Biochemical, micro and ultrastructural changes in vanilla pods (Vanilla planifolia, Andrews) during the curing process

Abstract

Vanilla is used in several industries, due to during the artisanal curing process, compounds responsible for a highly demanded aroma are synthesized. This process involves physical, biochemical, microbiological and structural changes, which through their study with high-resolution techniques allowed for deep introspection at the ultra-structural level, to identify cellular structures. Which, under conditions leading to the pod during the process, allow the synthesis, release, and storage of molecules aroma responsible. The integration of the referred changes will allow the strategies generation that lead to better use of the vanilla extract and its residue obtained after the extraction processes (∼95%) to which the sheath could be subjected. The proximal chemical analysis showed an increase in lipids (∼25%) at 10 SS (drying-sweating cycles) associated with oleoresins and aroma responsible compounds. Proteins increased (∼50%), a result of the catalytic activity of the enzymes present and associated with the endophytic flora. β-glucosidase associated with the synthesis of aromatic compounds, increased their activity at 10 SS (196 IU/mL). The mesocarp showed a folding and shrinkage of (∼50%), evaluated by SEM and image analysis. Using CLSM, the major compounds in the bean were located and their relationship with the micro and ultra-structure. Using TEM, plastoglobules responsible for the odorant compounds accumulation and plasmodesmata for their transport and storage were identified. The comprehensive study of the curing process and the phenomena conjunction involved, allowed the process key stage identification, important for the proposal of strategies that lead to the optimal use of the metabolites and their residues.