Multivariate optimization of extraction and validation of phenolic acids in edible mushrooms by capillary...

A "green" analytical method is reported for the determination of phenolic acids in mushrooms. The sample preparation involves aqueous extraction based on acid hydrolysis, followed by analysis of extracts by capillary electrophoresis with diode array detector (CE-DAD). A central composite design was used to obtain the optimum conditions for the extraction of compounds from mushrooms, including the concentration of hydrochloric acid (2 mol·L^-1), temperature (80 °C) and time (30 min). The proposed method avoids organic solvents such as methanol and acetonitrile commonly used as extraction solvent and/or mobile phase in studies on bioactive compounds in plant-based matrices by high-performance liquid chromatography, thus contributing to lower environmental impact. The validated CE-DAD method was applied to 42 samples of edible mushrooms, including the species Agaricus bisporus (white button mushroom and brown portobello), Lentinula edodes (shiitake), Pleurotus ostreatus (white oyster mushroom, hiratake and shimeji) and Pleurotus ostreatoroseus (pink oyster mushroom). The phenolic compounds homogentisic acid, cinnamic acid and p-coumaric acid were detected in the samples harvested in two seasons - summer and winter - with cinnamic acid reported as the major compound (levels between 53.88 and 440.42 mg·kg^-1). Therefore, edible mushrooms have proved to be an alternative source of phenolic compounds.