Green Extraction and Fractionation of Chestnut Wood Waste: A Sustainable Pathway to Biopolymers and Antimicrobial Solutions

Abstract

The disposal of agri-food biomass waste, such as chestnut wood waste (CWW), poses significant environmental and industrial challenges, contributing to resource depletion and waste accumulation. The development of sustainable strategies for biomass valorization is crucial for reducing waste and promoting a circular economy. In this study, microwave-assisted subcritical water extraction (MASWE) is investigated as an efficient and environmentally friendly method for the extraction of high-value bioactive compounds such as condensed tannins (CTs), hydrolyzable tannins (HTs), and low-weight polyphenols from CWW. The extraction process is followed by sequential membrane filtration and resin purification, adhering to green extraction principles to maximize yield and avoid water wastage. Furthermore, tannins are utilized in the synthesis of biopolymers, offering a promising strategy for developing novel materials with tailored properties. Their antimicrobial activity and enzyme-inhibiting properties improve biopolymer formulations, unlocking diverse applications in sustainable materials. This approach through advanced extraction and fractionation protocols not only enhances biomass valorization-aligning with the circular economy in agri-food waste management-but also supports advancements in green technology and the development of eco-friendly materials.

Keywords: biopolymers; chestnut wood waste; fractionation; green extraction; tannins.

Figure 1

Membrane filtration scheme.

Scheme 1

Polymers preparation and casting.

Figure 2

MASWE optimization: tannins and low‐weight polyphenols TPC yield, expressed in mg_GAE/g_mat.

Figure 3

Effect of process variables on extraction yields of low‐weight polyphenols and tannins: A) L/S ratio vs. water, B) temperature vs. water, and C) temperature vs. L/S ratio.

Figure 4

L/S ratio investigation: results expressed in dry yield (%) and low‐weight polyphenols and tannin yield (mg_GAE/g_mat).

Figure 5

Kinetic evaluation on extraction TPC yield. Experimental data and extrapolated PSO and Peleg models. Degradation onset highlighted with the green/red area.

Figure 6

Extract composition (low‐weight polyphenols, HTs, and CTs) according to A) extraction time and B) extraction temperature.

Figure 7

Extract concentration (mg mL⁻¹) and polyphenols distributions (%) in membrane fractions.

Figure 8

Variation in sugar content (%). Reference value set as “0” is the raw extract, starting material of the membrane filtration.

Figure 9

Water recycle for CWW valorization. Inner circle: water required from the process (extraction, diafiltrations, and dilutions); outer circle: aqueous by‐product reuse distribution added with required water integration.

Figure 10

Evaluation of weight loss (expressed in %) of polymer during burial test.

Figure 11

Screening of different resins for LF purification.

Figure 12

Adsorption process CCD optimization. A) Effect of parameters on the TPC and B) Pareto chart for parameter relevance (p = 0.1).

Figure 13

Desorption process CCD optimization. A) Effect of parameters on the TPC and B) Pareto chart for parameter relevance (p = 0.1).

Figure 14

Kinetic study of polyphenols adsorption/desorption on SB. Experimental data and PSO and Peleg model fitting.

Figure 15

Antioxidant activity and TPC selectivity in main CWW fractions.

Figure 16

Inhibition potential of different fractions (raw extract, HF, LF, and Res. Pur.) on β‐glucosidase, acetylcholinesterase, and tyrosinase.