Subcritical Water Extraction of Low-molecular-weight Phenolic Compounds from Oil Palm Biomass

Abstract

Subcritical water extraction of low-molecular-weight phenolic compounds from oil palm biomass (trunk, bark, petiole, rachis, leaves, empty fruit bunch fiber, midrib spine leaflets, stalk of fruit bunches, flesh, kernel shells, and albumen) was conducted. It was elucidated that gallic acid, protocatechuicaldehyde, p-hydroxybenzoic acid, p-hydroxybenzaldehyde, vanillic acid, syringic acid, vanillin, syringaldehyde p-coumaric acid and ferulic acid, all of which could be used as 2-pyrone-4,6-dicarboxylic acid (PDC) precursors, were contained in all parts of oil palm, although their composition differed. The peak yield of p-hydroxybenzoic acid was obtained among the PDC precursors. With regard to extraction conditions, temperature: 200°C, time: 20-60 min, and liquor ratio: 50-125 were the most efficient. The kernel shell exhibited the highest yield of PDC precursors, followed by the trunk, empty fruit bunch fiber, and bark. The results of our study indicate the oil palm is a potentially valuable source of PDC precursors.