Quantitative Determination of Hydroxycinnamic Acids in Wheat, Rice, Rye, and Barley Straws, Maize Stems, Oil Palm Frond Fiber, and Fast-Growing Poplar Wood

A new method has been developed for the quantitative determination of hydroxycinnamic acids participating in ester or ether linkages to the cell wall polymers. The method is based on mild alkaline hydrolysis followed by acid hydrolysis or mild alkaline hydrolysis, which partially removed esterified phenolic acids, and high-temperature concentrated alkaline treatment, which cleaved both the ester a…