Release characteristic and mechanism of bound polyphenols from insoluble dietary fiber of navel orange peel via mixed solid-state fermentation with Trichoderma reesei and Aspergillus niger

• Published in: Food science & technology 2022-05, Vol.161, p.113387, Article 113387
• Main Authors: Xue, Puyou, Liao, Wang, Chen, Yi, Xie, Jianhua, Chang, Xinxin, Peng, Guanyi, Huang, Qing, Wang, Yudan, Sun, Nan, Yu, Qiang
• Format: Article
• Language: English
• Subjects: Bound polyphenols; Insoluble dietary fiber; Mixed solid-state fermentation; Navel orange peel; Release mechanism
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2022.113387

Dietary fiber (DF) is a carrier of abundant bound polyphenols (BP). The present work was to investigate the release characteristic and mechanism of BP from the insoluble dietary fiber of navel orange peel (NOP-IDF) by mixed solid-state fermentation (SSF) with Trichoderma reesei and Aspergillus niger. The optimized fermentation conditions were set as follows: inoculation ratio of T. reesei to A. niger 3:1, delayed inoculation time 28 h and initial pH 6.5. The compositions of BP were identified and quantified by UPLC-ESI-QTOF-MS/MS and HPLC-ESI-QQQ-MS/MS, then the biotransformation pathways were partially speculated. Moreover, cellulase, xylanase and β-glucosidase activities were strongly correlated with the BP content. The SEM showed the cell wall and the crystalline structure of the NOP-IDF was effectively decomposed. Furthermore, mixed SSF significantly enhanced in vitro antioxidant activities of BP. In summary, our study demonstrated that mixed SSF was a feasible method for the BP release. •Mixed SSF with T. reesei and A. niger effectively facilitated the BP release.•Forty-four BP were identified and quantified from the NOP-IDF.•The biotransformation pathways of BP were partially speculated during mixed SSF.•Cellulase, xylanase and β-glucosidase activities were correlated with the BP.•SEM further suggested that mixed SSF might facilitate the BP release.