ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Extraction of lignin from Chinese quince fruit by acetic acid solution at above atmospheric pressure: Yield distribution, structural characterization, and antioxidant activities

Zhao Qin, Xi-Chuang Cheng, Hua-Min Liu, Qiao-Li Yang, and Xue-De Wang

College of Food Science and Technology, Henan University of Technology, Zhengzhou, China

E-mail: liuhuamin5108@163.com

Received: 27 October 2020  Accepted: 6 February 2021

Abstract:

Acetic acid at atmospheric pressure is an alternative solvent that can be used for high-efficiency separation of lignin. However, few studies reported the isolation of lignin using acetic acid at above atmospheric pressure. In this study, acetic acid solution at above atmospheric pressure was used to extract lignin from Chinese quince fruit. The influences of different extraction conditions on the lignin yields were firstly investigated. Among the five extraction parameters (extraction temperature/pressure, acetic acid concentration, extraction time, catalyst dosage, and solid/liquid ratio), catalyst dosage had the most important influence on lignin yields. Five acetic acid lignin (AAL₈₀, AAL₁₀₀, AAL₁₂₀, AAL₁₄₀, and AAL₁₆₀) samples obtained at different extraction temperatures/pressures (80 °C–160 °C/0.03–0.35 MPa) were used to analyze the influence of extraction temperatures/pressures on their structural features. Comparing to lignins extracted with acetic acid at atmospheric pressure, lignins obtained by acetic acid extraction at above atmospheric pressures (AAL₁₂₀, AAL₁₄₀, and AAL₁₆₀) had higher purity. The acetic acid could degrade lignin at temperatures above 120 °C. When extracted at 120 °C–160 °C, the depolymerization degree of lignins increased with rising temperatures. AAL₁₆₀ with more condensed structures was the most thermally stable. As the extraction temperature rose, the proportion of β–5 linkages in lignins gradually increased, while the proportion of β–O–4 and β–β linkages decreased. AAL₈₀ had the highest DPPH, while AAL₁₂₀ showed the highest ferric reducing activity. The study clarifies the lignins isolated with acetic acid at above atmospheric pressure from Chinese quince fruits and contributes to their potential application.

Graphic abstract

Keywords: Chinese quince; Above atmospheric pressure; Acetic acid; Lignin; Structure

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-01561-7

Chemical Papers 75 (7) 3155–3167 (2021)