Process for the preparation of the composition (C 1) comprising, for 100% of its mass: a) - from 60.0% by weight to 75.0% by weight of an organic solvent (SO 1) chosen from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, 1,8-octanediol, or a mixture of these compounds; b) - from 0.1% by mass to 2.0% by mass of a composition comprising a quantity by mass x 1, expressed as equivalent by mass of 1-O-(2-caffeoyl)maloyl-3,5-O-dicaffeoylquinic acid, greater than or equal to 200 mg/g of at least one compound of general formula: in which Q 1, Q 3, Q 4 and Q 5 independently of one another represent the hydroxyl radical or a salt thereof or a radical chosen from: (i) - The caffeoyl radical of formula: (ii) - The maloyl radical of formula (Illa) or (Illb): (iii) - The caffeoyl maloyl radical of formula (IVa) or (IVb): (iv) - The maloyl caffeoyl radical of formula (Va), (Vb), (Vc) or (Vd), it being understood that at least one of these radicals Q 1, Q 3, Q 4 and Q 5 represents neither the radical -OH; nor one of its salts; and c) - From 20.0% by mass to 35.0% by mass of water, said process comprising the following successive steps: - A step a) of growing the Arctium lappa plant in soilless conditions, fed with a nutrient solution, so as to obtain a biomass (BM 1); - A step b) of immersing the roots of the said biomass (BM 1) obtained in the preceding step a) in a medium (S 1), in such a way that the biomass (BM 1)/medium (S 1) ratio is between 0.5 kg/L and 1.5 kg/L, the said medium (S 1) comprising, for 100% of its own mass, from 20% to 35% by mass of water, the pH of which has been adjusted to a value between 1.5 and 3,5 by addition of a protic acid chosen from sulphuric acid, phosphoric acid and hydrochloric acid, and from 65% to 80% by weight of an organic solvent (SO 1) chosen from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, 1,8-octanediol or a mixture of these diols; - A step c) for separating the roots from the biomass at the end of the treatment defined in step b), in order to isolate a liquid phase (L 1); - A step d) of immersing the roots of said biomass (BM 2) from step c) in said medium (S 1); in a biomass (BM 2)/medium (S 1) ratio of between 0.1 kg/L and 1.5 kg/L; - A step e) of separating said biomass (BM 2) after the treatment defined in step d), to isolate a liquid phase (L 2), - A step f) of filtering said liquid phase (L 2) obtained in step e), to isolate a liquid phase (L 3), - A step g) of mixing the said liquid phases (L 1) and (L 3), then if necessary adding water and/or the said organic solvent (SO 1), to obtain the expected composition (C 1). a) - from 60.0% by weight to 75.0% by weight of an organic solvent (SO 1) chosen from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, 1,8-octanediol, or a mixture of these compounds; b) - from 0.1% by mass to 2.0% by mass of a composition comprising a quantity by mass x 1, expressed as equivalent by mass of 1-O-(2-caffeoyl)maloyl-3,5-O-dicaffeoylquinic acid, greater than or equal to 200 mg/g of at least one compound of general formula: in which Q 1, Q 3, Q 4 and Q 5 independently of one another represent the hydroxyl radical or a salt thereof or a radical chosen from: (i) - The caffeoyl radical of formula: (ii) - The maloyl radical of formula (Illa) or (Illb): (iii) - The caffeoyl maloyl radical of formula (IVa) or (IVb): (iv) - The maloyl caffeoyl radical of formula (Va), (Vb), (Vc) or (Vd), it being understood that at least one of these radicals Q 1, Q 3, Q 4 and Q 5 represents neither the radical -OH; nor one of its salts; and (i) - The caffeoyl radical of formula: (ii) - The maloyl radical of formula (Illa) or (Illb): (iii) - The caffeoyl maloyl radical of formula (IVa) or (IVb): (iv) - The maloyl caffeoyl radical of formula (Va), (Vb), (Vc) or (Vd), c) - From 20.0% by mass to 35.0% by mass of water, - A step a) of growing the Arctium lappa plant in soilless conditions, fed with a nutrient solution, so as to obtain a biomass (BM 1); - A step b) of immersing the roots of the said biomass (BM 1) obtained in the preceding step a) in a medium (S 1), in such a way that the biomass (BM 1)/medium (S 1) ratio is between 0.5 kg/L and 1.5 kg/L, the said medium (S 1) comprising, for 100% of its own mass, from 20% to 35% by mass of water, the pH of which has been adjusted to a value between 1.5 and 3,5 by addition of a protic acid chosen from sulphuric acid, phosphoric acid and hydrochloric acid, and from 65% to 80% by weight of an organic solvent (SO 1) chosen from 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2-methyl-2,4-pentanediol, 1,6-hexanediol, 1,8-octanediol or a mixture of these diols; - A step c) for separating the roots from the biomass at the end of the treatment defined in step b), in order to isolate a liquid phase (L 1); - A step d) of immersing the roots of said biomass (BM 2) from step c) in said medium (S 1); in a biomass (BM 2)/medium (S 1) ratio of between 0.1 kg/L and 1.5 kg/L; - A step e) of separating said biomass (BM 2) after the treatment defined in step d), to isolate a liquid phase (L 2), - A step f) of filtering said liquid phase (L 2) obtained in step e), to isolate a liquid phase (L 3), - A step g) of mixing the said liquid phases (L 1) and (L 3), then if necessary adding water and/or the said organic solvent (SO 1), to obtain the expected composition (C 1).