Deep Eutectic Solvents Mediated Extraction of a Pectin Polysaccharide from Processed Sweet Potato By-Products: Optimization and Characterization Studies

TL;DR

This study shows that using deep eutectic solvents to extract pectin from sweet potato waste is more efficient and produces a unique pectin with potential anti-inflammatory properties.

Contribution

A novel method for extracting pectin from sweet potato residue using deep eutectic solvents, achieving higher yields and unique structural properties.

Findings

Optimal extraction conditions achieved a 5.6% yield, 2.4 times higher than hot-water extraction.

DESP had a lower molecular weight and distinct monosaccharide composition compared to other pectins.

DESP showed anti-inflammatory activity, suggesting potential functional applications.

Abstract

In this study, a pectin polysaccharide named DESP was extracted using a deep eutectic solvent (DES) from sweet potato residue (SPR) and the extract was optimized through response surface methodology (RSM). The DESP, based on choline chloride–urea (ChCl-Ur), was characterized for yield, molecular weight (Mw), and monosaccharide composition. Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), 1H-nuclearmagnetic resonance (1H-NMR), and scanning electron microscopy (SEM) were used to analyze the structure. Optimal extraction conditions for DESP were ChCl-Ur in a molar ratio of 1:2, water content of 75 wt.%, extraction time of 125.7 min, extraction temperature of 83.2 °C, and a liquid-to-solid ratio of 37.0 mL·g−1. The optimized extraction yield was 5.6% ± 0.09%, which was 2.4 times higher than that of hot-water-extracted sweet potato pectin (HWSP, 2.32%). The monosaccharide analysis revealed that galacturonic acid (GalA) was the most abundant saccharide, followed by glucose (Glc), galactose (Gal), arabinose (Ara), and rhamnose (Rha). The Mw of DESP was 20.90 kDa, which was lower than that of HWSP and HASP. In addition, DESP exhibited certain anti-inflammatory activity.

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