Study on the Effect of pH Modulation on Lactic Acid Production by Electro-Fermentation of Food Waste

Nuohan Wang, Jianguo Liu (), Yongsheng Li, Yuanyuan Ren, Xiaona Wang, Tianlong Zheng and Qunhui Wang ()
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Nuohan Wang: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
Jianguo Liu: College of Resources and Environmental Engineering, Inner Mongolia University of Technology, Hohhot 010051, China
Yongsheng Li: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
Yuanyuan Ren: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
Xiaona Wang: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China
Tianlong Zheng: Research Center for Eco-Environmental sciences, Chinese Academy of Sciences, Beijing 100085, China
Qunhui Wang: School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, China

Sustainability, 2025, vol. 17, issue 15, 1-15

Abstract: Lactic acid (LA) synthesis through fermentation of food waste (FW) is an emerging techniques for utilizing perishable organic wastes with high value. Using food waste collected from a cafeteria as the substrate for fermentation, the current study was conducted by applying a micro electric field to the conventional LA fermentation process and performing open-ended electro-fermentation (EF) without sterilization and lactobacilli inoculation. Furthermore, the effects of pH adjustment on LA production were examined. The findings demonstrated that electrical stimulation enhances the electron transfer rate within the system, accelerates REDOX reactions, and thereby intensifies the lactic acid production process. The pH-regulated group produced LA and dissolved organic materials at considerably higher rates than the control group, which did not receive any pH modification. The maximum LA concentration and organic matter dissolution in the experimental group, where the pH was set to 7 every 12 h of fermentation, were 33.9 and 38.4 g/L, respectively. These values were 208 and 203% higher than those in the control group, indicating that the pH adjustment greatly aided the solubilization and hydrolysis of macromolecules. Among the several hydrolyzing bacteria ( Actinobacteriota ) that were enriched, Lactobacillus predominated, but Bifidobacterium also became a major genus in the neutral-acidic environment, and its abundance grew dramatically. This study provides a scientific basis for optimizing the LA process of FW.

Keywords: food waste; lactic acid fermentation; electro-fermentation; pH; Bifidobacterium (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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