Factors that limit the digestion of tropical forages are associated to the dynamic of cell wall phenolic acids. The study of these compounds in forages may be facilitated by the availability of sensible methods that permit processing large amounts of samples. The present paper describes a method for determining phenolic acids in forage cell wall through high-performance liquid chromatography (HPLC). Sugar cane bagasse, elephant grass and cassava leaves were used as experimental samples. To remove soluble low molecular weight products, ethanol 80% and neutral detergent were essayed to determine their effects on the recovery of molecules and other benefits to chromatography profile. The sample solubilization with NaOH 1 mol/L, 20ºC for 24 hours, was used to obtain the free phenolic acids. The method described proved appropriate showing great sensibility and lab productivity. To minimize the effects of salt formation as a consequence of acid neutralization, sample dilution and reduced injection volumes (5uL) are suggested. The action of ethanol 80% and neutral detergent differ between grasses and legumes. The amount of extractives in cassava leaves was greater than in other materials.The method described in the present paper is an important tool to study phenolic acids in tropical forage cell wall.
ferulic acid; HPLC; lignin; p-coumaric acid; vegetal cell wall
