Unveiling bioenergy-stimulating and electron-transporting characteristics of metabolites from Citrus microcarpa peels and pulps as medicated diet of sustainable energy resource

Abstract

As agricultural waste recycling and reuse is a top-priority task to follow “net zero by 2050″, this study selected Citrus microcarpa peels and pulps for a feasibility study to minimize bioenergy-related CO2 emissions. In the Philippines, C. microcarpa peels and pulps are considered agricultural wastes that contain an abundance of flavonoids, which possess an array of biological activities. Herein, the exploration of power augmenting capabilities and investigation of electron shuttling species in C. microcarpa extracts was implemented for bioenergy applications of circular economy. The phytochemical and antioxidant activity analysis of hot water and ethanol extracts was carried out using a microplate reader. Evaluation of the bioenergy-generating capabilities and electrochemical characteristics of the herbal extracts was implemented through the MFC platform and 50 cycles of cyclic voltammetry. The ethanol extracts of the C. microcarpa peels and pulps exhibited superior bioelectricity stimulation in MFCs. Furthermore, the ethanol extracts performed as better antioxidants compared to the water extracts. According to 50 cycles of CV scanning, only the ethanol extracts exhibited electron shuttling characteristics as indicated by the symmetry of their reduction and oxidation peaks. These results are attributed to the abundance of flavonoids and condensed tannins in the extracts, as revealed by principal component analysis.