Natural vanilla flavor is one of the most important in the world. However, the cost of this flavor is expensive. Production of this flavor by alternative methods, could reduce the cost. Towards... Show moreNatural vanilla flavor is one of the most important in the world. However, the cost of this flavor is expensive. Production of this flavor by alternative methods, could reduce the cost. Towards this end, using microbiological methods, fungal endophytes were isolated and identified, by morphological characters and PCR-based methods, from vanilla pods, the site of vanilla flavor. The fungal endophytes were tested for their involvement in the synthesis of vanilla flavor. In this way, three vanilla pod endophytes Hypoxylon investiens, Pestalotiopsis microspora, Diaporthe phaseolorum were found to modify the amounts of vanilla flavor and aroma metabolites vanillin, vanillyl alcohol, p-hydroxybenzoic acid, p-coumaric acid, p-xylene, α-phellandrene, 3-carene, α-terpineol, p-hydroxybenzaldehyde, α-cubebene, β-caryophyllene in Vanilla material containing media (in vitro) as well as in living Vanilla plant material (in vivo - acclimatized plants and calli). These metabolites were synthesized either de novo or through biotransformation reactions of precursors. That the latter describes the involvement of several metabolites related to vanilla flavor, implies complex flavor notes, typical of natural vanilla flavor, as opposed to the synthetic version. The analytical methods used include GC-MS, HPLC, 1H and 2D NMR. The results support the hypothesis that endophytes play a role in vanilla flavor metabolite biosynthesis. Show less
Vanilla planifolia, a flowering epiphytic orchid, is the major natural source of vanilla flavour. Largely used in dairy products, beverages, bakeries and perfume, vanilla flavour is obtained after... Show moreVanilla planifolia, a flowering epiphytic orchid, is the major natural source of vanilla flavour. Largely used in dairy products, beverages, bakeries and perfume, vanilla flavour is obtained after a long process: from eight to nine months after flower pollination, mature pods are harvested and then prepared during about one year in order to release the characteristic vanilla aroma. Nowadays, more than half of vanilla pods world production comes from Madagascar. To face the concurrence, a solution could be to develop higher quality pods. Selection of the most aromatic vanilla plant is then preferred. Nevertheless, amelioration program are facing up to a lack of knowledge in vanilla plant physiology. It is now essential to understand more the physiological and biochemical mechanisms implied in the aromatic production of V. planifolia pods. In this thesis, a metabolomic analysis of vanilla green pods and leaves has been performed by nuclear magnetic resonance. This technique has allowed the qualitative and quantitative analysis of primary (sugar, amino and organic acids__) and secondary metabolites (phenolic compounds__) present in vanilla plant according to various physiological conditions: developing pods, viral infection, inter-accession or seasonal variation. Show less
