Selective extraction of ferulic acid from agro-industrial biomasses

In the Mediterranean area the more abundant agro-industrial wastes are related to cereals, grapes and olives transformations. In Italy in 2004 the cereal production was 22,1 millions Tons, the grape production was 8 millions Tons, the olives 4,7 million Tons and the sugar beet 9,3 million Tons. Wastes from cereal transformation are approximately 11 million Tons per year and only 40 to 60 % of it, on a dry base, is used as animal feedstock and in the paper production. These wastes are renewable raw materials, a viable sources to synthetic products in many sectors or to bio-fuels if an Integrated Use Policy is made of their special functional properties such as biocompatibility, potential biodegradability, non-toxicity and a favourable CO2 balance. Biophenols, characteristic phenolic compounds of vegetables, due to their bioactivities and antioxidant properties can be used in several fields such as cosmetics, cosmetoceutic, nutraceutic and fine chemistry. Several phenolic compounds play a key role in the non-ligninic cell wall structures in wheat bran. Phenols can be as much as the 0.6% of the weight of this waste and ferulic acid can be as much as the 80% of it. These phenolics are mainly covalently linked to the polysaccharidic backbones in wheat bran strengthening these structures acting as cross-linkers. In this work we demonstrate the possibility to perform an extraction of the phenolic fraction of wheat bran throughout an adsorption/desorption process using the weak ion exchange Amberlite IRA 95 resin (Rohm & Hass). An enzymatic treatment was developed in order to hydrolyze the vegetable cell wall structures and solubilise the covalently linked phenolics. The bio-catalytic treatment was used instead of the typical acidic/basic hydrolysis because of the possibility of a easier scale up of the process. The hydrolytic step allowed to solubilise the 50% of the phenolic content, yield comparable to those of chemical hydrolysis. In model systems the adsorption/desorption procedure allowed to recover quantitatively the ferulic acid used as model phenol. On wheat bran hydrolysate the adsorption step allowed to recover the 54% of the solubilised phenols while the desorption was quantitative, with an overall recovery yield of 25%. Despite the improvements needed, especially in the hydrolytic and adsorption steps, we believe the proposed technology could be conveniently used on industrial scale, in order to recover high added value chemicals used in remunerative processes such as the bio-production of vanillin.