Effect of food waste thermal pretreatment on VFA production and microbial dynamics by anaerobic fermentation

Sustainable food waste (FW) management is increasingly vital for addressing environmental challenges and advancing the circular economy. Conventional practices, such as landfills and incineration, lead to resource loss and environmental challenges. Anaerobic fermentation (AF) offers an environmentally friendly and efficient alternative, enabling the transformation of food waste into valuable byproducts like volatile fatty acids (VFAs). This study aimed to investigate the thermal pretreatment effects and Saccharomyces cerevisiae inoculation on AF of FW, using cabbage (a carbohydrate-rich feedstock) and chicken breast (a protein-rich feedstock) as representative feedstocks of FW.

The results revealed that thermal pretreatment significantly enhanced the solubilization of polysaccharides in cabbage, resulting in the rapid production of soluble saccharides and VFAs within two days. Moreover, thermal-treated carbohydrates improved S. cerevisiae fermentation efficiency, highlighting the suitability of carbohydrate-rich feedstocks for AF applications. In contrast, thermal pretreatment of chicken breast facilitated protein denaturation but did not substantially increase VFA yields after 24 days, suggesting a limited potential for protein-rich substrates in AF efficiency. Comparatively, carbohydrate-rich feedstocks showed more favorable for optimized fermentation performance than protein-rich feedstocks.

Microbial community analysis showed that thermal pretreatment influenced microbial dynamics during the AF process. Cabbage feedstocks exhibited an increased abundance of carbohydrate-degrading bacteria, facilitating the efficient conversion of polysaccharides into VFAs. Conversely, protein-degrading bacteria dominated meat-based feedstocks, yet the fermentation efficiency remained constrained, reflecting the intrinsic differences in feedstock composition. These observations underlined the importance of feedstock selection and pretreatment strategies in achieving effective resource valorization. 

This research highlighted the role of thermal pretreatment in improving the AF of carbohydrate-rich substrates, providing a pathway for enhanced VFA production and resource recovery. The study also emphasized the need for further optimization of AF for protein-rich feedstocks, potentially through alternative pretreatment methods or microbial consortia adjustments. By advancing the understanding of the interplay between feedstock characteristics, thermal pretreatment, and microbial dynamics, this work contributed to developing sustainable waste management technologies and supported the broader goals of the circular economy.