The impact of cooking on anaerobic fermentation hydrogen production using vegetable waste as substrate

This study investigates the hydrogenogenic potential of anaerobic fermentation using vegetable waste either cooked or not through batch experiments, with Brassica chinensis L. (Shanghaiqing) as a representative substrate. Results show that cooking enhances the bioavailability of substrates, but on the contrary reduce maximum cumulative hydrogen yields, with uncooked unseparated (UU) and cooked juice (CJ) groups achieving 65.87 mL·gVS⁻¹ and 57.91 mL·gVS⁻¹ respectively. Cooking substantially reduces the hydrogen production lag phase with the most significant reduction being 45.2%. Cooking doesn’t change the overall fermentation type. GC analysis identifies butyrate-type fermentation as the dominant hydrogenogenic pathway and propionate-type fermentation as the competitive one. The accelerated substrate utilization in cooked groups induces intensified microbial competition and accumulation of inhibitory byproducts, causing premature termination of hydrogenogenesis. Consequently, the cooked unseparated (CU) group exhibited only 47.09% of the maximum cumulative hydrogen production achieved by the UU group, highlighting the subtle changes in hydrogenogenesis potential of vegetable waste caused by cooking and their possible mechanisms.