Development of an Energy Biorefinery Model for Chestnut (Castanea sativa Mill.) Shells

Abstract

Chestnut shells (CS) are an agronomic waste generated from the peeling process of the chestnut fruit, which contain 2.7-5.2% (w/w) phenolic compounds and approximately 36% (w/w) polysaccharides. In contrast with current shell waste burning practices, this study proposes a CS biorefinery that integrates biomass pretreatment, recovery of bioactive molecules, and bioconversion of the lignocellulosic hydrolyzate, while optimizing materials reuse. The CS delignification and saccharification produced a crude hydrolyzate with 12.9 g/L of glucose and xylose, and 682 mg/L of gallic acid equivalents. The detoxification of the crude CS hydrolyzate with 5% (w/v) activated charcoal (AC) and repeated adsorption, desorption and AC reuse enabled 70.3% (w/w) of phenolic compounds recovery, whilst simultaneously retaining the soluble sugars in the detoxified hydrolyzate. The phenols radical scavenging activity (RSA) of the first AC eluate reached 51.8 ± 1.6%, which is significantly higher than that of the crude CS hydrolyzate (21.0 ± 1.1%). The fermentation of the detoxified hydrolyzate by C. butyricum produced 10.7 ± 0.2 mM butyrate and 63.9 mL H 2 /g of CS.Based on the obtained results, the CS biorefinery integrating two energy products (H 2 and calorific power from spent CS), two bioproducts (phenolic compounds and butyrate) and one material reuse (AC reuse) constitutes a valuable upgrading approach for this yet unexploited waste biomass.

Bioactive Compounds of Chestnut (Castanea sativa Mill.)

“…The main components of the outer skin are Klason lignin (40%) and carbohydrates (40%). Among carbohydrates, cellulose is the predominant (28%), and significant amounts of xylan (8%) have also been detected [41,42]. Chestnut pericarp and integuments have also been described as containing significant levels of bioactive substances such as phenolic compounds [41].…”

“…Among carbohydrates, cellulose is the predominant (28%), and significant amounts of xylan (8%) have also been detected [41,42]. Chestnut pericarp and integuments have also been described as containing significant levels of bioactive substances such as phenolic compounds [41]. These phenolic compounds include mostly condensed tannins and ellagitannins (e.g., castalagin, vescalagin, acutissimin A, and acutissimin B) and phenolic acids (e.g., gallic acid and ellagic acid) [27,42].…”

Green-Sustainable Recovery of Phenolic and Antioxidant Compounds from Industrial Chestnut Shells Using Ultrasound-Assisted Extraction: Optimization and Evaluation of Biological Activities In Vitro

“…Indeed, flavonoids exert numerous biochemical and pharmacological activities, being associated with the increase resistance of blood vessels, treatment of chronic venous insufficiency and improvement of microvascular blood flow [9,10]. According to Morana et al, the inner shell can contain between 2.7% and 5.2% of phenolic compounds [11]. Aires et al reported that the main phenolic compounds present in aqueous extracts of chestnut shells are gallic acid, ellagic acid, vescalagin, castalagin, epigallocatechin, catechin, and epicatechin [12].…”

Improved conversion of bamboo shoot shells to furfuryl alcohol and furfurylamine by a sequential catalysis with sulfonated graphite and biocatalysts

“…3). The peaks at 3451 cm À1 (-OH stretching vibration), 26 1632 cm À1 (the deformation mode of water molecules adsorbed on graphite surface), 1401 cm À1 (C-C stretching vibration), and 1021 cm À1 (stretching vibration of sulfur-oxygen double bonds of SO 4 2À ) 27 were observed. The FT-IR measurement was performed to understand the structure of Sn-graphite.…”