Quality of Vanilla spp. from Madagascar: evolution of the compound fingerprints from the green beans to the vanilla pods’ preparation

Abstract

Description of the subject. Vanilla is a spice whose name comes from the spanish word “vanilla”, meaning little black pods. It comes from a variety of orchids, more specifically the vanilla plant. Although vanilla is the second most expensive spice, next to saffron, it is still the most used in the food, cosmetics, beverage, and tobacco industries. The quality of vanilla pods depends on their preparation. Objectives. This work aims to quantitatively determine the rate of five aromatic quality marker compounds in five selected vanilla species cultivated in Madagascar and to understand the evolution of these compounds during the maturity and preparation of the pods. Method. High-Performance Liquid Chromatography (HPLC) analysis was undertaken on five Vanilla species, including Vanilla planifolia Andrews, V. pompona Schiede, V. tsy taitry, V. planifolia var. sterile and V. planifolia var. tsy vaky, to assess the concentration of the marker compounds, including vanillin (VAN), p-hydroxybenzoic acid (p-HBAc), vanillic acid (VAc), guaiacol (GUA), and p-hydroxybenzaldehyde (p-HB), in the selected pods during their stage of collection and preparation. Results. VAN (2.63-45.30 µg·ml-1 at 6 months old; 8.72-122.66 µg·ml-1 at 9 months old; 26.81-60.69 µg·ml-1 after the drying process and 13.35-105.03 µg·ml-1 after the conditioning process) was the major component followed by the p-HB (7.59 µg·ml-1 for V. pompona at 6 months old; 5.52-24.47 µg·ml-1 at 9 months old; 5.40-14.72 µg·ml-1 after the drying process and 4.69-24.84 µg·ml-1 after the conditioning process) in each vanilla species. Generally, VAN concentration increased from the 6th to the 9th month then decreased after the drying process and increased again after the conditioning process. Guaiacol was not detected in all species during the stages of collection and preparation. Conclusions. Vanilla planifolia or V. fragrance remains the vanilla with the highest concentration of the important marker compounds suggesting that it could have the best quality among those selected in this study making this species still the most traded in the international market.