| Title |
Feasibility study of value-added production from onion peel agricultural wastes for circular economy |
| ID_Doc |
5424 |
| Authors |
Hsueh, CC; Roxas, TJ; Chan, YH; Juan, CN; Tayo, LL; Chen, YY; Wu, YC; Hua, KF; Tsai, PW; Sun, SY; Chen, BY |
| Title |
Feasibility study of value-added production from onion peel agricultural wastes for circular economy |
| Year |
2023 |
| Published |
|
| Abstract |
Background: As a highly populated and resource-limited Taiwan, material recycling and reuse are of great importance to satisfy net-zero waste accumulation while simultaneously developing value-added production for circular economy. Herein, quercetin-rich onion peel wastes were chosen as a model to consider the technical feasibility of material recycling through fermentation. Pretreatment of onion peels extracts (OPEs) through frozen-preservation methods and serial acclimation via lactose-degrading bacteria was implemented for comparative optimization. Methods: Optimal extraction conditions (e.g., solvent, temperature of extraction, and frozen-preservation time) were first determined. Batch cultures of Lactobacillus sp. and Yogurt mixed consortia were implemented to maximize quercetin product formation using OPEs as sole nutrient sources via fermentation. Comparative assessment was performed by assessing total phenolic content, total quercetin content, and quercetin concentration. Microbial fuel cells were used to investigate time courses of electrochemical characteristics of residual OPEs during fermentation. Significant findings: Comparative assessment revealed that OPEs could be optimized under extraction conditions of 50% ethanol as solvent, 75 degrees C extraction temperature, and frozen-preservation temperature of -20 degrees C. Yogurt mixed consortia yielded higher quercetin production that Lactobacillus sp. at 9 days fermentation. Phase-plane trajectories also revealed that using extracts frozen for 84 days at -20 degrees C through 9-day fermentation could achieve maximal quercetin production (ca. 1.5-1.75-fold compared to no fermentation). MFC results suggested that OPE fermentation was electrochemically favorable to enhance quercetin generation. Approximately two or three cycles of bacterial acclimation is sufficient to obtain maximal quercetin productivity and stable powerstimulating characteristics (ca. 1.35-1.5 fold power density amplification). To the best of our knowledge, this study was the first work to quantitatively decipher the most appropriate operation strategy for quercetin production from agricultural wastes (OPEs). |
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