High pressure processing and post-high pressure storage induce the change of polyglutamyl folate and total folate from different legumes.

The aim of this work was to study the effect of high pressure processing (HPP) and post-HPP cold storage on the distribution of polyglutamyl and monoglutamyl folate and the absolute concentration of total folate in green beans, yardlong beans and winged beans using a validated ultra-high performance liquid chromatography-tandem mass spectrometry method. The results showed that HPP led to the deglutamylation of polyglutamyl folate to monoglutamyl folate in all of the investigated beans. The degree of deglutamylation was increased with enhancing processing pressure and extending holding time. During HPP, significant loss of total folate was observed under 600 MPa/10 min treatment. Uniquely 300 MPa/5 min and 450 MPa/5 min could significantly release more folate from yardlong beans and green beans matrix. During the following cold-storage, the deglutamylation keep progressing. For those untreated beans, no significant deglutamylation and total folate loss was observed during cold storage for yardlong beans and green beans while there is slight change for the total folate in winged beans. For those HPP treated beans, total folate loss followed the first order kinetics over the storage. The rate constant of degradation was positively proportional to the applied pressure, holding time and the proportion of monoglutamyl folate. This research provided a reference for understanding the deglutamylation of polyglutamyl folate and folate loss during HPP treatment and further shelf life.