Anaerobic fermentation of peanut meal to produce even-chain volatile fatty acids using Saccharomyces cerevisiae inoculum

ABSTRACT

In this study, the effects of inoculating Saccharomyces cerevisiae (S. cerevisiae) on the production of volatile fatty acids (VFAs) via anaerobic fermentation of organic solid waste peanut meal were investigated. At 35°C (temperature of the medium), inoculums consisting of six different S. cerevisiae-peanut meal ratios were used in sequencing batch anaerobic fermentation, and the changes in VFA, protein, glycogen, pH, ${\mathrm{NH}}_4^{+}$, and soluble chemical oxygen demand (SCOD) levels during the fermentation process were studied. Results showed that after inoculation with S. cerevisiae, the anaerobic fermentation of peanut meal mainly produced even-chain VFAs (acetic acid and n-butyric acid); in the early stage of fermentation, inoculation of S. cerevisiae enhanced protein dissolution efficiency and degradation rate, and completely degraded soluble glycogen. The utilization ratio of the protein and soluble glycogen improved. Analysis of significant difference showed that compared to the peanut meal control, the experimental group correlated significantly with the VFAs. The VFA obtained with the inoculum: peanut meal ratio of 0.15 g g⁻¹ was mainly acetic acid, with peak concentration of 10,797.09 mg L⁻¹, which was 1.82 times higher than that obtained with only the peanut meal fermentation. Response surface methodology predicted that the inoculation ratio was 0.15 g g⁻¹, and the effect of producing VFAs was the best when the fermentation time was 8.63d. The results showed that S. cerevisiae inoculation may improve VFA production and increase the proportion of even acids.

GRAPHICAL ABSTRACT

KEYWORDS:

• Anaerobic fermentation
• volatile fatty acids (VFAs)
• even acids
• peanut meal
• Saccharomyces cerevisiae

Acknowledgements

The authors thank Guangzhou University for its support.

Data availability

The data used to support the findings of this study were supplied by the Department of Municipal Engineering under license and hence cannot be made freely available.

Disclosure statement

No potential conflict of interest was reported by the author(s).

ORCID

Lu Zhang http://orcid.org/0000-0002-6538-7846

Additional information

Funding

This project was financially supported by the National Natural Science Foundation of China [grant number 21207023] and Guangdong Provincial Natural Science Foundation [grant number 2017A030313273].