Extraction verte et caractérisation des molécules bioactives dans les coproduits de la production d'asperge (Asparagus officinalis L.)

Authors: Missaoui, Rafik
Advisor: Angers, PaulGosselin, André
Abstract: Plants belonging to the family of Asparagaceae, especially asparagus (Asparagus officinalis L.) contain a wide range of bioactive molecules such as polyphenols, flavonoids and saponins. These compounds have several health properties: antioxidant, anticancer and cardioprotective effects. In addition to that asparagus production generates a significant amounts of co-products, making it a good choice for the valorisation through the production of bioactive extracts for the functional food market. In this study, carried out with a green biorefinery view, we used only ethanol and water under optimum conditions rather than other solvents sometimes adopted in extraction of bioactive molecules and which may be harmful for human health. Total polyphenol and flavonoid were determined in different segments of the asparagus stem (upper and lower parts), differents varieties of asparagus and co-products of the Guelph Millenium variety. Identification of polyphenols was performed by UPLC-MS/MS and quantification of saponins was performed by a spectrophotometric method. The optimization of the extraction of polyphenols and flavonoids was accomplished by modulating the temperature, the ethanol concentration and the solute/solvent ratio. The polyphenols present in asparagus are especially flavonoids and phenolic acids with a dominance for rutin (92%) .The polyphenols have been found to be more concentrated in the upper part of the asparagus stem (1.15 %) and represent 0.6 % for the basal parts of the stem and 1.4 % for the lower grade asparagus based on dry matter. The optimized extraction parameters are 80 % ethanol at 70 °C for 3 hours with a solute/solvent ratio of 1:40. This study is not limited to protect the environment by removing asparagus co-products from landfills, but adds values to these co-products. Key words : Asparagus, co-products, optimization, polyphenols, flavonoids, saponins, UPLC-MS/MS.
Document Type: Mémoire de maîtrise
Issue Date: 2018
Open Access Date: 21 September 2018
Permalink: http://hdl.handle.net/20.500.11794/31327
Grantor: Université Laval
Collection:Thèses et mémoires

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