Recovery of flavor compounds from vanilla bagasse by hydrolysis and their identification through UPLC-MSE

Abstract

Vanilla is a globally treasured commodity, and the consequences of its unstable value affect social, environmental, economic, and academic ambits. The extensive range of aroma molecules found in cured vanilla beans is crucial to the complexity of this natural condiment and knowledge about their recovery is of the essence. Many strategies aim on reproducing the chemical intricacies of vanilla flavor, such as biotransformation and de novo biosynthesis. Few studies, however, aim at the exhaustion of the cured pods, of which the bagasse, after the traditional ethanolic extraction, might still bear a highly valued flavor composition. An untargeted liquid chromatography coupled with mass spectrometry (LC-MS^E) approach was applied to elucidate if sequential alkaline-acidic hydrolysis was effective in extracting flavor related molecules and chemical classes from the hydro-ethanolic fraction. Important vanilla flavor related compounds present in the hydro-ethanolic fraction were further extracted from the residue through alkaline hydrolysis, such as vanillin, vanillic acid, 3-methoxybenzaldehyde, 4-vinylphenol, heptanoic acid, and protocatechuic acid. Acid hydrolysis was effective on further extracting features from classes such as phenols, prenol lipids, and organooxygen compounds, though representative molecules remain unknown. Finally, sequential alkaline-acidic hydrolysis rendered natural vanilla's ethanolic extraction residues as an interesting supplier of its own products, which could be used as a food additive, and many other applications.

Keywords: Extraction methods; Metabolomic tools; Natural flavor; Residue.