Effect of endogenous and exogenous enzymatic treatment of green vanilla beans on extraction of vanillin and main aromatic compounds.

Abstract

Endogenous and exogenous enzymatic hydrolysis carried out to obtain vanilla extracts with higher concentrations of vanillin using green vanilla beans. Sequences initiated with freezing of green vanilla beans at - 1°C for 24h, followed by endogenous hydrolysis under optimal β-glucosidase activity at 4.2 and 35°C for 96h, exogenous hydrolysis with Crystalzyme PML-MX at pH 5.0 and 40°C for 72h, and ethanol extraction at 40% (vv-1) for 30days. In the proposed method, 200g of fresh green vanilla beans with 84% moisture (32g dry base) were used to obtain a liter of single fold vanilla extract. This method allowed the release of 82.57% of the theoretically available vanillin from its precursor glucovanillin with 5.78g 100g-1 green vanilla beans (dry base). Vanillic acid, p-hydroxybenzaldehyde and vanillyl alcohol were also released and found in commercial and enzymatic extracts. Glucovanillin was detected in commercial and traditional extracts but was absent in enzymatic extracts, indicating incomplete hydrolysis during the curing process. An in vitro assay was conducted to determine if the presence of peroxidase during hydrolysis might affect overall vanillin concentration. Results showed that POD can use vanillin as a substrate under conditions similar to those in which hydrolysis was conducted (pH 5.0 and 50°C), possibly explaining why vanillin concentration was not complete at the end of the process.