This invention produces technical (meth)acrylic acid without being confronted with problems of fouling of systems to purify the crude reaction mixture of (meth)acrylic acid synthesis, due to the presence of glyoxal formed during synthesis. The invention is based on the addition or generation of quinoline derivative in a glyoxal-containing (meth)acrylic acid flow in a quinoline/glyoxal derivative molar ratio ranging from 0.1 to 5, during the purification steps, said quinoline compound with one of formulas (I) or (II): wherein, groups R1, R2, R3, and R4 independently denote a hydrogen atom or a C1-C6, or R1 et R2 C-alkyl group combine and together with the atoms to which they are attached, form a saturated or unsaturated ring or heterocycle, preferably a phenyl group, and/or R3 and R4 combine and with the atoms to which they are attached, form a saturated or unsaturated ring or heterocycle, preferably a phenyl group.