Metabolite transformation and β-d-glucosidase activity during the high hydrostatic pressure assisted curing of vanilla beans (Vanilla planifolia) to improve phenolic compounds formation

Abstract

Current methods for vanilla bean curing are long and reduce the enzymatic activity necessary for flavor development. High hydrostatic pressure (HHP) at 50-600 MPa was used to improve phenolic compounds formation and β-d-glucosidase activity in vanilla beans compared with scalded beans. Phenolics were analyzed by HPLC and β-d-glucosidase activity by spectrophotometry. Vanillin was the main phenolic and it was formed by β-d-glucovanillin hydrolysis and vanillyl alcohol oxidation. HHP improved vanillin content and influenced β-d-glucosidase activity. At the beginning of the curing the highest increments of vanillin were produced at 400 MPa (up to 15%), while at the end, this was observed at 50 (138%) and 600 MPa (74%). Maximum increment of up to 400% in β-d-glucosidase activity was observed from 100 to 300 MPa, which was attributed to tissue decompartmentalization, and conformational changes induced by pressure. HHP could be used during vanilla curing to improve vanillin content and β-d-glucosidase activity.

Keywords: High hydrostatic pressure; Vanilla curing; Vanillin; β-d-Glucosidase; β-d-Glucovanillin hydrolysis.