Structural features and antioxidant activities of Chinese quince (Chaenomeles sinensis) fruits lignin during auto-catalyzed ethanol organosolv pretreatment

• Published in: International journal of biological macromolecules Vol. 164; pp. 4348 - 4358
• Main Authors: Cheng, Xi-Chuang, Guo, Xin-Ran, Qin, Zhao, Wang, Xue-De, Liu, Hua-Min, Liu, Yu-Lan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2020
• Subjects: Antioxidants - chemistry; Antioxidants - pharmacology; Catalysis; Chemical Phenomena; Chinese quince fruit; Fruit - chemistry; Gas Chromatography-Mass Spectrometry; Hydrolysis; Lignin - chemistry; Lignin - pharmacology; Lignin characterization; Magnetic Resonance Spectroscopy; Molecular Structure; Molecular Weight; Monosaccharides; Organosolv pretreatment; Rosaceae - chemistry; Spectroscopy, Fourier Transform Infrared; Structure-Activity Relationship; Thermogravimetry; Organosolv pretreatment; Chinese quince fruit; Lignin characterization
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2020.08.249

Chinese quince fruits (Chaenomeles sinensis) have an abundance of lignins with antioxidant activities. To facilitate the utilization of Chinese quince fruits, lignin was isolated from it by auto-catalyzed ethanol organosolv pretreatment. The effects of three processing conditions (temperature, time, and ethanol concentration) on yield, structural features and antioxidant activities of the auto-catalyzed ethanol organosolv lignin samples were assessed individually. Results showed the pretreatment temperature was the most significant factor; it affected the molecular weight, S/G ratio, number of β-O-4′ linkages, thermal stability, and antioxidant activities of lignin samples. According to the GPC analyses, the molecular weight of lignin samples had a negative correlation with pretreatment temperature. 2D-HSQC NMR and Py-GC/MS results revealed that the S/G ratios of lignin samples increased with temperature, while total phenolic hydroxyl content of lignin samples decreased. The structural characterization clearly indicated that the various pretreatment conditions affected the structures of organosolv lignin, which further resulted in differences in the antioxidant activities of the lignin samples. These results can be helpful for controlling and optimizing delignification during auto-catalyzed ethanol organosolv pretreatment, and they provide theoretical support for the potential applications of Chinese quince fruits lignin as a natural antioxidant in the food industry. [Display omitted] •Organosolv pretreatment was used to separate lignin from Chinese quince fruits.•The pretreatment condition of maximum lignin yield: 200 °C, 90 min, and 60% ethanol.•Pretreatment temperature was the most significant factor to affect lignin structure.•Lignin samples extracted at lower temperatures showed stronger antioxidant activity.