Oxygen promotes radical-mediated heterogeneous hygrothermal degradation of konjac glucomannan: Molecular structure and influence mechanism

Yuanyuan Chen; Ding An; Sha Li; Xinshuai Zhang; Hongshan Liang; Bin Li; Jing Li

doi:10.1016/j.ijbiomac.2024.138848

Oxygen promotes radical-mediated heterogeneous hygrothermal degradation of konjac glucomannan: Molecular structure and influence mechanism

Int J Biol Macromol. 2024 Dec 17:289:138848. doi: 10.1016/j.ijbiomac.2024.138848. Online ahead of print.

Authors

Yuanyuan Chen¹, Ding An², Sha Li², Xinshuai Zhang³, Hongshan Liang², Bin Li², Jing Li⁴

Affiliations

¹ College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Ministry of Education, China; College of Food and Bioengineering, Henan University of Science and Technology, Henan 471000, China.
² College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Ministry of Education, China.
³ College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; College of Food and Bioengineering, Henan University of Science and Technology, Henan 471000, China.
⁴ College of Food Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; Key Laboratory of Environment Correlative Dietology, Huazhong Agricultural University, Ministry of Education, China. Electronic address: lijingfood@mail.hzau.edu.cn.

PMID: 39701263
DOI: 10.1016/j.ijbiomac.2024.138848

Abstract

Heterogeneous hygrothermal degradation (HHTD) efficiently produces partially depolymerized konjac glucomannan (KGM). However, KGM degrades considerably faster in oxygen-containing air packaging than in oxygen-free vacuum packaging. This study investigated the effects of different atmosphere conditions on the molecular structure of KGM and the radicals involved in its degradation system. Results indicated that the presence of oxygen increased the CO generation in depolymerized KGM molecules and the chain conformation parameters α and β values but lowered the d_f value. The radical type responsible for the HHTD of KGM in different atmosphere conditions was primarily carbon-centered radicals with a g-factor of 2.0033. The relative radical intensity increased with increasing treatment temperature and time. The presence of oxygen dramatically enhanced the HHTD efficiency of KGM by increasing the radical generation rate in the degradation system. Therefore, the HHTD of KGM was a radical-mediated thermo-oxidative degradation reaction, and convenient air-containing heat-sealed packaging could achieve efficient HHTD similar to pure oxygen packaging. This study provides insight into the mechanism by which oxygen influences the HHTD of KGM, highlighting the great potential of HHTD as an efficient and convenient method for KGM degradation.

Keywords: Heterogeneous hygrothermal degradation; Influence mechanism; Konjac glucomannan; Oxygen; Radicals.