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.

Effects of High Pressure Processing on Bioavaliability of Food Components

“…The endogenous enzyme, γ-glutamyl hydrolase, hydrolyses the polyglutamyl folates into the more bioavailable short-chain or monglutamyl folates during cell decompartmentalization. Once this enzyme is inactivated by different processes such as freezing usually preceded by blanching, keeping the long chain polyglutamyl folates causes reduction of bioavailability of folates [36]. Unlike freezing usually preceded by blanching, cell decompartmentalization without inactivation of the enzyme and facilitation of the hydrolysis of long chain polyglutamyl folates potentially improving their bioavailability is enabled by HP treatment [22].…”

Quantification of Total Folate, Folate Species and Polyglutamyl Folate Distribution in Winged Beans (<i>Psophocarus tetragonolobus</i> (L) DC) from Different Cultivars and Growth Stages by Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometry

“…There are several studies about quantitative polyglutamyl folate profiles in vegetables (17,(20)(21)(22)(23)(24)(25)(26). An earlier study found pentaglutamyl and heptaglutamyl folate are the major forms in black beans while hexaglutamyl folate is the major form in the tomato fruit; however, the polyglutamyl folate forms in the alfalfa sprouts shift to short-chain forms such as monoglutamyl and tetraglutamyl forms (23).…”

“…The authors found a uniquely long 5-CH 3-H4PteGlun profile up to 17. 5-CH3-H4PteGlun in vegetables from different families has been profiled (17,19,21). The authors found 5-CH3-H4PteGlun in Brassicaceae is predominant as 5-CH3-H4PteGlu5 through 5-CH3-H4PteGlu7.…”

Comprehensive Vitamer Profiling of Folate Mono- and Polyglutamates in Baker’s Yeast (Saccharomyces cerevisiae) as a Function of Different Sample Preparation Procedures

“…Almost the entire research focuses on the respective monoglutamates after enzymatic deconjugation of the polyglutamate vitamers [20,49,63]. Only a few studies focused on the polyglutamate distribution of mammalian tissue [64,65], bacteria [65] and raw vegetables [64,[66][67][68]. Yeast, however, has not been analyzed in terms of polyglutamate vitamers which typically account for the major occurring form in vivo.…”