Valorization of solid wastes from chestnut industry processing: Extraction and optimization of polyphenols, tannins and ellagitannins and its potential for adhesives, cosmetic and pharmaceutical industry

摘要

The aim of the current study was to evaluate the potential of chestnut peels to produce pomaces enhanced with tannins to be used in the formulations of wood adhesives, leather tanning or as natural antioxidants in food, cosmetic and pharmaceutical industry. An analytical procedure was planned as 2 factorial design to analyze the influence of solvent (water, Na_2SO_3 and NaOH at different concentrations of 1, 2, 4, and 8% in water) and extraction time (30, 60, and 120, 240, 480 and 960 min) on extraction yield, pH, Stiasny index, and tannins. HPLC-diode array detector equipped with an ionization mass spec-trophotometer was used to assess the polyphenol composition. Our results showed that both extraction properties and phytochemicals were significantly affected (P＜ 0.001) by all independent factors. The main tannins identified were the hydrolyzable gallic acid, vescalagin castalagin and ellagic acid, and the condensed epigallocatechin, catechin and epicatechin. The solvent 1% Na_2SO_3 was more effective to extract the condensed tannins whilst hydrolyzable tannins were extracted efficiently by 1% NaOH. The multivariable analysis and the Pearson's correlation coefficients showed a direct association between Stiasny number and the average levels of condensed tannins.