Purification of ferulic acid from corn fibre alkaline extracts for bio-vanillin production using an adsorption process

Ferulic acid is the most widely studied precursor for bio-vanillin production. This work assesses the use of an alkaline extract from corn fibre for bio-vanillin production. The results show that after extraction an additional step is needed to purify ferulic acid removing toxic/inhibitor compounds. An adsorption process was selected to purify the ferulic acid. The performances of four different macroporous resins prepared from different matrix materials were evaluated. Macronet® MN102 (not yet reported for ferulic acid purification) offered the highest ferulic acid adsorption capacity. A column packed with Macronet® MN102 was used to perform dynamic adsorption and desorption experiments, which showed a maximum ferulic acid adsorption capacity of 176 mg_{ferulic acid}.g⁻¹_{dry resin} at pH 4.5 at a flow rate of 3.7 BV (bed volumes).h⁻¹. The breakthrough point was at 115 min, corresponding to an adsorption capacity of 85 mg_{ferulic acid}.g⁻¹_{dry resin}. In the desorption step, 90.9% of ferulic acid was recovered using absolute ethanol ≥ 99.8%) as eluent, at the same flow rate of 3.7 BV (bed volumes).h⁻¹. This procedure confirmed the removal of compounds with a microbial inhibitory effect, such as organic acids, metals and some aldehydes. The purified ferulic acid extract was then used to produce bio-vanillin. The bio-vanillin production by Amycolatopsis sp. ATCC 39116, using a single pulse of an extract with 10 g.L^-1 of ferulic acid extract, led to a maximum vanillin concentration of 5 g.L^-1 and a vanillin yield of 0.52 g_vanillin.g_{ferulic acid}^-1, values comparable to those obtained with a commercial solution containing 10 g.L^-1 of ferulic acid.