Introduction. The traditional curing of vanilla pods includes “killing” and
sweating steps when pods are exposed to heat (35–65 ℃) for various lengths of time.
Although it is known that liberation of vanillin and other phenolics from their
non-aromatic glucosides is due to the action of an endogenous β-glucosidase, its
in vivo kinetics remained unknown. Materials and methods.
Mature green vanilla pods were pretreated for 2 h at 50 ℃, 55 ℃ and 60 ℃, then stored for
118 days at 27 ℃. Phenolic glucosides and their aglycons were extracted at regular
intervals during the storage period and analyzed by HPLC. Results and
discussion. All phenolic β-glucosides were slowly hydrolyzed during the storage
period with production of vanillin, p-hydroxybenzaldehyde, vanillic acid,
and other unknown aglycons. Most of the β-glucosidase was heat-denatured by the
pretreatment, and analysis of its kinetic parameters showed that it adopts, in
vivo, an allosteric mode of functioning with a lower affinity for glucovanillin
than in vitro, where it behaves as a Michaelian enzyme.
Conclusion. Extensive research is needed to confirm the allosteric
mechanism of the vanilla β-glucosidase in vivo.