2.5-fold and the diglutamyl form 19-fold. Although some folate degradation was observed at certain intermediate HPP conditions, total 5MTHF folate was largely preserved at 600 MPa/5 min. Thus, HPP of raw vegetables is a feasible strategy for enhancing vegetable monoglutamate 5MTHF.
authors.affiliation: Department of Food Science and Technology, The Ohio State University, Columbus, Ohio 43210, United States.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Ken M
authors.initials: KM
authors.lastname: Riedl
authors.forename: Jeremy
authors.initials: J
authors.lastname: Somerville
authors.forename: V M
authors.initials: VM
authors.lastname: Balasubramaniam
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schwartz
mesh_terms: D001937:Brassica / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D018552:Daucus carota / Q000737:chemistry; D005511:Food Handling / Q000379:methods*; D011312:Pressure; D011624:Pteroylpolyglutamic Acids / Q000032:analysis*; D053719:Tandem Mass Spectrometry; D013763:Tetrahydrofolates / Q000032:analysis*; D014675:Vegetables / Q000737:chemistry*
chemical_list: D011624:Pteroylpolyglutamic Acids; D013763:Tetrahydrofolates; C005984:5-methyltetrahydrofolate